The controversy surrounding selenium and cardiovascular disease: a review of the evidence.

Selenium is an essential trace element that is an integral part of many proteins, with catalytic and structural functions. The antioxidant properties of some selenoproteins, such as glutathione peroxidase, may be particularly important in carcinogenesis and heart disease. The content of selenium in food depends on the selenium content of the soil where the plants are grown or the animals are raised. Moreover, the metabolism of selenium is determined by its dietary form: some forms are better utilized than others. Therefore, wide variations have been found in selenium status in different parts of the world. In animal studies, selenium deficiency is associated with cardiomyopathy and sudden death, as well as reduced T-cell counts and impaired lymphocyte proliferation and responsiveness. Abnormalities in liver function, brain, heart, striated muscle, pancreas and genital tract have also been reported. In humans, selenium deficiency has been implicated in the etiology of cardiovascular disease and other conditions in which oxidative stress and inflammation are prominent features, but there is still only limited evidence from epidemiological and ecological studies for this, and the therapeutic benefit of selenium administration in the prevention and treatment of cardiovascular diseases remains insufficiently documented. Interventions studies are currently in progress to assess the benefits of selenium supplements in primary and secondary prevention of atherosclerosis. The results to date are inconclusive and further controlled trials are needed.

Serum 25-hydroxy cholecalciferol in infants and preschool children in the Western region of Saudi Arabia. Etiological factors.

OBJECTIVE: Low vitamin D status has been frequently reported among Saudi subjects of all ages. No attempt has been made to relate this status to dietary intake or to diseases leading to malabsorption, for example diarrhea. This study was performed to investigate the various factors leading to low vitamin D status, and their relative importance in infants and preschool children. METHODS: Nine hundred and thirty-five healthy subjects aged 4-72 months were selected randomly form the Jeddah area of the Kingdom of Saudi Arabia. Medical history, time and frequency of exposure to sunlight and dietary intake were recorded. Blood samples were obtained form 739 subjects for the determination of 25-hydroxy cholecalciferol. The Subjects were divided into 5 age groups. The mean +/- standard deviation and other statistical parameters for serum 25-hydroxy cholecalciferol were calculated. Mean +/- standard deviations of exposure time and vitamin D intake were calculated, and subjects divided according to the adequacy of their intake. RESULTS: Age had no effect on the mean serum 25-hydroxy cholecalciferol (p=0.63). Mean dietary intake of the vitamin increased initially (p<0.05), decreased in the next group (p<0.005), then remained constant. There was significant correlation between serum level and dietary intake of the vitamin. No exposure to sunlight was noted in the youngest group. Low serum levels were associated mainly with repeated diarrheal attacks. This was the same in the next group. The mean exposure time in the 3rd group increased significantly (p<0.001). Low serum levels were found in subjects with low exposure time plus either or both of low dietary intake and repeated attacks of diarrhea. Increased mean exposure time (p<0.0005), and decreased incidence of repeated diarrheal attacks were found in the next age group with low serum levels noted in subjects with low exposure time and low dietary intake. In the oldest age group, mean exposure time increased further (p<0.0005), and low levels were found in subjects with low exposure time (mainly girls). CONCLUSION: Diet was the major source of the vitamin in subjects <12 months of age, and hence low levels were associated with frequent diarrheal attacks. A decrease in dietary intake, and more dependence on endogenous vitamin synthesis was apparent in older children, leading to low vitamin status in ones with low dietary intake and inadequate exposure to sunlight

Effect of chromium supplementation on glucose tolerance and lipid profile.

OBJECTIVES: To investigate chromium status of the adult population in the western region of Saudi Arabia and the possibility of using serum chromium status measurement as indicator of this status. METHODS: The effect of chromium supplement on glucose tolerance and lipid profile was studied in 44 normal, free living adults. 200mg chromium/day as CrCL3 or a placebo was given in a double blind cross-over study, with 8 weeks experimental periods. Fasting, 1 hour and 2 hour post glucose challenge (75 g of glucose) glucose, serum fructosamine, total cholesterol, high-density lipoprotein-cholesterol, triglycerides, chromium and dietary intakes were estimated at the beginning and the end of each stage. RESULTS: Mean serum chromium increased significantly after supplement (P<.001) indicating proper absorption of the element. Supplement did not effect the total cholesterol, however, the mean high-density lipoprotein-cholesterol level was significantly increased (P<.001), the mean triglycerides levels significantly decreased (P<.001), and the mean fructosamine level significantly decreased (P<.05). In addition, chromium supplement effected 1 hour and 2 hour post glucose challenge glucose levels in subgroups of subjects with 2 hour glucose level > 10% above or below fasting level and significantly differing to it (P<.05 in both cases), by decreasing or increasing them significantly (P<.05 in all cases) so that the 2 hour mean became not significantly different to the fasting mean. Since no significant changes in weight, dietary intake or habits were found, and placebo had no effect, all noted biochemical changes were attributed to chromium. CONCLUSION: Improved glucose control, and lipid profile following chromium supplement suggests the presence of low chromium status in the studied population. However, serum chromium could not be recommended for use as an indicator of chromium status as subjects with widely varying levels responded favorably to the chromium supplement.

Activity of serum cytidine deaminase during pregnancy.

A simple and reliable method for the estimation of cytidine deaminase (cytidine aminohydrolase; EC 3.5.4.5) activity in pregnancy serum is described. This enzyme does not require magnesium for activation and is also more stable than deoxycytidylate deaminase (dCMP deaminase, dCMP aminohydrolase; EC 3.5.4.12). There was excellent correlation between the two enzymes (r = 0.92). Both enzymes showed increased activity in abnormal pregnancy. Both enzymes activities were found to be similar in 1305 maternal serum samples and therefore due to the simplicity of cytidine deaminase estimation it is recommended for the screening of large numbers of antenatal sera for abnormal pregnancies.

Late third trimester unconjugated serum oestriol levels in normal and hypertensive pregnancy: relation to birth weight.

In 100 normal singleton pregnancies and in 44 patients with pregnancy hypertension (pre-eclampsia) linear regression analyses demonstrated highly significant positive correlations between birth weights and late third trimester maternal serum unconjugated oestriol (O3) levels. Correlation coefficients increased, though not significantly, after standardising birth weights according to maternal size, parity and sex of infant. Pregnancy hypertension was classified according to the duration of clinical signs. In 23 patients with short duration pregnancy hypertension (onset 14 days or less before delivery) neither maternal age nor birth weight differed from normal controls. Mid-pregnancy weights were greater and unconjugated O3 levels lower and only one infant was growth retarded. Twenty one patients with long duration pregnancy hypertension (onset more than 14 days before delivery) were found on average to be heavier at mid-pregnancy and older than those in whom the condition was short-lived. Unconjugated O3 levels in patients with long duration hypertension were significantly below those in the short duration group. One third of infants born following long duration hypertension were growth retarded.