High- versus low-meat diets: effects on zinc absorption, iron status, and calcium, copper, iron, magnesium, manganese, nitrogen, phosphorus, and zinc balance in postmenopausal women

The effects of three diets--high meat (HM), low meat (LM), or low meat with mineral supplements (LS)--on zinc absorption, elemental balance, and related clinical indexes were investigated in a metabolic study of 14 women aged 51-70 y. The women ate each of the three diets for 7 wk in random order. Lean beef, chicken, ham, and tuna in the HM diet replaced foods with a low mineral content in the LM diet. The LS diet was similar to the HM diet in K, P, Fe, Mg, and Zn contents. Compared with the other diets, the HM diet increased zinc absorption and retention, and slightly increased urinary zinc. Nitrogen and calcium balances and urinary calcium were not different for the HM and LM diets. Iron balance was not different for the HM and LS diets with similar iron content, but the HM diet was unexpectedly associated with lower iron status (higher iron-binding capacity and lower ferritin than LM and LS diets). These results indicate that 0.8 g protein/kg body wt meets protein requirements in older women, and that high meat consumption increases zinc retention without compromising calcium status and may reduce indexes of iron status, in contrast with iron absorption results from studies with radiolabeled test meals.