on methyl cobolamin
B-12 and mercury
We frequently hear unsupported claims, like "B12 deficiency seems to be a problem on vegan diets."
Actually, no it doesn't. There are very rare, isolated, single cases here and there, but those have local causes, and are clearly not evidence of the global cause being a vegan diet.
A poll of 968 adults (=>18 years old) reported that 0.9% claimed to be true vegans. Since there are more than 209 million people in the US in that age range, there are about 2,000,000 vegans in the US.
So, if an insignificant 1% of all US vegans actually had B-12 issues, the medical journals would be flooded with reports of these 20,000 cases, yet we do not see them. If 10% of vegans had B-12 problems, where are the 200,000 cases??? Where are they? Even if 10% of vegans had B-12 problems, these could be easily solved with inexpensive supplements and thus allow this 10% to also reap the considerable and documented health benefits of plant-based diets!
A PubMed search for "B-12 deficiency vegan" brings up only 25 hits since 1967, less than one per year, and the journals abstracted in PubMed pretty much cover the entire civilized planet. Some of these abstracts report no B-12 problems!
PMID 8926531 indicates that for Japanese vegan children who consumed 2-4 grams of Nori per day: "Not a single case of symptoms due to B12 deficiency was found".
PMID 3913054 states: "Deficiencies have been described for vitamin D and B12 but the evidence is often unconvincing."
PMID 6272567 states: "No clinical signs of nutritional deficiency were observed in the vegans".
PMID 646250 states: "Possibly such malabsorption may also be present in many of those vegans developing overt vitamin-B12 deficiency in whom Schilling test findings have been normal.", indicating that the deficiency was not caused by dietary deficiency, but instead by intrinsic absorption problems. Meat-eaters also have B-12 deficiencies due to internal malabsorption problems.
Significantly, most of the studies that reported "deficiency" in vegans are based on blood tests that are evaluated against meat-eaters' blood profiles. That is as meaningful as claiming that vegans are "deficient" in serum cholesterol, serum fats, high blood pressure, BMI, heart attacks, strokes, and cancers compared to meat-eaters when, in fact, these lower numbers indicate a superior health status and lowered morbidity/mortality. Similarly, other false and biased "evidence" of "deficiency" is determined by comparing to meat-eaters' consumption of certain nutrients. This is misleading, perhaps intentionally so, since no one would claim a vegan diet is "deficient" in cholesterol or animal fat.
Thus, there doesn't seem to be a real vegan B-12 deficiency issue, especially when supplements are cheap and readily available.
Where is the evidence that there is a real B-12 problem caused by an intelligently-chosen vegan diet?
Enrichment of some B-vitamins in plants with application of organic fertilizers.
Plant and Soil 167:305-311, 1994.
Organic food suppliers often claim that organic foods grown on soils with natural fertilizers have a better nutritional value than foods grown with inorganic fertilizers. Although past studies, such as those published by Gray and Daniel in 1959 or by Leclerc and colleagues in 1991, have shown that organically grown produce had more vitamins, it was unclear if the plants synthesized them or got them from the soil. In order to test the origins of vitamins in plants, this researcher selected vitamin B12 for study. This was because plants cannot manufacture it but microorganisms can. In addition, large amounts of B12 are found in animal manure, a commonly used organic fertilizer. This study looked at whether plants, specifically soybeans, barley, and spinach, grown on soils amended with pure B12 or B12 in manure would have a higher B12 content than plants grown with inorganic fertilizers. All plants contained a minimal amount of B12 in the inorganically fertilized soil. Barley showed a threefold increase of B12 in the harvested grain in both the pure B12 treatment (10.8 ng/g dry weight) and the manure treatment (9.1 ng/g dry weight). In spinach leaves, B12 increased twofold in the manure treatment (17.8 ng/g dry weight) and 34-fold in the pure B12 treatment (235 ng/g dry weight). Soybeans had a similar, but not as dramatic trend. In addition, soil samples in fields receiving manure over several years contained more B12 than those only receiving inorganic fertilizers. These results show that B12 levels can be increased in organically grown food through the use of manure fertilizers. This is good news for vegetarians, who often have trouble getting enough B12 in their diets. It is also good news for consumers who buy organic food because of its better nutritional value. While this preliminary trial does seem to indicate that vitamins can be absorbed from the soil, more studies should be done with other vitamins to confirm these observations.
See also: other references Mozafar
J Nutr. 2003 Nov;133(11):3636-42.
Dietary pattern is associated with homocysteine and B vitamin status in an urban chinese population.
Gao X, Yao M, McCrory MA, Ma G, Li Y, Roberts SB, Tucker KL.
The Jean Mayer U.S. Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA and. Institute of Nutrition and Food Safety, Chinese Center for Disease Control and Prevention, Beijing, China.
To identify existing
dietary patterns and examine associations between these patterns and plasma
homocysteine and B vitamin concentrations in an urban Chinese population
living in Beijing (n = 119), dietary information was collected with a
food frequency questionnaire designed for this population. Plasma homocysteine
and B vitamin concentrations were examined. Food group variables, expressed
as percentages of total energy intake, were entered into cluster analysis
to define three distinct dietary pattern groups. The prevalence of high
homocysteine (>11 micro mol/L for women and 12 micro mol/L for men), was
31.9%; of low folate (<6.8 nmol/L), 36.2%; of low vitamin B-12 (<221 pmol/L),
36.9%; and of low vitamin B-6 (<30 nmol/L), 16.0%. The three dietary patterns
derived were defined by relatively greater intake of 1) fruit and milk,
2) red meat and 3) refined cereals. More than 40% of subjects in the
refined cereals group had high plasma homocysteine and low plasma folate
concentrations, and 67% had low plasma vitamin B-12 concentrations. Those
following the refined cereals pattern were 4 and 5.2 times more likely
to have high homocysteine and low vitamin B-12 concentrations, respectively,
relative to the fruit and milk dietary pattern group (P < 0.01), after
adjustment for potential confounders. High intake of refined cereals
was associated with low B vitamin and high homocysteine concentrations,
whereas the pattern high in fruit and milk was associated with the lowest
homocysteine. Dietary patterns appear to play an important role in
the micronutrient and homocysteine status of these Chinese adults.
Am J Clin Nutr. 2003 Oct;78(4):765-72.
B vitamin status and concentrations of homocysteine and methylmalonic acid in elderly German women.
Wolters M, Hermann S, Hahn A. Institute of Food Science, Department of Applied Chemistry, University of Hanover, Hanover, Germany. email@example.com
BACKGROUND: Prior investigations
found that elderly persons are at higher risk than are younger persons
for B vitamin deficiency, which leads to elevated plasma total homocysteine
(tHcy) concentrations that are associated with an increased risk for certain
diseases such as coronary artery disease. To date, published data have
shown decreased vitamin status and elevated tHcy among the elderly.
