Submitted to: Recommended Dietary Allowances Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 9/10/1995
Publication Date: N/A
Technical Abstract: To evaluate the effect of a vegetarian diet on Fe and Zn bioavailability, the absorption of nonheme Fe and of Zn were determined in women consuming a lacto-ovo-vegetarian (V) and a nonvegetarian (N) diet under controlled feeding conditions. Twenty-one women, age 33 +/- 7 (20 to 42 yr), with serum ferritin from 6 to 149 ug/L consumed both diets for 8 wk each in a cross-over design. The N diet provided 40 g chicken and 120 g beef per 2000 kcal (8.4 MJ). The V and N diets provided, respectively, 9.7 and 11.1 mg total Fe, 0 and 1 mg heme Fe , 8.2 and 9.3 mg Zn, 872 and 888 mg Ca (analyzed), 12 and 16 % protein, 30 and 34 % fat, 58 and 50 % carbohydrate, 179 and 147 mg ascorbic acid, 35 and 14 g dietary fiber, and 1440 and 471 mg phytic acid (calculated) per 2000 kcal, with phytate: Zn molar ratios of 17 and 5, and phytate X Ca: Zn molar ratios of 379 and 111. Four wk into each diet, the entire 2-d menu cycle was labeled with either 59-Fe or 65-Zn and retention of nonheme Fe or of Zn was determined by whole body counting. Serum ferritin and plasma Zn were measured after 7 and 8 wk on each diet. Blood sampling was < 30 mL per diet period. Absorption of nonheme Fe (1.1 vs 3.8%, p < 0.001 , n = 10) and of Zn (26 vs 33%, p < 0.01, n = 11) were less from the V than from the N diet. Indexes of Fe status (hemoglobin, transferrin saturation, RBC, protoporphyrin, and ferritin) did not differ between the V and N diets (ferritin 33 vs 32 ug/L, NS, n = 20). Plasma Zn was less on the V than the N diet (13.9 vs 14.7 umol/L, p < 0.02, n = 21). These results indicate reduced absorption of both Fe and Zn from a lacto-ovo-vegetarian diet, but also emphasize the relative insensitivity of Fe indexes to changes in dietary Fe bioavailability.