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Assessment of zinc nutriture is often compromised by the lack of reliable biomarkers. In the present study the effect of dietary zinc deprivation on plasma extracellular superoxide dismutase (EC SOD) activity was investigated in rat and rhesus macaque models. This enzyme, which contains both zinc and copper, is distinct from cytosolic copper-zinc SOD. Young, growing rats fed zinc-deficient diets (1.5 nmol Zn/g diet) were characterized by low plasma zinc concentrations and plasma EC SOD activities (16% and 56% of controls, respectively). Adolescent rhesus macaques fed diets that contained a marginal amount of zinc (30.6 nmol Zn/g diet) also had low plasma zinc concentrations and low EC SOD activities compared with controls fed diets containing 765 nmol Zn/g diet (75% and 40%, respectively). Enzyme activity was not affected after in vitro addition of zinc to plasma samples from control, restrict-fed, and zinc-deficient rats. Taken together, these data support the concept that plasma EC SOD activity can be a biomarker for zinc status.

Young rhesus monkeys (Macaca mulatta, n = 14) 25-30 mo of age were fed a zinc-deficient (ZD) diet (2 [mu]g Zn/g diet) (moderate zinc deprivation) over 15 week. The ZD diet period was compared with a zinc-adequate (ZA) diet period (50 [mu]g Zn/g diet) of the same duration, which either preceded or followed it (crossover design). Plasma zinc was lower at the end of the ZD than after the ZA period. There were no overt signs of zinc deficiency or effects on growth rate. Spontaneous motor activity was lower and performance of a visual-attention task and short-term-memory task were poorer during the ZD period than during the ZA period. Behavioral effects were detected as changes from individual baseline values, and often represented a failure to improve. The results suggests that dietary zinc deprivation can modulate behavior in prepubertal monkeys without affecting growth. Am J Clin Nutr 1994;60:238-43.

Copper deficiency has been postulated to result in low selenoglutathione peroxidase (Se-GSHPx) activity, secondary to alterations in the antioxidant defense system. Type I iodothyronine 5'-deiodinase contains selenium; because it is not part of the antioxidant defense system its measurement provides a way to evaluate the influence of copper on selenoenzymes independent of the antioxidant system. Weanling rats were fed the control diet (125.9 nmol Cu/g diet), copper-deficient diet (7.9 nmol Cu/g diet), or the control diet restricted to the intake of the deficient rats (restrict-fed), for 21 d. Rats fed the copper-deficient diet had cardiomegaly, low hematocrit values, and low tissue copper concentrations, but normal liver selenium concentrations. Liver and plasma Se-GSHPx activities were lowest in the deficient rats. Non-Se-GSHPx activity was similar between control and copper-deficient groups. Liver selenodeiodinase activity was lowest in the copper-deficient rats; this reduction was functionally significant as evidenced by low plasma 3,3', 5-triiodothyronine and high plasma 3,3',5-triiodothyronine concentrations. Am J Clin Nutr 1994; 59:654--8.

Interest in maternal nutritional status as a critical factor for prenatal development has increased. When supplemented before conception, iodine prevents cretinism and folic acid reduces neural tube defect risks. Other nutrient supplements may also reduce pregnancy complications. Thus, should supplements be advocated for all women with childbearing potential? Potential supplementation benefits include 1) improved nutritional status, 2) reduced risk of some developmental defects, 3) improved antioxidant and immune defense systems, 4) lower incidence and/or slower progression of some diseases, and 5) harmonization of government and health care professionals' dietary recommendations for optimal health. Potential questions are, will the supplement reduce a woman's motivation to maintain and/or improve dietary quality? Will the supplement result in excessive nutrient intakes and/or adverse nutrient-nutrient interactions? Will supplement use encourage the perception that all women are, by definition, well nourished? These issues should be clarified before widespread supplementation programs are implemented.

Fetal body movements were studied in three groups of gravid rhesus macaques fed different amounts of dietary zinc (100 [mu]g Zn/g diet, control, n = 12;4 [mu]g Zn/g diet, marginal deprivation, n = 7; 2 [mu]g Zn/g diet, moderate deprivation, n = 11). Sonographic examinations were conducted during the third trimester in awake chair-restrained dams. Movement categories, derived from the human biophysical profile, were motor activity (trunk and limb movements), startle, and breathing movements. Moderately deprived fetuses were more active than controls on gestational day (GD) 115; maternal plasma zinc concentrations were significantly correlated with fetal activity at this time. In addition moderately deprived fetuses exhibited fewer breathing episodes on GDs 115-135. Biometrics measures indicated growth retardation in one moderately deprived fetus. These data suggest that moderate, but not marginal, dietary zinc deprivation influences fetal status as evaluated by sonography.

Copper is known to be an essential nutrient, but scientists have not established a Recommended Dietary Allowance (RDA) for this mineral. Instead they have set an Estimated Safe and Adequate Daily Dietary Intake range of 2 to 3 milligrams (mg). However, some experts have suggested that this range is too high and lower intakes may be preferable. Surveys have found that the average copper intake in the US is approximately 1 mg/day, yet copper deficiency is rare. A study was conducted to investigate the human copper requirement. Eleven young men were admitted to a metabolic unit where their diet could be carefully controlled; the study lasted 90 days. In this period the subjects progressed from a diet supplying an adequate copper intake to a low-copper diet and then to a high-copper diet. Levels of copper in the saliva, urine and blood were tested to check for signs of copper deficiency. No measure of copper in the body differed according to the diet the subjects were consuming; even on the diet lowest in copper, laboratory tests showed no decrease in copper levels. The authors conclude that the lowest copper intake, 0.79 mg/day, was adequate for normal healthy men for a period of at least 42 days, the length of time the subjects consumed this amount of copper in the diet. (Consumer Summary produced by Reliance Medical Information, Inc.)

There is increasing appreciation that dietary components influence and interact with genes important to metabolism. How such influences impact developmental regulation and programming or risks of chronic diseases remains unclear. Nutrition is recognized to affect development and chronic diseases, but our understanding about how genes essential to nutrient metabolism regulate development and impact risks of these diseases remains unclear. Historically, mammalian models, especially rodents such as rats and mice, have been the primary models used for nutrition and developmental nutrition science, although their complexity and relatively slow rate of development often compromise rapid progress in resolving fundamental, genetic-related questions. Accordingly, the objective of this review is to highlight the opportunities for developmental models in the context of uncovering the function of gene products that are relevant to human nutrition and provide the scientific bases for these opportunities. We present recent studies in zebrafish related to obesity as applications of developmental models in nutritional science. Although the control of external factors and dependent variables, such as nutrition, can be a challenge, suggestions for standardizations related to diet are made to improve consistency in findings between laboratories. The review also highlights the need for standardized diets across different developmental models, which could improve consistency in findings across laboratories. Alternative and developmental animal models have advantages and largely untapped potential for the advancement of nutrigenomics and nutritionally relevant research areas.