J Nutr. 2003 Aug;133(8):2643-9.
Serum Total Homocysteine Concentrations in Children and Adolescents: Results from the Third National Health and Nutrition Examination Survey (NHANES III).
Must A, Jacques PF, Rogers G, Rosenberg IH, Selhub J. Jean Mayer U.S. Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA. Department of Family Medicine and Community Health, Tufts University School of Medicine, Boston, MA.
Although the elevation of circulating total serum homocysteine (tHcy) concentration in a fasting state is associated with an increased risk of occlusive vascular disease in adults, the implications of elevated levels in children are not known. The goals of this study were to describe the distribution of tHcy among a representative sample of children and adolescents in the United States, and to test for differences in tHcy among sex, age and race-ethnicity categories. Using surplus sera from Phase 2 of the third National Health and Nutrition Examination Survey, we measured tHcy for a nationally representative sample of 942 boys and 1085 girls aged 4-19 y. The age-adjusted geometric mean tHcy concentrations were 6.2 and 5.8 micro mol/L in non-Hispanic Caucasian boys and girls, 6.4 and 6.1 micro mol/L in non-Hispanic African-American boys and girls, and 6.4 and 5.5 micro mol/L in Mexican American boys and girls, respectively. A significant interaction between age and sex (P < 0.01) reflected the divergence of tHcy concentrations at about age 10 y, with higher concentrations in boys than in girls throughout adolescence. These first data on homocysteine concentrations in a nationally representative sample of American youth suggest that sexual dimorphism of tHcy concentrations occurs earlier, at approximately 10 y of age, than previously reported on the basis of smaller nonrepresentative samples. Improved understanding of the determinants of levels during growth and development may provide important clues to the etiology of adult disease.
Am J Clin Nutr. 2003 Jul;78(1):131-6.; Comment in: Am J Clin Nutr. 2003 Jul;78(1):3-6.
Vitamin B-12 status, particularly holotranscobalamin II and methylmalonic acid concentrations, and hyperhomocysteinemia in vegetarians.
Herrmann W, Schorr H, Obeid R, Geisel J. Central Laboratory, Department of Clinical Chemistry, Saarland University Hospital, Homburg, Germany. firstname.lastname@example.org
have a lower intake of vitamin B-12 than do omnivores. Early and reliable
diagnosis of vitamin B-12 deficiency is very important.
Eur J Obstet Gynecol Reprod Biol 2003 Mar 26;107(1):57-61
Serum folate and Vitamin B12 levels in women using modern oral contraceptives (OC) containing 20 microg ethinyl estradiol.
Sutterlin MW, Bussen SS, Rieger L, Dietl J, Steck T. Department of Obstetrics and Gynecology, University of Wurzburg, Josef-Schneider-Str 4, D-97080 Wurzburg, Germany.
effects of modern oral contraceptives (OC) on serum concentrations
of folate and cobalamin are controversial.
Eur J Nutr 2003 Apr;42(2):84-90
The status of plasma homocysteine and related B-vitamins in healthy young vegetarians and nonvegetarians.
Huang YC, Chang SJ, Chiu YT, Chang HH, Cheng CH. School of Nutrition, Chung Shan Medical University, Taichung 402, Taiwan. email@example.com
Exclusion of animal products and having only plant protein in vegetarian
diets may affect the status of certain B-vitamins, and further cause the
elevation of plasma homocysteine concentration.
MMWR Morb Mortal Wkly Rep 2003 Jan 31;52(4):61-4
Neurologic impairment in children associated with maternal dietary deficiency of cobalamin--Georgia, 2001. During 2001, neurologic impairment resulting from cobalamin (vitamin B12) deficiency was diagnosed in two children in Georgia. The children were breastfed by mothers who followed vegetarian diets. This report summarizes the two cases and provides guidance for health-care providers on identifying and preventing cobalamin deficiency among breastfed infants of vegetarian mothers.
[Note: these types of reports are used by anti-vegan/vegetarian propagandist to "prove" the inadequacies of plant-based diets. However, considering the tens of thousands of vegetarians/vegans that live in Georgia, this infinitesimal amount of neurologic impairment indicates that these problems are strictly tied to the individual mother's poor diet or genetic issues rather than a real problem with plant-based diets in general. That is, if the problem was really a result of plant-based diets alone, then thousands of cases would be evident. -- ljf]
The Bacterial Flora of Humans
© 2002 Kenneth Todar University of Wisconsin-Madison Department of Bacteriology
Cas Lek Cesk 2002 Jul;141(13):417-20
[Nutritional determinants of homocysteinemia] [Article in Slovak]
Krajcovicova-Kudlackova M, Blazicek P. Ustav preventivnej a klinickej mediciny, Bratislava Nemocnica Ministerstva obrany, Bratislava. firstname.lastname@example.org
B12, folate and vitamin B6 are the main determinants of homocysteinemia.
These B-group vitamins influence two metabolic pathways of homocysteine
reduction, which prevail in dependence to methionine intake. Transsulfuration
(vitamin B6) dominates under condition of overnutrition with prevalence
of animal food sources, remethylation (vitamin B12 and folic acid) is
decisive under conditions of malnutrition, alternative nutrition or optimal
Asian Pac J Cancer Prev 2002;3(2):155-162
Vitamin B(12) and Folate Status in Head and Neck Cancer.
Raval GN, Sainger RN, Rawal RM, Patel JB, Patel BP, Jha FP, Patel DD, Patel PS. Biochemistry Research Division, The Gujarat Cancer and Research Institute, Ahmedabad-380 016, INDIA. email@example.com, firstname.lastname@example.org
Deficiency of vitamin B(12) and folate is associated with causation of certain precancerous conditions and cancer. The present study was carried out on 56 controls, 167 patients with oral precancerous conditions (OPC) and 214 head and neck cancer patients, to evaluate the plasma vitamin B(12) and folate levels to determine their association with tobacco habits and vegetarianism and several sociodemographic factors. The subjects were interviewed using a health habit and diet questionnaire at the time of blood collection. Simultaneous estimations of plasma vitamin B(12) and folate were done by Dual Count Radioassay. It was found that the habit of tobacco consumption, lower education and low income were among the risk factors. A decrease in the plasma vitamin B(12) and folate levels with respect to tobacco habits, disease progression, and vegetarian diet was also observed. The individuals in the ower quartile for vitamin B(12) and folate were at a higher risk of developing OPC, as compared to those in higher quartiles. Similarly, the patients with OPC in lower quartiles were found to be at a higher risk of developing cancer than their counterparts. There was a significant positive correlation between vitamin B(12) and folate levels in the subjects consuming tobacco, and more so in patients with OPC (r=0.4330, p=0.000). Folate levels were significantly lower in patients with advanced as compared with early disease (ANOVA p=0.006 and Spearman's Rho = -0.211 and p=0.01). The results suggest, potential significance of plasma vitamin B(12) and folate levels in head and neck malignancies which needs to be confirmed by further studies on a large population.
