Nutritional therapist Ian Marber on why we may not be getting the vitamin D our body needs – even in the summer
Although vitamin D is one of the better-known nutrients, it seems that we are still not getting enough of it. Vitamin D has many scientifically proven roles, including supporting calcium utilisation (and therefore helping bone and teeth health), as well as assisting the immune system and helping cells grow. Other claims are contested, such as the idea that it may combat some forms of cancer.
Nonetheless, its importance is undeniable, yet the National Institute for Health and Care Excellence (NICE) estimates that one in five adults and one in six children in England alone may have low vitamin D status.
How it works
Vitamin D is actually a group of chemicals but in short, exposure to UV light allows one variant, known as D3, to be made in the skin, which is then taken to the liver where it is turned into calcitriol, the active form of the vitamin. Supplements of vitamin D tend to be another variant, D2, which is also converted into the active form. Food sources include oily fish, egg yolks and liver, which is bad news for vegetarians and vegans or anyone wanting to eat less animal produce.
Sunlight is vital when it comes to vitamin D and we need around 15 minutes of direct exposure, ideally between 10am and 2pm, for enough vitamin D production to take place in the skin. The skin should not be covered by UV protection for it to gain the benefits of vitamin D, but we do need to ensure that we don’t spend too much time in the sun without appropriate precautions. It’s not enough to have just your face in the rays – ideally your arms, legs and even some torso would be exposed too for optimal effect.
The NHS suggests that spending this time in the sun and reaping the benefits should not be a problem from April until September, but in reality, sunlight is not guaranteed in this part of the world, even in the summer months, and exposure is potentially limited by a lack of time too – how many of us are actually free during the day to enjoy the warmth?
The general advice is to supplement vitamin D in the winter months, but people with darker skins are advised to take a supplement throughout the year. It is my opinion that unless we do get the necessary sunlight every day and also eat vitamin D rich foods, then it would be wise for the wider population to take a supplement year-round.
As for dosage, the NHS advise at least 10mcg or iu daily, although other health sources suggest taking far more, often as much as 500iu, although 100iu daily is probably the upper limit for most people.
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