Nutrition. 2004 May;20(5):492-3.
Effect of fruit on net acid and urinary calcium excretion in an acute feeding trial of women.
Bell JA, Whiting SJ.
College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.

  OBJECTIVE: Consumption of fruits and vegetables has been implicated in lowering net acid excretion (NAE), but few studies have directly examined NAE and urinary calcium effects. Further, there is no evidence that only fresh fruits and vegetables must be consumed for a beneficial effect on bone.
  METHODS: A crossover, acute-load study was designed to investigate whether processed fruit was as effective as fresh fruit in reducing NAE and protein-induced hypercalciuria. Fifteen women completed three dietary treatments on three different mornings. A fasting urine sample was collected before consuming one of the following three isocaloric high-protein treatments: control, fresh apples, and processed applesauce. [One must wonder how "high-protein" was supplied by apples - ljf] The serving size for the applesauce treatment was 2.5 times that for fresh apples. Urine was collected at baseline (0 h) and at 1.5, 3.0, and 4.5 h.
  RESULTS: Compared with baseline, NAE increased after control treatment but decreased after fresh or processed apple treatment (P = 0.041). Calcium excretion increased with all treatments by 3 h; however, the increase was less for fresh apple and applesauce (P = 0.024).
  CONCLUSIONS: In an acute feeding model, fruit intake reduced NAE and urinary calcium excretion. Processed fruit appears to be effective, although a larger serving size was needed than with fresh fruit.

PMID: 15105040

Am J Clin Nutr. 2004 Feb;79(2):311-7.
Fruit and vegetable intakes are an independent predictor of bone size in early pubertal children.
Tylavsky FA, Holliday K, Danish R, Womack C, Norwood J, Carbone L.
Health Science Center, University of Tennessee, Memphis, TN 38105, USA.

  BACKGROUND: Adequate intakes of fruit and vegetables are recommended for optimum health in children.
  OBJECTIVE: The objective of this study was to determine whether consuming fruit and vegetables >3 times per day is beneficial to bone mass in children.
  DESIGN: Fifty-six white females (Tanner stage 2) recorded dietary intake on 3 independent days. The numbers of servings of fruit and vegetables were recorded for each day and tallied, and the subjects were divided into 2 consumption groups for analysis (low consumption: <3 servings/d, n = 22; high consumption: > or = 3 servings/d, n = 34). Bone area and the bone mineral content of the whole body and radius were assessed by using dual-energy X-ray absorptiometry. Radioimmunoassays measured serum parathyroid hormone and 25-hydroxyvitamin D. Twenty-four-hour urine samples were assessed for calcium, sodium, and creatinine. RESULTS: After adjustment for age, body mass index, and physical activity, those children who reported consuming > or = 3 servings fruit and vegetables/d had more bone area of the whole body (6.0%; P = 0.03) and radius (8.3%; P = 0.03), lower urinary calcium excretion (2.6 +/- 0.2 compared with 1.8 +/- 0.3 mg/kg; P = 0.04), and lower parathyroid hormone (19.6 +/- 1.9 compared with 25.0 +/- 1.6 pg/mL; P = 0.01) than did those children who reported consuming <3 servings fruit and vegetables/d.
  CONCLUSIONS: High fruit and vegetable intakes have beneficial effects on the bone area of the radius and whole body in early pubertal girls. The lower urinary calcium output associated with higher fruit and vegetable intakes may be a modulating factor.

PMID: 14749239

J Nutr 2003 Mar;133(3):862S-5S
Dietary animal and plant protein and human bone health: a whole foods approach.
Massey LK. Food Science and Human Nutrition, Washington State University Spokane, Spokane, WA 99210.

  Urinary calcium excretion is strongly related to net renal acid excretion. The catabolism of dietary protein generates ammonium ion and sulfates from sulfur-containing amino acids. Bone citrate and carbonate are mobilized to neutralize these acids, so urinary calcium increases when dietary protein increases. Common plant proteins such as soy, corn, wheat and rice have similar total S per g of protein as eggs, milk and muscle from meat, poultry and fish. Therefore increasing intake of purified proteins from either animal or plant sources similarly increases urinary calcium. The effects of a protein on urinary calcium and bone metabolism are modified by other nutrients found in that protein food source. For example, the high amount of calcium in milk compensates for urinary calcium losses generated by milk protein. Similarly, the high potassium levels of plant protein foods, such as legumes and grains, will decrease urinary calcium. The hypocalciuric effect of the high phosphate associated with the amino acids of meat at least partially offsets the hypercalciuric effect of the protein. Other food and dietary constituents such as vitamin D, isoflavones in soy, caffeine and added salt also have effects on bone health. Many of these other components are considered in the potential renal acid load of a food or diet, which predicts its effect on urinary acid and thus calcium. "Excess" dietary protein from either animal or plant proteins may be detrimental to bone health, but its effect will be modified by other nutrients in the food and total diet.

PMID: 12612170

J Bone Miner Metab 2003;21(1):28-33
Calcium balance in young adults on a vegan and lactovegetarian diet.
Kohlenberg-Mueller K, Raschka L. University of Applied Sciences, Marquardstrasse 35, D-36039 Fulda, Germany.

  For people in Western countries, the vegan diet has the advantage of low energy intake, but the calcium status of this strictly plant-based diet is still unclear. The aim of this study was to determine the calcium balance of individuals on a vegan diet in comparison with a lactovegetarian diet in a short-term investigation. Seven women and one man, ranging in age from 19 to 24 years, received during the first 10 days a vegan diet based on plant foods and calcium-rich mineral water and a lactovegetarian diet during the following 10 days. Portion size was adapted to the subjects' individual energy requirements. Calcium status was assessed by means of calcium intake in food and calcium output in feces and urine as measured by flame atomic absorption spectrophotometry. In addition, deoxypyridinoline was measured in urine as a marker of bone resorption. The results show a significantly smaller daily calcium intake with an average of 843 +/- 140 mg in the vegan versus 1322 +/- 303 mg in the lactovegetarian diet. Apparent calcium absorption rates were calculated as 26% +/- 15% in the vegan and 24% +/- 8% in the lactovegetarian group (NS). The calcium balance was positive both in the vegan diet (119 +/- 113 mg/day) and in the lactovegetarian diet (211 +/- 136 mg/day) (NS). Deoxypyridinoline excretion showed no significant difference between the two diets (105 +/- 31 and 98 +/- 23 nmol/day). The present results indicate that calcium balance and a marker of bone turnover are not affected significantly when calcium is provided either solely by plant foods or by a diet including dairy products, despite the significantly different calcium intake levels in the diets. We conclude that a well-selected vegan diet maintains calcium status, at least for a short-term period.

PMID: 12491091

J Bone Miner Res 2002 Jul;17(7):1230-6
Onion and a mixture of vegetables, salads, and herbs affect bone resorption in the rat by a mechanism independent of their base excess.
Muhlbauer RC, Lozano A, Reinli A. Department Clinical Research, University of Bern, Switzerland.

