Effect of oral contraceptive agents on the metabolism of some trace minerals

Abstract

Biochemical and metabolic alterations noted in women taking the oral contraceptive agents have included changes in blood levels of some trace minerals. Only a few of these, namely, iron, copper and zinc, have been studied. This paper intends to review the changes reported and outline the beginning of a series of studies to attempt to determine whether there is any metabolic significance to these alterations. The alterations reported in blood levels are generally believed to be related in large measure to alterations in levels of specific "transport" proteins induced primarily by estrogen. The significance of these changes is generally unknown, however, they involve slight elevations in serum iron and copper and possibly a reduction in serum zinc, although these are not as clear-cut as those of the other two trace minerals. In an attempt to determine whether any metabolic significance could be attributed to these changes, several studies have been instituted. The first, reported in this paper, consisted of a metabolic study on a group of seven women aged 18–32 who had been taking oral contraceptives for at least 3 years. The subjects were studied over four metabolic periods for a total length of 116 days. They were studied in a random fashion, generally 2 months on and 2 months off the pill, although this varied slightly. The subjects were fed a controlled formula diet throughout this study and vitamins and trace minerals, other than copper, iron and zinc, were given orally in capsules. A trace mineral solution was administered so that the total daily iron, copper and zinc could be fed in four equal feedings per day with the formula. Measurements consisted of studies of the blood levels of the trace minerals as well as their binding proteins, various indices of blood chemistry to assess health, hematological indices and total balance studies for each of the trace minerals and nitrogen. The balance studies included not only urine and fecal loss but also skin, menstrual and hair losers. Preliminary results are discussed as well as the formidable problems involved in trace mineral studies in humans. These problems are not only related to contamination but also are analytic in nature.