Vitamin B12 and folate bioavailability from two prenatal multivitamin/multimineral supplements.

In this crossover, single-blind study, the bioavailability of B12 and folate, fasting and postprandially, was measured in 30 pregnant women for two prenatal multivitamin/multimineral supplements (Stuartnatal Plus and Materna, Wyeth-Ayerst Pharmaceuticals, Philadelphia, PA) and a placebo. Blood samples were obtained before supplementation and at 1, 3, 6, and 8 hr after supplementation serum levels of the two vitamins were measured by radioimmunoassay. The maximum postabsorption serum level was multiplied by the total body plasma levels to obtain the total rate of body absorption. The absorption peak of both vitamins occurred at 3 hours after ingestion of a supplement. The total body absorption of the two vitamins was greater during fasting than it was postprandially. There was 30% greater B12 absorption for Stuartnatal Plus (371 +/- 56 vs. 285 +/- 34 pmol) and 33% for Materna (315 +/- 34 vs. 236 +/- 4 pmol, p < or = 0.05). Similarly, there was 117% greater folate absorption fasting for Stuartnatal Plus (163 +/- 15 vs. 75 +/- 15 nmol, p < or = 0.001) and 57% greater absorption for Materna (207 +/- 21 vs. 132 +/- 13 nmol, p < or = 0.01). Both vitamins were readily absorbed (within 3 hours) into the maternal hepatic portal circulation. The absorption of both vitamins was significantly less when ingested after the test meal than when fasting.

Bioavailability of iron in two prenatal multivitamin/multimineral supplements.

OBJECTIVE: To determine the iron bioavailability in two popular prenatal multivitamin/multimineral supplement tablets containing 27 mg elemental iron. STUDY DESIGN: Iron absorption during an eight-hour period following ingestion of a multivitamin/multimineral formulation, both fasting and with a standardized meal, was measured in a group of 30 pregnant women (24-32 weeks of gestation) and statistically compared. The prenatal formulations were Stuartnatal Plus and Materna (Wyeth-Ayerst Pharmaceuticals, Philadelphia, Pennsylvania), and each contains 27 mg of elemental iron. A placebo was included in the study for the control group in this crossover, single-blind study. RESULTS: The net iron bioavailability (mean +/- SE) of Stuartnatal Plus and Materna, accounting for diurnal variation, and the iron ingested with the standardized meal was 5.4 +/- 0.4 and 4.6 +/- 0.2 mg, respectively, while fasting and 2.9 +/- 0.4 and 2.7 +/- 0.4 mg, respectively, postprandially. The total amount of iron absorption in the fasting states from both prenatal formulations exceeded the 3 mg of supplemental iron absorption per day recommended by the National Academy of Sciences. CONCLUSION: The results of this study indicate that these two prenatal multivitamin/multimineral formulations provide > 3.0 mg of supplemental iron absorption (fasting) as recommended by the National Academy of Sciences and 2.7 mg of iron absorption above the levels achieved following ingestion of a standard, low-iron test meal.

The apparent effect of iron supplementation on serum selenium levels in teenage pregnancy.

Numerous studies have suggested a significant role of selenium in the prevention of gynecological carcinoma. These were epidemiological and prospective in humans and therapeutic in laboratory animals. However, no studies have been reported regarding the normal serum selenium levels during pregnancy. The maternal total blood volume increases 30-50% during the second and third trimesters, resulting in lower measured serum levels for those metabolites, which are not increased significantly during pregnancy. A longitudinal study of the serum selenium levels in teenage pregnancy during the last two trimesters and 3 mo postpartum showed progressive elevation from 49 +/- 7 microg/dL after the 32nd week of pregnancy to 114 +/- 7 microg/dL at term, which was statistically significant (p < or = 0.001). Prenatal supplementation with 18 mg of iron per day prevented this elevation. The results of this study suggest that serum selenium levels in women normally double during pregnancy and this doubling is prevented by the minimal daily supplementation of 18 mg of iron, which may be due to increased absorption of selenium into the erythrocytes and incorporation into the glutathione peroxidase enzyme.

The effect of ascorbic acid supplementation on the nicotine metabolism of smokers.

BACKGROUND: The relationship of serum ascorbic acid (AA) levels and excretion of nicotine metabolites was determined in 75 men who smoked at least one pack of cigarettes per day. METHODS: The subjects were randomly divided into three groups of 25 each who received a placebo, 200 mg of supplementation, or 1000 mg of supplementation of AA per day for 1 month. Baseline and weekly serum AA levels were determined and simultaneous estimates of urinary excretion of nicotine metabolites as cotinine equivalents (CE). RESULTS: The group mean serum AA levels in the placebo group decreased 13% after 2 weeks; the group mean serum levels of the supplemented groups increased significantly after 1 week (P

The effect of ascorbic acid supplementation on the blood lead levels of smokers.

