Abstract
Energy metabolism is facilitated by exposure to cold because of thermogenesis. However, it is unclear how a low temperature environment affects vitamin B1 requirements. Therefore, in this study, we examined how the requirement for vitamin B1 in rats is increased upon exposure to cold. Rats housed for 14 days at 4ºC showed a 1.1-fold increase in food intake and a 0.6-fold decrease of body weight gain. Hence, the cold environment increased energy expenditure 1.7-fold. Furthermore, these rats had larger brown adipose tissue depots, while urinary excretion of vitamin B1 was decreased 0.5-fold. These results suggest that the requirement for vitamin B1 was increased by cold exposure. We then examined the effects of feeding cold-exposed rats a diet containing the minimum level of vitamin B1, in terms of changes in body weight, in comparison with rats fed a diet containing a sufficient level of vitamin B1. Urinary excretion of vitamin B1 was lower in rats housed for 14 days at 4ºC than at 22ºC. However, no marked changes in body weight were observed. These results indicate that exposure to a low-temperature environment increases energy metabolism, and that the requirement for vitamin B1 also increases.
