A balance study was conducted for twenty-eight days on pregnant women consuming self-selected diets. Subjects were divided into the following groups: low zinc (9.98 ± 2.90, no supplement), high zinc (23.36 ± 2.59, on supplement), low nitrogen (below 10 gm/day) or high nitrogen (above 10 gm/day). Zinc and nitrogen data were determined from food, beverage and supplement intakes and urine and fecal excretions. Zinc retentions were 3.32 ± 6.33 in the supplemented group, 4.94 ± 10.91 in the non-supplemented group. Zinc retention in the nitrogen divided groups was -1.88 ± 9.43 for the group with intake above 10 gm/day, 4.26 ± 6.49 for the group with intake below 10 gm/day.

No significant difference was found between the zinc supplemented group and the non-zinc supplemented group for either zinc or nitrogen retention.

Nitrogen retentions were 2.42 ±. 2.17 mg/day for the zinc supplemented group and 3.53 ±. 3.29 mg/day for the non-zinc supplemented group. Nitrogen retention for the group with intake above 10 gm/day was 3.99 ±. 2.50 mg/day for the group with intake below 10 gm/day was 1.10 ±. 1.45 mg/day.

Significant differences were found for nitrogen retention in the groups based on nitrogen intake. Higher nitrogen intake was associated with higher nitrogen retentions (p<.01). Significant differences were also found in zinc retention based on nitrogen consumption. Higher nitrogen intake was associated with lower zinc retention (p<.001).

Plasma zinc was also measured. The mean plasma zinc was 70.46 ± 12.78 micrograms of zinc per 100 ml. The subject with the lowest zinc plasma level in the group also had a premature infant.