BACKGROUND: The study subjects were 75 adult men (20 to 30 years of age), who smoked one pack of cigarettes per day (minimum) and had no clinical signs of ascorbic acid deficiency or lead toxicity. None had a history of industrial exposure to lead, and the blood-lead levels were anticipated to be below 1.45 micromol/L, the minimum blood level associated with toxicity symptoms. METHODS: The men were randomly assigned to three study groups of 25, and each group was provided a four-week supply of one level of daily ascorbic acid supplements (placebo, 200 mg or 1000 mg of ascorbic acid). We measured baseline and weekly serum and urine ascorbic-acid levels as well as blood and urine lead levels. The weekly group means and variations of the measured data were statistically compared by means of ANOVA and Pearson's correlation. RESULTS: The serum ascorbic-acid levels of the groups receiving ascorbic acid increased significantly after one week (p< or =.001). There was no effect of placebo or 200 mg ascorbic-acid supplementation on the blood or urine lead levels. However, there was a 81% decrease in blood-lead levels in the 1000 mg ascorbic acid group after one week of supplementation (p< or =.001). CONCLUSIONS: Daily supplementation with 1000 mg of ascorbic acid results in a significant decrease of blood-lead levels associated with the general population. Ascorbic acid supplementation may provide an economical and convenient method of reducing blood-lead levels, possibly by reducing the intestinal absorption of lead.

Iron in prenatal multivitamin/multimineral supplements. Bioavailability.

OBJECTIVE: To determine the effect of the differences in the content of essential and nonessential ingredients and of a standardized meal on iron bioavailability from four popular prenatal multivitamin/multimineral supplements. STUDY DESIGN: Iron absorption during an eight-hour period following ingestion of a multivitamin/multimineral formulation, both fasting and postprandial, after a standardized meal, was measured in five groups of 20 pregnant women (24-32 weeks of gestation) and statistically compared. The prenatal formulations were Natalins Rx, Prenatal 1/1, Stuartnatal Plus and Prenate 90. One-A-Day (without iron) was included in the study for the control group. RESULTS: The descending order of absorption, both fasting and postprandial, were Prenate 90, Stuartnatal Plus, Prenatal 1/1 and Natalins Rx. Total iron absorption for each formulation group during the postprandial phase was higher than during the fasting phase. However, the net amount of iron absorption (in both the fasting and postprandial phases) from three of the four formulations (Stuartnatal Plus, Prenatal 1/1 and Prenate 90) provided the minimal 3.0 mg of supplemental iron per day recommended by the National Academy of Science. CONCLUSION: The observed differences in iron absorption between prenatal supplements apparently reflect the effects of the various combinations of vitamins, essential minerals and additives. The absolute amount of elemental iron contained in a prenatal multivitamin/ multimineral formulation does not ensure availability.

Serum zinc changes due to iron supplementation in teen-age pregnancy.

Serum zinc and iron concentrations in a group of pregnant teen-agers supplemented with a multivitamin were compared during pregnancy with a group supplemented with a multivitamin containing 18 mg Fe. Serum measurements were at 13 wk of gestational age (prestudy) and during supplementation at 20, 32, and 38 wk, delivery, and 4 and 12 wk postpartum. Hematocrit measurements were used to adjust the measured metal concentrations for the diluting effect of the normal blood-volume increase. The non-Fe-group mean, adjusted serum Zn concentrations showed no change, but the serum Fe decreased to 28% below prestudy concentrations at 38 wk. In contrast, the Fe-supplementation group showed a progressive increase in Fe concentrations to a maximum of 38% above prestudy concentrations at 4 wk postpartum and a 35% decrease from prestudy Zn concentrations during the third trimester. The results of this study suggest that 18 mg Fe/d is adequate supplementation for nonanemic teen-age pregnancy and depresses the serum Zn concentration.

Serum ferritin levels after multivitamin iron ingestion during teenage pregnancy.

The postabsorptive serum ferritin levels following normal dosages of prenatal multivitamin/multimineral supplements were studied in 17 pregnant teenagers, whose fetuses were between 16 and 20 weeks gestational age. The purpose of the study was to determine the effect of a single oral dose of differing prenatal multivitamin/multimineral tablets containing 60 or 65 mg of elemental iron on the postabsorptive serum ferritin levels. Each woman was randomly tested following the ingestion of one of three different tablets, both in a fed and a fasting state. Blood samples were obtained for ferritin measurement immediately prior to ingestion of the prenatal tablet, with or without a standard meal, and at 1, 3, 6, and 8 hours postabsorption. The group mean serum ferritin levels increased dramatically during the fasting state following ingestion of the Stuart Prenatal tablet and decreased when the Stuartnatal 1 + 1 or Materna 1.60 was ingested. The opposite results were observed when the tablets were ingested postprandially. The results of the study indicate that Stuart Prenatal was most suitable for consumption while fasting (ie, at the hour of sleep), and both Stuartnatal 1 + 1 and Materna 1.60 with a meal.

