Vitamin D and Sunshine: an essential vitamin! Protects against cancer, heart and bone disease

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See also Vitamin D - most of us do not get enough


Western cultures have become almost phobic about any exposure of unprotected skin to sunshine with the well-recognised association between skin cancer and exposure to sunshine.

But a certain amount of sun exposure is essential for normal good health in order to produce vitamin D - and partly as a result of current recommendations, we are seeing declining levels of vitamin D and the problems that go with it.

Vitamin D levels and incidence of disease

Human beings evolved over hundreds of thousands of years in equatorial areas and were daily exposed to sunshine. Dark skins evolved to protect against sun damage. However, as hominids migrated north, those races which retained their dark skins were unable to make sufficient vitamin D in the skin and did not survive. Only those hominids with paler skins survived. Thus the further away from the Equator, the paler the skin became. Races in polar areas survived because they were able to get an alternative source of vitamin D from fish and seafood.

There is an interesting inverse correlation between sunshine exposure, vitamin D levels, and incidence of disease as one moves away from the Equator. Even correcting for other factors such as diet, there is strong evidence to show that vitamin D protects against osteoarthritis, osteoporosis, bone fractures (vitamin D strengthens the muscles thereby improving balance, movement and preventing falls), cancer, hypertension, hypercholesterolaemia, diabetes, heart disease, multiple sclerosis and vulnerability to infections. Multiple sclerosis is a particularly interesting example of a possible vitamin D deficiency disease. Indeed mice bred for susceptibility to multiple sclerosis can be completely protected against development of this disease by feeding them high doses of vitamin D.

See Vitamin D and Chronic Diseases - an excellent and detailed paper with 104 referenced links. One paragraph of this study reads as below and this is not a comprehensive list of the diseases associated with low Vitamin D levels -

[25OHD = 25-hydroxy vitamin D]

The outcome of 25OHD deficiency in terms of osteoporosis, osteomalacia and increased fracture risk is well known. Furthermore, vitamin D may be relevant in the physiopathology of chronic liver diseases because of its effect on the immune system and its anti-fibrotic effect. A high percentage of chronic hepatitis C virus infection patients (46% to 92%) have low 25OHD levels, and more than 25% those were suffering from severe 25OHD deficiency. In a recent clinical study of adults with non-alcoholic fatty liver disease (NAFLD), Targher et al showed that the 25OHD levels had an effect on the development of hepatic steatosis and in the severity of the histological lesion. A possible role of vitamin D has also implicated in several other diseases, including multiple sclerosis, psoriasis, OA, and chronic kidney disease. Taken together, 25OHD levels affect the multiple diseases.


How much

For people living in equatorial areas, blood levels of 25OHD usually exceed 100nmol/l and often 200nmol/l. Since we evolved in hot climates, this is probably what is physiologically desirable. However, normal ranges in laboratories are still stated at around 40 to 100nmol/l. This almost certainly represents sub-optimal levels - it may be enough to prevent rickets and osteomalacia (bone softening), but is not sufficient for optimal health. You can test your levels of Vitamin D very easily and cheaply - see Vitamin D Home Test Kit


For a pale skinned Caucasian, whole body sunlight exposure barely sufficient to trigger tanning (the so called minimum melanogenesis dose) is as little as 15 minutes and is equivalent to the consumption of 10,000i.u. of vitamin D. If this is compared to the US recommended dietary allowance now standing at 200i.u. (which is the amount in a teaspoon of cod liver oil), one can readily see that the best source of vitamin D is sunshine.


It is extremely difficult to get blood levels up to an optimum level on diet alone. Furthermore, dark-skinned individuals need very much more sunshine exposure in order to achieve the same blood levels of vitamin D. As people get older their requirements also increase - however, typically they spend less time in the sunshine and are much more prone to vitamin D deficiency and the problems that go with it.

In a study in which groups of elderly people started to take calcium and vitamin D, the occurrence of fractures is reduced by a third in the first year even though bone density is not increased sufficiently to account for the fewer fractures. What is not yet common knowledge is that vitamin D improves muscle strength and balance and it is thought that this is what reduces the occurrence of falls leading to fractures. See The use of calcium and vitamin D in the management of osteoporosis

How to get more vitamin D

It is impossible for people living in Britain to get adequate vitamin D levels through full spectrum light. To receive sufficient vitamin D, you need to get the equivalent of at least 15 minutes per day whole body exposure to sunshine, probably more depending on the colour of your skin, to trigger tanning, but not burning of the skin. How likely is that? So what do you need to do to optimise your vitamin D levels?

  • Lack of sunshine in the UK is an excellent excuse to book a holiday in a sunny climate during the winter! In order to get an equivalent dose through eating fish, one would have to consume 25 teaspoonfuls of cod liver oil or its equivalent. Eskimos and Inuit Indians probably achieve this easily with their diet, but I cannot see myself persuading my patients to do this. A foreign holiday sounds much more attractive.

You can buy Vitamin D3, Multi Mineral Mix and Sunshine Salt from my Online store:

Vitamin D supplements

In choosing a good vitamin D supplement, one needs to know a little of the biochemistry. Vitamin D2, ergocalciferol is made from yeast and is about a quarter as potent as vitamin D3. In order for D3 to be activated it needs to be twice hydroxylated in the liver and the kidney - bear in mind that anybody with liver or kidney problems may have a requirement for the active twice hydroxylated vitamin D (calcitriol) rather than D3.

In studies where vitamin D3 is supplemented at 10,000i.u. daily there have been no cases of hypercalcaemia. As one example, see this study - A phase 2 trial exploring the effects of high-dose (10,000 IU/day) vitamin D(3) in breast cancer patients with bone metastases - the use of the phrase 'high-dose' reflects RDAs rather than optimal levels. Vitamin D RDAs range from 600iu to 800iu

Sunning - "aprication"

The Ancients knew the benefits of sunbathing and even had a verb for it – apricari (to bask in the sunshine). This gives us one of the great unused words in the English language – to apricate, meaning to bask in the sunshine.

People will be delighted to hear that sunshine is good for them - the overwhelming majority feel much better for sitting out in the sunshine. If the skin goes red then they are having too much exposure - they need just sufficient to promote mild tanning.

People with dark skins need much more than people with fair skins, but again they can judge this from the degree to which their skin darkens with exposure to sunshine. Redness means inflammation due to skin damage and should be avoided. It's the old story - with any substance from water to sunshine, there is potential to underdose and overdose - it's all about getting the balance right!

Vitamin D and its co-factors

Often people ask me about taking co-factors to improve absorption of Vitamin D. Vitamin D co-factors are vitamins K1 and K2 and others such as boron, vitamin A, omega 3 and magnesium. You will get enough K1 and K2 from the PK diet, and boron, vitamin A, omega 3 and magnesium are all covered by the basic supplements package - boron and magnesium are in sunshine salts [or multi mineral mix], omega 3 is in the recommended essential fatty acids and vitamin A is in the recommended Biocare multi vitamin / mineral - see Nutritional Supplements - what everybody should be taking all the time even if nothing is wrong

See Vitamin K

Vitamin D and Covid-19

Please see the More tab of this website for studies supportive of the beneficial effect of Vitamin D in cases of Covid-19 - NHS CORONA DOCTORS ON THE FRONTLINE - Corona Virus Treatment and Prevention

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