Nutrient-nutrient interactions in the small intestine

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Molasses and fructose-containing syrups from agricultural crops are increasingly utilized in the diets of humans and of animals in farms and zoos and may have disrupted millions of years of adaptation to a relatively low sugar diet. This drastic increase in dietary sugar content coincidentally parallels dramatic increases in incidence of metabolic bone diseases. No previous study has been able to conceptualize a mechanism underlying the link between excessive intake of sugars and bone health. This investigator?s recent discovery that fructose may inhibit intestinal absorption of calcium, a mineral required to build and maintain bones, now provides a testable explanation of this link between overconsumption of caloric sweeteners and bone disease. Intestinal perfusion, cell culture, mutant mice and dietary manipulations, in combination with molecular biological tools, will be used to examine how and why fructose inhibits intestinal calcium absorption and eventually compromises bone quality. Fructose likely decreases the concentrations of two important compounds. First, it may bind to, then sequester a chemical required as fuel by intestinal transporters that absorb calcium. Second, since fructose is suspected to disrupt kidney function, it may also interfere with the manufacture by kidney cells of a compound required to make these calcium transporters. Findings from this NSF award should ultimately lead to nutritional recommendations that can minimize the impact of increased sugar consumption on bone disease in humans and animals that already cost the US health care system and agricultural/pet industries ~$20 billion annually. This award, which involves collaboration among American, Japanese and French investigators supports the training of four young scientists and provides the opportunity for student teaching of science in inner city high schools.