Bioavailability of iron in prenatal multivitamin/multimineral supplements administered to pregnant teenagers.

Absorption of elemental iron from three single-daily-dose prenatal multivitamin/multimineral supplements was compared in bioavailability studies of subjects under fasting and postprandial conditions. Each of the supplements (Stuartnatal 1 + 1, Stuart Prenatal, and Materna 1.60) contained 60 or 65 mg of iron. The subjects, teenagers in the second trimester of pregnancy, were assigned to the fasting or postprandial conditions at intervals of three to seven days. For the postprandial condition, subjects took the supplement after eating a standardized meal that had been designed to provide a minimal amount of iron and no caffeine (which inhibits iron absorption); blood was drawn at 0, 1, 3, 6, and 8 hours. Bioavailability studies showed that all three supplements provided adequate levels (at least 3.5 mg) of absorbed iron when taken postprandially. The highest quantity of net iron transport as well as the most rapid intestinal transport in either condition was yielded by Stuartnatal 1 + 1 taken in the fasting state. In the postprandial condition, Materna 1.60 demonstrated the fastest transport time and highest net iron transport; when given to a subject in the fasting condition, however, this supplement provided less than the recommended 3.5 mg of absorbed iron. These results suggest that iron absorption is influenced by supplement formulation as well as the presence or absence of food. Considering variations in compliance when iron is to be taken on an empty stomach as well as variable absorption in the fasting state, the most reliable supplementation would appear to be achieved by instructing pregnant women to take multivitamin/multimineral supplements at mealtime.

Protection of maternal iron stores in pregnancy.

Forty-two healthy young women, less than 16 weeks pregnant, with normal hematologic status, were selected at random to receive either a multivitamin/multimineral with 65 mg of iron or one without iron. During pregnancy and the puerperium, a full hematologic evaluation of the iron, folate and B12 status was performed. Those receiving the multivitamin without iron had significantly lower mean serum ferritin levels (P less than .05). During the study, 9 of these 21 noniron subjects (43%) failed to maintain an acceptable hemoglobin level (greater than 11.0 g/dL) and were medicated with 110 mg ferrous iron daily. Use of the multivitamin/multimineral supplement with iron during pregnancy and for 12 weeks postpartum maintained maternal iron stores, eliminated the need for additional iron medication and prevented the development of iron deficiency anemia. This 36-week longitudinal evaluation demonstrated the need for iron supplementation during pregnancy and for three months postpartum. Measurements of serum ferritin at 16-20 weeks of pregnancy will detect hematologic risk in young pregnant women not identified by usual hematologic assessments. The results of this study show that adequate maternal iron stores during pregnancy and the puerperium cannot be maintained by prevailing dietary patterns and therefore that iron supplementation is essential.

Maternal-fetal cyst(e)ine transfer.

In order to investigate the mechanisms by which cyst(e)ine (referring in the following to the mixture, in any proportion, of the sulfhydryl form of this compound - cysteine - and the disulfide form - cystine) transfer across the placenta to the fetus might be limited we first assessed the original observation that cyst(e)ine concentrations in fetal plasma are less than or equal to maternal cyst(e)ine concentrations. Second, we determined the capacity of the placenta to concentrate cyst(e)ine. And third, using an animal model, we determined the effects of providing excess cysteine to maternal rats on maternal-fetal cyst(e)ine transfer. Our data confirm (1) that cyst(e)ine is present in concentrations in human cord plasma that are equal to maternal plasma cyst(e)ine concentrations; (2) establish that cyst(e)ine is concentrated in the placenta, and (3) suggest that the incorporation of cyst(e)ine into glutathione in the placenta may limit the transfer of cyst(e)ine to the fetus.

Relationship of metal metabolism to vascular disease mortality rates in Texas.

The annual mortality rates for 1968 of six types of cardiovascular diseases among those persons over 45 years of age in 24 Texas communities were compared with respective community drinking water and urine metal levels of calcium, magnesium, potassium, lithium, strontium, and silicon. Numerous inverse correlations were found between mortality rates and the levels of various metals in both drinking water and urine. Positive correlations were also observed between several of the mortality rates and the ratio of the concentration of sodium to that of the other metals in both water and urine. Mean community urinary levels of lithium, magnesium, strontium, and silicon showed a direct correlation to the levels of exposure via the drinking water. The results of this study suggest that calcium, magnesium, lithium strontium, and silicon may protect against cardiovascular mortality; possibly, by competing with sodium and potassium for transport in the intestinal lumen, increasing excretion of sodium, or other mechanism.