  Prevention of low bone mass is important to reduce the incidence of osteoporotic fractures. In man, the consumption of fruits and vegetables is associated with greater bone mineral density (BMD), an effect that is claimed to be caused by their base excess buffering metabolic acid, thought to dissolve bone. We showed previously that in the rat the consumption of several vegetables, salads, and herbs inhibits bone resorption and that onion increases bone mass. In this study we show that, although the intake of onion is associated with a decrease in urinary noncarbonic acid excretion and a concomitant inhibition of bone resorption of similar magnitude, the two findings are not causally related. Onion retains its bone resorption inhibitory activity in the rat even when added to a vegetarian diet with typical base excess. Onion and a mixture of vegetables, salads, and herbs retain their inhibitory activity even when metabolic acid is buffered with potassium citrate. In addition, neither the pH nor the potassium content of individual ashed vegetables, salads, and herbs correlates with inhibition of bone resorption. The effect of vegetables, salads, and herbs, which inhibit bone resorption in the rat, therefore is not mediated by their base excess but possibly by a pharmacologically active compound(s).

PMID: 12096836

Nutr Rev 2002 Jul;60(7 Pt 1):212-4
Stop dietary calcium restriction in kidney stone-forming patients.
Martini LA Nutrition Department, Faculdade de Saude Publica, Universidade de Sao Paulo, Brazil.

  Epidemiologic studies have demonstrated an increased incidence of kidney stones in individuals with low calcium intake. More recently, a 5-year clinical study found the recurrence of kidney stones was higher in stone-formers on a low dietary calcium treatment. Considering these important new findings, and the known adverse effect on bone mass, dietary calcium restriction should be avoided in kidney stone-forming individuals.

PMID: 12144200

Am J Clin Nutr 2002 Jul;76(1):156-64
Diet and iron status of nonpregnant women in rural Central Mexico.
Backstrand JR, Allen LH, Black AK, De Mata M, Pelto GH Department of Nutrition and Food Studies, New York University, New York (JRB).

  BACKGROUND: Few studies have examined the relation of iron status to diet in populations from developing countries with high levels of iron deficiency and diets of poor quality.
  OBJECTIVE: The objective was to identify nutrients, dietary constituents, and foods that are associated with better iron status in a rural Mexican population.
  DESIGN: A prospective cohort study was conducted in rural central Mexico. The subjects were 125 nonpregnant women aged 16-44 y. During the 12 mo before blood collection, food intakes were assessed repeatedly by a combination of dietary recalls, food weighing, and food diaries [mean (+/-SD) days of food intake data: 18.8 +/- 5.9 d]. Hemoglobin, hematocrit, and plasma ferritin were measured at the end of the study.
  RESULTS: Higher plasma ferritin concentrations were associated with greater intakes of nonheme iron and ascorbic acid after control for age, BMI, breast-feeding, season, and the time since the birth of the last child. Higher ascorbic acid intakes, but not higher intakes of heme and nonheme iron, predicted a lower risk of low hemoglobin and hematocrit values after control for the background variables. Consumption of the alcoholic beverage pulque predicted a lower risk of low ferritin and low hemoglobin values. Seasonal variation in ferritin, hemoglobin, and hematocrit values was observed.
  CONCLUSION: Better iron status was associated with greater intakes of foods containing nonheme [plant-ljf] iron and ascorbic acid. PULQUE:a beverage containing iron, ascorbic acid, and alcohol-may influence the iron status of women in rural central Mexico.

PMID: 12081829

Proc Nutr Soc 2002 May;61(2):151-64
Nutrition Society Medal lecture.
The role of the skeleton in acid-base homeostasis.
New SA. Centre for Nutrition and Food Safety, School of Biomedical & Life Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK.

  Nutritional strategies for optimising bone health throughout the life cycle are extremely important, since a dietary approach is more popular amongst osteoporosis sufferers than drug intervention, and long-term drug treatment compliance is relatively poor. As an exogenous factor, nutrition is amenable to change and has relevant public health implications. With the growing increase in life expectancy, hip fractures are predicted to rise dramatically in the next decade, and hence there is an urgent need for the implementation of public health strategies to target prevention of poor skeletal health on a population-wide basis. The role that the skeleton plays in acid-base homeostasis has been gaining increasing prominence in the literature; with theoretical considerations of the role alkaline bone mineral may play in the defence against acidosis dating as far back as the late 19th century. Natural, pathological and experimental states of acid loading and/or acidosis have been associated with hypercalciuria and negative Ca balance and, more recently, the detrimental effects of 'acid' from the diet on bone mineral have been demonstrated. At the cellular level, a reduction in extracellular pH has been shown to have a direct enhancement on osteoclastic activity, with the result of increased resorption pit formation in bone. A number of observational, experimental, clinical and intervention studies over the last decade have suggested a positive link between fruit and vegetable consumption and the skeleton. Further research is required, particularly with regard to the influence of dietary manipulation using alkali-forming foods on fracture prevention. Should the findings prove conclusive, a 'fruit and vegetable' approach to bone health maintenance may provide a very sensible (and natural) alternative therapy for osteoporosis treatment, which is likely to have numerous additional health-related benefits.

PMID: 12133196

Plant Foods Hum Nutr 2002 Spring;57(2):197-204
Impact of tofu or tofu + orange juice on hematological indices of lacto-ovo vegetarian females.
Kandiah J. Department of Family and Consumer Sciences, Ball State University, Muncie, IN 47306, USA.

  The purpose of this study was to investigate iron status of premenopausal vegetarian women consuming tofu or tofu plus orange juice. Following a three day pre-period, 14 lacto-ovo vegetarians were randomly divided into two experimental periods of 30 days each. For the first 30 days, one half of the subjects (n = 7) received 6 oz (173 grams) of tofu/day (T) while the other half of the subjects (n = 7) received 6 oz of tofu/day along with 303 mg of vitamin C/d (TO). After 30 days, there was a crossover of the diets. Iron status was assessed by measuring serum ferritin and hemoglobin concentrations on the first day of the study and at the end of each experimental period. The Mann Whitney-U test was significant during the first (W = 17.5; Z = -2.095; p = 0.0361) and over the second (W = 40.0; Z = -2.611; p = 0.009) experimental periods which indicated the change in hemoglobin levels for the T and TO groups were different. Mean ranks showed a greater increase in hemoglobin levels for the TO group. There was no significant difference in the change in serum ferritin levels between the T and TO groups over the first and second experimental periods. In conclusion, bioavailability of iron from tofu is enhanced by supplementation with ascorbic acid.