Clin Chim Acta 2002 Dec;326(1-2):47-59
Vegetarian lifestyle and monitoring of vitamin B-12 status.
Herrmann W, Geisel J. Department of Clinical Chemistry-Central Laboratory, University Hospital of the Saarland, Bld. 40, D-66421 Homburg/Saar, Germany
Vegetarians are at risk to develop deficiencies of some essential nutrients, especially vitamin B-12 (cobalamin). Cobalamin occurs in substantial amounts only in foods derived from animals and is essential for one-carbon metabolism and cell division. Low nutritional intake of vitamin B-12 may lead to negative balance and, finally, to functional deficiency when tissue stores of vitamin B-12 are depleted. Early diagnosis of vitamin B-12 deficiency seems to be useful because irreversible neurological damages may be prevented by cobalamin substitution. The search for a specific and sensitive test to diagnose vitamin B-12 deficiency is ongoing. [Note: if a test to diagnose B-12 deficiency does not exist, then how may any comments be made about it? -- ljf] Serum vitamin B-12 measurement is a widely applied standard method. However, the test has poor predictive value. [Note: then "conclusions" obtained by measuring or comparing serum B-12 of people on plant-based vs. animal-product-based diets are meaningless -- ljf] Optimal monitoring of cobalamin status in vegetarians should include the measurement of homocysteine (HCY), methylmalonic acid (MMA), and holotranscobalamin II. Vitamin B-12 deficiency can be divided into four stages. In stages I and II, indicated by a low plasma level of holotranscobalamin II, the plasma and cell stores become depleted. Stage III is characterized by increased levels of HCY and MMA in addition to lowered holotranscobalamin II. In stage IV, clinical signs become recognizable like macroovalocytosis, elevated MCV of erythrocytes or lowered haemoglobin. In our investigations, we have found stage III of vitamin B-12 deficiency in over 60% of vegetarians, thus underlining the importance of cobalamin monitoring in this dietary group. [Or taking an inexpensive supplement - ljf]
Am J Clin Nutr 2002 Jul;76(1):100-6
Dietary intake and nutritional status of young vegans and omnivores in Sweden.
Larsson CL, Johansson GK. Department of Food and Nutrition, Umea University, Umea, Sweden. email@example.com
BACKGROUND: Adolescents sometimes become vegetarian for ethical
rather than health reasons. This may result in health problems caused
by lack of interest in and knowledge of nutrition. [Yet, the identical
"lack of interest in and knowledge of nutrition" of meat-eaters
is ignored, perhaps revealing a bias of the investigator - ljf]
Am J Hematol 2002 Jun;70(2):107-14
Hyperhomocysteinemia and cobalamin deficiency in young Asian Indians in the United States.
Carmel R, Mallidi PV, Vinarskiy S, Brar S, Frouhar Z. Department of Medicine, New York Methodist Hospital, 506 Sixth Street, Brooklyn, NY 11215, USA. firstname.lastname@example.org
Hyperhomocysteinemia, a risk factor for vascular disease, may be a particular problem in Asian Indians, but information is limited, especially in the U.S., despite its growing Asian population. Moreover, suggestions have been made that folate deficiency is responsible for the hyperhomocysteinemia in Indians. Therefore, we studied homocysteine status in healthy Asian Indians in the U.S. prospectively, determined the frequency of cobalamin and folate deficiency as contributors to it, and examined whether food-cobalamin absorption contributed to cobalamin deficiency. Homocysteine levels were higher in Asian Indian men than in 4 other ethnic groups (P < 0.0001); 10/39 Indian men (25.6%) were hyperhomocysteinemic. Cobalamin levels were lower in Indian men (P = 0.000005) and women (P = 0.03) than in non-Indians; low levels were found more frequently in both Indian men (23/39; 59.0%) and women (5/21; 23.8%) than in others. Measuring methylmalonic acid in 10 selected subjects showed that the low cobalamin levels reflected cobalamin deficiency, and high methylmalonic acid levels were found in some subjects without hyperhomocysteinemia. Evidence of folate deficiency was not found in any subjects. Food-cobalamin absorption was normal in all 13 Indian subjects tested, including those with Helicobacter pylori infection. The results show that hyperhomocysteinemia is strikingly common in apparently healthy, young Asian Indian men. The cause appears to be cobalamin deficiency, which affected more than half of the Indian men, may be largely subclinical, is underestimated by homocysteine levels alone [yet, homocysteine levels are claimed to be a useful metric for B-12 deficiency -- ljf] which were not always abnormal, and is probably largely dietary in origin. Folate deficiency is rare. This public health problem is amenable to prevention and treatment in this growing segment of the U.S. population. It was, parenthetically, noteworthy that many of the affected subjects were young physician trainees.
Arch Pediatr Adolesc Med 2002 May;156(5):431-7
Comment in: Arch Pediatr Adolesc Med. 2002 May;156(5):426-7.
Adolescent vegetarians: how well do their dietary patterns meet the healthy people 2010 objectives?
Perry CL, McGuire MT, Neumark-Sztainer D, Story M. Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis, MN 55454, USA. email@example.com
To examine whether adolescent vegetarians were more likely than nonvegetarian
peers to meet the dietary recommendations of the Healthy People 2010 objectives
and to examine differences in other nutrients between these 2 groups.
DESIGN: A total of 4746 adolescents from 31 middle and high schools in
the Twin Cities area of Minnesota. Data were collected via self-report
surveys, with a student response rate of 81.5%.
Am J Clin Nutr 2001 Aug;74(2):233-41 Comment in: Am J Clin Nutr. 2001 Aug;74(2):157-9.
Hyperhomocysteinemia and elevated methylmalonic acid indicate a high prevalence of cobalamin deficiency in Asian Indians.
Refsum H, Yajnik CS, Gadkari M, Schneede J, Vollset SE, Orning L, Guttormsen AB, Joglekar A, Sayyad MG, Ulvik A, Ueland PM. Department of Pharmacology and the Locus for Homocysteine and Related Vitamins, University of Bergen, Norway. firstname.lastname@example.org
In India, most people adhere to a vegetarian diet, which may lead to cobalamin
Br J Nutr 2001 Jun;85(6):699-703
Feeding dried purple laver (nori) to vitamin B12-deficient rats significantly improves vitamin B12 status.
Takenaka S, Sugiyama S, Ebara S, Miyamoto E, Abe K, Tamura Y, Watanabe F, Tsuyama S, Nakano Y.
