RESUMEN

Biochemical measurements and 24-h dietary recalls were conducted early (18.9 +/- 5.9 wk) and late (35.1 +/- 2.0 wk) in pregnancy in women attending clinics in Montemorelos, Mexico. Mean weight gain per week (0.4 +/- 0.2 kg) and birth weight (3381 +/- 456 g) were normal. Intakes tended to decline during pregnancy and declined significantly for zinc (p less than 0.05) and vitamin B-6 (p less than 0.03). Mean Zn intake late in pregnancy was low (7.8 +/- 3.3 mg/d). Various supplements were taken but none contained Zn. During pregnancy mean plasma Zn levels fell (p less than 0.001) and late in pregnancy 57% of the women had values suggestive of poor Zn status (less than or equal to 8.1 mumol/L). These data indicate that Zn intakes of approximately 8 mg/d will not maintain plasma Zn levels in late pregnancy. Erythrocyte glutamic-pyruvic transaminase (EGPT) index and the index of diamine oxidase (DAO), a vitamin B-6-requiring enzyme of placental origin, were correlated suggesting that DAO index may be useful in evaluating vitamin B-6 status in pregnancy.

PIP: Biochemical measurements and 24 hour dietary recalls were conducted early (18.9 +0- 5.9 weeks) and late (35.1 +or- 2.0 weeks) in pregnancy in women attending clinics in Montemorelos, Mexico. Mean weight gain per week (0.4 +or- 0.2 kg) and birth weight (3381 +or- 456 grams) were normal. Intakes tended to decline during pregnancy and declined significantly for zinc (p 0.05) and vitamin B-6 (p 0.03). Mean zinc intake late in pregnancy was low (7.8 +or- 3.3 mg/d). Various supplements were taken but none contained zinc. During pregnancy mean plasma zinc levels fell (p 0.001) and late in pregnancy 57% of the women had values suggestive of poor zinc status (or= 8.1 micromoles/liter). These data indicate that zinc intakes of approximately 8 mg/d will not maintain plasma zinc levels in late pregnancy. Erythrocyte glutamic-pyruvic transaminase (EGPT) index and the index of diamine oxidase (DAO), a vitamin B-6-requiring enzyme of placental origin, were correlated suggesting that DAO index may be useful in evaluating vitamin B-6 status in pregnancy.

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As a follow-up of our study of pregnant women, we report effects of zinc supplementation during pregnancy in another population of 138 Hispanic teenagers in Los Angeles. Teenagers were randomized (double-blind) to a control or zinc-supplemented group and received similar daily vitamin and mineral supplements except for 20 mg zinc added to the zinc-supplemented group's capsules. Initially, mean dietary zinc intakes of both groups were about 50% of the Recommended Dietary Allowance and their mean serum zinc levels did not differ significantly (69.8 +/- 11.2 micrograms/dl in control and 69.0 +/- 11.4 micrograms/dl in zinc-supplemented group). Zinc supplementation did not maintain mean serum zinc levels during pregnancy but, as in our earlier study, it reduced (p = 0.018) the number of low serum zinc values (less than or equal to 53 micrograms/dl) in late pregnancy. Zinc supplementation did not affect outcome of pregnancy but serum zinc levels were lower (p = 0.038) in teenagers with pregnancy-induced hypertension than in normotensives.

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The effects of zinc supplementation on levels of various blood constituents and the outcome of pregnancy in 213 Hispanic women attending a prenatal clinic in Los Angeles was assessed in this double-blind study. The women were randomized into either a control (C) or a zinc-supplemented (Z) group and received similar vitamin and mineral supplements except that 20 mg zinc was added to the Z group's capsules. At the final interview, women (C + Z) with low serum Zn levels (less than or equal to 53 micrograms/dl) had higher (p less than 0.01) mean ribonuclease activity and lower (p less than 0.01) mean delta-aminolevulinic acid dehydratase activity than women with acceptable serum zinc levels. The incidence of pregnancy-induced hypertension was higher (p less than 0.003) in the C than in the Z group, but pregnancy-induced hypertension was not associated with low serum zinc levels at either the initial or final interview. The expected increase in serum copper levels was greater (less than 0.001) in women with pregnancy-induced hypertension (C + Z) than in normotensives. Except for pregnancy-induced hypertension, there was a higher incidence of abnormal outcomes of pregnancy in the noncompliers than in the compliers (C + Z).