PMID: 12049152

J Am Coll Cardiol 2002 Jan 16;39(2):225-30
High coronary artery calcium scores pose an extremely elevated risk for hard events.
Wayhs R, Zelinger A, Raggi P. Christ Hospital and University of Illinois, Oak Lawn, Illinois, USA

  We sought to assess the natural history of a cohort of asymptomatic individuals with very high (>/=1,000) calcium scores (CSs) on a screening electron beam tomography (EBT) not submitted to further testing after the initial scan. We also compared the outcome of our prospective cohort with that of historical controls with severe abnormalities on myocardial perfusion imaging (MPI). Coronary calcium detected on EBT imaging has been shown to correlate with the total plaque burden. However, there is still controversy as to the prognostic significance of calcium, as some investigators believe that the presence of coronary calcification may stabilize the atherosclerotic plaque. Ninety-eight asymptomatic subjects (mean age: 62 +/- 10) were followed for an average of 17 +/- 11 months (range: 4 to 36 months) after undergoing EBT screening for the occurrence of hard coronary events (HCEs), defined as myocardial infarction or coronary death. All patients had an initial CS >/=1,000, and in none did the results of the EBT screening lead to further invasive or non-invasive testing. During the follow-up period, 35 patients (36%) suffered an HCE. All events were recorded in the first 28 months of follow-up. Subjects with HCEs had higher initial CSs than subjects not suffering HCEs (1,561 +/- 270 vs. 1,199 +/- 200, p < 0.001). The annualized event rate in subjects with a CS >/=1,000 was significantly greater than that of historical controls with severe perfusion abnormalities on MPI (25% vs. 7.4%, respectively; p < 0.0001). A high CS (>/=1,000) on a screening EBT in an asymptomatic person portends a very high risk of an HCE in the short term. This risk appears to be greater than the risk associated with a severe perfusion abnormality on MPI.

PMID: 11788211

Am J Clin Nutr 2001 Dec;74(6):803-7
Apparent copper absorption from a vegetarian diet.
Hunt JR, Vanderpool RA. US Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, Grand Forks, ND, USA.

  BACKGROUND: Vegetarian diets often contain more copper than do nonvegetarian diets, but observations of decreased plasma copper associated with vegetarian diets suggest that these diets have lower copper bioavailability than do nonvegetarian diets.
  OBJECTIVE: Our objective was to determine apparent copper absorption from controlled lactoovovegetarian and nonvegetarian diets.
  DESIGN: Eighteen women aged 20-43 y consumed lactoovovegetarian and nonvegetarian weighed diets for 8 wk each in a randomized, crossover design. The lactoovovegetarian and nonvegetarian diets provided 1.45 and 0.94 mg Cu, 38 and 16 g dietary fiber, and 1584 and 518 mg phytic acid, respectively, per 9.2 MJ (2200 kcal). After the women had been consuming each diet for 4 wk, their apparent copper absorption was determined by measuring the fecal excretion of the 65Cu stable isotope, extrinsically added to the entire menu as 65CuCl2.
  RESULTS: Plasma copper and ceruloplasmin were not affected by diet. The efficiency of apparent copper absorption from the lactoovovegetarian diet was less (33%) than that from the nonvegetarian diet (42%) (pooled SD: 9%; P < 0.05). However, because the lactoovovegetarian diet contained approximately 50% more copper, the total apparent copper absorption from the lactoovovegetarian diet (0.48 mg/d) was greater than that from the nonvegetarian diet (0.40 mg/d) (pooled SD: 0.09 mg; P < 0.05).
  CONCLUSION: Although copper was less efficiently absorbed from a vegetarian diet than from a nonvegetarian diet, total apparent copper absorption was greater from the vegetarian diet because of its greater copper content.

PMID: 11722963

Nutrition 2001 Sep;17(9):709-12
Effect of vitamin and trace-element supplementation on cognitive function in elderly subjects.
Chandra RK. Memorial University of Newfoundland, St. John's, Canada.

  OBJECTIVE: To determine whether supplementation with vitamins and trace elements in modest amounts influences cognitive function in apparently healthy, elderly subjects.
  METHODS: The study was designed as a randomized, double-blind, placebo-controlled trial. Ninety-six, apparently healthy, independent men and women older than 65 y of age were recruited and randomized to receive a supplement of trace elements and vitamins or a placebo daily for 12 mo. Blood-nutrient levels were estimated at baseline and at the end of the study. The major outcome measure assessed was cognitive function consisting of immediate and long-term memory, abstract thinking, problem-solving ability, and attention.
  RESULTS: Eighty-six subjects completed the 1-y trial. The supplemented group showed a significant improvement in all cognitive tests (P < 0.001 to 0.05) except long-term memory recall (P > 0.1). Those whose blood-nutrient levels were below the reference standard showed lower responses on cognitive tests. There was no significant correlation between individual nutrient levels and performance on various cognitive function tests.
  CONCLUSIONS: Cognitive functions improved after oral supplementation with modest amounts of vitamins and trace elements. This has considerable clinical and public health significance. We recommend that such a supplement be provided to all elderly subjects because it should significantly improve cognition and thus quality of life and the ability to perform activities of daily living. Such a nutritional approach may delay the onset of Alzheimer's disease.

PMID: 11527656

Int J Paediatr Dent 2001 May;11(3):184-92
Vegetarian children and dental erosion.
al-Dlaigan YH, Shaw L, Smith AJ. Department of Paediatric Dentistry, University of Birmingham, Dental School, St Chads Queensway, Birmingham, B4 6NN, UK.

  BACKGROUND: There have been recent changes in teenage lifestyle and diet. The increasing consumption of soft drinks and foods containing significant acidic components may play a role in the development of dental erosion.
  OBJECTIVE: The aims of this investigation were firstly to assess the prevalence of vegetarian children in a cluster random sample of 14-year-old children in Birmingham, United Kingdom. Secondly, to determine the prevalence of dental erosion in these children, and thirdly, to see if there were any differences between vegetarian and non-vegetarian children in the prevalence of dental erosion and dietary intake.
  DESIGN: A cluster random sample of 418 14-year-old children (209 males and 209 females) were examined from 12 different schools in Birmingham, United Kingdom; a dietary questionnaire was completed and the levels of tooth wear were recorded using a modification of the (TWI) index. All data were analysed using SPSS with t-test and Chi-square analysis. Significance was accepted at the P < 0.05 level.
  RESULTS: The results showed that 10% of the children were vegetarian; 52% of them had low dental erosion and 48% moderate dental erosion. Statistically there were no significant differences between vegetarian and non-vegetarian children in the prevalence of erosion; however, there were significant differences in some food and drink consumption.
  CONCLUSIONS: It was concluded that dental erosion is common in teenage children, but there were no significant differences in prevalence between vegetarian and non-vegetarian children.

PMID: 11484468

Forsch Komplementarmed Klass Naturheilkd 2001 Aug;8(4):228-31
[Clinical remission of an HLA B27-positive sacroiliitis on vegan diet.] [Article in German]
Huber R, Herdrich A, Rostock M, Vogel T. Ambulanz fur Naturheilverfahren und Umweltmedizin, Abteilung Innere Medizin II, Universitatsklinik Freiburg.