Laboratory of Nutrition and Food Science, Hagoromo-gakuen College, Sakai 592-8344, Japan. email@example.com
To clarify the bioavailability of vitamin B12 in lyophylized purple laver (nori; Porphyra yezoensis), total vitamin B12 and vitamin B12 analogue contents in the laver were determined, and the effects of feeding the laver to vitamin B12-deficient rats were investigated. The amount of total vitamin B12 in the dried purple laver was estimated to be 54.5 and 58.6 (se 5.3 and 7.5 respectively) microg/100 g dry weight by Lactobacillus bioassay and chemiluminescent assay with hog intrinsic factor respectively. The purple laver contained five types of biologically active vitamin B12 compounds (cyano-, hydroxo-, sulfito-, adenosyl- and methylcobalamin), in which the vitamin B12 coezymes (adenosyl- and methylcobalamin) comprised about 60 % of the total vitamin B12. When 9-week-old vitamin B12-deficient rats, which excreted substantial amounts of methylmalonic acid (71.7(se 20.2) micromol/d) in urine, were fed the diet supplemented with dried purple laver (10 &mgr;g/kg diet) for 20 d, urinary methylmalonic acid excretion (as an index of vitamin B12 deficiency) became undetectable and hepatic vitamin B12 (especially adenosylcobalamin) levels were significantly increased. These results indicate that vitamin B12 in dried purple laver is bioavailable to rats.
J Agric Food Chem 2001 Nov;49(11):5685-8
Inactive corrinoid-compound significantly decreases in Spirulina platensis grown in a cobalt-deficient medium.
Watanabe F, Miyamoto E, Nakano Y. Department of Health Science, Kochi Women's University, Kochi 780-8515, Japan. firstname.lastname@example.org
Spirulina platensis NIES-39 was grown under open culture system in the presence or absence of CoSO(4) (12 microg/L) and/or vitamin B(12) (10 microg/L) to confirm whether CoSO(4) and/or vitamin B(12) stimulate or are essential for growth of the algal cells and for accumulation of vitamin B(12). The addition of CoSO(4) and/or vitamin B(12) could not affect both cell growth and cell yield of the alga. The amount of corrinoid-compound was increased significantly by the addition of CoSO(4) but not by vitamin B(12). A C18 reversed-phase HPLC pattern of the Spirulina corrinoid-compound increased by the addition of CoSO(4) was identical to that of authentic pseudovitamin B(12), which is inactive for human. These results indicate that the algal cells grown in the absence of CoSO(4) are suitable for use of human health foods because the inactive corrinoid-compound can be reduced significantly.
J Am Diet Assoc 2001 Jun;101(6):670-7
Considerations in planning vegan diets: infants.
Mangels AR, Messina V. Vegetarian Resource Group, Baltimore, Md., USA.
Appropriately planned vegan diets can satisfy nutrient needs of infants. The American Dietetic Association and The American Academy of Pediatrics state that vegan diets can promote normal infant growth. It is important for parents to provide appropriate foods for vegan infants, using guidelines like those in this article. Key considerations when working with vegan families include composition of breast milk from vegan women, appropriate breast milk substitutes, supplements, type and amount of dietary fat, and solid food introduction. Growth of vegan infants appears adequate with post-weaning growth related to dietary adequacy. Breast milk composition is similar to that of non-vegetarians except for fat composition. For the first 4 to 6 months, breast milk should be the sole food with soy-based infant formula as an alternative. Commercial soymilk should not be the primary beverage until after age 1 year. Breastfed vegan infants may need supplements of vitamin B-12 if maternal diet is inadequate; older infants may need zinc supplements and reliable sources of iron and vitamins D and B-12. Timing of solid food introduction is similar to that recommended for non-vegetarians. Tofu, dried beans, and meat analogs are introduced as protein sources around 7-8 months. Vegan diets can be planned to be nutritionally adequate and support growth for infants.
J Am Diet Assoc 2001 Jun;101(6):661-9
Considerations in planning vegan diets: children.
Messina V, Mangels AR. Nutrition Matters, Inc, 1543 Lincoln St, Port Townsend, WA 98368, USA.
This article reviews research on the growth and nutrient intake of vegan children and provides guidelines for counselling parents of vegan children. Although diets of vegan children meet or exceed recommendations for most nutrients, and vegan children have higher intakes of fiber and lower intakes of total fat, saturated fat, and cholesterol than omnivore children, some studies indicate that they may be low in calcium. In addition, bioavailability of zinc and iron from plant foods can be low. Protein needs are slightly higher for vegan children but are easily met with a varied diet that provides adequate energy. Special attention should be given to dietary practices that enhance absorption of zinc and iron from plant foods. Further, good sources of the omega-3 fatty acid linolenic acid should be emphasized to enhance synthesis of the long-chain fatty acid docosahexanoic acid. Dietetics professionals who counsel vegan families should help parents identify good sources of vitamin B-12, riboflavin, zinc, calcium and, if sun exposure is not adequate, vitamin D. This should not be problematic, due to the growing number and availability of fortified vegan foods that can help children meet all nutrient needs. Therefore, with appropriate food choices, vegan diets can be adequate for children at all ages.
The nutritional health of New Zealand vegetarian and non-vegetarian Seventh-day Adventists: selected vitamin, mineral and lipid levels.
Harman SK, Parnell WR N Z Med J 1998 Mar 111:91-4 BROWSE : N Z Med J • Volume 111 • Issue 1062
AIM: To determine whether
adult non-vegetarian Seventh-day Adventists differ in selected nutrition
related health aspects from adult vegetarian Seventh-day Adventists.
Clin Nutr 2000 Apr;19(2):137-9
Prolonged exclusive breast-feeding from vegan mother causing an acute onset of isolated methylmalonic aciduria due to a mild mutase deficiency.
Ciani F, Poggi GM, Pasquini E, Donati MA, Zammarchi E. Department of Pediatrics, University of Florence, Meyer Children Hospital, Italy.
We describe a case of methylmalonic aciduria (MMA) occurred in a 22-month-old boy whose diet was exclusively based upon breast-feeding from a mother following a long-lasting strict vegetarian diet. Clinical picture showed a dramatic onset, with a profound drowsiness associated with a severe metabolic acidosis, hyperammonemia, macrocytic anemia, ketonuria, and massive methylmalonic aciduria without homocystinuria. Both symptoms and biochemical findings quickly improved thanks to prompt vitamin B(12)parenteral therapy. Biochemical and enzymatic findings allowed a diagnosis of mild mutase deficiency, which only and [sic] inadequate dietary B(12)contribution might have revealed. Our case highlights the risk of a prolonged strictly vegetarian diet of lactating mother for providing inadequate amounts of some nutrients to the breast-fed baby. Moreover, such a dietary behaviour could dramatically unmask otherwise clinically unapparent metabolic defects in the baby. Copyright 2000 Harcourt Publishers Ltd.
