Oral contraceptives did not affect biochemical folate indexes and homocysteine concentrations in adolescent females

OBJECTIVE

The study was designed to determine the impact of currently available oral contraceptive agents (OCAs), smoking, and alcohol on biochemical indexes of folate and vitamin B-12 in adolescent females.

DESIGN

Subjects completed a 3-day weighed food record along with a detailed lifestyle questionnaire that included questions on OCA, cigarette, and alcohol use. After subjects had fasted overnight, blood samples were collected and analyzed for levels of serum and red blood cell (RBC) folate and serum B-12 and homocysteine.

SUBJECTS/SETTINGS

Two hundred twenty-nine adolescent females (aged 14 to 20 years) were recruited from southern Ontario, Canada, by advertisements in newspapers, high schools, universities, shopping malls, adolescent drop-in centers, and community groups.

STATISTICAL ANALYSES PERFORMED

Multiple regression models were used to determine the effect of lifestyle factors and covariates (e.g., dietary folate intake, supplemental folate intake, and age) on biochemical indexes.

RESULTS

OCA use, alcohol use, and smoking were not significantly associated with lower serum or RBC folate levels, after controlling for folate intake. Serum homocysteine levels were not associated with smoking or OCA use; however, we estimated a 13% higher concentration among alcohol users than nonusers. Smoking and alcohol use were not associated with serum B-12 levels, but OCA use was associated with an estimated 33% lower serum B-12 level than nonuse.

APPLICATIONS

Our findings provide no evidence to suggest that currently available OCAs have a negative impact on the folate status of adolescent females; thus, dietary advice designed to specifically encourage an increase in folate intake among adolescents who use OCAs is not supported. In contrast, serum B-12 levels were lower among OCA users than nonusers, which suggests that an interaction between OCA and some vitamins may persist. The suboptimal biochemical folate indexes of smokers may have more to do with the dietary quality of smokers than previously appreciated. Thus, efforts to improve dietary folate intakes of adolescents who smoke may be an important strategy for improving the folate status of young women.

Effects of sub-50 oral contraceptives on homocysteine metabolism: a preliminary study

The influence of a monophasic sub-50 oral contraceptive (OC), Marvelon, on fasting total homocysteine levels was investigated in OC users and controls. Homocysteine levels in serum of OC users were significantly higher (P less than .01) than in controls during the low-hormonal phase of the cycles and comparable with levels determined in heterozygotes for homocystinuria. Blood levels of pyridoxal phosphate (PLP) were significantly lower (P less than .05) in OC users both in the low and high hormonal phase. However, there were no significant differences in the levels of homocysteine nor in folate and vitamin B12 between both groups in the high-hormonal phase. In contrast to the control group, the homocysteine levels in OC users in the high-hormonal phase of the cycle were significantly decreased compared with those on a low-hormonal day (P less than .05). These data suggest that cyclically recurrent periods of hyperhomocysteinemia do occur during sub-50 OC use in normal women and might be considered a predisposition to the occurrence of vascular complications.

Maternal serum folacin levels during and after normal pregnancy

Maternal serum folacin levels decrease during pregnancy. This decrease could not be explained by hemodilution. Postpartum levels did not increase significantly compared to values measured at partum. In a healthy Dutch pregnant population receiving no vitamin supplementation the folacin status is at risk and after pregnancy it takes considerable time to refill folacin stores.

Drugs and folate metabolism

Folates are a group of compounds which are required in the diet and are important in DNA, amino acids and possibly also amine metabolism. The biologically active folates are in the tetrahydro form. Tetrahydrofolates are produced from unreduced dietary folates by the enzyme dihydrofolate reductase. A number of drugs such as aminopterin, methotrexate (amethopterin), pyrimethamine, trimethoprim and triamterene act as folate antagonists and produce folate deficiency by inhibiting this enzyme. With other drugs which produce low serum and tissue concentrations of folate such as anticonvulsants, antituberculosis drugs, alcohol and oral contraceptives, the mechanism of this effect is uncertain. Possible mechanism include reduced absorption, prevention of release of folate from tissue stores, altered plasma protein binding, or increased folate metabolism in the liver. Treatment with folic acid antagonists such as methotrexate readily causes megaloblastic anaemia; this can be prevented by therapy with folinic acid (5-formyltetrahydrofolate). The role of other drugs in producing megaloblastic anaemia is less certain, e.g. it occurs in less than 0.75% of patients receiving anticonvulsants. The possible neurological and psychiatric effects of folate deficiency are also uncertain. However, in patients with folate deficiency who have neuropsychiatric symptoms, neuropathy or myelopathy, and normal vitamin B12 levels, it may be of value to try therapy with folic or folinic acid.