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The effect of zinc supplementation on concentrations of zinc in hair and serum of 213 pregnant Hispanic women attending a clinic in Los Angeles was assessed using a random, double-blind experiment. Both the treatment (T) and control (C) groups received similar vitamin and mineral supplements except that 20 mg zinc was added to the supplements for the treatment group. Nutrient intakes were calculated from 24-h recalls. The initial mean dietary zinc intake of both groups was about 50% of the Recommended Dietary Allowance (9 +/- 5 mg). Initially there were no significant differences between the two groups in mean zinc levels in serum (66 +/- 11 micrograms/dl, C, and 65 +/- 12 micrograms/dl, T) or in hair (184 +/- 41 micrograms/g, C, and 175 +/- 38 micrograms/g, T). Zinc supplementation did not alter mean zinc levels in serum or hair but significantly (p less than 0.05) reduced the number of low serum zinc values (less than or equal to 53.3 micrograms/dl) toward the end of pregnancy. Although serum zinc levels do decline in pregnancy, our results suggest that severely depressed levels (less than or equal to 50 to 55 micrograms/dl) indicate inadequate zinc status.

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Zinc intakes of low-income pregnant women of Mexican descent were estimated by the use of 24-hr dietary recalls. Recalls were obtained during the first two trimesters for 344 women and again during the third trimester of pregnancy for 279 of the same women. The daily mean zinc intake was calculated as 9.4 +/- 3.8 mg during the first two trimesters and as 10.0 +/- 4.3 mg during the third trimester. For about 85% of the women, the reported intakes were below two-thirds of the Recommended Dietary Allowance for zinc. In a subsample of the women, no significant correlation was shown between low dietary zinc intakes and low serum zinc levels during either early or late pregnancy. Zinc and protein intakes were highly correlated in both early and late pregnancy (r = 0.83 and 0.89, respectively). Diets that provided 90 to 100 g of protein (about 125% of the Recommended Dietary Allowance) provided a mean of 13.6 g of zinc (67% of the Recommended Dietary Allowance).

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Biochemical parameters of nutritional status were investigated in 300 women of Mexican descent during the first and second trimesters of pregnancy. Blood samples were obtained from the women during clinic visits, and measurements were made of serum iron, hemoglobin, hematocrit, serum protein, and transferrin saturation. Additionally, the nutritional status of seven vitamins was determined either by direct assay of the vitamin levels in blood or by measurement of erythrocyte enzyme stimulation. Thiamin and riboflavin were also determined in causal urine samples. Very few women, 8% or less, were classified as being low or deficient in hemoglobin, serum protein, iron, transferrin saturation, vitamin C, carotene, vitamin A, or vitamin B12. Thirty-one percent had low or deficient hematocrit values according to the guidelines used. Folic acid was the most prevalent vitamin deficiency, with 69% of the women having low or deficient serum levels. Based on the erythrocyte enzyme stimulation tests, 22% of the women were low or deficient in thiamin, 29% were low or deficient in riboflavin, and 9% were deficient in pyridoxine. None of the women had a low urinary excretion of thiamin, but 8% had excretion values of riboflavin below the acceptable level. Fewer deficiencies of thiamin and serum folic acid were observed in women taking vitamin and mineral supplements than in those who were not.

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Low-income pregnant women of Mexican descent were studied to determine whether their food habits could be improved by nutrition education. Biochemical indices of nutritional status were also investigated. Twenty-four-hour dietary recalls were obtained at an initial interview and again at a final interview after a nutrition education program, which was offered to a randomly selected treatment group. At the initial interview, the mean nutrient intakes that were most often below two-thirds of the Recommended Dietary Allowance (RDA) were iron, vitamin A, thiamin, and calcium. The mean energy value of the diets was also frequently below the RDA. At the final intakes, although the mean energy values and the calcium and carbohydrate of both the control and treatment groups increased significantly, the following improvements in dietary intakes were seen only within the treatment group: 1) there were significant increases in the mean intake of protein, ascorbic acid, niacin, riboflavin, and thiamin, 2) there were significant decreases in the percentage of intakes below two-thirds of the RDA for ascorbic acid and riboflavin, and 3) there was a significant decrease in the incidence of multiple low nutrient intakes. These dietary improvements, which occurred only in the treatment group, suggest the effectiveness of the nutrition education program. The most common biochemical deficiencies were of folic acid, thiamin, and riboflavin. Except for an improvement in mean serum folate levels, the biochemical indices for the treatment group did not appear to be influenced by the nutrition education. It is possible that the vitamin and mineral supplements which were taken by 80% of the women could have obscured improvements in biochemical indices which may have been due to the education program.

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