Dr. Hunt's research emphasis has been the bioavailability and requirements of calcium, iron and zinc in human nutrition. This work includes the effects of ascorbic acid, meat, and vegetarian diets on iron status; the effects of dietary protein on calcium and zinc utilization and requirements; adaptation in enteric iron and zinc absorption; effective approaches to improve the bioavailability of iron and zinc in human diets; and the effects of inflammation on the regulation of iron absorption and metabolism.
Current research objectives:
Determine the absorption of non-heme iron from menus that meet current dietary guidelines, and use the data to evaluate proposed algorithms for predicting dietary iron absorption.
Compare calcium retention from diets with modifications in meat, grains, fruits and vegetables to result in substantial differences in potential renal acid load.
Determine the influence of inflammatory stress on dietary iron requirements for optimal iron metabolism and immune function.
Determine the role of hepcidin in the regulation of enteric iron absorption by healthy men and women, to distinguish nutritional iron deficiency anemia from inflammatory anemia, and in maintaining antimicrobial defenses.
Found that the 10% of the population that carry (from one parent) the genetic mutation associated with the iron storage disease hemochromatosis did not absorb heme or nonheme iron differently than non-carriers.
Found that the elemental iron powders used for food fortification are 20 to 65% as effective as ferrous sulfate for treating iron deficiency anemia in animals.
Found that daily iron supplementation reduces the efficiency of nonheme, but not heme iron absorption from food by about 36%, even in women with low iron stores.
Demonstrated that men partially adapt to differences in dietary iron bioavailability, but women adapt considerably less. Iron is absorbed in inverse proportion to body iron, but only if the dietary iron is at least moderately bioavailable.
Showed that women of child-bearing age absorbed about 85% less iron and 35% less zinc, but somewhat more copper, from a lacto-ovo-vegetarian, compared with an omnivorous diet.
By conducting studies with complete, practical diets, determined that typical zinc absorption from US diets is 25-30%. Assessed human adaptation in zinc absorption to high and low bioavailability diets, and to zinc supplemented diets; the results helped validate proposed algorithms for estimating zinc absorption.
Demonstrated that ascorbic acid enhances iron absorption and helps correct iron deficiency, but has little influence on iron stores after iron requirements have been met.
Demonstrated that lean meat consumption enhances zinc retention without impairing calcium retention or excessively increasing body iron stores. Further studies with a calcium tracer confirmed that eating meat did not adversely affect body calcium retention.
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