Determinants of serum 25(OH)D concentration in young and middle-aged adults. The Cardiovascular Risk in Young Finns Study.

Introduction: We studied prevalence of hypovitaminosis D, its determinants, and whether achievement of recommended dietary vitamin D intake (10 μg/d) is associated with absence of hypovitaminosis D in adults.

Methods: The study is part of the Cardiovascular Risk in Young Finns Study. We collected serum samples of 25-hydroxyvitamin D as part of the 27-year follow-up (994 men and 1,210 women aged 30-45 years). Hypovitaminosis was defined as vitamin D concentration ≤ 50 nmol/L.

Results: Hypovitaminosis D was found in 38% of men and 34% of women. Dietary vitamin D intake (OR 0.90, 95% CI 0.86-0.93), use of vitamin-mineral supplements (0.66, 0.51-0.85), sunny holiday (0.55, 0.41-0.75), and oral contraceptive use in women (0.45, 0.27-0.75) were independently associated with reduced odds of hypovitaminosis. Increase in body mass index (1.06, 1.03-1.09), being a smoker (1.36, 0.97-1.92), investigation month (December versus other) (1.35, 1.12-1.61), and risk alleles in genotypes rs12785878 (1.31, 1.00-1.70) and rs2282679 (2.08, 1.66-2.60) increased odds of hypovitaminosis. Hypovitaminosis D was common also when recommended dietary intake was obtained (men 29%, women 24%).

Conclusion: Several factors were associated with hypovitaminosis D. The condition was common even when recommended vitamin D intake was reported. The results support the importance of vitamin D fortification and nutrient supplement use.