The Body Vitamin B1 Levels of Rats Fed a Diet Containing the Minimum Requirement of Vitamin B1 Is Reduced by Exercise

It is thought that increasing energy expenditure increases consumption of vitamin B-1, leading to an increase in the requirement of vitamin B-1. However, evidence supporting this hypothesis is lacking. To examine the hypothesis, initially, we determined the minimum requirement of vitamin B-1 for weaning rats. We found that the minimum requirement of vitamin B-1 for optimum growth of weaning rats was around 0.786 mg thiamin/kg diet. Next, rats fed a diet containing the minimum requirement of vitamin B-1 were forced to swim until exhaustion. Concentrations of vitamin B-1 in the blood and liver as well as urinary excretion of swimming rats decreased significantly compared with those of non-swimming rats (p<0.05), while in rats fed the diet containing a sufficient amount of vitamin B-1 (4.720 mg thiamin/kg diet), vitamin B-1 amounts in the blood, liver and urine were not affected by swimming. We clearly and firstly showed the reduction of body vitamin B-1 following increases in energy expenditure.