Myth:
Meat is a "good" source of iron.

Iron content
mg/100g edible

Iron content
mg/100g edible

The Heme Iron Problem

     Heme (blood) iron, cancer, and cardiovascular disease.  

     Iron encourages production of free radicals which can damage DNA and presumably increase cancer risk.  In a study of over 14,000 individuals, high iron intake and high iron body stores were both positively linked to the risk of colon cancer.  Higher levels of iron were associated with higher incidence of colon polyps, possible forerunners of colon tumors.  However, cancer patients themselves had low levels of stored iron, indicating that cancer itself can deplete iron stores. [1]

      Controversy has surrounded the question as to whether too much iron in your diet raises your risk for heart disease.  A new study from the Harvard University School of Public Health brings new insight to the debate.  Lasting for 4 years, this research involved more than 50,000 male health professionals.  It was found that total iron intake was not associated with heart disease risk.  But the source of the iron came was the principle factor.  High levels of heme iron raised risk for heart disease twofold.  Heme iron is the type of iron found in meat, chicken and fish.
     Plant foods contain non-heme iron which appears to not be associated with risk for heart attack.  Traditionally, many nutritionists used to consider non-heme iron to be inferior to the iron found in animal products, because non-heme iron is somewhat less well absorbed.  But new evidence suggests that non-heme iron seems to be preferable.  
      When the body is low in iron, it can increase absorption of non-heme iron, and it can reduce adsorption when it already has sufficient amounts.  The heme iron in meats tends to pass quickly right through the adsorption mechanism, thus entering the blood stream whether it is needed or not.  Since vegetarians generally have adequate iron intake, it is clear that non-heme iron can easily meet nutritional needs.  Also, plant iron doesn't create the health risks of heme iron.  
      Iron increases heart disease risks because heme iron acts as a pro-oxidant, causing LDL-cholesterol -- the 'bad' cholesterol -- to react with oxygen.  This reaction is involved in the formation of plaques in the arteries and therefore increases one's risk of cardiovascular problems. [2]

[1] Nelson, Davis, Suffer, Sobin, Kikeenddl, Bowen. Body iron stores and risk of colonic neoplasia. J Natl Canc Inst 1994; 86:455-60

[2] Ascherio, Willett, Rimm, Giovannucci, Stampger. Dietary iron intake and risk of coronary disease among men. Circulation 1994; 89:969-74

  BACKGROUND AND OBJECTIVES: From 1954 to 1987, flour in Denmark was fortified with 30 mg carbonyl iron per kg. This mandatory fortification was abolished in 1987. The aim of this study was to compare iron status in Danish men before and after abolition of iron fortification.
  METHODS: Iron status (serum ferritin, haemoglobin), was assessed in population surveys in Copenhagen County during 1983-84 comprising 1324 Caucasian men (1024 non-blood-donors, 300 blood donors) and in 1993-94 comprising 1288 Caucasian men (1103 non-blood-donors, 185 donors), equally distributed in age cohorts of 40, 50, 60 and 70 yr.
  RESULTS: In the 1984 survey median serum ferritin values in the four age cohorts in non-blood-donors were 136, 141, 133 and 111 microg/L, and in the 1994 survey 177, 173, 186 and 148 microg L(-1), respectively. The difference was significant in all age groups (P<0.001). There was no significant difference between the two surveys concerning the prevalence of small iron stores (ferritin 16-32 micro g L(-1)), depleted iron stores (ferritin <16 microg L(-1)) or iron-deficiency anaemia (ferritin <13 microg L(-1) and Hb <5th percentile for iron-replete men). However, from 1984 to 1994, the prevalence of iron overload (ferritin >300 microg L(-1)) increased from 11.3% to 18.9% (P<0.0001). During the study period there was an increase in body mass index (P<0.0001), alcohol consumption (P<0.03) and use of non-steroid anti-inflammatory drugs (NSAID) (P<0.0001), and a decrease in the use of vitamin-mineral supplements (P<0.04) and in the prevalence of tobacco smoking (P<0.0001). In contrast, median ferritin in blood donors showed a significant fall from 1984 to 1994 (103 vs. 74 micro g L(-1), P<0.02).
  CONCLUSION: Abolition of iron fortification reduced the iron content of the Danish diet by an average of 0.24 mg MJ(-1), and the median dietary iron intake in men from 17 to 12 mg d(-1). From 1984 to 1994, body iron stores and the prevalence of iron overload in Danish men increased significantly, despite the abolition of food iron fortification. The reason appears to be changes in dietary habits, with a lower consumption of dairy products and eggs, which inhibit iron absorption, and a higher consumption of alcohol, meat, and poultry, containing haem iron and enhancing iron absorption. The high prevalence of iron overload in men may constitute a health risk.

