Rethink of vitamin D guidelines are urged after publication of study

Health authorities around the globe are being urged to rethink official guidelines about vitamin D as a result of a new study from the University of Surry that reveals the disparity between the nutritional value of vitamin D2 and D3.

The study, published in the American Journal of Clinical Nutrition, investigated the two types of vitamin D — D2 (plant-based) and D3 (animal-derived) — to see which was more effective in raising levels of the nutrient in the body.

The team measured the vitamin D levels in 335 women (South Asian and white European) over two consecutive winter periods, when the nutrient is known to be lacking. The women were then separated into five groups.

These five groups were each given either a placebo, a juice containing vitamin D2 or D3, or a biscuit containing vitamin D2 or D3. It was found that vitamin D3 was doubly effective at raising the levels of vitamin D in the body than vitamin D2.

In those participants who received a juice or biscuit containing vitamin D3, vitamin D levels increased by 75% and 74%, respectively, compared with the women who had received vitamin D2 in those forms. Over the 12-week study period, those receiving vitamin D3 did have an increase of vitamin D levels to 33% and 34%.

Those who received the placebo were found to have a reduced level of vitamin D in their bodies (25% reduction) over the same period of time.

It is currently stated by various government bodies around the world, however, that the two forms of vitamin D are equivalent and can be used to equal effect.

“However, our findings show that vitamin D3 is twice as effective as D2 in raising vitamin D levels in the body, which turns current thinking about the two types of vitamin D on its head,” said lead author Dr Laura Tripkovic from the University of Surrey. “Those who consume D3 through fish, eggs or vitamin D3 containing supplements are twice as likely to raise their vitamin D status than when consuming vitamin D2 rich foods such as mushrooms, vitamin D2 fortified bread or vitamin D2 containing supplements, helping to improve their long-term health.”

The recommended daily intake of vitamin D has been increased to 10 µg per day for the general population by Public Health England as a result of there being one in five of the population with a low level of vitamin D. Consuming vitamin D3 rich foods or supplements rather than vitamin D2 could help to meet these recommended intake levels.

“The importance of vitamin D in our bodies is not to be underestimated, but living in the UK it is very difficult to get sufficient levels of it from its natural source, the sun, so we know it has to be supplemented through our diet,” stated Tripkovic.

The findings of this study will impact not only the health sector but also retail, which should now look to be fortifying products with vitamin D3 as it is the most effective way to increase vitamin D levels in the body.

“This is a very exciting discovery which will revolutionise how the health and retail sector views vitamin D,” summarised Professor Susan Lanham-New, head of the Department of Nutritional Sciences at the University of Surrey and principal investigator of the trial. “Vitamin D deficiency is a serious matter, but this will help people to make a more informed choice about what they can eat or drink to raise their levels through their diet.”