  BACKGROUND: Positive effects of fasting and vegan diet in patients with rheumatic diseases are reported in the literature.
  MEDICAL HISTORY: We present a 33-year-old patient with double-sided HLA B27-positive sacroiliitis, which was diagnosed by magnetic resonance tomography. Since about 10 years he therefore had pain in the iliosacral region. Numerous sessions of physiotherapy, a cure treatment, and treatment with sulfasalazine and doxycycline were not effective. The patient was dependent on the daily intake of the nonsteroidal antirheumatics meloxicam 2 x 7.5 mg and ibuprofen 400-800 mg and the analgetic tramadol 50-150 mg, but evening and night pain and morning stiffness persisted under this treatment.
  TREATMENT: We recommended a temporary vegan diet, i.e. to completely avoid animal fats and proteins.
  COURSE: 3-4 days after changing on vegan diet the complaints improved distinctly and persistently. After consumption of meat 6 weeks later, complaints worsened. Consequent vegan diet again resulted in significant improvement of the pain and morning stiffness. At follow-up 3 months after the initial contact, tramadol and ibuprofen intakes had been stopped, meloxicam had been reduced to 1 x 7.5 mg. The patient was almost completely free of complaints.
  CONCLUSIONS: It was demonstrated that in a single case of sacroiliitis which was refractory to other treatment, vegan diet resulted in a convincingly improvement of complaints. Copyright 2001 S. Karger GmbH, Freiburg

PMID: 11574747

Am J Clin Nutr 2001 Jan;73(1):118-22 Comment in: Am J Clin Nutr. 2001 Jan;73(1):5-6
A high ratio of dietary animal to vegetable protein increases the rate of bone loss and the risk of fracture in postmenopausal women.
Study of Osteoporotic Fractures Research Group. Sellmeyer DE, Stone KL, Sebastian A, Cummings SR. Division of Endocrinology, the General Clinical Research Center, and the Department of Epidemiology and Biostatistics, University of California, San Francisco, USA.

  BACKGROUND: Different sources of dietary protein may have different effects on bone metabolism. Animal foods provide predominantly acid precursors, whereas protein in vegetable foods is accompanied by base precursors not found in animal foods. Imbalance between dietary acid and base precursors leads to a chronic net dietary acid load that may have adverse consequences on bone. OBJECTIVE: We wanted to test the hypothesis that a high dietary ratio of animal to vegetable foods, quantified by protein content, increases bone loss and the risk of fracture. DESIGN: This was a prospective cohort study with a mean (+/-SD) of 7.0+/-1.5 y of follow-up of 1035 community-dwelling white women aged >65 y. Protein intake was measured by using a food-frequency questionnaire and bone mineral density was measured by dual-energy X-ray absorptiometry. RESULTS: Bone mineral density was not significantly associated with the ratio of animal to vegetable protein intake. Women with a high ratio had a higher rate of bone loss at the femoral neck than did those with a low ratio (P = 0.02) and a greater risk of hip fracture (relative risk = 3.7, P = 0.04). These associations were unaffected by adjustment for age, weight, estrogen use, tobacco use, exercise, total calcium intake, and total protein intake. CONCLUSIONS: Elderly women with a high dietary ratio of animal to vegetable protein intake have more rapid femoral neck bone loss and a greater risk of hip fracture than do those with a low ratio. This suggests that an increase in vegetable protein intake and a decrease in animal protein intake may decrease bone loss and the risk of hip fracture. This possibility should be confirmed in other prospective studies and tested in a randomized trial.

PMID: 11124760

Br J Nutr 2000 Jan;83(1):27-33
Zinc intake and status in Australian vegetarians.
Ball MJ, Ackland ML. School of Biological and Chemical Sciences, Deakin University, Melbourne, Australia.

  Vegetarians have a lower incidence of many chronic diseases than omnivores. However, vegetarian diets could potentially result in lower intakes of some minerals, particularly Zn. In a cross-sectional study, dietary Zn intake was measured using 12 d weighed records in ninety-nine vegetarians (ten vegans) aged 18-50 years and forty-nine age- and sex-matched omnivores. In men, the mean daily Zn intake and Zn density values were similar in omnivores, ovolactovegetarians and vegans, but in women they were significantly lower in vegetarians (mean intake 6.8 mg v. 8.4 mg in omnivores) and few achieved the recommended intake. Significantly more vegetarian than omnivorous women had a daily Zn intake < 6 mg (44% v. 13%). Mean serum Zn concentrations were similar in female omnivores and vegetarians, despite the differences in intake. However, omnivorous men had a lower mean serum Zn concentration (0.85 microgram/ml v. 0.95 microgram/ml) and more subjects had levels below the reference range of 0.72-1.44 micrograms/ml than ovolactovegetarians (P < 0.01). Overall more women than men had low Zn concentrations; and these women generally had intakes below 6 mg/d. There was a significant correlation between serum Zn concentration and dietary Zn density in vegetarians, especially females (P < 0.001), but not in omnivores. Ovolactovegetarians did not have a significantly greater risk of low Zn status than omnivores.

PMID: 10703461

J Nutr 2000 Feb;130(2):193-8
Current methods for estimating dietary iron bioavailability do not work in China.
Du S, Zhai F, Wang Y, Popkin BM. Institute of Nutrition and Food Hygiene, Chinese Academy of Preventive Medicine, Beijing.

  Three current equations for estimating iron bioavailability were evaluated, and adjustments were proposed that would allow us to most effectively study iron bioavailability in China. Dietary intake data were obtained from 24-h dietary recalls taken over three consecutive days as part of the third Chinese National Nutrition Survey. Hemoglobin status was measured for 42,606 Chinese adults aged 18-60 y. The mean iron intake was 24.4 mg per capita per day, which was 177% of the Chinese RDA (209% of U.S. RDA). About 18% of the sample was classified as being anemic, indicating a large iron deficiency anemia and iron bioavailability problem in China. A number of methods proposed by World Health Organization and U.S. scholars were examined for adjusting iron bioavailability. Even the methods that consider several iron enhancers and inhibitors did not work adequately for the Chinese diet. The statistical assessment of the fit between iron bioavailability and hemoglobin status provided direction for adjusting the best of these predictive equations. We propose a new predictive approach for iron bioavailability which is more predictive of Chinese iron status. Consideration of additional dietary elements such as rice and bean consumption patterns are important. Our findings provide insight into additional factors which may influence iron bioavailability as well as possible improved methods for estimating the combined effect of multiple dietary factors on iron bioavailability, particularly in a vegetarian diet.

PMID: 10720169

J Clin Endocrinol Metab 1999 Mar;84(3):1052-5
Changes in bone turnover in young women consuming different levels of dietary protein.
Kerstetter JE, Mitnick ME, Gundberg CM, Caseria DM, Ellison AF, Carpenter TO, Insogna KL. School of Allied Health, University of Connecticut, Storrs 06269-2101, USA.

