Thinking and writing about the Mediterranean diet last week got me thinking about the Mediterranean in general and the extra sunlight that many Mediterranean inhabitants are exposed to….oh it would be nice to be in the sun right now….anyway, back to the point in hand! Vitamin D, the sunshine vitamin, has numerous health benefits and I am sure that the Mediterranean peoples gain from exposure in addition to their traditional healthy diet.
This month the American Journal of Clinical Nutrition is full of papers discussing Vitamin D (1,2,3,4). Readers of my blog will know that this year seems to have been the year for Vitamin D research! Many scientists are stepping up and extolling the virtues of the ‘sunlight vitamin’, for health. Here in the UK we are well into winter and the days are short giving us very little opportunity to step into the light for any length of time. Even if we can get out while the sun is bright we are wrapped up because of the cold so our skin isn’t exposed to the light and vitamin D cannot be manufactured. A supplement could be the answer?
Vitamin D seems to be important in relation not only to bone health but also in the prevention of heart disease and cancer. It also seems to be important for our immune system, muscles and brain and low levels have been linked to SAD, chronic fatigue syndrome, migraine headache and depression.
As I was writing and thinking about this post I came across a very recent and interesting study (5). Most evidence with regards vitamin D has been carried out in adults, this study was different as it involved 90 young women aged 16-22. The researchers measured vitamin D levels in the participants via a simple blood test and found that around 59% had insufficient levels, a huge proportion. The result is particularly surprising since the women in this study live in Southern California, which receives abundant supplies of sunlight.
The scientists also found that the young women with vitamin D insufficiency were significantly heavier, had a higher body mass index (BMI) and had a greater level of abdominal fat, a well recognised risk factor for heart disease and diabetes. They were also shorter in height compared to the women with sufficient vitamin D levels. Whether or not the low vitamin D levels are causal in weight gain cannot be known from this study, but it is worrying that so many young individuals do not have good levels of this essential nutrient, even though they live in a sunny environment.
The authors of the study indicate that health professionals could easily check for vitamin D insufficiency via a simple blood test. Vitamin D is so important for health and so many of us in the UK are not getting enough.
There have been calls for a raising of the recommended intakes of vitamin D and some scientists are even stating that vitamin D insufficiency has now reached epidemic proportions(5). In light of all the recent and advancing evidence it seems wise that we consider a vitamin D supplement, providing around 500-800 IU per day, especially over the autumn/winter months when sunlight exposure on our skin is minimal.
Some individuals may prefer to try and gain extra vitamin D from their diet. Unfortunately only small amounts of vitamin D are found in food sources such as oily fish e.g. mackerel, salmon and sardines (especially in canned varieties where the bones are soft and can be eaten) and eggs.
(1)Norman AW. 2008. A vitamin D nutritional cornucopia: new insights concerning the serum 25-hydroxyvitamin D status of the US population. Am J Clin Nutr. 88:1455
(2)Looker AC et al. 2008. Serum 25-hydroxyvitamin D status of the US population: 1988–1994 compared with 2000–2004. Am J Clin Nutr. 88:1519-1527
(3)Cashman KD et al. 2008. Estimation of the dietary requirement for vitamin D in healthy adults. Am J Clin Nutr. 88:1535-1542
(4)Ishihara J et al. 2008. Dietary calcium, vitamin D, and the risk of colorectal cancer. Am J Clin Nutr. 88:1576-1583
(5)Kremer R et al. 2008. Vitamin D Status and its Relationship to Body Fat, Final Height, and Peak Bone Mass in Young Women. Journal of Clinical Endocrinology & Metabolism. E Pub November 4 2008 doi:10.1210/jc.2008-1575
Written by Ani Kowal
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- The importance of vitamin D for calcium utilisation in the body
- Low vitamin D levels linked to increased fat in muscle tissue and reduced muscle strength
- New evidence points toward the importance of B vitamins for bone health
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- Low vitamin D levels linked to preeclampsia
