Sunshine vitamin: ethnic differences (Image: I Love Images/Rex Features)

A woman’s race may determine whether vitamin D helps them to conceive through IVF.

The sunshine vitamin is famed for its benefit to bones and the immune system, but it also plays a role in conception. Now, evidence suggests that the vitamin’s benefits may only apply to certain racial groups – while white women can boost their IVF success rates with vitamin D, the opposite appears to be true for Asian women.

For couples struggling to conceive, in vitro fertilisation (IVF) is a popular option. The technique involves extracting eggs from a woman and fertilising them with sperm outside of the body. The resulting embryo is then transferred into the uterus. As many women know, IVF isn’t a guaranteed ticket to pregnancy – less than a third of treated women under 35 will go on to have a baby, and the odds decrease with age.


In 2010, Sebiha Özkan at Kocaeli University in Turkey and her colleagues found that women with the recommended levels of Vitamin D (30 ng/mil) appeared to boost their chances of IVF success. Women with the highest levels of vitamin D were four times more likely to get pregnant than those with the lowest levels (Fertility and Sterility, DOI: 10.1016/j.fertnstert.2009.05.019).

Both IVF success rates and vitamin D levels are known to vary by race. To find out whether vitamin D carries the same benefits in women of different races, Briana Rudick at Columbia University Medical Center in New York and her colleagues compared vitamin D levels and IVF success rates in white Hispanic, white non-Hispanic, and Asian women from south-east Asia and the Indian subcontinent. All 188 women were having IVF for the first time.

Of these women, only 42 per cent had the recommended levels of vitamin D – just over a third had insufficient levels, while a fifth were completely deficient.

White women who were vitamin D replete were four times more likely to have a successful pregnancy than women of the same race who were deficient in the vitamin. Surprisingly, the reverse was true for Asian women – those with the lowest vitamin D levels were most likely to get pregnant.

“I’m thrilled the findings [in white women] corroborate our observation,” says Lubna Pal at Yale School of Medicine, Connecticut, who co-authored the 2010 paper. The racial difference is something of a mystery, though. “It’s an intriguing association that merits further study,” she says.

Rudick’s team aren’t sure why the difference exists, but they think it might have something to do with the enzyme that deactivates vitamin D. There are also ethnic differences in the gene for the vitamin D receptor, which may affect the link between vitamin D and conception, they say.

Pal cautions that only a relatively small number of women in the study were Asian, and that lumping south-east Asian and Indian races together may be too crude. “They’re very different in terms of skin colour, diet and culture,” she says.

Rudick agrees that it’s too soon to say for sure how much vitamin D is beneficial for Asian women. “I would never tell an Asian woman not to take vitamin D – there are too many other benefits, including pregnancy benefits [after conception],” says Rudick. But she adds that she wouldn’t necessarily encourage them to follow the current recommendations of increasing their vitamin D levels either.

Journal reference: Human Reproduction, DOI: 10.1093/humrep/des280