Effects of a progestogen and a sequential type oral contraceptive on plasma vitamin A, vitamin E, cholesterol and triglycerides1

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1 original communications Effects of a progestogen and a sequential type oral contraceptive on plasma vitamin A, vitamin E, cholesterol and triglycerides1 D. L. Yeung, Ph.D.,2 and P. L. Chan, M.D., M.R.C.O.G., F.RC.S. (C)3 ABSTRACT Fasting blood samples were taken from 13 college students who had never been on oral contraceptives in two mentrual cycles. During the first cycle, the control cycle, each girl donated three blood samples: the first sample was given between days I and 5, the second sample between days 13 and 17, and the third sample between days 22 and 26 of the menstrual cycle. In the second menstrual cycle, the experimental cycle, nine girls were given Micronor, a progestogen type oral contraceptive and four girls were given Ortho-Novum SQ. a sequential type oral contraceptive. Four blood samples were obtained from each of the subjects: the first three samples were obtained in the three periods corresponding to those in the control cycle, and the fourth was taken 2 days after the subjects had stopped taking the oral contraceptives. Results showed that estrogen significantly raised plasma vitamin A and triglycerides. The progestogen, at low concentration, had little or no effect on these two lipid materials. At a higher concentration the progestogen enhanced the effect of the estrogen on plasma vitamin A and triglycerides. These effects were extended to at least 2 days after the subjects had ceased taking the oral contraceptive. Plasma vitamin E levels in the subjects given Ortho-Novum SQ. were consistently but not statistically higher in the experimental cycle than in the control cycle. The correlation coefficient between vitamin E and triglycerides was statistically significant while those between the vitamin A and vitamin E and between vitamin A and triglycerides were not. Cholesterol was not affected by either Micronor or Ortho-Novum SQ. Am.J. Chin. Nutr. 28: , A number of reports on the effects of oral contraceptives (OC) on serum or plasma lipids have appeared in the literature. In studies using estrogen containing OC, total serum lipids, fatty acids, phospholipids cholesterol and triglycerides have been found to be higher in subjects on the pill than in control subjects (1-8). These changes are apparently estrogen induced. Females using the combined preparations have also been shown to have raised levels of serum or plasma vitamin A (9-Il). It has been postulated that the effect of OC on vitamin A is due to the progestogen as there appeared to be some correlations between the progestogen content of the pill and vitamin A levels (9). However, there are no data to substantiate this suggestion. Heretofore, there has been no report of the effects of OC on vitamin E. Thus the objectives of this study were 1) to determine whether the rise in plasma vitamin A was due to progestogen as postulated by Gal and co-workers, 2) to examine the level of vitamin E, and 3) to determine possible relationship between these two vitamins and plasma triglycerides and cholesterol in subjects taking OC. Materials and method Treatment of subjects Thirteen healthy University of Guelph female students between the ages of 19 and 22 who had never been on OC participated in this study. Initial interviews with these Supported by Sunnybrooke Hospital Research Fund Department of Family Studies. University of 2 Guelph. Guelph. Ontario, Canda. Consultant in Obstetrics and Gynaecology, Sunnybrooke Hospital, University of Toronto Clinic, Toronto, Ontario, Canada. 686 The American Journal of Clinical Nutrition 28: JULY 1975 pp Printed in U.S.A.

2 PROGESTOGEN AND ORAL CONTRACEPTIVE EFFECTS 687 students indicated that they were neither habitual smokers nor drug users. During the experimental period none of the subjects was on any form of medication or on vitamin therapy. The subjects were asked to donate blood samples in two menstrual cycles. During the first cycle no OC was prescribed. During the second cycle nine subjects were provided with Micronor for 35 days. Because of clinical problems one subject of this group had to drop out during the latter part of the second cycle. The remaining four subjects were provided with Ortho-Novum SQ for 21 days. In this way the subjects served as their own controls. Micronor contains 0.35 mg norethindrone as its sole ingredient. This preparation is taken daily as of day I of the menstrual cycle. Ortho-Novum SQ is a sequential type OC. It is taken beginning on the 5th day of the menstrual cycle: from day 5 to l8 the preparation contains 0.08 mg mestranol and from day 19 to 26 it contains 0.08 mg mestranol and 2.0 mg norethindrone. All the subjects were instructed to take the pill at the same time each evening. Throughout the study no dietary restrictions were imposed. In this experiment no dietary record was taken