(EA03-12-25) The Effect on Habitual Dietary Vitamin D Intake of Changing to a Plant-based Diet

Scientific conference where the work was recently presented: The Nutrition Society Congress 2024 (Belfast, UK)

Date on which the work was previously presented at the scientific conference listed: July 2, 2024

Objectives: The number of people following a plant-based (PB) diet is increasing. This has led to concerns about vitamin D intake, as natural dietary sources are primarily animal based and lower intakes have been reported amongst vegetarians and vegans; however some PB foods are now fortified. Whilst vitamin D is synthesised in the skin following exposure to UV light, this does not happen in the autumn/winter months in northern latitudes. Hence, dietary sources become particularly important. This study investigated whether it is possible to maintain dietary vitamin D intake when transitioning to a PB diet, through careful choice of PB alternatives.

Methods: Four-day food diaries, from 81 women (72 Caucasian, 9 South Asian, mean age 52±12 y) living in South East England, were analysed for vitamin D intake. Data modelling was carried out to substitute animal-based foods with equivalent amounts of PB alternatives. For dairy products, fortified alternatives were chosen. Meat, fish and eggs were replaced with equivalent amounts of protein from PB sources, such as lentils and tofu, as no fortified direct alternatives were found. The diaries were then re-analysed.

Results: There were no differences in vitamin D intake between ethnicities at baseline (p=0.087) or post-substitution (p=0.361). Intake increased in the South Asian group post-substitution (from 2.4±1.3 to 4.3±1.8 µg/day, p=0.002), with no change observed in the Caucasian group (3.6±2.0 to 3.7±1.8 µg/day, p=0.660). There was no difference between pre- and post-substitution intakes when groups were combined.

Conclusions: This study demonstrates that it is possible to move to a PB diet, whilst maintaining existing dietary patterns, without a reduction in vitamin D intake, but it is dependent on sufficient dairy intake in the original diet, as no meat/fish substitutes in the UK are currently fortified. It also requires care when choosing PB dairy substitutions as many, including organic options, are not fortified. Mean intakes, both pre- and post-substitution, were substantially below the UK recommendation of 10 µg/day, suggesting that supplementation may be necessary, particularly during winter months.

Funding Sources: Biotechnology and Biological Sciences Research Council, UK