Influence of obesity and malnutrition on the metabolism of some cancer-related hormones.

It has been suggested that the well-documented relationship of dietary composition to the incidence of human breast cancer is mediated by the effects of dietary constituents on hormone levels. There is fairly good evidence for diet-hormone relationships in animals, but the evidence in humans is unconvincing. In this paper, we describe three of our findings relating nutrition to hormone levels: (a) that obesity causes retention of a tracer of estradiol in women but not in men, a finding we attribute to the presence of specific estrogen receptor in the adipose tissue of women but not men; (b) that obese men have elevated plasma estrone and estradiol levels but obese women do not, a finding we attribute to greater androstenedione-to-estrone conversion in the adipose tissue of men than in that of women; and (c) that cachectic girls with anorexia nervosa fail to have the normal nocturnal surge of prolactin secretion, a finding that we attribute to deficiency of tryptophan, which is an adequate stimulus for prolactin secretion. These findings give support to the concept that dietary factors affect hormone secretion and/or metabolism in humans.