Ann Nutr Metab 2000;44(5-6):229-34
Metabolic vitamin B12 status on a mostly raw vegan diet with follow-up using tablets, nutritional yeast, or probiotic supplements.
Donaldson MS. Hallelujah Acres Foundation, Shelby, N.C., USA. email@example.com
BACKGROUND: Pure vegetarian
diets might cause cobalamin deficiency due to lack of dietary intake.
It was hypothesized that a population following a vegan diet consuming
mostly raw fruits and vegetables, carrot juice, and dehydrated barley
grass juice would be able to avoid vitamin B12 deficiency naturally.
Clin Chem 2001 Jun;47(6):1094-101
Total homocysteine, vitamin B(12), and total antioxidant status in vegetarians.
Herrmann W, Schorr H, Purschwitz K, Rassoul F, Richter V. Department of Clinical Chemistry/Central Laboratory, University Hospital of the Saarland, D-66421 Homburg/Saar, Germany. firstname.lastname@example.org
Decreasing or eliminating animal products from the diet decreases the
intake of some essential nutrients, such as vitamin B(12), which may lead
to hyperhomocysteinemia. We investigated vitamin B(12)-dependent metabolism
and oxidative stress in groups with various or no intake of meat or animal
Vopr Pitan 2001;70(4):7-12 [Article in Russian]
In 1996 for the first
time a study of state of health, living conditions and nutrition status
of 84 persons from the Siberian settlement of the rigorous vegetarians--vegans
and 26 aboriginal inhabitants who feed on a traditional mixed diet was
carried out. The clinical and laboratory investigations are kept. The
positive influencing vegan ration on a serum lipids, body weight, state
of cardiovascular system was showed. The contents of vitamin B12
and serum iron in vegans was in normal physiological range. The level
of blood calcium was reduced in comparison with control. Increased contents
of copper and zinc in blood was marked both in vegans and in control group.
The repeated examination of 77 vegans of the same settlement in 1999
has revealed positive alterations in serum lipids: augmentation of cholesterol
of high density lipoproteins on the average on 54.3%, that result in a
reliable decrease of atherogenicity coefficient. The decrease to normal
amounts of blood copper and zinc, and also increase of blood calcium on
the average on 16% was marked. However level of calcium remained below
than physiological values.
Am J Public Health 2000 Oct;90(10):1636-8
The association of dietary folate, B6, and B12 with cardiovascular mortality in Spain: an ecological analysis.
Medrano MJ, Sierra MJ, Almazan J, Olalla MT, Lopez-Abente G. National Centre for Epidemiology, Carlos III Institute of Health, Madrid, Spain. email@example.com
OBJECTIVES: This study assessed the association of dietary folate, vitamin B6, and vitamin B12 with cardiovascular mortality. METHODS: Poisson regression analyses assessed coronary/cerebrovascular mortality rates via nutrient data obtained from the National Nutrition Survey, which recorded 7-day food intakes from a national sample of 21,155 households. RESULTS: In regard to coronary mortality, male and female rate ratios (highest vs lowest quintile) were 0.83 (95% confidence interval [CI] = 0.77, 0.91) and 0.95 (95% CI = 0.86, 1.05), respectively, for folate and 0.74 (95% CI = 0.65, 0.84) and 0.86 (95% CI = 0.73, 0.99), respectively, for B12. Intake of folate and B6 (but not B12) was significantly associated with cerebrovascular mortality. CONCLUSIONS: B vitamins are associated with cardiovascular mortality in the general population.
Am J Clin Nutr 1999 Sep;70(3 Suppl):586S-593S
Dietary intake and biochemical, hematologic, and immune status of vegans compared with nonvegetarians.
Haddad EH, Berk LS, Kettering JD, Hubbard RW, Peters WR Department of Nutrition, School of Public Health, Loma Linda University, CA92350, USA. ehaddad@sph.LLU.edu
Dietary and nutritional status of individuals habitually consuming a vegan diet was evaluated by biochemical, hematologic, and immunologic measures in comparison with a nonvegetarian group. On the basis of 4-d dietary records, the intake of female and male vegans tended to be lower in fat, saturated fat, monounsaturated fat, and cholesterol and higher in dietary fiber than that of vegetarians. With computed food and supplement intakes, vegan diets provided significantly higher amounts of ascorbate, folate, magnesium, copper, and manganese in both female and male participants. The body mass index (BMI; in kg/m(2)) of the vegans was significantly lower than that of the nonvegetarians and 9 of the 25 vegans had a BMI <19. Serum ferritin concentrations were significantly lower in vegan men but iron and zinc status did not differ between the sexes. Mean serum vitamin B-12 and methylmalonic acid concentrations did not differ; however, 10 of the 25 vegans showed a vitamin B-12 deficit manifested by macrocytosis, circulating vitamin B-12 concentrations <150 pmol/L, or serum methylmalonic acid >376 nmol/L. Vegans had significantly lower leukocyte, lymphocyte, and platelet counts and lower concentrations of complement factor 3 and blood urea nitrogen but higher serum albumin concentrations. Vegans did not differ from nonvegetarians in functional immunocompetence assessed as mitogen stimulation or natural killer cell cytotoxic activity.
N Z Med J 1998 Mar 27;111(1062):91-4
The nutritional health of New Zealand vegetarian and non-vegetarian Seventh-day Adventists: selected vitamin, mineral and lipid levels.
Harman SK, Parnell WR. Department of Human Nutrition, University of Otago, Dunedin.
AIM: To determine whether adult non-vegetarian Seventh-day Adventists differ in selected nutrition related health aspects from adult vegetarian Seventh-day Adventists. METHODS: One hundred and forty-one Seventh-day Adventist church members responded to a general health questionnaire. Forty-seven sex and age matched subjects (23 non-vegetarians and 24 vegetarians) were selected for further investigation. Blood lipids, serum vitamin B12, folate, haemoglobin and ferritin levels were measured along with stature, weight and blood pressure. A quantitative 7-day diet record was also completed. RESULTS: Body mass index was similar between the non-vegetarian and vegetarian groups but diastolic blood pressure was higher for non-vegetarian than vegetarian males. Even though the dietary vitamin B12 intake was significantly lower (p < 0.01) in the vegetarian group both vegetarians and non-vegetarians recorded similar serum vitamin B12 levels. The vegetarian and non-vegetarian groups had similar haemoglobin concentrations. While dietary iron intake was higher in the female vegetarian group, though predominantly in the non-haem form, the difference was not significant. Low serum ferritin levels were found in both female dietary groups even though the vegetarian group had a significantly (p < 0.05) higher vitamin C intake. Blood lipid levels were similar in the two diet groups even though the vegetarian group had a lower percentage energy contribution from total and saturated fat (p < 0.01) and consumed significantly less cholesterol. CONCLUSION: Both non-vegetarian and vegetarian Seventh-day Adventists appear likely to enjoy a lower risk of nutrition related chronic degenerative disease than the average New Zealander and have a satisfactory iron and vitamin B12 status.