PMID: 12225390

  BACKGROUND: We were interested in identifying possible nutritional reasons for growth faltering among breastfed infants in the rural farming community of San Mateo, Capulhuac, Mexico (2800 m above sea level).
  OBJECTIVE: We examined the prevalence of inadequate iron and folate status among lactating Otomi women and determined to what extent their iron and folate nutriture influenced the milk concentrations of these nutrients.
  DESIGN: Lactating women (n = 71) provided blood and milk samples and dietary information at a mean (+/- SD) of 22 +/- 13 d postpartum. Blood indexes included hemoglobin, hematocrit, serum iron, total-iron-binding capacity, ferritin, transferrin receptor, mean cell volume, plasma folate, and erythrocyte folate.
  RESULTS: Approximately 62% and 58% of the women had nutritional anemia defined as a hemoglobin concentration Milk iron content was unrelated to maternal iron status, and the milk provided more than adequate amounts of iron to the infants. In contrast, the infants' predicted folate intake was approximately 45 micro g/d, or 70% of the current recommended intake.
  CONCLUSION: Milk folate concentrations in Otomi women are low and may not support optimal folate status in all breastfed infants.

PMID: 14522737

  Iron may induce oxidative damage to the intestinal mucosa by its catalyzing role in the formation of highly reactive hydroxyl radicals. This study aimed to determine iron-induced oxidative damage provoked by a single clinical dosage of ferrous sulfate and to elucidate the antioxidant defense mechanisms in the human small intestine in vivo. A double-lumen perfusion tube was positioned orogastrically into a 40-cm segment of the proximal small intestine in six healthy volunteers (25 +/- 5 yr). The segment was perfused with saline and subsequently with saline containing 80 mg iron as ferrous sulfate at a rate of 10 ml/min. Intestinal fluid samples were collected at 15-min intervals. Thiobarbituric acid reactive substances concentrations as an indicator of lipid peroxidation increased significantly from 0.07 microM (range, 0-0.33 microM) during saline perfusion to 3.35 microM (range, 1.19-7.27 microM) during iron perfusion (P < 0.05). Nonprotein antioxidant capacity increased significantly from 474 microM (range, 162-748 microM) to 1,314 microM (range, 674-1,542 microM) (P < 0.05). These data show that a single dosage of ferrous sulfate induces oxidative damage and the subsequent release of an antioxidant in the small intestine in vivo in healthy volunteers.

PMID: 12724133

  Iron status is not an unusual concern for current as well as potential vegetarians since meat, a strong iron source, must be replaced by other foods. In the previous piece researchers Wells, Haub, Fluckey, Williams, Chernoff, and Campbell compared the iron status of older men consuming a vegetarian (lacto-ovo) diet to those consuming a beef diet. The 21 men, aged 59 to 78 years and having a BMI range of 24 to 33 kg/[m.sup.2], were observed over 12 weeks while resistive training.
  These results suggest that a beef-containing diet may better maintain or improve hematological indexes during resistive training," the researchers say, adding that it "should be noted that the [v]egitarian group's hematological profile was maintained within normal ranges and did not decline over time with resistance training and continued consumption of a meat-free diet."
  "That's basically the take home message: vegetarian diets aren't automatically going to lead to poor iron status," says Enette Larson-Myer PhD, assistant professor of Health and Performance Enhancement at Pennington Biomedical Research Center in Baton Rouge, LA.
  However, Larson-Myer says that the research does give a word of advice for vegetarians. "I think they suggest that vegetarians need to be a little bit more cautious in their iron choices or in the foods that they consume along with their iron sources.
  " For example, she says vegetarians should add a glass of citrus juice or another organic acid during the meal to facilitate iron absorption and avoid tea or other drinks that inhibit iron absorption. Larson-Myer, who is also Director of the Pennington Nutrition and Exercise Lab, says that "when working with vegetarian athletes, always urge them to increase a variety of good sources of iron: cereals, organic acids, legumes... to help insure that any iron in that meal facilitates absorption.
  Reed Mangels PhD, RD, FADA, Nutrition Advisor for the nonprofit Baltimore, MD-based Vegetarian Resource Group, found two major points in the results. "One, it would reassure dietitians that people with vegetarian diets with adequate iron can maintain a normal hematological profile. Secondly, that a vegetarian diet may offer some advantages to older men because of lower fat intake on this partially self-selecting vegetarian diet group."
  For Mangels, whose organization publishes the quarterly magazine The Vegetarian Journal, it is a comfort to hear positive results regarding vegetarians and iron.
  "As you look at this study, it's interesting how everything really stayed within the normal range. It's reassuring," Mangels says. "There's this old myth that vegetarians don't get enough iron and can't absorb it as well, and here's this research saying that both [vegetarian and non-vegetarian] groups are getting the iron they need."

