• Associations of physical activity with vitamin D status depends on obesity status in old adults.

      OG, Geirsdottir; M, Chang; Pv, Jonsson; I, Thorsdottir; A, Ramel; 1The Icelandic Gerontological Research Center, Reykjavik, Iceland; Faculty of Food Science and Nutrition, University of Iceland, Reykjavik, Iceland. 2The Icelandic Gerontological Research Center, Reykjavik, Iceland; Sport Science, School of Science and Engineering, Reykjavik University, Reykjavik, Iceland. 3The Icelandic Gerontological Research Center, Reykjavik, Iceland; Department of Geriatrics, National University Hospital of Iceland, Reykjavik, Iceland. 4School of Health Sciences, University of Iceland, Reykjavik, Iceland. 5The Icelandic Gerontological Research Center, Reykjavik, Iceland; Faculty of Food Science and Nutrition, University of Iceland, Reykjavik, Iceland. Electronic address: alfonsra@hi.is. (Elsevier, 2020-07-12)
      Purpose: Obesity has been associated with low 25-hydroxy-vitamin D (25OHD). The causes of hypovitaminosis D in obese individuals are not known. The present work aimed to investigate 25OHD in obese and normal-/overweight subjects with consideration of leisure-time physical activity (LTPA). Methods: Community-dwelling old adults (N = 229, 73.7 ± 5.7yrs, 58.2% female) from the Reykjavik capital area in Iceland participated in this cross-sectional study. LTPA, vitamin D intake, body composition and background variables were assessed. 25OHD was measured in fasting blood samples. Results: Mean LTPA was 5.7 ± 5.6 h/week and the common activities were walking and gardening. Mean 25OHD was 66.7 ± 28.1 nmol/L and 8.5/21.2% were below 30 and 50 nmol/L, respectively. Obese participants (n = 84) had lower 25OHD (-11.0 ± 3.8 nmol/L,P < 0.001) and lower LTPA (-2.5 + 0.8 h/week,P = 0.001) than normal-/overweight subjects (n = 145). Linear models showed that LTPA (h/week) was associated with higher 25OHD in normal-/overweight participants only (1.3 nmol/L, P < 0.001) but not in obese (-0.7 nmol, P = 0.245). Fish oil intake was associated with higher 25OHD both in normal-/overweight (19.2 ± 4.5 nmol/L, P = 0.001) and obese subjects (13.4 ± 5.3 nmol/L, P = 0.013). Conclusions: Obese community-dwelling old adults in Iceland have lower 25OHD than their normal-/overweight counterparts. LTPA was associated with a higher 25OHD in normal-/overweight, but not in obese participants. However, fish oil was associated with higher 25OHD independently from obesity status. Thus, vitamin D supplementation is important for obese old adults to maintain vitamin D levels. Keywords: Aging; Fish oil; Leisure-time physical activity; Obesity; Vitamin D.