since Yeung (I I) has observed no relationship between the level of fasting plasma vitamin A and dietary vitamin A intake of the day before blood collection. Collection of samples At three intervals during each of the two menstrual cycles fasting venous blood samples were taken from the subjects before 10 AM. The intervals were chosen to coincide with the steroid regimen in the sequential pill. Thus the first blood sample was taken between day I and 5 (phase I). the second between days 13 and 17 (phase II) and the third between days 22 and 26 (phase Ill). An additional blood sample was obtained from each subject 2 days after the subjects had stopped taking the pill (phase IV). Biochemical anal vses Blood was collected in heparinized tubes. Upon removing aliquots for hematocrit determination, the blood was centrifuged and the plasma stored at - 15C for not more than 2 weeks before biochemical analyses. Plasma vitamins A and E were determined spectrofluorometrically according to Thompson et al. (12). Plasma carotene was measured by the method described by Neeld and Pearson (13). Plasma triglycerides were analyzed using a Technicon AutoAnalyzer (14). Cholesterol was determined by the method of Pearson et al. (15). Results Plasma vitamin A There was no change in hematocrit values before and after the subjects were given the OC. As apparent in Fig. I, there was no statistical difference in the plasma vitamin A levels in subjects given Micronor between the control and experimental phases. In subjects given Ortho-Novum SQ the plasma vitamin A levels were significantly raised in phase II, further raised in phase III and were maintained at the higher level in phase IV. These results indicated that mestranol significantly raised the level of plasma vitamin A, norethindrone alone in small dosage had no effect but when norethindrone was taken, at a higher dosage, with mestranol it appeared to enhance the estrogen effect on plasma vitamin A. Figure 1 also shows that neither mestranol, norethindrone nor the combination of these two steroids had any significant effect on plasma carotene. This confirms earlier observations in our laboratory (11) Statistical anal vses 180 Significance of the differences between means were calculated by Student s t-tests. Statistical analysis using paired observations was not carried out because samples obtained from each subject during each experimental phase were not matched for days in the menstrual cycles. The authors also recognized cyclic fluctuation of plasma vitamin A and cholesterol in the menstrual cycle (16). Relations between parameters were tested by correlation coefficient and regression. 170 PHASE II III IV DAYS OF NSTRUAL DAYS CYCLE OFF PILL FIG. I. Effect of OC on plasma vitamin A and E carotene. a, Significantly different from controls in same phase P < b, Significantly different from values of same group in phase II P < c, Significantly different from controls in phase I P < 0.01.

3 688 YEUNG AND CHAN Plasma vitamin E Levels of plasma vitamin E in subjects given Micronor were not found to be different from that in the control periods (Fig. 2). In subjects given Ortho-Novum SQ. the plasma vitamin E values were consistently higher in the experimental phases than in the control phases. However, because of variability in the plasma vitamin E levels in these subjects and because of the small number of subjects used in this group the difference was not statistically significant. Plasma cholesterol and trig! vcerides Neither Micronor nor Ortho-Novum SQ showed any significant effect on the plasma cholesterol levels (Fig. 3). In agreement with previous observations in other laboratories (17, 18) norethindrone alone tended to lower, while menstranol alone or in combination with norethindrone significantly raised plasma triglycerides. These effects were extended to at least 2 days after discontinuation of steroid treatments. Correlative factors Statistical analysis indicated no significant correlation between the parameters studied in subjects given Micronor. For those subjects given Ortho-Novum SQ the significant correlations are shown in Table 1. Discussion In studies of the effects of combined OC on serum vitamin A, Gal et al. (9, 10) suggested that the elevation of vitamin A was due to the 16. II.bj.... III., PHASE I II III IV DAYS OF 113 STRIJAL DAYS CYCLE OFF PILL FIG. 2. Effect of OC on plasma vitamin E. a IIbj,Y PHASE I II III IV DAYS OF YIEMSTRUAL DAYS CYCLE OFF PILL FIG. 3. Effect of OC on plasma triglycerides and cholesterol. a, Significantly different from controls in same phase P < b, Significantly different from controls in phase I P < TABLE I Statistically significant correlations between vitamin A, vitamin E and triglycerides in women treated with ortho-novum SQ Parameter...= Correlation coefficient SQ (r) Probability (P) Vitamin A vs. vitamin E Vitamin A vs. triglycerides 0.43 <0.05 Vitamin E vs. triglycerides 0.65 <0.01 progestogen content in these preparations. Results obtained in the present experiment showed that mestranol when taken as the only steroid raised the level of plasma vitamin A. The progestogen, norethindrone, taken at a low concentration had no effect on vitamin A. However, taken at a higher concentration norethindrone appeared to have an enhancing effect on estrogen in raising plasma vitamin A. Previously it has been observed in our laboratory (II) and by Gal et al. (9) that the