  Pregnancy, mostly because of the mitochondria-rich placenta, is a condition that favors oxidative stress. Transitional metals, especially iron, which is particularly abundant in the placenta, are important in the production of free radicals. Protective mechanisms against free radical generation and damage increase throughout pregnancy and protect the fetus, which, however, is subjected to a degree of oxidative stress. Oxidative stress peaks by the second trimester of pregnancy, ending what appears to be a vulnerable period for fetal health and gestational progress. Conditions restricted to pregnancy, such as gestational hypertension, insulin resistance and diabetes, exhibit exaggerated indications of free radical damage. Antioxidants as well as avoidance of iron excess ameliorate maternal and early fetal damage. In rats both iron deficiency and excess result in free radical mitochondrial damage. Estimates of gestational iron requirements and of the proportion of iron absorbed from different iron supplemental doses suggest that with present supplementation schemes the intestinal mucosal cells are constantly exposed to unabsorbed iron excess and oxidative stress. Unpublished work carried out in Mexico City with nonanemic women at midpregnancy indicates that 60 mg/d of iron increases the risk of hemoconcentration, low birth weight and premature birth and produces a progressive decline in plasma copper. These risks are not observed in women supplemented with 120 mg iron once or twice per week. Studies on the influence of iron supplementation schemes on oxidative stress are needed. [Note: the Life Extension Foundation removed iron from their supplements when information of this type first became available - ljf.]

PMID: 12730487

  OBJECTIVE: To test the hypothesis that older men who consumed a vegetarian (lacto-ovo) diet would develop a lower iron status compared with older men who consumed a beef-containing diet during a period of resistive training (RT).
  DESIGN: Experimental, repeated measures study.
  SUBJECTS: Twenty-one healthy men aged 59 to 78 years, with a BMI range of 24 to 33 kg/m(2), completed the study.
  INTERVENTION: All men consumed a vegetarian diet for 2 weeks (baseline). After this, the men were randomly assigned to one of two dietary groups. Eleven men consumed a beef-containing diet, and 10 men continued to consume a vegetarian diet for 12 weeks. During this time all subjects participated in RT three days per week, designated as RT1 to RT12.
  MAIN OUTCOME MEASURES: Serum ferritin and serum iron concentrations, transferrin saturation, transferrin receptor, total iron binding capacity, and selected hematological variables, as well as selected nutrient intakes and estimated iron bioavailability from three-day diet records, were determined at baseline, RT5, and RT12.
  STATISTICAL ANALYSES: A general linear model repeated-measures ANOVA was used to examine the effects of group, time, and group x time interactions for iron status and dietary data.
  RESULTS: Total iron intake was not different between the two groups; however, the beef group had a three to four times greater intake of bioavailable iron (P<.01) than the vegetarian group. Serum iron, total iron binding capacity, transferrin saturation, and transferrin receptor were not significantly different between the beef and vegetarian groups, or changed over time with RT. Serum ferritin decreased over time in both the beef and vegetarian groups during RT (P<.01). Re-introduction of beef into the diets of the beef group increased hemoglobin concentration and hematocrit compared with the vegetarian group during the 12 weeks of RT (group x time, P<.05). These changes were within clinically normal limits.
  APPLICATIONS/CONCLUSIONS: Older men who consume a beef-containing, higher-bioavailable-iron diet, compared with a vegetarian, lower-bioavailable-iron diet, have an increased hematological profile during a 12-week period of RT. Older men who consume either a beef-containing or a vegetarian diet maintain a hematological profile within clinically normal limits during 12 weeks of RT.

