Yet again vitamin D, or rather the lack of it has hit the headlines again. The completely tragic case of the young parents arrested for the murder of their baby, who turned out to actually have severe rickets, has reinforced the importance of this vitamin. Actually vitamin D is less of a vitamin and more of a hormone. Produced mainly by the action of sunlight on skin it is mainly known for its effect on calcium metabolism. Rickets, a disease characterised by malformed, fragile bones is raising its ugly head in many areas of the UK.
However, research has also found that vitamin D has a profound effect on other aspects of health like the immune system; deficiency is a risk factor for certain cancers like bowel and breast for example. People who are overweight, have diabetes or PCOS may be deficient; and these conditions are on the rise in the UK.
Traditionally the most vulnerable groups are those with darker skins because dark skin protects itself more easily from UV radiation. If your faith requires you to cover up too that adds to the risk. If you religiously cover yourself with high factor sun screen when there is a bit of sunshine, or you spend much of your life indoors then you risk deficiency and the consequences. Many older people especially in a care setting are deficient in vitamin D.
There are receptors for vitamin D in the reproductive organs; the testicles, prostate and the ovaries so it has a role even though we are not sure how it works. Researchers do hypothesise however that low maternal levels in pregnancy are a risk factor for multiple sclerosis in offspring and studies are looking at other conditions from autism (Cannell V, Autism and Vitamin D, Medical Hypotheses Volume 70, Issue 4, 2008, Pages 750-759) to schizophrenia (McGrath J, Hypothesis: Is low prenatal vitamin D a risk-modifying factor for schizophrenia? Schizophrenia Research 40 1999 173-177). Moreover some drugs such as Clexane and steroids used with IVF also reduce vitamin D levels. And additionally with a multiple pregnancy deficiency is a further risk.
I have tested more than a thousand clients coming for fertility advice and probably about 2/3 fall into the at least the sub-optimal range (including myself) with the vast majority of my black and Asian clients being distinctly deficient. Having a blood test is really the only way to find out what your level is so if you fall into any of the groups mentioned above then I suggest you ask your GP for a blood test. This is important because the doses of vitamin D needed to address any deficiency are very variable and you do need advice from a professional as to what the right dose is. The current RNI of 400iu/d is simply inadequate to address most deficiencies in my opinion especially if pregnancy is part of the picture. The ranges for acceptable vitamin D levels are also changing so advice that takes that into account is also important. I arrange testing privately for my clients so please contact me if you need specific vitamin D advice.
What to do
From November to March the spectrum of light, no matter how sunny, does not allow vitamin D to be metabolised. So in the late Spring and Summer months try and get outside every day; 20 minutes on arms, legs and chest (and a little through the eyes) without an SPF on your skin will give you a good dose. Vitamin D is not found in many foods but butter, fortified margarines and eggs do contain it and it is also present in cod liver oil (NOT to be taken in pregnancy). However I recommend taking a supplement of vitamin D3 (cholecalciferol) in Winter, at least and considering a test in order to ascertain your own level.