The processes of tryptophan metabolism have many interesting and well documented facets. Much credit is due to Lavel M. Henderson who with his graduate students and post-docs worked out many of the relationships between tryptophan and its metabolites.
History records that in the early days of our Republic, it was discovered that pellagra, a wasting disease occurred in those individuals that consumed diets in which corn was the major ingredient. This should have come as a surprise since corn was a basic ingredient in the diets of American Indians and yet they suffered no ill consequences. Why? Because their diet was varied and contained meats from their hunting activities and beans, squash and pumpkin seeds which also contained some life giving (or disease preventing) substance. When it was discovered that niacin the vitamin could be used to treat pellagra, it came as a surprise that meat and vegetables contain no niacin. What is then contained in these meats and seeds that is niacin like in activity. The answer was found to be tryptophan which is metabolized by the cells to form the vitamin, niacin. So, if one consumes tryptophan in abundance, a niacin deficiency is avoided as is pellagra.
Or the converse when tryptophan is limiting, growth is slowed and a niacin deficiency is produced. Both results can be reversed by the addition of "supplementary" tryptophan to the diet. In fact, if supplementary niacin is added instead of tryptophan, growth improves. This is termed a "sparing action" on the part of niacin.
See the discussion under amino acid imbalances , for more information regarding the interrelationships between tryptophan and other amino acids and how they affect growth and niacin-like deficiencies.
In rats much affects their well being. How so for Homo sapiens? We really don't know, but it is accepted that with the evidence at hand, conversion of tryptophan to niacin would be lessened and pellagra could appear.
So much for rats and pigs and things that go bump in the night. Before you rush into the health store and load your arms with the product of the day, maybe you should think about what is happening to your body. It's the only one that's issued to you and if you don't take care of it, it will be recalled by the maker.
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