The Absorption of Iron from Spinach by Six Young Women, and the Effect of Beef Upon the Absorption

Abstract

Data are presented for the intake and fecal excretion of iron by 6 young women on three controlled diets. More iron was found in the feces of two subjects for one 4-week period than was in the diet; reasons are given for not including these data in evaluating the performance of the group. The mean amount of iron absorbed daily by the remaining 4 young women over a period of 8 weeks from 120 gm of cooked spinach containing 5.04 mg of iron was found to be 0.66 ± 0.248 mg, or 13% of the amount present. Since this percentage compares favorably with the percentage of iron absorbed from diets composed of a wide variety of foods, and since the iron content of spinach is higher than that of a majority of foods, spinach may be regarded as a valuable source of iron for young women. The mean absorption of iron was greater in the period when the spinach was fed in the presence of beef for 4 of the 5 subjects on whom data were obtained. The difference in the amount of iron absorbed from the spinach when fed away from or in the presence of beef was not statistically significant, however, and on the basis of the data obtained in this study beef cannot be said to increase the amount of iron absorbed from spinach. The total amount of iron absorbed from the 6.44 mg of iron in the basal diet and from the 11.51 mg in the basal diet with spinach added was estimated to be 12% in each case. This estimate is somewhat low if the feces contain a measurable quantity of iron from unreabsorbed bile and sloughed-off cells from the intestine. A possible relationship between the menstrual cycle and iron absorption is suggested by the limited data obtained.