Selenium and vitamin status in the Al‐Kharj district, Saudi Arabia

Abstract

Purpose. To determine the status of selenium, dl-a-tocopherol and all-trans-retinol in children and adults living in the Al-Kharj district, using serum and toenail samples. Design. A cross-sectional study. The samples were collected randomly from 1255 healthy Saudi subjects attending the Primary Health Care Units (PHCUs), Al-Kharj for different common health problems. Materials and methods. Serum and toenail selenium concentrations were measured using an atomic absorption spectrophotometer coupled with an electrothermal temperature controller, whereas the levels of dl-a-tocopherol, all-trans-retinol and malondialdehyde in serum were determined using highperformance liquid chromatography. Results. The arithmetic means of selenium, dl-a-tocopherol and all-trans-retinol in serum for the tested population were 102.165¡22.936 mg l 21 (n51255, range 18.25-210.12 mg l 21 ), 22.715¡6.908 mmol l 21 (n51250, range 2.53-79.44 mmol l 21 ) and 1.601¡0.802 mmol l 21 (n51256, range 0.39-13.99 mmol l 21 ), respectively. Toenail selenium levels were 0.613¡0.217 mg g 21 (n51069, range ,detection limit-1.797 mg g 21 ).Conclusions. The prevalence of subjects with serum selenium below the threshold limit of clinical importance in coronary and cardiovascular diseases (45 mg l 21 ) was only 0.56%, whereas 45.4% of the tested subjects had toenail selenium ,0.56 mg g 21 , a low level, as indicated in a previous study. There was an influence of the geographical location of the PHCU on selenium levels, reflecting different dietary habits. To confirm this finding, it would be useful to study selenium dietary intake. dl-atocopherol deficiency (,11.6 mmol l 21 ) was found in only 2.6% of the screened subjects, suggesting sufficient vitamin E intake. However, none of the participants in this study had a severe all-transretinol deficiency (,0.35 mmol l 21 ) and the percentage of participants with marginal deficiency ,0.7 mmol l 21 was only 3.2%. The present data provide support that the dietary habits among the different PHCUs studied are adequate regarding all-trans-retinol nutritional requirements. Malondialdehyde as a marker of lipid peroxidation was evaluated and a significant negative association between dl-a-tocopherol and malondialdehyde levels in the serum was found, confirming the role of vitamin E in reducing oxidative stress.