  Although high protein diets are known to increase urinary calcium excretion and induce negative calcium balance, the impact of dietary protein on bone turnover and fractures is controversial. We therefore evaluated the effect of dietary protein on markers of bone turnover in 16 healthy young women. The experiment consisted of 2 weeks of a well balanced diet containing moderate amounts of calcium, sodium, and protein followed by 4 days of an experimental diet containing one of three levels of protein (low, medium, or high). On day 4, serum and urinary calcium, serum PTH, 1,25-dihydroxyvitamin D, serum osteocalcin, bone-specific alkaline phosphatase, and urinary N-telopeptide excretion were measured. Urinary calcium excretion was significantly higher on the high than on the low protein diet. Secondary hyperparathyroidism occurred on the low protein diet. Urinary N-telopeptide excretion was significantly greater during the high protein than during the low protein intake (48.2 +/- 7.2 vs. 32.7 +/- 5.3 nM bone collagen equivalents/mM creatinine; P < 0.05). There was no increase in osteocalcin or bone-specific alkaline phosphatase when comparing the low to the high diet, suggesting that bone resorption was increased without a compensatory increase in bone formation. Our data suggest that at high levels of dietary protein, at least a portion of the increase in urinary calcium reflects increased bone resorption.

PMID: 10084594

J Am Coll Nutr 1998 Jun;17(3):244-9
Effects of supplementation with a combination of antioxidant vitamins and trace elements, at nutritional doses, on biochemical indicators and markers of the antioxidant system in adult subjects.
Preziosi P, Galan P, Herbeth B, Valeix P, Roussel AM, Malvy D, Paul-Dauphin A, Arnaud J, Richard MJ, Briancon S, Favier A, Hercberg S. Institut Scientifique et Technique de la Nutrition et l'Alimentation, Conservatoire National des Arts et Metiers, Paris, France.

  OBJECTIVE: To test the impact of supplementation with nutritional doses of antioxidant nutrients on biochemical indicators of vitamin and trace element levels.
  DESIGN: A randomized double-blind trial was performed comparing two groups receiving daily either a combination of vitamins (beta-carotene, 6 mg; vitamin C, 120 mg; and vitamin E, 30 mg) and trace elements (zinc, 20 mg; and selenium, 100 micrograms); or a placebo.   SUBJECTS: 401 subjects (166 males aged 45 to 60 years and 235 females aged to 35 to 60 years).
  MEASURE OF OUTCOME: Biological markers of vitamin and trace element status and free radical parameters were measured initially, 3 months, and 6 months after supplemention.   RESULTS: Mean serum concentrations of alpha-tocopherol, vitamin C, beta-carotene, zinc and selenium increased significantly after 3 months of supplementation in the group receiving multivitamins associated with minerals. At baseline, 18.2% of the men and 5.1% of the women had low concentrations of serum vitamin C (< 20 mumol/l): 2.4% of the men and 17% of the women presented low concentrations of serum retinol (< 1.4 mumol/l): 18.7% of men and 10% of women had serum beta-carotene < 0.30 mumol/l. None of the study subjects had serum alpha-tocopherol concentrations below the limit cut-off point (< 9.3 mumol/l). Low serum zinc concentrations (< 10.7 mumol/l) were found in 15.1% of men and 23.8% of women. Low serum selenium concentrations (< 0.75 mumol/l) were found in 6% of men and 6.4% of women. A significant increase in plasma and red cell GPx activity was observed in groups receiving supplementation. No modifications were observed after 6 months of supplementation for malondyaldehyde.
  CONCLUSION: This study demonstrates the efficacy of an intake of antioxidant vitamins and trace elements, given at nutritional doses, on biochemical indicators of vitamin and trace elements status.

PMID: 9627910

Indian J Pediatr 1998 Nov-Dec;65(6):883-9
Epidemiological study of dental caries.
Venugopal T, Kulkarni VS, Nerurker RA, Damle SG, Patnekar PN. Department of Pediatrics, Dr. R.N. Cooper Municipal General Hospital, Mumbai.

  A total of 2000 children (1-14 year age group) attending pediatric OPD, school clinic & well body clinic of Dr. R.N. Cooper Municipal Hospital & K.E.M Hospital, Mumbai were examined for caries prevalence and 35.6% had dental caries. Parental income was not shown to have any bearing on caries prevalence. Parental literacy, particularly maternal literacy was shown to influence caries prevalence in children. The prevalence was low in well-nourished children and in those taking vegetarian type of diet. Frequency of sweet consumption was shown to be associated with prevalence of dental caries. In 1-4 year age group it was noted that bottle fed children were more affected by dental caries. Tooth brush with paste was the commonest method used for cleaning their teeth in all age groups in our study. Caries prevalence was low in those children using tooth brush than in those using tooth powder. Those children who were using neem datun were found to be less affected with dental caries. Dental caries was also found to be low in those who rinsed their mouth with water after food.

PMID: 10773954

Nutr Rev 1997 Nov;55(11 Pt 1):400-4
Micronutrient supplementation and infection in institutionalized elders.
Johnson MA, Porter KH. Department of Foods and Nutrition, University of Georgia, Athens 30602, USA.

  A randomized, double-blind, placebo-controlled clinical trial was conducted to determine the effects of a low-dose (< 2 times the Recommended Dietary Allowance) micronutrient supplement containing trace minerals (zinc and selenium) and/or vitamins/provitamins (vitamin C, alpha-tocopherol, and beta-carotene) on the incidence of respiratory and urogenital infections in institutionalized elderly. After 2 years, there was a significant decrease in the mean number of infections in elders given trace elements (p < 0.01) but not vitamins.

PMID: 9420452

J Bone Miner Res 1997 Sep;12(9):1486-94
Reduced bone mass in Dutch adolescents fed a macrobiotic diet in early life.
Parsons TJ, van Dusseldorp M, van der Vliet M, van de Werken K, Schaafsma G, van Staveren WA Department of Human Nutrition, Wageningen Agricultural University, The Netherlands.

  This study investigated the effect of a macrobiotic (vegan-type [NOTE: macrochaotics is a particularly poor diet, not representative of vegan diets LF]) diet, low in calcium and vitamin D, consumed in early life, on bone mineral during adolescence. Bone mineral content (BMC) and bone area were measured in 195 adolescents (103 girls, 92 boys) aged 9-15 years, using dual-energy X-ray absorptiometry. Ninety-three adolescents (43 girls, 50 boys) had followed a macrobiotic diet in childhood, and 102 (60 girls, 42 boys) were control subjects. After adjustment for bone area, weight, height, percent body lean, age, and puberty, BMC was significantly lower in macrobiotic subjects, in boys and girls, respectively, at the whole body, -3.4% and -2.5%, spine, -8.5% and -5.0%, femoral neck, -8.0% and -8.2%, midshaft radius, -6.8% and -5.6%, and also in girls, at the trochanter, -5.8% (p < 0.05). No group differences were observed at the wrist. Group differences were not explained by current calcium adjusted bone mass at age 9-15 years, observations which may hold important implications for fracture risk in later life.

