PURPOSE: Seasonal variations in circulating vitamin D levels provide vital information as to the most appropriate time to either start or increase vitamin D supplementation to maintain optimal vitamin D levels. In this follow-up study, we determined seasonal differences in serum 25(OH)-vitamin D (25(OH)D) levels, as well as parallel changes in metabolic parameters, in a cohort of adult, overweight and obese Saudis. METHODS: A total of 121 adult, overweight, obese, and consenting Saudis aged 18-70 years were randomly recruited from four Primary Health Care Centers in Riyadh, Saudi Arabia. They were divided according to the season when baseline measurements were made [74 summer (April-October); 47 winter (November-March)]. Anthropometrics were obtained, and fasting blood samples were taken at baseline and every 3 months for 1 year. Fasting blood glucose, corrected calcium levels, and lipid profiles were measured routinely. Serum 25(OH)-vitamin D was quantified using a specific enzyme-linked immunosorbent assay (ELISA). RESULTS: Age- and BMI-matched mean 25(OH)-vitamin D levels from the winter group were significantly higher than those of the summer group (P < 0·001). In both groups, HDL-C levels improved significantly as 25(OH)-vitamin D levels increased with subsequent follow-ups, even after adjusting for age, gender and BMI (P < 0·001). CONCLUSION: Seasonal differences in serum 25(OH)-vitamin D levels in Saudi Arabia are counterintuitive, with circulating levels being higher during the winter than the summer season. Increased vitamin D supplementation is thus recommended to maintain optimal serum 25(OH)-vitamin D levels during the summer season.
PURPOSE: Seasonal variations in circulating vitamin D levels provide vital information as to the most appropriate time to either start or increase vitamin D supplementation to maintain optimal vitamin D levels. In this follow-up study, we determined seasonal differences in serum 25(OH)-vitamin D (25(OH)D) levels, as well as parallel changes in metabolic parameters, in a cohort of adult, overweight and obese Saudis. METHODS: A total of 121 adult, overweight, obese, and consenting Saudis aged 18-70 years were randomly recruited from four Primary Health Care Centers in Riyadh, Saudi Arabia. They were divided according to the season when baseline measurements were made [74 summer (April-October); 47 winter (November-March)]. Anthropometrics were obtained, and fasting blood samples were taken at baseline and every 3 months for 1 year. Fasting blood glucose, corrected calcium levels, and lipid profiles were measured routinely. Serum 25(OH)-vitamin D was quantified using a specific enzyme-linked immunosorbent assay (ELISA). RESULTS: Age- and BMI-matched mean 25(OH)-vitamin D levels from the winter group were significantly higher than those of the summer group (P < 0·001). In both groups, HDL-C levels improved significantly as 25(OH)-vitamin D levels increased with subsequent follow-ups, even after adjusting for age, gender and BMI (P < 0·001). CONCLUSION: Seasonal differences in serum 25(OH)-vitamin D levels in Saudi Arabia are counterintuitive, with circulating levels being higher during the winter than the summer season. Increased vitamin D supplementation is thus recommended to maintain optimal serum 25(OH)-vitamin D levels during the summer season.
Authors: Mansour K Al-Zahrani; Abdulrahman M Elnasieh; Farhan M Alenezi; Abdulrahman A Almoushawah; Mohammed Almansour; Fahad Alshahrani; Saeed Ur Rahman; Abdullah Al-Zahrani Journal: Int J Clin Exp Med Date: 2014-12-15
Authors: N M Al-Daghri; N Aljohani; S Rahman; S Sabico; O S Al-Attas; M S Alokail; A Al-Ajlan; G P Chrousos Journal: J Endocrinol Invest Date: 2016-06-16 Impact factor: 4.256
Authors: Abdulaziz Al-Othman; Sara Al-Musharaf; Nasser M Al-Daghri; Soundararajan Krishnaswamy; Deqa S Yusuf; Khalid M Alkharfy; Yousef Al-Saleh; Omar S Al-Attas; Majed S Alokail; Osama Moharram; Shaun Sabico; George P Chrousos Journal: BMC Pediatr Date: 2012-07-03 Impact factor: 2.125
Authors: N M Al-Daghri; O S Al-Attas; M S Alokail; K M Alkharfy; A Al-Othman; H M Draz; S M Yakout; Y Al-Saleh; M Al-Yousef; S Sabico; M Clerici; G P Chrousos Journal: J Endocrinol Invest Date: 2011-12-15 Impact factor: 5.467