Association of serum vitamin D status with dietary intake and sun exposure in adults

Background & aims: Serum 25(OH)D deficiency is becoming an epidemic. The aim was to assess vitamin D status of the adult Greek population in relation to intake, sun exposure and other factors, using data from the Hellenic National Nutrition and Health Survey (HNNHS).

Methods: Data from 1084 adult participants (37.8% males) were analyzed. Vitamin D intake was assessed using 24-h recalls. Serum 25(OH)D concentration was evaluated and related to anthropometric measurements and other covariates including supplements used, by sex. Variables significantly associated with 25(OH)D < 20 ng/ml were assessed using simple and multiple logistic regression.

Results: Median vitamin D intake from food was 1.23 mcg/day (0.60, 2.44), with 9.1% consuming supplements. Median serum 25(OH)D was 16.72 ng/ml, with no sex differences (P = 0.923). The odds of having 25(OH)D < 20 ng/ml significantly decreased with being very active (OR 0.55, 95% CI 0.35, 0.98), increasing length of sun exposure [1-3 h/day (OR 0.59, 95% CI 0.44, 0.80), >3 h/day (OR 0.36, 95% CI 0.24, 0.55)], and skin colour [light to medium skin (OR 0.47, 95% CI 0.24, 0.91), fairly dark skin colour (OR 0.34, 95% CI 0.17, 0.67) and dark or very dark skin colour (OR 0.34, 95% CI 0.15, 0.75)], compared to respective baseline levels. The odds significantly increased with obesity (OR 1.95, 95% CI 1.24, 3.08), and spring season of blood sample collection (OR 1.75, 95% CI 1.22, 2.50).

Conclusions: Vitamin D deficiency is highly prevalent in Greek adults. Relevant public health policies are highly recommended, which could include vitamin D fortification. and suggestion for increased but safe sun exposure.