Isotopic composition, animal food sources

The carbon isotope composition of food ingested by animals is generally reflected in the metabolized products. For example, it is possible to differentiate between animals that have primarily C3 versus C4 diets based on the measurement of the d C value of hair, finger nails, bone collagen, etc. This information is useful in food web studies to determine primary nutrient sources and to discover who is the prey and who the hunter. Nitrogen isotopes are... 

Body water oxygen isotopic composition in mammals is a function of the oxygen mass balance of the specific animal. In general, it can be related to three major oxygen sources air oxygen, drinking water, and food (both the... 

Animal tissues faithfully record the isotopic composition of their food sources (Tieszen et al, 1983 Hobson, 1999), but often are not preserved in the fossil records or are subject to alteration... 

The issue of bioavailability from food sources and the interactions between food groups and copper availability remains a critical question. Lonnerdal et al. demonstrated that heat treatment of cows milk formula decreases the copper bioavailability. Transitional complexes form in the milk upon heating that have a similar configuration to copper and thereby directly inhibit copper absorption. High doses of zinc also reduce copper bioavailability, as does combined iron and zinc supplementation. The dilemma is how to prepare an infant formula containing adequate copper, iron, and zinc that will meet the RDA for copper. Other nutrients dramatically affect copper absorption from foods. Soy protein-based diets promote less copper retention in tissues than lactalbumin-based diets. However, it is unclear if this effect is solely due to the soy protein composition or to the higher zinc in these soy-based formulas. In animals, phytate causes a drop in serum copper but human stable isotope studies reveal no... 

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