Comparison of haematological indices between women of four ethnic groups and the effect of oral contraceptives

Six-hundred-and-eighty-two women volunteers from four ethnic groups--Black, Indian, Oriental and White took part in a study to assess differences in haematological indices between the groups. This study was part of a broad investigation into the metabolic effects of oral contraceptives. The effect of the oral contraceptive (OC) on haematological indices was analysed but not found to be significant. The haemoglobin concentrations were lower than normal laboratory reference values for White subjects in 12.5% of Indian, 16.5% of Black and 4.3% of Oriental control groups respectively. All the White control group were within the normal range. These findings were considered in relation to age, weight, pregnancies, smoking, alcohol consumption, nutritional status, and disorders of haemoglobin synthesis. A deficient iron intake accounted for the high incidence of low haemoglobin in the Indian group in whom low transferrin saturation and serum ferritin were observed. With the possible exception of inherited disorders of haemoglobin synthesis, none of the factors we considered could account for the low haemoglobins found in the Black group. Separate reference values for haematological indices in different ethnic populations are considered.

Oral contraceptives: effect of folate and vitamin B12 metabolism

Women who use oral contraceptives have impaired folate metabolism as shown by slightly but significantly lower levels of folate in the serum and the erythrocytes and an increased urinary excretion of formiminoglutamic acid. The vitamin B12 level in their serum is also significantly lower than that of control groups. However, there is no evidence of tissue depletion of vitamin B12 associated with the use of oral contraceptives. The causes and clinical significance of the impairment of folate and vitamin B12 metabolism in these women is discussed in this review of the literature. Clinicians are advised to ensure that women who shop taking "the pill" because they wish to conceive have adequate folate stores before becoming pregnant.

Improvement in cervical dysplasia associated with folic acid therapy in users of oral contraceptives

Forty-seven young women with mild or moderate dysplasia of the uterine cervix (cervical intraepithelial neoplasia) diagnosed by cervical smears, received oral supplements of folic acid, 10 mg, or a placebo (ascorbic acid, 10 mg) daily for 3 months under double-blind conditions. All had used a combination-type oral contraceptive agent for at least 6 months and continued it while returning monthly for follow-up examinations. All smears and a biopsy obtained at the end of the trial period were classified by a single observer without knowledge of treatment status using an arbitrary scoring system (1 normal, 2 mild, 3 moderate, 4 severe, 5 carcinoma in situe). Mean biopsy scores from folate supplemented subjects were significantly better than in folate-unsupplemented subjects (2.28 versus 2.92, respectively; p less than 0.05). Final versus initial cytology scores were also significantly better in supplemented subjects (1.95 versus 2.32, respectively; p less than 0.05), unchanged in patients receiving the placebo (2.27 versus 2.30, respectively). Before treatment the mean red cell folate concentration was lower among oral contraceptive agent users than nonusers (189 versus 269 ng/ml, respectively; p less than 0.01) and even lower among users with dysplasia (161 versus 269 ng/ml, respectively; p less than 0.001). Morphological features of megaloblastosis were associated with dysplasia and also improved in folate supplemented subjects. These studies indicate that either a reversible, localized derangement in folate metabolism may sometimes be misdiagnosed as cervical dysplasia, or else such a derangement is an integral component of the dysplastic process that may be arrested or in some cases reversed by oral folic acid supplementation.

The effects of ascorbic acid, vitamin B6, vitamin B12, and folic acid supplementation on the breast milk and maternal nutritional status of low socioeconomic lactating women

In this double-blind study, the effects of ascorbic acid, vitamin B6, vitamin B12, and folate supplementation on the maternal nutritional status and vitamin content of breast milk in 16 low socioeconomic lactating women were studied. Nine subjects were administered a commercial multivitamin-multimineral supplement and seven were given placebos. Milk samples were collected four times per day at 4-h intervals from 5 to 7 and 43 to 45 days postpartum. Fasting blood samples were taken from all mothers at the end of each milk collection period. Dietary records of all foods consumed were kept from 4 to 7 and 42 to 45 days postpartum. There were no significant differences in milk or plasma levels of ascorbic acid between the unsupplemented and supplemented groups. Both the EGPT index and milk concentration of vitamin B6 were significantly different (p less than 0.01) between the unsupplemented and supplemented groups. The milk concentrations of vitamin B12 increased significantly (p less than 0.05) in the supplemented group, as did the milk concentrations of folate (p less than 0.01). Because of consistently low levels of dietary vitamin B6 and folic acid in this group of low socioeconomic lactating women, either dietary changes or supplements could be necessary to maintain recommended levels of these vitamins in the womens' breast milk.