PMID: 9286766

J Food Sci 1997 May-Jun;62(3):619-21, 631
Calcium bioavailability of vegetarian diets in rats: potential application in a bioregenerative life-support system.
Nickel KP, Nielsen SS, Smart DJ, Mitchell CA, Belury MA. Dept. of Foods & Nutrition, Purdue Univ., West Lafayette, IN 47907, USA.

  Calcium bioavailability of vegetarian diets containing various proportions of candidate crops for a controlled ecological life-support system (CELSS) was determined by femur 45Ca uptake. Three vegetarian diets and a control diet were labeled extrinsically with 45Ca and fed to 5-wk old male rats. A fifth group of rats fed an unlabeled control diet received an intraperitoneal (IP) injection of 45Ca. There was no significant difference in mean calcium absorption of vegetarian diets (90.80 +/- 5.23%) and control diet (87.85 +/- 5.25%) when calculated as the percent of an IP dose. The amounts of phytate, oxalate, and dietary fiber in the diets did not affect calcium absorption.

PMID: 11540533

Physiol Rev 1997 Jul;77(3):643-69
Effects of milk and milk components on calcium, magnesium, and trace element absorption during infancy.
Lonnerdal B Department of Nutrition, University of California, Davis, USA.

  During early life, infants usually consume a diet that is heavily dominated by milk. It is generally believed that breast-fed infants absorb adequate quantities of minerals and trace elements, whereas there is some concern about how well infants can utilize these nutrients from cow's milk formula and other infant diets. Therefore, most infant formulas contain much higher concentrations of minerals and trace elements than those of breast milk. [probably not a good ides LF] Our knowledge of how infants can utilize these nutrients from different diets is very limited. This paper critically reviews the effects of various components in breast milk, cow's milk, and infant formula and how they either facilitate or inhibit the absorption of minerals and trace elements. Particular emphasis is put on milk proteins such as lactoferrin, casein, and whey proteins, but phytate in soy formula is also discussed. Competition among minerals for absorptive pathways as well as other nutrient-nutrient interactions are considered in the context of infant nutrition. The difficulties involved in assessing mineral and trace element status in infants, as well as the potential consequences of suboptimal and excessive intakes of calcium, magnesium, iron, zinc, copper, manganese, and selenium are also discussed, particularly in the light of infant requirements.

PMID: 9234961

Int J Vitam Nutr Res 1996;66(1):55-8
The effect of preconceptional multivitamin supplementation on fertility.
Czeizel AE, Metneki J, Dudas I. Department of Human Genetics and Teratology, WHO Collaborating Centre for the Community Control of Hereditary Disease, Budapest, Hungary.

  A significantly higher rate of conceptions occurred after preconceptional multivitamin supplementation in comparison with a placebo-like trace element supplementation in the Hungarian randomised, double-blind, controlled trial. This difference was explained by 5% shorter time in the achievement of conception.

PMID: 8698547

Jpn J Physiol 1996 Oct;46(5):383-8
High-lipid diet intake is a possible predisposing factor in the development of hypogonadal osteoporosis.
Chanda S, Islam MN, Pramanik P, Mitra C Department of Physiology, Presidency College, Calcutta, India.

  The effects of a high-lipid diet on the intestinal transference of Ca2+ and the activities of intestinal enzymes were studied in ovariectomized rats. The plasma Ca2+ level and urinary loss of Ca2+ were also observed. Ovariectomy decreased both alkaline phosphatase (AP) and calcium ATPase (Ca(2+)-ATPase) activity, and also reduced the mucosal transference of Ca2+ in all parts of the small intestine. Although the plasma Ca2+ level did not change significantly, the urinary loss of Ca2+ was enhanced. A high-lipid diet supplement enhanced all these parameters in ovariectomized rats. It is therefore believed that a high-lipid diet may promote osteoporosis in ovariectomized rats as the result of Ca2+ transfer and enhanced urinary Ca2+ loss.

PMID: 9048216

Am J Epidemiol 1996 Mar 1;143(5):472-9
Protein consumption and bone fractures in women.
Feskanich D, Willett WC, Stampfer MJ, Colditz GA Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA.

  Dietary protein increases urinary calcium losses and has been associated with higher rates of hip fracture in cross-cultural studies. However, the relation between protein and risk of osteoporotic bone fractures among individuals has not been examined in detail. In this prospective study, usual dietary intake was measured in 1980 in a cohort of 85,900 women, aged 35-59 years, who were participants in the Nurses' Health Study. A mailed food frequency questionnaire was used and incident hip (n = 234) and distal forearm (n = 1,628) fractures were identified by self-report during the following 12 years. Information on other factors related to osteoporosis, including obesity, use of postmenopausal estrogen, smoking, and physical activity, was collected on biennial questionnaires. Dietary measures were updated in 1984 and 1986. Protein was associated with an increased risk of forearm fracture (relative risk (RR) = 1.22, 95% confidence interval (Cl) 1.04-1.43, p for trend = 0.01) for women who consumed more than 95 g per day compared with those who consumed less than 68 g per day. A similar increase in risk was observed for animal protein, but no association was found for consumption of vegetable protein. Women who consumed five or more servings of red meat per week also had a significantly increased risk of forearm fracture (RR = 1.23, 95% Cl 1.01-1.50) compared with women who ate red meat less than once per week. Recall of teenage diet did not reveal any increased risk of forearm fracture for women with higher consumption of animal protein or red meat during this earlier period of life. No association was observed between adult protein intake and the incidence of hip fractures, though power to assess this association was low.

PMID: 8610662

Int J Vitam Nutr Res 1995;65(2):117-21
Effect of vitamin and trace element supplementation on immune indices in healthy elderly.
Pike J, Chandra RK. Department of Pediatrics, Memorial University of Newfoundland, St. John's, Canada.

  Aging is associated with a progressive decline in the immune system and a greater susceptibility to infection. This double-blind, placebo-controlled study, examined the effect of a vitamin and trace element supplement on immune responses of healthy, noninstitutionalized elderly subjects. Forty-seven subjects aged 61-79 years were randomly assigned to receive placebo or micronutrient supplementation for one year. Thirty-five individuals completed the one-year study. Immune function was assessed before and after the period of supplementation. Cell-mediated immune function assessed by the number of T cells and subsets remained constant in the supplemented group and there was a significant increase in CD57 natural killer cells. In contrast, a significant decrease in T cells, CD4 cells, and CD4: CD8 ratio was noted in the placebo group. Supplementation with micronutrients can play a crucial role in the maintenance of normal immune function in the elderly.

