Skip to main content
ARS Home » Plains Area » Grand Forks, North Dakota » Grand Forks Human Nutrition Research Center » Dietary Prevention of Obesity-related Disease Research » Research » Publications at this Location » Publication #63834
Title: IDIORHYTHMIC DOSE-RATE VARIABILITY IN DIETARY ZINC INTAKE GENERATES A DIFFERENT RESPONSE PATTERN OF ZINC METABOLISM THAN CONVENTIONAL DOSE- RESPONSE FEEDING

Author
item MOMCILOVIC, BERISLAV - UNIV OF ZAGREB
item Reeves, Phillip
item BLAKE, MICHAEL - UND

Submitted to: British Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Human daily intake of zinc varies considerably depending upon eating habits, seasonal availability, and affordability of foods. The consequences of such a variability on nutrient metabolism in our body are mostly unknown. In this experiment we used a recently developed experimental feeding design which is sensitive to time, and is called idiorrhythmic. It shows that the efficiency with which we handle nutrients depends upon the quality and quantity of the nutrients in the diet as well as upon when we eat the nutrient, zinc in this case. We observed that coupling the amount of zinc in the diet with when an animal eats the diet in a regularly recurring pattern, had a profound effect on the deposition of zinc in bone and teeth without increasing the production of intestinal metallothionein, a small protein considered to be involved in the absorption of zinc. The results of this study are an important contribution to our understanding of how an intake of zinc exceeding the amount thought to be required, may compensate for a previously low intake.

Technical Abstract: We studied the metabolic consequences of variability in zinc intake upon the intestinal metallothionein (iMT) induction, aortal restrain stress- induced (ars-i) heat shock protein 70 (HSP70mRNA) expression, and zinc deposition in the femur and incisor of weanling male rats with idiorrhythmic dose-rate feeding (IRF), and compared them to those when graded amounts of zinc were fed daily (DF). In IRF the dose (x) is viewed over the time of the entire experimental epoch as a dose-time equivalent modulo (Mx) which can be divided into a series of equal products of different dose and different frequency (idiorrhythm, Ix) and administered in a regularly recurring pattern to deliver the same dose as DF, albeit at a different rate. Four different Mx were tested, M3, M6, M12, and M24 providing 3, 6, 12, and 24 mg Zn.kg**-1.d**-1 (DZn) over the 24 day epoch, each Mx had 7 analogous Ix where zinc dosing days were separated by 1-7 days of feeding the diet without zinc. In DF, calcified tissues reacted as an ultra sensitive switch with a break-point at 13.7 and 14.4 DZn for the femur and incisor, the 1n(iMT) increased linearly with dietary 1n(Zn), and ars-i HSP70mRNA expression was depressed in 3 DZn fed animals. IRF affected zinc deposition in the calcified tissues in a complex Mx and Ix dependant pattern, showing the secondary peak when zinc was dosed every 5th and 6th day, and without a change in iMT induction and ars-i HSP70mRNA expression. Dose-rate is a powerful infradian cycle, co-dependent modifier of zinc metabolism, an asset to cope with nutritionally stohastic environment.