Nutritional effects of oral contraceptive use: a review

Oral contraceptives agents (OCA) have been in use for more than two decades, and at the present time, 150 to 200 million women are using the preparations. Apart from their gynecologic influence, the hormones have been shown to affect a number of metabolic and nutritional processes, some advantageously and others disadvantageously. Concern over the nutritional status of females consuming OCA prompted this review. Eight vitamins and three minerals were investigated. Contraceptive steroid ingestion was shown to depress the physiologic levels of six nutrients (riboflavin, pyridoxine, folacin, vitamin B12, ascorbic acid and zinc), elevate the levels of three others (vitamin K, iron and copper) and provide little or no change in one (alpha tocopherol) and questionable increases in another (vitamin A). It was concluded that females consuming OCA should pay particular attention to vitamin and mineral intake and, if warranted, consume physiologic supplements of needed nutrients.

[Study of oral contraceptives action on blood folate levels (author's transl)]

In 95 women taking reduced-level-oral contraceptives and in 24 same-aged women controls, the measure of erythrocyte and serum folate led to the following conclusions: 1) Folate levels in women consuming the pill were generally found to be of the same range as those of controls. 2) No significant difference could be shown between results for different kinds of contraceptives.

Clinical and laboratory observations on serum folate-binding protein

We studied the effect of serum folate-binding protein (FBP) on folate radioassays and the relationship of the serum level of unsaturated FBP to the serum folate level in various clinical states. Our modification of a heat-extracted radioassay was compared to a whole serum radioassay. Our results confirmed the existence of elevated serum levels of unsaturated FBP in some normal subjects, in some women taking oral contraceptives, and in most patients with uremia. Elevated levels of unsaturated FBP will produce falsely low results in folate radioassay unless the FBP has been destroyed by heat, as was done in the modified radioassay here presented. In normal and uremic subjects, serum folate and unsaturated FBP levels tended to correlate, whereas in patients taking large doses of folic acid the level of unsaturated FBP fell as the level of serum folate rose.

Estrogen stimulation of conjugase activity in the uterus of ovariectomized rats

Recent observations have indicated that uterine folic acid conjugase (pterolypolyglutamyl hydrolase) undergoes rhythmic variation during the reproductive cycle of the rat. In the present study conjugase activity and ratios of "total" folate to "free" folate were determined in uterine homogenates of ovariectomized rats, with ane without estrogen stimulation. An increase in conjugase levels and a relative increase in the "free" folate component occurred in castrated animals 12 to 18 hours following injection of 10 mug of estradiol-17beta.

Effect of oral contraceptive agents on nutrients: II. Vitamins

Clinical, biochemical and nutritional data were collected from a large population of women using oral contraceptive agents. Higher incidence of abnormal clinical signs related to malnutrition were observed in the lower (B) as compared to the higher (A) socioeconomic groups, and also in the nonsupplemented groups as compared to the supplemented groups in the B subjects. As a rule the intake of oral contraceptive agent subjects of vitamin A, C, B6 and folic acid did not differ from that of the controls As expected, subjects from the supplemented groups had higher intake of vitamin A, C, B6, thiamin, riboflavin and folic acid, and A groups had higher intake of vitamin C, B6, riboflavin and folic acid. Increased plasma vitamin A and decreased carotene levels were observed in oral contraceptive agent users. In general oral contraceptive agents had little or no effect on plasma ascorbic acid. Urinary excretion of both thiamin and riboflavin in subjects using oral contraceptive agents were lower in A groups. Erythrocyte folate and plasma pyridoxal phosphate was decreased in A groups due to oral contraceptive agents. Subjects who took supplements had higher levels of plasma vitamin A, ascorbic acid and folate. But urinary thiamin and riboflavin were higher only in group A subjects who took supplements.

The effect of oral contraceptives on folate metabolism. III. Plasma clearance and urinary folate excretion

The plasma clearance of folic acid (PGA) and urinary excretion of folates were determined in women on oral contraceptives and in control subjects. The initial phase of plasma clearance of PGA (first 5 minutes) was much faster in oral contraceptive users than in the controls, but the subsequent rate of clearance was the same in the two groups. There was a good correlation between the 12-hour urinary folate excretion and serum or red cell folate in both groups. The women on oral contraceptives excreted more folate in their urine for any given level of serum or red cell folate. The increased urinary folate excretion may partly explain the lower serum and red cell folate in oral contraceptive users.