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).

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.

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.

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).

Balance studies for Zn and Cu were conducted over 40 days in 10 obese men housed in a metabolic balance unit. Two weight reduction diets providing 400 kcal and 100 g protein daily were administered; to five subjects, a collagen diet which was severely deficient in both Zn and Cu, and to another five subjects, a soy diet which provided a marginal intake of Zn and an adequate intake of Cu. Zn and Cu content of diets, plasma, red blood cells, urine, and feces were determined during eight 5-day periods. Balances were corrected for lean tissue catabolism or deposition. Holter ECG monitoring and measurement of the QTc interval were done on days 0 and 40. Both diets resulted in elevated plasma and red blood cell concentrations of Zn and Cu and in high urinary and fecal losses of Zn. By day 40, 6 of 10 subjects were in negative Zn balance. Urinary Zn was inversely correlated with measures of lean tissue catabolism. During each period, Cu balance was markedly positive in the soy-diet group and negative in the collagen-diet group. Shortening of prolonged QTc intervals was related to the Cu but not Zn status of the individual.