PMID: 12728219

  OBJECTIVE: To test the hypothesis that older men who consumed a vegetarian (lacto-ovo) diet would develop a lower iron status compared with older men who consumed a beef-containing diet during a period of resistive training (RT).
  DESIGN: Experimental, repeated measures study.
  SUBJECTS: Twenty-one healthy men aged 59 to 78 years, with a BMI range of 24 to 33 kg/m(2), completed the study.
  INTERVENTION: All men consumed a vegetarian diet for 2 weeks (baseline). After this, the men were randomly assigned to one of two dietary groups. Eleven men consumed a beef-containing diet, and 10 men continued to consume a vegetarian diet for 12 weeks. During this time all subjects participated in RT three days per week, designated as RT1 to RT12.
  MAIN OUTCOME MEASURES: Serum ferritin and serum iron concentrations, transferrin saturation, transferrin receptor, total iron binding capacity, and selected hematological variables, as well as selected nutrient intakes and estimated iron bioavailability from three-day diet records, were determined at baseline, RT5, and RT12.
  STATISTICAL ANALYSES: A general linear model repeated-measures ANOVA was used to examine the effects of group, time, and group x time interactions for iron status and dietary data.
  RESULTS: Total iron intake was not different between the two groups; however, the beef group had a three to four times greater intake of bioavailable iron (P<.01) than the vegetarian group. Serum iron, total iron binding capacity, transferrin saturation, and transferrin receptor were not significantly different between the beef and vegetarian groups, or changed over time with RT. [So where is the effect of the alleged "greater intake of bioavailable iron"? - ljf] Serum ferritin decreased over time in both the beef and vegetarian groups during RT (P<.01). Re-introduction of beef into the diets of the beef group increased hemoglobin concentration and hematocrit compared with the vegetarian group during the 12 weeks of RT (group x time, P<.05). These changes were within clinically normal limits.
  APPLICATIONS/CONCLUSIONS: Older men who consume a beef-containing, higher-bioavailable-iron diet, compared with a vegetarian, lower-bioavailable-iron diet, have an increased hematological profile during a 12-week period of RT. Older men who consume either a beef-containing or a vegetarian diet maintain a hematological profile within clinically normal limits during 12 weeks of RT.

PMID: 12728219

  With reduced intake of meat and increased intake of phytate-containing legumes and whole grains, movement toward plant-based diets reduces dietary iron and zinc absorption. Although vegetarians have lower iron stores, adverse health effects of lower iron and zinc absorption have not been demonstrated with varied, plant-based diets consumed in developed countries. Improved assessment methods and monitoring are needed to detect and prevent possible iron and zinc deficiency with plant-based diets.

PMID: 12030275

  BACKGROUND: Despite the possible overall health benefits of a vegetarian diet, there is concern that some vegetarians and infrequent meat eaters, particularly females, may have inadequate iron status because of low or no heme-iron intakes.
  OBJECTIVE: The objective was to investigate the nutritional intake and iron status of vegetarian women.
  DESIGN: The nutritional intakes of 50 free-living vegetarian women aged 18-45 y and 24 age-matched omnivorous control women were assessed by using 12-d weighed dietary records. Iron status was assessed by measuring hemoglobin and serum ferritin concentrations.
  RESULTS: There was no significant difference between mean (+/-SD) daily iron intakes of vegetarians and omnivores (10.7 +/- 4.4 and 9.9 +/- 2.9 mg, respectively), although heme-iron intakes were low in the vegetarians. Vegetarians had significantly lower intakes of protein (P < 0.01), saturated fat (P < 0.01), and cholesterol (P < 0.001), and significantly higher intakes of dietary fiber (P < 0.001) and vitamin C (P < 0.05). Mean serum ferritin concentrations were significantly lower (P = 0.025) in vegetarians (25.0 +/- 16.2 microg/L) than in omnivores (45.5 +/- 42.5 microg/L). However, similar numbers of vegetarians (18%) and omnivores (13%) had serum ferritin concentrations <12 microg/L, which is a value often used as an indicator of low iron stores. Hemoglobin concentrations were not significantly different.
  CONCLUSION: It is important that both vegetarian and omnivorous women maintain an adequate iron status and follow dietary practices that enhance iron absorption.

PMID: 10479197