No abstract

The diagnosis of marginal copper deficiency has not been perfected despite an increased understanding of the physiologic roles of copper. The use of nonstandardized procedures and the effects of factors other than copper nutriture have impeded identification of an ideal indicator of copper nutritional status in humans. A review of studies of experimental copper deprivation conducted in adult humans over the past 12 y indicated that between 1.0 and 1.25 mg Cu/d is needed by adults for copper maintenance for periods of up to 6 mo and that < or = 2.6 mg Cu/d for periods of up to 42 d is not sufficient for recovery from copper deprivation. Copper-containing enzymes in blood cells, such as erythrocyte superoxide dismutase and platelet cytochrome-c oxidase, may be better indicators of metabolically active copper and copper stores than plasma concentrations of copper or ceruloplasmin because the enzyme activities are sensitive to changes in copper stores and are not as sensitive to factors not related to copper nutriture.

Anaerobic bacteria that metabolize oxalic acid have only recently been isolated from the rumen and from other gastrointestinal habitats. They constitute a new genus and species, Oxalobacter formigenes. This report presents the first comparison of cultural counts of these organisms from human feces and indicates that numbers as high as 10(7)/g may be present in feces from normal humans. Rates of oxalate degradation by mixed bacterial populations in feces from seven normal humans ranged from 0.1 to 4.8 mumol/(g X h). With fecal samples from eight patients that had undergone jejunoileal bypass surgery, rates were much lower [0-0.006 mumol/(g X h)]. We propose that oxalic acid degradation by Oxalobacter formigenes may influence absorption of oxalate from the intestine and that lower rates or lack of oxalate degradation in the colons of jejunoileal bypass patients may contribute to the increased absorption of dietary oxalate and the hyperoxaluria commonly associated with such patients.

The effects of 8 wk of daily chromium supplementation (3.3-3.5 mumol as chromium chloride or chromium picolinate) or placebo (0.1 mumol Cr) and weight training were examined in 36 men in a double-blind design. Strength, mesomorphy, fat-free mass, and muscle mass increased with resistance training independently of chromium supplementation (P < 0.0001). Protein, magnesium, zinc, copper, and iron intakes equalled or exceeded the recommended dietary allowance (RDA) or estimated safe and adequate daily dietary intake (ESADDI) during training and did not change significantly from pretraining intakes (P > 0.05). Chromium supplementation increased the serum chromium concentration and urinary chromium excretion without a difference as a result of the chemical form of chromium (P < 0.05). Resistance training was associated with a significant decrease (P < 0.05) in serum ferritin, total-iron-binding capacity, transferrin saturation, the ratio of enzymatic to immunoreactive ceruloplasmin, and plasma copper, independently of chromium supplementation. However, transferrin saturation was decreased more with chromium picolinate supplementation (24%) than with chromium chloride or placebo (10-13%). Compared with pretraining values, urinary magnesium excretion increased (P < 0.05) and urinary zinc output tended to decrease during the first 4 wk of resistance training and then returned to baseline values for the final 4 wk, which suggests an adaptation in mineral excretion in response to weight training. These findings suggest that routine chromium supplementation has no beneficial effects on body- composition change or strength gain in men. Whether chromium supplementation of individuals with diminished chromium nutriture facilitates propitious changes in body structure and function remains to be determined.

Magnesium balance may be a suitable indicator of magnesium depletion under experimental conditions. Magnesium deficiency resulting from feeding a diet that would not be considered having an atypical menu induces heart arrhythmias, impairs glucose homeostasis, and alters cholesterol and oxidative metabolism in post menopausal women. A dietary intake of about 4.12 mmol (100 mg) Mg/8.4 MJ is inadequate for healthy adults and may result in compromised cardiovascular health and glycemic control in post menopausal women.

Dietary zinc intake and plasma zinc each have a positive association with BMD in men.

Healthy, free-living men and women aged 20-83 y (n = 127) were studied to determine the effects of age and sex on copper absorption, biological half-life (BH), and status. Copper absorption was greater in women (71%) than in men (64%) aged 20-59 y (P = 0.02), but did not differ in men and women aged 60-83 y. BH of 67Cu ranged from 13 to 33 d and differed between men and women aged 20-59 y (P = 0.006), but not between men and women aged 60-83 y. Plasma copper, enzymatic ceruloplasmin (Cp), and immunoreactive (RID) Cp were significantly higher in women than in men (P < 0.005), but superoxide dismutase (SOD) and in vitro 67Cu uptake by red blood cells did not differ. Plasma copper, RID Cp, and cytochrome oxidase in platelets and mononuclear cells were significantly affected by age (P < 0.005). Oral contraceptives elevated plasma copper, enzymatic Cp, and SOD activity but not copper absorption and BH in women aged 20-39 y. Copper intake from self-selected diets was 0.9-1.2 mg/d for women and 1.2-1.3 mg/d for men, but net copper absorption (micrograms Cu.kg body wt-1.d-1) did not differ. Thus, dietary copper intake requirements may differ between men and women.

Of 824 women screened, 410 were enrolled at midpregnancy in a prospective, randomized, controlled nutrition intervention study. Of these, 226 were predicted as likely to have small or large babies, 184 to have average-sized babies. Two hundred thirty eight mothers received USDA Women, Infants and Children (WIC) Food Supplementation vouchers from midpregnancy, 172 did not. Leukocyte protein synthesis (as a cell model) was significantly higher (p = 0.009) by 36 weeks gestation in supplemented mothers. Mean birth weight of their babies was greater, 3254 vs 3163 g, (+91 g) p = 0.039, adjusted for sex, gestational age, prenatal visits, pregnancy interval, smoking, and previous low birth weight infants. Controlling for entry weight obviated the significance of the difference, except for WIC supplemented smokers (greater than 10 cigarettes/day) whose babies were significantly heavier by +168 g (p = 0.017) than those of unsupplemented smokers. WIC partially protects fetal growth in smokers.