Alexandre Giroux

Effects of age, smoking, drinking, exercise and estrogen use on indices of copper status in healthy adults1

Abstract Erythrocyte Cu, Zn-superoxide dismutase activity (SOD), ceruloplasmin activity (CP) and serum copper concentration (SCu) were determined in normal adult males (n=239) and females (n=145). The effects of age, smoking, drinking frequency, exercise and oral contraceptive use or estrogen replacement therapy on these indices of copper status were investigated. For males, the mean SOD (U/mg hemoglobin±SD) was 77.42±15.7 and for females, 75.7±19.9. CP and SCu were highly correlated, while no significant relationship between these two indices of copper status and SOD could be detected. Both SCu and CP varied significantly with age in females but not in males. No age-related differences in SOD were found. Estrogen use, both in oral contraceptive preparations by pre-menopausal women and as replacement therapy by postmenopausal women significantly increased both SCu and CP but had no effect on SOD. Smoking, drinking frequency and activity level had no significant effect on any of these parameters of copper status.

Effects of low copper and high zinc intakes and related changes in Cu,Zn-superoxide dismutase activity on DMBA-induced mammary tumorigenesis

The effect of low copper and high zinc intakes on Cu,Zn-superoxide dismutase (Cu,Zn-SOD) activity and mammary tumorigenesis induced by 9,10-dimethyl-1,2-benzanthracene (DMBA) was investigated. Groups of 40 weanling female Sprague-Dawley rats were fed a modified AIN-76 diet containing the following (/kg diet): 1 mg Cu (0.016 mmol) and 30 mg Zn (0.459 mmol); 6 mg Cu (0.094 mmol) and 30 mg Zn (0.459 mmol) (control); or 6 mg Cu (0.094 mmol) and 150 mg Zn (2.295 mmol) for 21 wk. At 5 wk, 30 rats/group were given 4 mg (15.6 μmol) DMBA in corn oil intragastrically, and controls (10/group) received corn oil alone. Erythrocyte Cu,Zn-SOD activity was measured at 3, 5 (just before DMBA), 9, 13, 17, and 21 wk. The group fed the high-Zn diet had a slightly lower weight gain and food consumption. DMBA treatment had no effect on these parameters. Plasma and liver Cu concentration decreased in the low-Cu group. Femur zinc was significantly elevated in the high-Zn group. Erythrocyte Cu,Zn-SOD activity was decreased in the low-Cu group from 3 to 21 wk and was significantly elevated in the high-Zn group at 3 and 5 wk. In the low-Cu group, there were 5 nonmalignant adenomas and 3 malignant adenocarcinomas; in the control group, there were 4 adenomas and 3 adenocarcinomas; in the high-Zn group, there were 5 adenomas and 3 adenocarcinomas. No relationship between Cu,Zn-SOD activity and the presence of tumors could be found.

Sodium and potassium content of the Canadian diet

Abstract On the basis of the food consumption data obtained in the Canadian Nutrition Survey, representative food samples were collected in Vancouver, Winnipeg, Montreal and Halifax during summer and winter. After preparing the foods in a normal way, but without adding salt, ten food group composites were prepared. They were analysed for sodium and potassium. The total diet was found to contain 1142 mg sodium and 1194 mg potassium per 1000 kcal. The sodium included that added by the food manufacturing industry to about one-quarter of the 120 food items included in the diet. About 70 percent of the sodium and 50 percent of the potassium were provided by three major food groups viz. milk and dairy products; meat, fish and poultry; cereals and cereal products. Fruit products, vegetables, potatoes and mixed dishes supplied 9–16 percent of the potassium. Vegetables and mixed dishes contained about 10 percent of the sodium. The amounts of potassium in the diets of various physiological groups, including pregnant women, were more than the Canadian recommendations. The sodium intakes were 2 to 5 times the recommended amounts.

Estimated mineral nutrients in a representative Canadian diet

Abstract The calcium, phosphorus, magnesium, iron, zinc, copper and managenese content of a representative Canadian diet was determined by analysing 11 different food group composites. The amounts of food included in the diet were based on the Nutrition Canada Food Consumption Patterns Report. The minerals in the diet were (mg/1000 kcal): Ca, 380; P, 567; Mg, 107; Fe, 4.5; Zn, 5.2; Cu, 0.49; Mn, 0.82. The proportion of the minerals, except calcium, provided by the diet groups was correlated with the energy contribution of each group. With the exception of some adults over 50 y, the content of minerals per 1000 kcal of the diet would be sufficient to meet the recently recommended intakes in Canada.

Effect of magnesium deficiency on mineral excretion and concentration in rat serum, heart and kidney

Abstract Epidemiological evidence suggests that magnesium deficiency may be a factor in the etiology of cardiovascular and renal disease. During moderate magnesium deficiency in rats, caused by feeding 80 mg Mg/kg, however, magnesium levels in the soft tissues were previously shown to vary little. Consequently, in the present study, rats were fed either 80 or 500 mg Mg/kg for 6 weeks, and the concentrations of sodium, potassium, calcium, phosphate and magnesium were determined in serum, heart, kidneys, urine and feces to see whether changes in the levels of these elements, caused by the magnesium deficiency, play a role in the pathogenesis of these diseases. The concentration of oxalate was also determined in the urine. In the heart, both sodium and calcium were increased, while magnesium was decreased slightly in the deficient animals. In the kidney, nephrocalcinosis occurred, along with an increase in sodium and phosphate concentration. The feces contained increased levels of sodium and potassium. The data suggest that magnesium deficiency alters sodium transport. In the case of the heart, this may alter the membrane potential and could account for the cardiac arrhythmias associated with magnesium deficiency.