4 PROGESTOGEN AND ORAL CONTRACEPTIVE EFFECTS 689 level of plasma vitamin A in subjects taking oral contraceptives remained high during menstruation, when the subjects were off the pill. In the present experiment in subjects given the Ortho-Novum SQ the levels of vitamin A in the plasma remained high 2 days after they had stopped taking the pill. Gal and Parkinson (10) recently reported that the vitamin A did not return to pretreatment levels until 3 months after discontinuation of the pill. Gal et al. (9) and Briggs et al. (19) reported a decline in plasma carotene in patients given OC. It was suggested that this might reflect enhanced conversion of carotene to vitamin A or impaired storage of the vitamin. In a later report Gal and Parkinson (10) in agreement with Yeung (11) and our present data, observed that OC had no effect on plasma carotene. These latter observations do not lend support to the hypothesis of Gal et al. (9) and Briggs et al. (19) that OC either enhanced conversion of carotene to vitamin A or impaired storage of vitamin A. Of equal interest to vitamin A in this study is vitamin E. Heretofore the effect of OC on vitamin E metabolism has not been reported. Subjects given the Ortho-Novum SQ but not Micronor had consistently higher plasma vitamin E values. However, although the elevation is small the results do suggest that vitamin E may be affected by mestranol and not by norethindrone. In the present study plasma cholesterol was found not to be affected by either Micronor or Ortho-Novum SQ. Gowland and Jones (18) have observed that women treated with a daily dose of 0.35 mg norethisterone for 6 weeks had lower levels of cholesterol. On the other hand various laboratories have reported that women taking estrogen containing OC for over 3 months had higher levels of blood cholesterol (7, 8, 20). Sachs et al. (21) observed that the effect of the combined OC, Ovulen, on cholesterol became apparent only after the subjects had been on the OC for 4 weeks. Thus the response of cholesterol to OC may be time dependent. This may explain the lack of an effect of Micronor or Ortho-Novum SQ on cholesterol observed in the present study since the treatment periods of the respective OC were only 35 and 21 days. Plasma triglycerides were found to be elevated in subjects given mestranol alone and further raised when mestranol was given in combination with norethindrone but slightly lowered in subjects given a low level of norethindrone as the sole steroid. These observations agree with those reported by Brody et al. (22), Gowland and Jones (18) and Spellacy et al. (17) who have shown that the 19-norprogestogen steroids lowered plasma triglycerides. Spellacy et al. (17) have also demonstrated that although norethindrone when given alone had a triglyceride lowering effect it could synergistically interact with estrogen in raising plasma triglycerides. Presently it is not known by what mechanism norethindrone interacts with estrogen to cause the further rise in plasma triglycerides. In those subjects taking Ortho-Novum SQ statistically significant correlation was observed between plasma vitamin E and triglycerides (r = 0.65), vitamin E and vitamin A (r = 0.42) and between vitamin A and triglycerides (r = 0.43). The correlation coefficient between vitamin E and triglycerides was statistically highly significant. The correlation coefficient between vitamin A and vitamin E approached statistical significance while that between vitamin A and triglycerides was statistically significant. In the opinion of the authors the results may not represent cause and effect responses of these three lipid materials to estrogen. The rise in plasma vitamin A, vitamin E and triglyceride was probably a consequence of increases in the transport proteins. Yeung (II) has previously postulated that the rise in vitamin A in the plasma of subjects given OC might be due to an increase in the retinol-binding protein, an a1-globulin. The rise in plasma triglycerides and vitamin E may be due to the low-density lipoproteins which have been observed to be higher in women taking OC (7, 8, 23). Since plasma triglycerides and vitamin E are both bound to the low-density lipoproteins (24, 25), it may explain the higher correlation coefficient observed between these two substances and the statistically significant F factor for the regression line (Fig. 4). The latter implies that in women taking