Tidsskr Nor Laegeforen 1994 Sep 20;114(22):2601-2
[Vegetarians and vitamin B12. A controlled trial of vitamin B12 status in 63 lactovegetarians]. [Article in Norwegian] Solberg EE, Magnus E, Sander J, Loeb M. Medisinsk klinikk, Ulleval sykehus, Oslo.
In this study vitamin B12 status was assessed in 63 adult long-term lactovegetarians and 63 controls. No significant difference in mean plasma levels of vitamin B12 was found between the two groups. In contrast to what might have been expected, the vegetarians showed a slight increase in the vitamin B12 levels with increasing number of years as vegetarians. There was a significant (r = 0.34, p = 0.01) correlation between oral intake of vitamin B12 in the lactovegetarians and the plasma levels of the vitamin. Folate in plasma and whole blood were significantly higher (p < 0.001) in the vegetarian group than in the control group. The findings do not indicate that lactovegetarians risk developing dietary-induced vitamin B12 deficiency.
Int J Vitam Nutr Res 1999 Nov;69(6):412-8
Bioavailability of dried asakusanori (porphyra tenera) as a source of Cobalamin (Vitamin B12). Yamada K, Yamada Y, Fukuda M, Yamada S Department of Liberal Arts and Sciences, School of Health Sciences, Sapporo Medical University, Japan.
We have already reported that raw nori (Porphyra tenera) contains cobalamin (Cbl) but not Cbl analogues (J. Nutr. Sci. Vitaminol., 42, 497, 1996). It seems, therefore, that it is an excellent natural vegetable source of Cbl. On the other hand, it has been reported that the Cbl nutritional status of vegetarian children deteriorated as estimated by the hematological index, mean corpuscular volume (MCV), after they had dried nori as a source of Cbl. Such a discrepancy between raw and dried nori as a source of Cbl led us to investigate whether Cbl in dried nori had different properties from that in raw nori. We found that contents of Cbl homologues determined by a bioassay method in both raw and dried nori were similar. The urinary methylmalonic acid excretion increased when human female volunteers were given 40 g of dried nori daily during the test period. On the other hand, the urinary methylmalonic acid excretion did not change when volunteers were daily given 320 g of raw nori, which was equivalent to 40 g of the dried one on the basis of dehydrated weight, during the test period. By paper chromatography, 65% of the Cbl homologues were found to be comprised of Cbl analogues in dried nori, while 73% of the Cbl homologues in the raw nori were genuine Cbl. These results were confirmed by the finding that the bioassay method gave higher values for Cbl homologues than those obtained by a competitive binding assay method using an intrinsic factor as a Cbl-binding protein. Our present data demonstrated that Cbl in raw nori can be changed into harmful Cbl analogues by the drying process.
J Nutr Sci Vitaminol (Tokyo) 1995 Dec;41(6):587-94
Serum vitamin B12 levels in young vegans who eat brown rice.
Suzuki H Department of Internal Medicine, Social Insurance Institute of Nagahori, Clinic, Osaka, Japan.
A nutritional analysis was conducted on the dietary intake of a group of 6 vegan children aged 7 to 14 who had been living on a vegan diet including brown rice for from 4 to 10 years, and on that of an age-matched control group. In addition, their serum vitamin B12 levels and other data (red blood cell count, hematocrit, hemoglobin, etc.) were determined in the laboratory. In vegans' diets, 2-4 g of nori (dried laver), which contained B12, were consumed daily. Not a single case of symptoms due to B12 deficiency was found. There were no statistically significant differences between the two groups with respect to any of the examination data, including B12 levels (p < 0.05). Therefore, consumption of nori may keep vegans from suffering B12 deficiency.
J Agric Food Chem 1999 Jun;47(6):2341-3
Dried green and purple lavers (Nori) contain substantial amounts of biologically active vitamin B(12) but less of dietary iodine relative to other edible seaweeds.
Watanabe F, Takenaka S, Katsura H, Masumder SA, Abe K, Tamura Y, Nakano Y. Department of Health Science, Kochi Women's University, Japan. firstname.lastname@example.org
Vitamin B(12) concentrations of dried green (Enteromorpha sp.) and purple (Porphyra sp.) lavers (nori) were determined by both Lactobacillus leichmannii ATCC 7830 microbiological and intrinsic factor chemiluminescence methods. The values determined by using the microbiological method (63.58 +/- 2.90 and 32.26 +/- 1.61 microg/100 g of dry weight) were identical to those found by using the chemiluminescence method (69.20 +/- 2.21 and 25.07 +/- 0.54 microg/100 g of dry weight) in both dried green and purple lavers, respectively. A silica gel 60 thin-layer chromatography of both laver extracts shows that non-coenzyme forms (hydroxo and cyano forms) of vitamin B(12) predominate in both dried lavers. The dried lavers contained lesser amounts of dietary iodine ( approximately 4-6 mg/100 g of dry weight) relative to other seaweeds, suggesting that excessive intake of the dried lavers is unlikely to result in harmful intake of dietary iodine. These results indicate that the dried lavers (nori) are the most excellent source of vitamin B(12) among edible seaweeds, especially for strict vegetarians.
J Nutr Sci Vitaminol (Tokyo) 1996 Dec;42(6):497-505
Content and characteristics of vitamin B12 in some seaweeds.
Yamada S, Shibata Y, Takayama M, Narita Y, Sugawara K, Fukuda M. Department of Home Economics, Faculty of Education, Hokkaido University of Education, Sapporo, Japan.
The vitamin B12 (B12) content in seven species of seaweed that are consumed frequently in Hokkaido, Japan, was microbiologically measured using Escherichia coli 215. Asakusanori (Porphyra tenera), maruba-amanori (Porphyra suborbiculata) and akaba-gin-nansou (rhodo-glossum pulcherum) showed higher B12 content than the other species, although the content varied greatly among samples in the same species. A bioautography on a thin-layer plate holding a mixture of silica gel and cellulose, differentiation of B12 and its analogues using a binding specificity of intrinsic factor and haptocorrin, and comparison of the B12 concentration determined by the radioisotope dilution assay method using the intrinsic factor as the B12-binding protein with that by the bioassay method, predominantly showed B12 in maruba-amanori and B12 analogues in wakame (Undaria pinnatifida) and akaba-gin-nansou. The B12 uptake of akaba-gin-nansou from artificial seawater was similar to that of asakusanori that contained only B12.
Ann Nutr Metab 1982;26(4):209-16
Serum vitamin B12 and blood cell values in vegetarians.
Dong A, Scott SC.