Magnesium status and excretion in age-matched subjects with normal and elevated blood pressure

Plasma, erythrocyte, and leucocyte magnesium (Mg) concentration, as well as urinary Mg, calcium (Ca), and phosphorus (P) excretion were determined in male subjects with elevated diastolic blood pressure (DBP) > 90 mmHg. These parameters were compared to those in normotensive age-matched (DBP < 85 mmHg) and drug-treated hypertensive subjects. Mg and Ca were determined by atomic absorption spectroscopy and P was determined by a colorimetric method. Urinary excretion was expressed in terms of creatinine (Cr) excretion. There were no significant differences in plasma, erythrocyte, or leucocyte Mg concentrations. Both urinary Ca and Mg were significantly decreased in the group with elevated blood pressure (BP) and the drug-treated group compared to the normotensive group. Urinary P was elevated in the drug-treated hypertensive group. Of all the variables studied, urinary Mg was the only one that was significantly inversely correlated with both systolic (SBP) and DBP. These data suggest that decreased urinary Mg, which may be indicative of a decreased Mg intake, is associated with hypertension.

An evaluation of plasma and erythrocyte magnesium concentration and the activities of alkaline phosphatase and creatine kinase as indicators of magnesium status

Rats were fed diets containing magnesium at concentrations ranging from 3.3 to 26.7 mmol/kg of diet (80 to 650 mg/kg). The magnesium concentration of their plasma and erythrocytes, and the activities of plasma alkaline phosphatase and creatine kinase were investigated to determine their usefulness as indices of magnesium status. All the indices increased with increasing dietary magnesium levels. The best correlations were observed between dietary intake and plasma concentration of magnesium (r = 0.846, p less than 0.001) and between intake and femur concentration (r = 0.811, p less than 0.001). There was an extremely high correlation between plasma concentration and femur concentration (r = 0.930, p less than 0.001). Although significant, the correlations between intake and the enzyme activities were not strong. It is concluded that plasma magnesium concentration is the most useful indicator of magnesium status and that the activities of the two magnesium-requiring enzymes can only be used for the purpose of diagnosing severely deficient magnesium status.

BIOAVAILABILITY OF IRON IN GROUND BEEF AND PLANT PROTEIN CONCENTRATES

Abstract Weanling male Wistar rats were fed a low iron basal diet for 4 weeks. They were then divided into 16 groups according to a randomized block design based on hemoglobin level. During the repletion period of 2 weeks, one group was fed the basal diet. The other fifteen groups received ferrous sulphate, freeze-dried ground beef, ground granular soy product, a 2:1 mixture of beef and the soy product, or rapeseed protein concentrate as iron sources at three levels. All diets were isocaloric and isonitrogenous. The efficiency of iron utilization was calculated on the basis of iron gained in hemoglobin and iron consumed, applying appropriate correction for iron obtained from the ingredients of the basal diet. The relative biological value (RBV) of iron in the test source was calculated as the ratio between the efficiency for the test and the standard source (ferrous sulphate). The RBVs were: freeze-dried ground beef, 0.53; ground soy product, 0.62; 2:1 mixture of beef and soy product, 0.71; rapeseed protein concentrate, 0.55. The low availability of iron in beef containing 60% heme iron indicated that the anemic rat is not a suitable model for normal man, since the absorption of heme iron by man is much higher than that of inorganic or non-heme iron.

Iodine content of Canadian retail milk samples II. After the ethylenediamine dihydroiodide ban

Abstract Whole and partially skimmed (2% fat) retail milk samples were collected from across Canada and analysed for their iodine content to determine whether this had decreased since the imposition of a ban on the use of ethylenediamine dihydroiodide (EDDI) to prevent foot rot in cattle. The mean iodine concentration ± standard deviation ranged from 177 ± 35 μg/litre to 456 ± 151 μg/litre, with individual samples ranging from 87 to 1304 μg/litre. The national mean concentrations for both whole and partially skimmed samples were not significantly different (p > 0·05) from the values obtained prior to the imposition of the EDDI ban, although some differences were observed in a few regions. Thus, except in a few instances, the change in regulations on the use of EDDI has had minimal effect on the iodine levels in milk.

Effect of zinc supplementation on the copper status and cholesterol levels of Cynomolgus monkeys

Abstract Twenty male and twenty female Cynomolgus monkeys were fed a specially formulated monkey chow containing 30 mg Zn and 6 mg Cu per kg. A control group was given daily supplements of 10 mg of zinc as the gluconate, while the experimental (supplemented) group received 25 mg. The 10 mg were given to the control group to compensate for the amount of zinc bound to the phytate present in the chow. The objective of the study was to determine the effects of prolonged consumption of the high zinc dose on copper status, cholesterol level and other biochemical parameters. No effect of the larger amount of zinc was observed on hemoglobin, hematocrit plasma glucose, blood urea nitrogen (BUN), serum glutamic oxaloacetic transaminase (SGOT) activity, serum glutamic pyruvate transaminase (SGPT), activity, HDL-cholesterol, triglycerides, total plasma protein and albumin. Plasma zinc increased in the supplemented groups, and plasma copper was lower in the female supplemented monkeys. No differences between the control or supplemented groups were observed in the activities of erythrocyte Cu, Zn-superoxide dismutase and ceruloplasmin (ferroxidase). Plasma cholesterol increased in the supplemented groups. We conclude that zinc supplementation affects copper status in the Cynomolgus monkey, but that this interaction is moderated by the presence of phytate in the chow. In addition, zinc has a hypercholesterolemic effect in these animals.