The role of food, fortification, and supplements for nutrition in pregnancy and childhood, with a focus on vitamin D

Abstract

The aim of this thesis was to assess the role of food, fortification, and supplements for nutrition during pregnancy and childhood, with a focus on vitamin D. Data from two studies conducted within antenatal care in southwest Sweden were used: the pregnancy cohort GraviD (Paper I and II) and its follow-up GraviD-Child (Paper III), and the randomised controlled trial Pregnancy and Vitamin D Intervention (PREDIN) (Paper IV). Paper I assessed supplement use in relation to dietary intake and adherence to the Nordic Nutrition Recommendations among 1044 pregnant women. While adherence to average requirements (AR) was high for most nutrients through diet, supplementation contributed substantially to reach AR for vitamin D. Paper II simulated the effect of the extended Swedish vitamin D fortification policy on vitamin D intake among 1761 pregnant women. This revealed an overall positive impact on vitamin D intake. However, the impact may be smaller for individuals from Asia and Africa, compared to those born in Europe. Paper III evaluated vitamin D status and its determinants in 145 early school-aged children, and explored the tracking of vitamin D intake and status in mother-child pairs from pregnancy to childhood. Vitamin D status in children was generally adequate, with higher vitamin D status associated with blood sampling in summer months. Vitamin D intake and status tracked from pregnancy to childhood, although correlations were weak. Paper IV determined the effect of vitamin D3 supplements in two doses compared with standard care (advice on vitamin D supplementation) on changes in vitamin D status in pregnant women with a predicted risk of vitamin D deficiency (n = 105). Provision of 40 µg/day, but not 20 µg/day, resulted in a greater increase in vitamin D status over pregnancy compared with standard care. The findings of this thesis highlight the complementary roles of food, fortification, and supplements for vitamin D intake and status during pregnancy and childhood. Further research is needed to better understand barriers to the uptake of fortification and supplementation strategies to inform equitable and effective public health interventions.