Serum vitamin B12 and complete blood count values were determined for 83 volunteer subjects from an American vegetarian society conference (USA). Among subjects who did not supplement their diets with vitamin B12 or multiple vitamin tablets, 92% of the vegans (total vegetarians), 64% of the lactovegetarians, 47% of the lacto-ovovegetarians and 20% of the semivegetarians had serum vitamin B12 levels less than 200 pg/ml (normal = 200-900 pg/ml). However, their complete blood count values did not deviate greatly from those found for nonvegetarians, even though some had been vegans or lactovegetarians for over 10 years. Macrocytosis among the vegetarians was minimal; none had mean corpuscular volume greater than 103 fl.
Vopr Pitan 1998;(3):3-7
[Data from an expedition to study a Siberian vegan settlement]. [Article in Russian] Medkova IL, Manchuk VT, Mosiakina LI, Polivanova TV, Lundina TA, Koroleva-Munts LI
Health status, the way of life and nourishment of 84 vegans in Siberian village (Krasnoyarsk region) were studied and compared with those of 26 meat-eaters. The investigation included work with a questionnaire, clinico-diagnostic and laboratory research. It was shown that a vegetarian diet improves the serum lipid spectrum (cholesterol, LPLD, cholesterol of LPNP, atherogenic coefficient), normalizes weight and cardiovascular system. The vegans had normal levels of vitamin B12 and serum Fe but the calcium level in this group was lowered as compared with the control group. The pathology of internals (nephroptosis, lithic diathesis, tendency to lithogenesis) was observed. Apparently, the high serum Zn levels found in both groups aren't directly caused by the diet but by climate and geographic factors.
J Agric Food Chem 1999 Nov;47(11):4736-41
Pseudovitamin B(12) is the predominant cobamide of an algal health food, spirulina tablets. Watanabe F, Katsura H, Takenaka S, Fujita T, Abe K, Tamura Y, Nakatsuka T, Nakano Y. Department of Health Science, Kochi Women's University, Kochi 780-8515, Japan. email@example.com
The vitamin B(12) concentration of an algal health food, spirulina (Spirulina sp.) tablets, was determined by both Lactobacillus leichmannii ATCC 7830 microbiological and intrinsic factor chemiluminescence methods. The values determined with the microbiological method were approximately 6-9-fold greater in the spirulina tablets than the values determined with the chemiluminescence method. Although most of the vitamin B(12) determined with the microbiological method was derived from various vitamin B(12) substitutive compounds and/or inactive vitamin B(12) analogues, the spirulina contained a small amount of vitamin B(12) active in the binding of the intrinsic factor. Two intrinsic factor active vitamin B(12) analogues (major and minor) were purified from the spirulina tablets and partially characterized. The major (83%) and minor (17%) analogues were identified as pseudovitamin B(12) and vitamin B(12), respectively, as judged from data of TLC, reversed-phase HPLC, (1)H NMR spectroscopy, ultraviolet-visible spectroscopy, and biological activity using L. leichmannii as a test organism and the binding of vitamin B(12) to the intrinsic factor.
Are You Vitamin B12 Deficient?
Nearly two-fifths of the U.S. population may be flirting with marginal vitamin B12 status—that is, if a careful look at nearly 3,000 men and women in the ongoing Framingham (Massachusetts) Offspring Study is any indication. Researchers found that 39 percent of the volunteers have plasma B12 levels in the "low normal" range—below 258 picomoles per liter (pmol/L).
While this is well above the currently accepted deficiency level of 148 pmol/L, some people exhibit neurological symptoms at the upper level of the deficiency range, explains study leader Katherine L. Tucker. She is a nutritional epidemiologist at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston.
"I think there's a lot of undetected vitamin B12 deficiency out there," says Tucker. She noted that nearly 9 percent of the study population fell below the current deficiency level. And more than 16 percent fell below 185 pmol/L. "Many people may be deficient at this level," she says. "There is some question as to what the clinical cutoff for deficiency should be."
Deficiency can cause a type of anemia marked by fewer but larger red blood cells. It can also cause walking and balance disturbances, a loss of vibration sensation, confusion, and, in advanced cases, dementia. The body requires B12 to make the protective coating surrounding the nerves. So inadequate B12 can expose nerves to damage.
Tucker and colleagues wanted to get a sense of B12 levels spanning the adult population because most previous studies have focused on the elderly. That age group was thought to be at higher risk for deficiency. The researchers also expected to find some connection between dietary intake and plasma levels, even though other studies found no association. Some of the results were surprising. The youngest group—the 26 to 49 year olds—had about the same B12 status as the oldest group—65 and up. "We thought that low concentrations of B12 would increase with age," says Tucker. "But we saw a high prevalence of low B12 even among the youngest group."
The good news is that for many people, eating more fortified cereals and dairy products can improve B12 status almost as much as taking supplements containing the vitamin. Supplement use dropped the percentage of volunteers in the danger zone (plasma B12 below 185 pmol/L) from 20 percent to 8. Eating fortified cereals five or more times a week or being among the highest third for dairy intake reduced, by nearly half, the percentage of volunteers in that zone—from 23 and 24 percent, respectively, to 12 and 13 percent.
The researchers found no association between plasma B12 and meat, poultry, and fish intake, even though these foods supply the bulk of B12 in the diet. "It's not because people aren't eating enough meat," Tucker says. "The vitamin isn't getting absorbed." The vitamin is tightly bound to proteins in meat and dairy products and requires high acidity to cut it loose. As we age, we lose the acid-secreting cells in the stomach. But what causes poor absorption in younger adults? Tucker speculates that the high use of antacids may contribute. But why absorption from dairy products appears to be better than from meats is a question that needs more research. Fortified cereals are a different story. She says the vitamin is sprayed on during processing and is "more like what we get in supplements."
—By Judy McBride, Agricultural Research Service Information Staff. This research is part of Human Nutrition, an ARS National Program (#107) described on the World Wide Web. Katherine L. Tucker is at the Jean Mayer USDA-ARS Human Nutrition Research Center on Aging at Tufts University, 711 Washington St., Boston, MA 02111; phone (617) 556-3351, fax (617) 556-3344. [NOTE: Jean Mayer, avid meat-eater, died of heart attack. ljf]
"Are You Vitamin B12 Deficient?" was published in the August 2000 issue of Agricultural Research magazine.
