New research published in the Official Journal of the British Dietetic Association confirms that once again, there is still quite a bit of work to do in the realm of educating on vitamin D.
Last week, I highlighted the lack of research in educating on vitamin D. The same holds true in the lack of research examining the public’s level of knowledge on vitamin D.
To date, only a few studies have examined attitudes and knowledge toward sunlight and vitamin D and how these attitudes and knowledge influence vitamin D status.
In the present study, researchers from Trinity College and University College Dublin teamed up to see the relationship between vitamin D knowledge and vitamin D status in pregnant women. The researchers note that to their knowledge, no study exists of its kind for pregnant women.
The researchers studied 116 pregnant women who were seeking antenatal services at the National Maternity Hospital in the Rotunda Hospital, Ireland, from April to May 2012. Of the 116 women, 31 were Irish, 28 were Sub-Saharan African (SSA), 33 were Asian and 24 were Middle Eastern and North African (MENA).
The researchers administered a questionnaire on the women’s knowledge on vitamin D and sun exposure and also tested their vitamin D level. They wanted to see if knowledge of vitamin D correlated at all with better vitamin D status.
The median vitamin D level was 10.4 ng/ml. Sixty-eight percent of the women had levels less than 12 ng/ml. The highest level was 40.8 ng/ml, which was explained by the woman recently vacationing in Hawaii, so the researchers threw out her results as an outlier.
Irish women had the highest vitamin D levels, with a median level of 19.1 ng/ml. SSA women had a median level of 8.9 ng/ml. Asian women had a median level of 11.1 ng/ml. And MENA women had severely low vitamin D levels, with a median level of 5.1 ng/ml.
On the questionnaire, here’s what the researchers found:
- 23% did not know any source of vitamin D.
- Of the women who knew a source, 74% reported the sun as a source, 43% reported dairy foods and 23% reported a variety of incorrect foods like fruit and vegetables.
- In total, 19% reported fish as a source of vitamin D.
- The proportion of women who identified good sources of vitamin D including sunlight and oily fish were not significantly different across any of the ethnic subgroups.
As to vitamin D levels, the researchers found that the following correlated with higher vitamin D levels:
- Taking a supplement
- Drinking vitamin D fortified milk
- Living in Ireland for more than 4 years
The researchers also found that of women who reported recent sun exposure, only Irish women’s vitamin D levels were higher. Perplexingly, the researchers did not report any data on whether or not there was a correlation between vitamin D/sun exposure knowledge and vitamin D status.
The researchers concluded,
“The findings obtained in the present study explicitly highlight the urgent need to establish practice guidelines for improving vitamin D status among pregnant women in Ireland, with a particular focus on the most vulnerable ethnic populations.”
This study confirms a few things. For one, it highlights that skin types are very much evolved to specific regions around the world. Only Irish women’s vitamin D levels were higher if they reported higher sun exposure. Since the Asian, SSA and MENA women had skin types that evolved nearer the equator and/or in more sun-intense regions, even getting some sun exposure in Ireland did not improve vitamin D status. As most here know, the darker your skin, the more sun exposure you need to make the same amount of vitamin D.
This study also highlight some solutions, and reasons why public health officials are keen on both supplementation and food fortification. Consuming fortified foods correlated with higher vitamin D levels, as did taking a supplement. In the 21st century, it’s perhaps impractical to expect people to get good sun exposure on a regular basis. This, coupled with the fact that humans in the past 400 years – for the first time in their evolutionary history – are living away from where their skin type evolved, strongly suggests that universal vitamin D supplementation is necessary and perhaps even food fortification, too.
Finally, North African and Middle Eastern women’s vitamin D levels were severely deficient. There is a strong likelihood that many of these women are suffering from undiagnosed osteomalacia. And there’s a strong likelihood that their neonates will be hypocalcemic and/or have rickets. These are serious conditions that should not be taken lightly. Health officials in Ireland should take action to help improve population wide levels in pregnant women immediately.