The seasonal variation of basal metabolism and activity of thyroid gland in man.

Since Gessler (1) reported a seasonal variation of his own standared metabolism in 1924, this problem has been investigated by many authors. Their opinions are, however, not in complete accord with one another. Most of the American authors (e. g. Tilt (2), Benedict and Carpenter (3), Du Bois (4)) support the view that the basal metabolism is almost constant throughout the year, while many Japanese investigators (e. g. Sirai (5), Fukuda (6), Sasaki (7), Inoue (8), Fukuhara (9)) claim the presence of seasonal variation, i. e. increase in winter, and decrease in summer. Sirai (7) studied the interrelation between his own basal metabolism and the heights of enviromental temperature. It was found that the basal metabolism increased by about 6% as the room temperature fell from 15•Ž. to 5•Ž. Fukuda (6) confirmed Sirai's results and assumed that the findings on Americans differ from those on Japanese because the latter, living in the house with a poor heating plant, have to adapt to the cold of winter by raising their own metabolism, while it is not the case with the former living in a stable temperature even in the winter. It is known in animals that the activity of the thyroid gland increases when the animal is adapted to cold environment. It may, therefore, be presumed that a seasonal variation in the thyroid activity is one of the essential factors causing the seasonal changes of basal metabolism in man. The purpose of the