PMID: 7591530

Am J Clin Nutr 1994 May;59(5 Suppl):1233S-1237S
Iron status of vegetarians. Craig WJ Department of Nutrition, Andrews University, Berrien Springs, MI 49104-0210.

  An appropriately planned well-balanced vegetarian diet is compatible with an adequate iron status. Although the iron stores of vegetarians may be reduced, the incidence of iron-deficiency anemia in vegetarians is not significantly different from that in omnivores. Restrictive vegetarian diets (eg, macrobiotic) are associated with more widespread iron-deficiency anemia. [grains have chemicals which inhibit mineral absorption LF] Western vegetarians who consume a variety of foods have a better iron status than do those in developing countries who consume a limited diet based on unleavened, unrefined cereals. Whereas phytates, polyphenolics, and other plant constituents found in vegetarian diets inhibit nonheme-iron absorption, vitamin C, citric acid, and other organic acids facilitate nonheme-iron absorption.

PMID: 8172127

Calcif Tissue Int 1992 Jan;50(1):14-8
Cross-cultural association between dietary animal protein and hip fracture: a hypothesis.
Abelow BJ, Holford TR, Insogna KL Yale University School of Medicine, New Haven, Connecticut 06510.

  Age-adjusted female hip fracture incidence has been noted to be higher in industrialized countries than in nonindustrialized countries. A possible explanation that has received little attention is that elevated metabolic acid production associated with a high animal protein diet might lead to chronic bone buffering and bone dissolution. In an attempt to examine this hypothesis, cross-cultural variations in animal protein consumption and hip fracture incidence were examined. When female fracture rates derived from 34 published studies in 16 countries were regressed against estimates of dietary animal protein, a strong, positive association was found. This association could not plausibly be explained by either dietary dietary calcium or total caloric intake. Recent studies suggest that the animal protein-hip fracture association could have a biologically tenable basis. We conclude that further study of the metabolic acid-osteoporosis hypothesis is warranted.

PMID: 1739864

Int J Cardiol 1991 Nov;33(2):191-8
Comment in: Int J Cardiol. 1992 Feb;34(2):227-8. Int J Cardiol. 1992 May;35(2):281-3.
Is calcium excess in western diet a major cause of arterial disease?
Seely S.

  The daily requirement of a young adult for calcium is 300-400 mg, the quantity consumed in many third-world countries. The dietary intake can be doubled or trebled by consumption of milk, thus half a litre of milk, consumed by many individuals daily in prosperous countries, adds 600 mg. The need for calcium is greatly reduced in old age, so that the excess from a given intake becomes more pronounced. The potential hazard of a high intake is that a small fraction finds its way into soft tissues. The aorta is notably prone to calcification, resulting in loss of elasticity. The aorta and its large branches constitute an elastic reservoir, distended during systole and contracting in diastole. This contraction provides the energy for the maintenance of diastolic pressure, which decreases with the deterioration of elasticity and needs a continually increasing systolic pressure to restore its normal value. The heart is disadvantaged in two ways. Its work is increased by having to eject the systolic volume into a stiffer reservoir, and the diastolic filling of the coronary arteries is reduced. This is the main cause of hypertension in old age--there is no increase in blood pressure with age in undeveloped countries where intake of calcium is low. The best cure would be prevention: the reduction of intake of calcium in prosperous countries. Failing that, phytic acid is suggested as the best calcium antagonist. Phytic acid, a natural product present in grains, converts dietary calcium into insoluble phosphates which pass unabsorbed through the digestive tract. The presently used calcium antagonists are not so satisfactory.

PMID: 1743778

Meikai Daigaku Shigaku Zasshi 1990;19(1):43-62
[Time-course of changes in alveolar bone surrounding and vascular system of molars of rats fed a high-protein low-calcium diet]. [Article in Japanese]
Abe J Department of Orthodontics, Meikai University School of Dentistry, Saitama, Japan.

  The purpose of this study was to demonstrate changes in alveolar bone surrounding and blood vessels in the molar teeth of rats fed a high-protein low-calcium diet for various periods of time. Five-week-old male Sprague-Dawley rats were used. Control rats were given a normal diet; whereas the experimental rats were fed a high-protein low-calcium diet for 3, 5, 7, 10, 14, 18 or 21 days. Samples were observed by means of light microscopy and scanning electron microscopy, and the following results were obtained. 1. The changes appeared earlier in the dental alveolus than in the diaphysis of the femur. 2. Early changes in the alveolus were observed clearly in the 7-day experimental group. 3. Bone resorption progressed mesio-distally and cervically from spongy bone with the passage of time, and severe osteoporosis was observed in the 18-day experimental group. 4. An enlarged marrow cavity caused by bone resorption was observed, but the height and overall shape of the alveolar bone showed no changes, indicating the continuance of its support function. 5. The architecture of blood vessels in the bone marrow changed its form gradually from 7-day experimental diet and the vessels appeared to have been functioning like a cushion against mastication or physiological force acting on bone. 6. The vessels in the periodontal membrane exhibited characteristic changes in the cervical and apical resins of the membrane as bone resorption proceeded and changes in vessels in the bone marrow also progressed, and the vessels showed a relatively dense distribution there.

PMID: 2134286

Int J Cardiol 1989 Dec;25(3):333-8
Similarities and differences between the epidemiology and possible dietary causes of coronary arterial disease and strokes.
Seely S. Department of Cardiology, University of Manchester, Royal Infirmary, U.K.

  The findings of a previous statistical study of the relationship between food consumption and mortality from coronary arterial disease are compared with those of a new study of food consumption and cerebrovascular disease. The previous study found strong positive correlation between male mortality from coronary arterial disease and the consumption of two food items, milk and oats. Stroke mortality appears to be linked with the consumption of a wide variety of proteinaceous plants. These can be divided into two groups, one with an apparently strong and the other with an apparently mild effect. The strong group consists of the protein content of pulses, oats, maize and rye, the milder group of the protein content of wheat, rice, barley, potatoes and vegetables. The relative effect of the two groups of proteins is of the order of 6/1, but the proteins with a relatively mild effect are consumed in large quantities in comparison with those having a strong effect so that their effect is not negligible. The correlation coefficient between male cerebrovascular mortality in the younger age groups and the combined consumption of the two groups of plant proteins is 0.91. That between male mortality from coronary arterial disease and the consumption of milk and oats found in the previous study was 0.94.

PMID: 2613381

Adv Food Nutr Res 1989;33:103-56
Calcium in the diet: food sources, recommended intakes, and nutritional bioavailability.
Miller DD Institute of Food Science, Cornell University, Ithaca, New York 14853.

