Are You Consuming the Right Kind of Vitamin D?


Not all vitamin D is created equal. That’s what a new study found, and the results may have significant implications for public health strategies seeking to boost levels of the important vitamin.

The study, appearing in the American Journal of Clinical Nutrition, found that food supplements containing one type of the vitamin – D3 – were far more effective at raising vitamin levels in the body compared to supplements containing another form, vitamin D2.

Credit: Collin Grady/Flickr, CC BY 2.0

“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.

Both substances are found naturally, but they come from different sources. Vitamin D3 derives from animal products, while D2 comes from plants.

For the study, researchers assessed total vitamin D levels in 335 women over a two-year span. To gauge the effectiveness of the different vitamins, they had one group of women consume juice or eat a biscuit containing D3 and the other group do the same with D2. The experiment lasted over the course of two winters.

Related: Vitamin D May Ease Sunburns by Reducing Skin Damage

After the trial ended, the women who consumed D3 had about a 75 percent increase in circulating levels of vitamin D in their bodies, compared to a 34 percent boost among those who consumed D2.

The study may overturn current dietary guidelines, which consider both forms of vitamin D to have equal health benefits.

Large Public Health Impact

“This is a very exciting discovery which will revolutionize how the health and retail sector views vitamin D,” said professor Susan Lanham-New, Head of the Department of Nutritional Sciences at the University of Surrey.

In regions where sunlight is scarce, such as parts of North America and the United Kingdom, people rely on vitamin D supplements to ensure healthy levels of the vital nutrient. Healthy vitamin D levels are linked to disease-fighting prowess, bone health and other important factors.

People may want to reconsider their dietary choices in light of the new findings.

“Those who consume D3 through fish, eggs or vitamin D3 containing supplements are twice as more 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,” said Tripkovic.

Related: Vitamin D Deficiency May Cause Early Menopause

“Vitamin D deficiency is a serious matter, but this will help people make a more informed choice about what they can eat or drink to raise their levels through their diet,” said Lanham-New.  

The difference in vitamin D fortification is particularly important for pregnant women, notes a previous study from the University of Surrey.

“The importance of vitamin D sufficiency should not be underestimated. It is well-known to be good for our musculoskeletal systems, but our research shows that if levels are low in expectant mothers, it can affect the development of their children in their early years of life,” said Dr. Andrea Darling, who led a separate study on vitamin D and health outcomes related to pregnancy.

“Vitamin D is found in oily fish (e.g. salmon, sardines, mackerel and fresh tuna) and in small amounts of red meat, eggs, fortified fat spreads and some breakfast cereals.  However, unless a large portion of oily fish (100g) is eaten daily it is difficult to get the recommended daily intake of 10 micrograms per day from food alone,” said Darling.