Am J Clin Nutr 2000 Feb;71(2):514-22
Plasma vitamin B-12 concentrations relate to intake source in the Framingham Offspring study. Tucker KL, Rich S, Rosenberg I, Jacques P, Dallal G, Wilson PW, Selhub J. Jean Mayer Human Nutrition Research Center on Aging at Tufts University, Boston MA 02111, USA. firstname.lastname@example.org
BACKGROUND: Low vitamin B-12 status is prevalent among the elderly, but few studies have examined the association between vitamin B-12 status and intake. OBJECTIVE: We hypothesized that vitamin B-12 concentrations vary according to intake source. DESIGN: Plasma concentrations and dietary intakes were assessed cross-sectionally for 2999 subjects in the Framingham Offspring Study. The prevalence of vitamin B-12 concentrations <148, 185, and 258 pmol/L was examined by age group (26-49, 50-64, and 65-83 y), supplement use, and the following food intake sources: fortified breakfast cereal, dairy products, and meat. RESULTS: Thirty-nine percent of subjects had plasma vitamin B-12 concentrations <258 pmol/L, 17% had concentrations <185 pmol/L, and 9% had concentrations <148 pmol/L, with little difference between age groups. Supplement users were significantly less likely than non-supplement-users to have concentrations <185 pmol/L (8% compared with 20%, respectively). Among non-supplement-users, there were significant differences between those who consumed fortified cereal >4 times/wk (12%) and those who consumed no fortified cereal (23%) and between those in the highest and those in the lowest tertile of dairy intake (13% compared with 24%, respectively), but no significant differences by meat tertile. Regression of plasma vitamin B-12 on log of intake, by source, yielded significant slopes for each contributor adjusted for the others. For the total group, b = 40.6 for vitamin B-12 from vitamin supplements. Among non-supplement-users, b = 56.4 for dairy products, 35.2 for cereal, and 16.7 for meat. Only the meat slope differed significantly from the others. CONCLUSIONS: In contrast with previous reports, plasma vitamin B-12 concentrations were associated with vitamin B-12 intake. Use of supplements, fortified cereal, and milk appears to protect against lower concentrations. Further research is needed to investigate possible differences in bioavailability. [NOTE: meat is NOT a good source of B-12. LJF]
Tijdschr Kindergeneeskd. 1985 Dec;53(6):208-16.
[Health and nutritional status of 'alternatively' fed infants and young children, facts and uncertainties. II. Specific nutritional deficiencies; discussion] [Article in Dutch]
Dagnelie PC, Van Staveren WA, Hautvast JG.
This article, which is the second in a series of two articles, discusses available scientific information on the nutritional status of infants and preschool children on alternative diets with regard to calcium, iron, vitamin B12 and D. Some favourable aspects of alternative food habits in such children are also mentioned. Most studies report low intakes of vitamin D and in vegan and macrobiotic children also of calcium and vitamin B12, but it cannot be excluded that some alternative sources of these nutrient may have been missed. Deficiencies have been described for vitamin D and B12 but the evidence is often unconvincing. For example, exposure to sunlight has not been measured in most of the studies on rickets. From the literature available, it would appear that there is a need for longitudinal research on the growth and development of alternatively fed infants and preschool children and for information on the nutrient composition of alternative foods.
Am J Clin Nutr. 1981 Nov;34(11):2464-77.
Nutrient intake and health status of vegans. Chemical analyses of diets using the duplicate portion sampling technique.
Abdulla M, Andersson I, Asp NG, Berthelsen K, Birkhed D, Dencker I, Johansson CG, Jagerstad M, Kolar K, Nair BM, Nilsson-Ehle P, Norden A, Rassner S, Akesson B, Ockerman PA.
A strict vegetarian diet [vegan diet (VD)] was investigated. Six middle-aged vegans (three men and three women) collected copies of 24-h diets using the duplicate portion sampling technique. By chemical analyses, the nutrient composition was determined in detail and compared with corresponding figures of a normal mixed Swedish diet. In the VD 30% of the energy originated from fat compared with 40% in normal Swedish mixed diet (MD). Linoleic acid was the dominant fatty acid (60% of total fat in VD versus 8% in MD). The VD contained 24 g protein/1000 kcal compared to 30 g/1000 kcal in MD, but the intake of essential amino acids by the vegans exceeded the recommendations. Dietary fiber was about 5 times higher in the vegan diet (29 versus 6 g/1000 kcal) and sucrose similar to MD (18 versus 21 g/1000 kcal). Among the inorganic nutrients the concentration of calcium (351 versus 391 mg/1000 kcal) and sodium (53 versus 49 mmol/1000 kcal) were similar in both types of diets but the amount of potassium (56 versus 30 mmol/1000 kcal, magnesium (300 versus 110 mg/1000 kcal), iron (9 versus 6.5 mg/1000 kcal), zinc (6.5 versus 4.7 mg/1000 kcal), and copper (2 versus 0.7 mg/1000 kcal) were nearly doubled. Iodine (39 versus 156 micrograms/1000 kcal and selenium (5 versus 17 micrograms/1000 kcal) were much lower in the VD, selenium even being undetectable in several 24-h diets. The VD was rich in folic acid (301 versus 90 micrograms/1000 kcal in MD) but the intake of vitamin B12 was only 0.3 to 0.4 microgram/day (MD: 3 to 4 micrograms/day). No clinical signs of nutritional deficiency were observed in the vegans. Serum protein levels of the vegans as well as their serum lipoproteins were near the lower range of the reference group. In addition, none of the vegans was overweight and their blood pressures were low for their age.
Nature. 1980 Feb 21;283(5749):781-2.
Vitamin B12 synthesis by human small intestinal bacteria.
Albert MJ, Mathan VI, Baker SJ.
In man, physiological amounts of vitamin B12 (cyanocobalamin) are absorbed by the intrinsic factor mediated mechanism exclusively in the ileum. Human faeces contain appreciable quantities of vitamin B12 or vitamin B12-like material presumably produced by bacteria in the colon, but this is unavailable to the non-coprophagic individual. However, the human small intestine also often harbours a considerable microflora and this is even more extensive in apparently healthy southern Indian subjects. We now show that at least two groups of organisms in the small bowel, Pseudomonas and Klebsiella sp., may synthesise significant amounts of the vitamin.
Ann Intern Med. 1978 May;88(5):647-9. Related Articles, Links
Nutritional vitamin-B12 deficiency. Possible contributory role of subtle vitamin-B12 malabsorption.
Dietary deficiency of vitamin B-12 has been reported, yet most people ingesting vitamin-B12-deficient diets even for many years appear to achieve a balance that does not lead to overt signs and symptoms of deficiency. I present the case of a vegan of 25 years' duration who developed severe neurologic abnormalities due to vitamin-B12 deficiency. His diet provided 1.2 microgram of vitamin B12 daily at most. Despite normal Schilling test findings, he absorbed subnormal amounts of vitamin B12 given with ovalbumin. This poor absorption appeared to be related to his gastritis, achlorhydria, and subnormal intrinsic-factor secretion. Probably, vitamin-B12 deficiency in this patient resulted from both dietary restriction and the subtle malabsorption, neither of which would have sufficed alone to produce the clinical problem. Possibly such malabsorption may also be present in many of those vegans developing overt vitamin-B12 deficiency in whom Schilling test findings have been normal.