QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Oduho, G. W. Articles by Baker, D. H. Search for Related Content PubMed PubMed Citation Articles by Oduho, G. W. Articles by Baker, D. H.

Iron Deficiency Reduces the Efficacy of Tryptophan as a Niacin Precursor^1,2,

Department of Animal Sciences and Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, IL 61801

A niacin-deficient purified amino acid diet that contained adequate (40 mg/kg) or deficient (10 or 15 mg/kg) iron was used to assess the growth promoting efficacy of tryptophan as a niacin precursor. Basal diets contained 1400 mg/kg tryptophan, a level that was established as meeting the requirement for tryptophan per se in diets containing excess nicotinic acid. Chicks fed the iron-deficient diets had markedly lower hemoglobin concentrations than those fed the iron-adequate diets. Regardless of iron level, chicks exhibited linear growth responses to either nicotinic acid or tryptophan supplementation. Using multiple-linear regression of weight gain on supplemental tryptophan or nicotinic acid intake, the efficiency (wt:wt) of tryptophan conversion to niacin activity (i.e., tryptophan slope ÷ nicotinic acid slope) was a mean of 1.77% (56:1) for chicks fed the iron-deficient diet. This was significantly (P < 0.05) lower than the 2.39% (42:1) efficiency calculated for chicks fed the iron-adequate diet. Thus, iron deficiency reduced tryptophan utilization (for NAD synthesis) but had no effect on nicotinic acid utilization. The results suggest that pellagra in populations having endemic anemia and protein-energy malnutrition may be due not only to inadequate intakes of bioavailable niacin but also to inadequate intakes of bioavailable iron.

KEY WORDS: • chicks • tryptophan • niacin • iron deficiency

¹ Partial funding was provided by Degussa Corp., Allendale, NJ, Nutri-Quest, Chesterfield, MO, Moorman Mfg. Co., Quincy, IL and Ajinomoto, Inc., Tokyo, Japan.

² The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 USC section 1734 solely to indicate this fact.

³ Current address: Animal Science Department, Egerton University, P.O. Box 536, Njoro, Kenya.

⁴ To whom correspondence should be addressed: 290 Animal Sciences Laboratory, 1207 West Gregory Drive, Urbana, IL 61801.

Manuscript received 2 September 1993. Revision accepted 15 November 1993.

This article has been cited by other articles:

				D. H. Baker Animal Models in Nutrition Research J. Nutr., February 1, 2008; 138(2): 391 - 396. [Abstract] [Full Text] [PDF]

				N. R. Augspurger and D. H. Baker Excess Dietary Lysine Increases Growth of Chicks Fed Niacin-Deficient Diets, but Dietary Quinolinic Acid Has No Niacin-Sparing Activity Poult. Sci., February 1, 2007; 86(2): 349 - 355. [Abstract] [Full Text] [PDF]

				D. H. Baker Inaugural Article: Comparative nutrition and metabolism: Explication of open questions with emphasis on protein and amino acids PNAS, December 13, 2005; 102(50): 17897 - 17902. [Abstract] [Full Text] [PDF]