5 690 YEUNG AND CHAN contraceptive steroids on serum lipids. Am. J. Obstet. Gynecol. 116: 727, HAZZARD, W., M. SPIGER, J. BAGDALE ANt) E. BIERMAN. Studies on the mechanism of increased plasma triglyceride levels induced by oral contraceptives. New EngI. J. Med. 280: 471, S FIG. 4. Comparison of plasma vitamin E and triglycerides in subjects before and during treatment with Ortho-Novum SQ. Regression line: y = x. r = 0.65: P < Ortho-Novum SQ the level of plasma vitamin E may be predicted from the level of plasma triglycerides and vice versa. Summary The present study has produced evidence to show that the elevated levels of vitamin A observed in women taking oral contraceptives are due to the estrogen content in the contraceptive steroid preparations. The progestogen, norethindrone, at a low dose does not have an effect while at a higher concentration it enhances the effect of mestranol in raising plasma vitamin A. Plasma triglycerides are slightly lowered by norethindrone, raised by mestranol and further raised when norethindrone, at a higher level, is given simultaneously with mestranol. Vitamin E levels in the plasma of women taking the mestranol containing OC preparation are slightly raised. There appears to be a significantly positive correlation between triglycerides and vitamin E in the plasma of the subjects. Plasma cholesterol is not affected in the subjects. D The authors thank Dr. A. Malkin, Sunnybrooke Hospital, Toronto. for his technical advice and Dr. J. N. Thompson, Health Protection Branch, Ottawa, for the spectrofluorometric determination of plasma vitamins A and E. The authors are also indebted to Mrs. C. Gillis, Misses A. Blain, J. Chappel, and L. Cheung. for their technical assistance. References I. DE ALVAREZ, R. R., F. M. JAHED, K. J. SPITALNY, H. ELKIN AND I. JAUNAKAIS. The influence of oral 3. LARSSON-COHN, U., R. BESLIN AND 0. VIKROT. Effects of combined and low dose gestagen oral contraceptives on plasma lipids including phospholipids. Acta Endocrinol. 63: 71, l OSMAN, M., H. T0PP0zADA, M. GHANEM AND F. GUERGIS. Effects of an oral contraceptive on serum lipids. Contraception 5: SPELLACY, W. N., W. C., BUHI, S. A. BIRK AND S. A. MACREADY. Metabolic studies in women taking norethindrone for 6 months time (measurements of blood glucose, insulin, and triglyceride concentration). Fertility Sterility 24: 419, STOKES, T., AND V. WYNN. Serum lipids in women on oral contraceptives. Lancet 2: 677, WYNN, V., J. W. H. DOAR ANE) G. L. MILLS. Some effects of oral contraceptives on serum-lipid and lipoprotein levels. Lancet 2: 720, AURELL, M., K. CRAWER AND G. RYBO. Serum lipids during long-term administration of an oral contraceptive. Lancet 2: 291, GAL, I., C. PARKINSON AND I. CRAFT. Effects of oral contraceptives on human plasma vitamin A levels. Brit. Med. J. 2: 436, GAL, I., AND C. PARKINSON. Changes in serum vitamin A levels during and after oral contraceptive therapy. Contraception 8: 13, II. YEUNG, D. L. Effects of oral contraceptives on vitamin A metabolism in the human and rat. Am. J. Clin. Nutr. 27: 125, THOMPSON, J. H., P. ERODY ANI) W. MAXWELL. Simultaneous determinations of vitamins A and E in human serum and plasma. Biochem. Med. 8: 403, NEELD,J. B.,JR., AND W. N. PEARSON. Macro-and micromethods for the determination of serum vitamin A using trifluoroacetic acid. J. Nutr. 79: 454, Triglyceride method: Technicon AutoAnalyzer method, N78a. 15. PEARSON, S.. S. STERN AND T. H. McGAVACK. A rapid, accurate method for the determination of total cholesterol in serum. Anal. Chem. 25: 813, LAWRENCE, P. H., AND A. E. SOBEL. Changes in serum vitamin A level during the human menstrual cycle. J. Clin. Endocrinol. Metab. 13: 1192, SPELLACY, W. N., W. C. BUHI, S. A. BIRK AND R. CABAL. The effects of estrogens, progestogen, oral contraceptives and intrauterine devices on fasting triglyceride and insulin levels. Fertility Sterility 24: 178, GOWLAND, E., AND R. A. JONES. The effect of oral norethisterone in serum lipid level in premenopausal women. J. Obstet. Gynaecol. Brit. Commonwealth 80: 357, BRIGGS, M., M. BRIGGS AND M. BARNUM. Steroid contraceptives and plasma carotenoids. Contraception 6: 275, 1972.

6 PROGESTOGEN AND ORAL CONTRACEPTIVE EFFECTS KUKU, S. B., AND P. A. AKINYANJU. Fasting serum lipids and serum lipoprotein distribution during oral contraceptive therapy in Nigerians. J. Obstet. Gynaecol. Brit. Commonwealth 80: 750, SACHS, B. A., L. WOLFMAN AND N. HERZIG. Plasma lipids and lipoprotein alterations during oral contraceptive administration. Obstet. Gynecol. 34: 530, BRODY, S., J. KERSTELL, L. NILSSON AND A. SVANBORG. The effects of some ovulation inhibitors on the different plasma lipid fractions. Acta Med. Scand. 183: 1, LAURELL, C. B., S. KULLANDER AND J. THORELL. Effects of administration of a combined oestrogenprogestin contraceptive on the level of individual plasma proteins. Scand. J. Clin. Lab. Invest. 21: 337, SMELLIE, R. M. S. Plasma Lipoproteins. London: Academic. 1971, p DAvIEs, T., J. KELLEHER AND M. S. LOSOWSKY. Interrelation of serum lipoprotein and tocopherol levels. Clin. Chem. Acta 24: 43, l969.