Zinc and copper nutriture in obese men receiving very low calorie diets of soy or collagen protein

Relationship between pre-pregnancy BMI and plasma zinc concentrations in early pregnancy

We previously reported that pregnant women whose plasma Zn concentrations were below the 50th percentile tended to have high pre-pregnancy BMI (kg/m2) values. We therefore hypothesized that in pregnant women, plasma Zn concentrations are negatively correlated with BMI. We evaluated the association between BMI values and plasma Zn concentrations in 1474 women whose blood samples were obtained before 15 weeks of gestation. Their mean age was 22·7 years and mean gestational age at blood sampling was 10 weeks. The mean plasma Zn concentration and BMI were 11·6 μmol/l and 26·6 kg/m2 respectively. Because plasma Zn concentrations decrease as gestational age increases, plasma Zn concentrations were standardized by Z-scores. Z-score distributions were compared among the quartiles of BMI. The highest BMI group had the lowest plasma Zn concentrations, whereas the lowest BMI group had the highest; the differences were significant between the BMI groups (P<0·0001). The interpretation of plasma Zn concentrations to assess Zn nutriture in pregnancy may be complicated not only by the well-established factor of gestational age at blood sampling, but also by a previously unrecognized factor, maternal BMI.

Soy isoflavone supplementation elevates erythrocyte superoxide dismutase, but not plasma ceruloplasmin in postmenopausal breast cancer survivors

Soy isoflavone antioxidant effects may help prevent breast cancer re-occurrence, but isoflavone estrogen-like actions may increase breast cancer risk. These isoflavone actions can be reflected by effects on two copper enzymes activities, superoxide dismutase 1 (SOD 1), which has antioxidant function relevant to breast cancer prevention, and ceruloplasmin, which has its synthesis up-regulated by estrogen, and for which high values are associated with high breast cancer risk. A soy isoflavone-rich concentrate supplement was examined for effects on these two copper enzyme activities in post-menopausal breast cancer survivors (n = 7) in a crossover design with a placebo (24 days on supplement or placebo; 14 day wash out). The soy concentrate, but not the placebo, increased erythrocyte SOD 1 activities, but not ceruloplasmin activities or protein. The effect on superoxide dismutase activities was not likely due to increased copper intake since analysis of the soy extract showed little copper. The effect on superoxide dismutase was not accompanied by a change in urinary contents of 8-deoxyhydroxyguanosine, a DNA oxidant product, though perhaps this would change with a longer intervention. In summary, in regard to two copper enzyme activities, an isoflavone-rich soy concentrate showed an antioxidant effect considered relevant to breast cancer, but not an effect associated with estrogenic activity and increased breast cancer risk.

Cutaneous copper and zinc losses in burns

To measure the exudative cutaneous copper (Cu) and zinc (Zn) losses in burns, 10 patients, aged 36 +/- 9 years (mean +/- s.d.) with burns covering 33 +/- 10 per cent of the total body surface area, were studied from the first postburn day (D1) until D7. All intakes and losses were analysed for Cu, Zn and nitrogen (N) content. Cutaneous losses were extracted from textiles surrounding the patients. Urinary excretions were 0.12 +/- 0.06mg/24h for Cu, 0.9 +/- 0.6mg/24h for Zn, and 14.1 +/- 4.4g/24h for N. Mean daily exudative losses through wound seepage from D1 to D7 were 4.7 +/- 2.1mg/24h for Cu, 27.1 +/- 14.4mg/24h for Zn, and 8.7 +/- 3.8g/24h for N. The cumulated mean losses over 7 days were 37mg for Cu, and 212mg for Zn, representing respectively 20-40 per cent and 5-10 per cent of normal body content. Serum Cu and Zn levels were strongly depressed. The urinary Cu/N ratios correlated with clinical improvement. We conclude that the exudative Cu and Zn losses during the first week postburn contribute significantly to the increased nutrient requirements in burns.

[Trace elements in artificial nutrition. Art and practice]

The trace elements known to be necessary for man are iron, zinc, copper, selenium, chromium, manganese, molybdenum, cobalt and iodine. This review article, which excludes iron, deals with the need for supplemental trace elements during artificial feeding, and the way they should be administered. The biological importance of these trace elements is argued on the basis of their biochemical involvement and the clinical pictures seen in accidental or experimental deficiency states. Assessing a patient's trace element status is rather difficult. The relative merits of different laboratory investigations is discussed: plasma, erythrocyte, capillary and urinary levels, specific enzyme activities, loading tests. The different situations when trace elements are required, assessing the amount needed and the possible toxic risks, are presented from a literature survey.