Page 124 - Small Animal Clinical Nutrition 5th Edition

Minerals and Vitamins 125

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Figure 6-4. The role of B vitamins in intermediary metabolism.

niacin requirements because tryptophan is the precursor for min deficiency in patients. Pellagra is a classic example, in
that vitamin. which deficiencies of niacin and tryptophan are usually accom-
Finally, certain foods may contain antivitamin activity, for panied by deficiencies of vitamin B and riboflavin.
6
example, thiaminases in tissues of some fresh water fish may Many critical pathways require the concerted action of sever-
deactivate thiamin. al B-complex vitamins (Figure 6-4). For example, one of the
Feeding scientifically based formulas that specifically target key reactions of metabolism is the conversion of pyruvate to
the lifestage, nutrient interaction and disease condition will acetyl-CoA. It is a key reaction because it occurs at the inter-
address changing vitamin requirements. section of glycolysis and the TCA cycle. This pathway point is
critical in the production of energy and the synthesis of fat and
Vitamin Interactions protein. Four different vitamins (niacin, thiamin, pantothenic
Much of the experimental work with vitamin deficiency disease acid and biotin) act as coenzymes in this one enzymatic conver-
has focused on the deficiency of a single vitamin. However, sion. Thus, a deficiency of any one of these four vitamins com-
multiple deficiencies occur more frequently than a single-vita- promises the efficiency of the other three.