Women in Western countries are urged to consume dairy products to enhance calcium intake to reduce the risk of osteoporosis. As a result, intake of lactose (the major carbohydrate in dairy products) is substantial. Since half of the lactose molecule is galactose, dietary galactose intake can reach 5-20 g/day. A role for galactose in ovarian toxicity is evidenced by the well-recognized early ovarian failure in young women with galactosemia, and studies showing earlier age of menopause and increased incidence of ovarian cancer in women with partial deficiency of the same enzyme on high galactose diets. Our own previous study of perimenopausal women showed that the degree of elevation of FSH (as a marker of ovarian senescence) was associated wight the level of intake of galactose irrespective of the level of transferase enzyme. Ovarian failure leads to a drastic decline in estrogen levels, and, in turn, low estrogen levels lead to vasomotor symptoms, progression of coronary artery atherosclerosis, osteoporosis, urogenital atrophy and possible cognitive dysfunction. If adult dietary galactose intake hastens ultimate ovarian failure or reduces ovarian function prior to menopause per se, these age- associated diseases will be increased. Thus, women ingesting large amounts of galactose may unknowingly foreshorten the functional life span of their ovaries. Women who consume large quantities of dairy products to increase calcium intake for osteoporosis prevention may actually exacerbate osteoporosis, and other serious estrogen deficiency diseases if their diet concurrently advances ovarian failure or inhibits normal ovarian function prior to ultimate ovarian failure. To address this important public health concern, we propose to study the effects of dietary galactose exposure in adult female rats. We will determine the effect of different levels of galactose on ovarian cyclicity, rate of ovarian follicular depletion, and onset of acyclicity (reproductive senescence). Dietary advice to women may drastically change. Decreased intake of lactose-rich foods (primarily dairy products) and increased alternative sources of dietary calcium may have to be advocated to maintain a normal reproductive life span and to prevent an increased risk of chronic diseases later in life.
