Author
 |
Hunt, Janet |
|
Roughead, Zamzam |
|
Submitted to: The American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/17/1998 Publication Date: N/A Citation: N/A Interpretive Summary: Iron absorption from vegetarian diets is a concern because these diets eliminate meat, which contains considerable amounts of highly absorbable iron, and because these diets commonly contain more inhibitors of iron absorption, such as phytic acid. Nonheme iron absorption, blood indices of iron status, and fecal ferritin excretion were measured in women consuming controlled lacto-ovo-vegetarian and non-vegetarian diets. Twenty-one women of child-bearing age consumed both weighed diets for 8 wk each. In comparison to the non-vegetarian diet, the lacto-ovo-vegetarian diet contained similar amounts of iron and calcium, about 20% more ascorbic acid from fruits and vegetables, and 3 times as much phytic acid from whole grains and legumes, but no meat, poultry or fish. The results indicated 1) a 70% decrease in nonheme iron absorption from a lacto-ovo-vegetarian diet, 2) an associated decrease in fecal ferritin excretion, suggesting partial physiological adaptation to increase the efficiency of iron absorption, and 3) an insensitivity of blood iron indices, including serum ferritin, to substantial differences in dietary iron absorption for 8 weeks. These findings are consistent with other studies showing that vegetarians have lower body iron stores, but not necessarily a higher risk of anemia or iron deficiency under these dietary conditions. Technical Abstract: Nonheme iron absorption, blood indices of iron status, and fecal ferritin excretion were measured in women consuming controlled lacto-ovo-vegetarian (V) and non-vegetarian (N) diets. Twenty-one women, age 20 to 42 y, with serum ferritin from 6 to 149 ug/L consumed each weighed diet for 8 wk in a cross-over design. The V and N diets provided, respectively, 0 and 184 g meat, 12.6 and 13.6 mg total iron, 0 and 1.2 mg heme iron, 970 and 952 mg Ca, 206 and 170 mg ascorbic acid, 40 and 16 g dietary fiber, and 1656 and 542 mg phytic acid per 9.6 MJ (2000 kcal). Nonheme iron absorption was measured from the whole diets after 4 wk, but using extrinsic Fe-59 and whole body counting. Ferritin was measured by ELISA in 14-d fecal composites and in serum after 7 and 8 wk on each diet. Absorption of nonheme iron was less form the V than from the N diet (1.1 vs. 3.8%, p<0.01, n =10). Diet did not affect hemoglobin, transferrin saturation, erythrocyte protoporphyrin, or serum ferritin. Substantially less fecal ferritin were excreted on the V as compared to the N diet (1.1 vs. 6.0 ug/d, respectively, p<0.01, n=21). This research indicates 1) a 70% decrease in nonheme iron absorption from a lacto-ovo-vegetarian diet, 2) an associated decrease in fecal ferritin excretion, which suggests partial physiological adaptation to increase the efficiency of iron absorption, and 3) an insensitivity of blood iron indices, including serum ferritin, to substantial differences in dietary iron absorption of 8 wk. |