  Calcium nutritional status among some groups in the United States is suboptimal when judged by calcium intakes and the high prevalence of osteoporosis. Unfortunately, however, it is not clear that increases in calcium intake will have a significant impact on osteoporosis or other chronic diseases that have been linked to calcium nutriture. There is still considerable controversy surrounding the issue of calcium RDAs. The body's ability to adapt to varying levels of calcium intakes, the lack of sensitive indicators of calcium status, and the complexity and slow progression of chronic diseases such as osteoporosis make it very difficult to establish the role of diet in this regard. Great progress has been made in the study of calcium absorption. Much is known about the mechanisms involved in calcium absorption and its regulation. Thus, a rapidly advancing field and further developments will be invaluable to our understanding of the role of diet in calcium nutrition. Calcium bioavailability is affected by diet composition and the chemical form of calcium in foods. The calcium in dairy products is readily absorbed in the intestine. Lactose enhances calcium absorption efficiency under some conditions. Components of plants such as fiber, phytate, and oxalic acid may depress calcium absorption. High intakes of protein increase urinary losses of calcium but this effect may be partially offset by the phosphate association with most high-protein foods. Calcium absorption from salts used in supplement tablets is generally good. Absorption from salts such as calcium carbonate which require acid for dissolution may be poor in persons with achlorhydria unless the tablets are consumed with a meal. The practical significance of factors that may alter calcium bioavailability in normal mixed diets is difficult to assess. It may be a significant factor when calcium intakes are marginal or when absorption by the active transport, vitamin D-dependent process is impaired or not fully developed, i.e., it may be significant when vitamin D status is poor, in the elderly, and in young infants.

PMID: 2697231

Int J Cardiol 1988 Aug;20(2):183-92
Diet and coronary arterial disease: a statistical study.
Seely S. Department of Cardiology, University of Manchester, Royal Infirmary, U.K.

  Statistical analysis comparing mortality rates from coronary arterial disease with food consumption in 21 countries belonging to the Organisation of Economic Cooperation and Development is presented. In a preliminary process correlation coefficients are calculated for coronary mortality and all food items appearing in statistics collected for food consumption as well as for some combinations of food items. The highest correlations obtain with oats, milk proteins (other than the protein content of cheese), milk fats and sugar. These items are investigated in greater detail with respect to mortality from coronary arterial disease in males and females in various age groups and for various time intervals between the dates of mortality and statistics for food consumption. Correlations tend to increase in the older age groups and with longer time intervals. The highest correlation coefficient found is 0.94 for deaths due to coronary arterial disease for males in the 65-74 age group with the combined consumption of oats and milk proteins.

PMID: 3209250

J Clin Endocrinol Metab 1988 Jan;66(1):140-6
Relationship of animal protein-rich diet to kidney stone formation and calcium metabolism.
Breslau NA, Brinkley L, Hill KD, Pak CY Center in Mineral Metabolism and Clinical Research, Department of Internal Medicine, Dallas, Texas.

  We wished to determine whether different types of dietary protein might have different effects on calcium metabolism and on the propensity for renal stone formation. Fifteen young normal subjects were studied during three 12-day dietary periods during which their diet contained vegetable protein, vegetable and egg protein, or animal protein. While these three diets were constant with respect to Na, K, Ca, P, Mg, and quantity of protein, they had progressively higher sulfur contents. As the fixed acid content of the diets increased, urinary calcium excretion increased from 103 +/- 15 ( +/- SEM) mg/day (2.6 +/- 0.4 mmol/day) on the vegetarian diet to 150 +/- 13 mg/day (3.7 +/- 0.3 mmol/day) on the animal protein diet (P less than 0.02). Despite the increased urinary calcium excretion, there was a modest reduction of urinary cAMP excretion and serum PTH and 1,25-dihydroxyvitamin D levels consistent with acid-induced bone dissolution. There was no change in fractional intestinal 47Ca absorption. The inability to compensate for the animal protein-induced calciuric response may be a risk factor for the development of osteoporosis. The animal protein-rich diet was associated with the highest excretion of undissociated uric acid due to the reduction in urinary pH. Moreover, citrate excretion was reduced because of the acid load. However, oxalate excretion was lower than during the vegetarian diet [26 +/- 1 mg/day (290 +/- 10 mumol/day) vs. 39 +/- 2 mg/day (430 +/- 20 mumol/day); P less than 0.02]. Urinary crystallization studies revealed that the animal protein diet, when its electrolyte composition and quantity of protein were kept the same as for the vegetarian diet, conferred an increased risk for uric acid stones, but, because of opposing factors, not for calcium oxalate or calcium phosphate stones.

PMID: 2826524

Fed Proc 1981 Jul;40(9):2434-8
Calcium, phosphorus, and osteoporosis.
Draper HH, Scythes CA

  Gross epidemiological data indicate there are no significant differences in rates of aging osteopenia among countries with substantially different amounts of Ca in their national food supplies. This-observation, plus the fact that Ca administration fails to reverse osteoporotic bone loss, has led some investigators to conclude that Ca nutrition is an insignificant factor in the etiology of osteoporosis. However, it has become apparent that a Ca intake that may be adequate for adults consuming a low protein, low P, neural, or alkaline cereal-based diet is not necessarily adequate for subjects consuming a high protein, high P, acidic mixed Western diet. Ca administration inhibits postmenopausal osteopenia and there is epidemiological evidence that a liberal Ca intake reduces bone loss in middle adulthood. Ca intakes in the United States and Canada appear generally satisfactory among children and young adults, but low intakes by many individuals of middle age is a cause for concern, especially among women. Although the Ca:P ratio for the average diet consumed in these countries (about 1:1.6) appears to be satisfactory, a low intake of dairy foods, coupled with a high intake of other foods rich in natural and added phosphorus, may raise the ratio above 1:2, a value beyond which animal studies indicate that there is a risk of increased bone loss.

PMID: 7250388

J Nutr 1981 May;111(5):804-16
Influence of high protein diets on cartilage and bone formation in rats.
Weiss RE, Gorn A, Dux S, Nimni ME

  The influence of diets containing combinations of high protein and low calcium on discrete stages of bone formation was investigated in 28-day-old rats. A bone matrix-induced bone forming system was utilized to determine the stages of endochondral ossification that were being affected. Mesenchymal cell proliferation as assessed by [3H]-thymidine incorporation and ornithine decarboxylase activity were unchanged in animals fed a high protein (80% casein)/normal calcium (0.61% Ca; 0.40% P) diet. However, osteogenesis was reduced by 78% in the rats fed high protein/normal calcium as measured by 45Ca incorporation. Alkaline and acid phosphatase activities in bone were increased 2.5 and 2.3 times, respectively, reflecting increased matrix turnover induced by the high protein availability. Bone that did form was not remodeled nor was there evidence of marrow formation. The animals were normocalcemic and normophosphatemic and showed no evidence of acidosis. A combination diet of high protein and low calcium resulted in a 62% reduction of cell proliferation and chondrogenesis and a 98% inhibition of bone formation. High dietary protein-induced osteoporosis in animals is due to a failure of osteogenesis of the stage of ossification possibly a result of restricted availability of calcium at the site of mineralization.

PMID: 7229730


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