A stable isotope study of zinc absorption in young men: effects of phytate and a-cellulose

Abstract

A 63-day study was conducted with young men confined to a metabolic unit to study the effects of a alpha-cellulose and phytate on zinc absorption. A liquid formula diet was used throughout the experiment. During each of three dietary treatments, (basal diet, basal diet + alpha-cellulose, or basal diet + phytate), 67Zn, a stable isotope of zinc, was added to the diets to measure zinc absorption. Zinc absorption was determined by fecal monitoring of 67Zn, measured by thermal ionization mass spectrometry. Analytical precision of all measurements was within 1%. Average zinc absorption was 34.0 +/- 6.2% from the basal diet and 33.8 +/- 2.9% from the diet with 0.5 g alpha-cellulose per kg body weight added. Zinc absorption fell to 17.5 +/- 2.5% when 2.34 g of phytate as sodium phytate were added to the basal diet. The phytate/zinc molar ratio of the diet was 15. The decrease in zinc absorption was accompanied by increased fecal zinc and decreased urinary zinc. The results suggest that phytate inhibits zinc absorption and high levels of dietary phytate could result in zinc deficiency in man.

Influence of germination and fermentation on bioaccessibility of zinc and iron from food grains

“…Unlike iron, a relationship between tannin content of foods and zinc bioaccessibility has not been established so far. The inhibitory effect of phytate on zinc bioavailability in foods has been reported by Oberleas and Harland (1981) and Turnland et al (1984). The absence of any increase in zinc bioaccessibility upon germination of the tested food grains in our study is consistent with a lack of significant reduction of phytate content of these grains.…”

Nutritional status of indigenous children at boarding schools in northern Mexico

“…About one-third of rural children in the NNS did not meet the recommended daily allowances for zinc (Rivera-Dommarco et al, 2001). Although zinc intake was not quantified in our study, the many high-phytate foods served at the schools could in part explain our results, as phytates reduce zinc absorption (Turnlund et al, 1984). This study adds to other evidence that goitre still constitutes a public health problem in certain populations in Mexico (Martínez-Salgado et al, 2002).…”

Complementary foods for infant feeding in developing countries: their nutrient adequacy and improvement

“…It is noteworthy that most of the complementary foods based on cereals have [Phy]:[Zn] molar ratios above 15 (Table 1), a value associated with suboptimal zinc status (Bindra et al, 1986;Turnlund et al, 1984). Notable exceptions are those prepared from rice and dried ®sh (without sesame seeds) (number 16), sago (number 23), or sweet potatoes mixed with dried skim milk powder and egg (number 21) or ®sh (number 22).…”