Last Saturday the Times newspaper here in the UK carried a piece I’d written summarising some of the most salient issues regarding vitamin D deficiency and what we might do about it. Here it is…
The shortened days at this time of year will for some people usher in a downturn in mood that may culminate in full-blown depression. However, research also suggests that the winter months pose other hazards to health linked to the bottoming out of vitamin D – a critical nutrient made in the skin through the action of sunlight. Recently published research connecting lower light exposure and depressed vitamin D levels with impaired fertility in women undergoing IVF. This research, though, is just the tip of the iceberg of evidence linking higher vitamin D levels with a glowing array of benefits for health.
There exists, for example, a wealth of research linking sunlight exposure with relative protection from several different forms of cancer. A review published earlier this year in the journal Anticancer Research found greater exposure to the sun to be strongly associated with a reduced risk of 15 different types of cancer including those of the breast, colon, bladder and cervix.
Yet, when sunlight is mentioned with regard to cancer, its relationship with skin cancer tends to put it in a negative light. Higher levels of sun exposure are indeed strongly linked with the relatively harmless non-melanoma skin cancers (known as squamous cell and basal cell cancers), as partly evidenced by the fact that these cancers usually crop-up on sun-exposed parts of the body such at the face and back of the hands. However, the link between sunlight exposure and the much more deadly malignant melanoma is not clear-cut, with most of these occurring in not typically sun-exposed parts of the body. Also, indoor workers are at increased risk of melanoma compared to outdoor workers, and some studies link higher levels of sun exposure with lower melanoma risk.
However, even if we assume that sunlight exposure is a potent factor in melanoma, the evidence shows that greater sun exposure is linked with protection from cancer as a whole. This evidence should remind us that when advising about any lifestyle factor, we should take as broad a view as possible and not confine ourselves to one condition (skin cancer).
Evidence linking sun exposure with a reduced risk of heart disease tips the balance further in sunlight’s favour. VitaminD may lower blood pressure, at least in part through it’s ability to influence blood-pressure determining hormones such as renin. Also, a basic chemical building block of vitamin D is cholesterol, and sunlight therefore has some capacity to lower cholesterol levels by catalysing cholesterol’s transformation into vitamin D. This has led some to suggest that ‘raised’ levels of cholesterol may be the result of ‘sunlight deficiency’. Vitamin D is also known to have natural anti-inflammatory actions in the body, which has relevance as inflammation has emerged as an important underlying mechanism in atherosclerosis (the ‘gumming up’ process on the inside of the arteries which can lead to heart attacks and strokes). In one study published in the Archives of Internal Medicine in 2008, men with levels of vitamin D < 15 ng/ml (see below for more on levels) were more than twice as likely to suffer a heart attack compared to those with levels > 30 ng/ml.
Other research links sunlight exposure and heightened vitamin D levels with relatively protection from auto-immune diseases – those conditions in which the body’s immune system is reacting against its own tissues. One example of this is the neurological condition multiple sclerosis, the incidence of which is close to zero in equatorial regions and but increases steadily the further one gets from the equator.
As voluminous as the research revealing links between sunlight, vitamin D and improved health is, it’s important to bear in mind that this work is ‘epidemiological’ in nature. This sort of evidence may reveal associations between things, but that does not necessarily mean one is causing the other. To establish a ‘causal’ link between these things and demonstrate that vitamin D is disease protective we require what are known as intervention studies. Here, individuals are treated with vitamin D, and the outcomes are compared with those taking a placebo (dummy pill).
Such studies require considerable manpower and funds, and perhaps as a result there’s a relative dearth of them. The studies that do exist can be somewhat limited in their usefulness partly because the dosages used in them are often insufficient to optimise vitamin D levels, as well as their relatively short duration (it may take many years for the beneficial effects on conditions such as heart disease and cancer to becomes apparent). However, even with these limitations there have been some encouraging findings, with a major review published in the Journal of Clinical Endocrinology and Metabolism in August of this year
finding that supplementation with vitamin D along with calcium (though not vitamin D alone) for an average of 3 years reduced overall risk of death by 9 per cent.
Other evidence has found that vitamin D alone has potential as an antidepressant. In one study published in the Journal of Internal Medicine in 2008, vitamin D therapy was found to improve the symptoms of depression compared to a placebo. In clinical practice, I have found that optimisation of vitamin D is often very beneficial for reducing or even eliminating the symptoms of ‘season affective disorder’ (winter blues), which suggests that this condition may be caused, at least in part, by low vitamin D levels at this time of year.
The role of vitamin D in physical and mental health has risen up the agenda in recent years, and a driving factor has been the growing recognition of widespread deficiency in some countries including the UK. In recent times we have heard doctors alerting us to a resurgence of rickets (malformed and weakened bones as a result of vitamin Ddeficiency) in the UK.
The only way to know for sure whether the body has sufficient levels of vitamin D is via blood testing. However, even here it needs to be borne in mind that references ranges are set on a largely deficient population, which means ‘normal’ ranges do not represent optimal levels for health and wellbeing.
My preference is for levels to be around 50 ng/ml = 125 nmol/l (toxicity does not appear to occur at levels under 200 ng/ml). Yet, evidence suggests that in the UK, approaching 90 per cent of 45-year-olds will have levels lower than 30 ng/ml in the winter, though in the summer and autumn, still about 60 per cent fall into this category. Bearing in mind the research linking higher vitamin D levels with benefits for a range of health parameters, it may well be that generalised vitamin D deficiency is contributing to the disease burden in the UK.
The research on vitamin D levels quoted above was conducted in Caucasians and the relevance of this is that, for a given amount of sunlight, fairer skins generally make more vitamin D than darker ones. What this means is that vitamin D deficiency is likely to be even more prevalent in those of Asian and Afro-Caribbean decent. Those living at more northerly latitudes are also at increased risk of vitamin D deficiency, as are those whose exposure to sunlight is limited (such as the elderly).
Vitamin D levels can be improved with sunlight exposure, but it should be borne in mind that when the sun is low in the sky, vitamin D cannot be made in the skin. As a general rule, in the UK vitamin D can only be made from the end of March through to September, and only in the middle of the day. A decent rule of thumb is that good vitamin D-generating potential is to be had when one’s shadow is shorter than one’s height. While it is important not to allow the skin to burn, even 10 or 20 minutes of daily sun exposure (without sunscreen) to bare legs, arms and torso can do much to boost vitamin D levels.
Boosting levels in the summer will help build up vitamin D stores that may help tide us through the winter. Another approach is to increase our consumption of vitamin D-rich foods such as oily fish. However, the amount of vitamin Dfound in food generally pales into insignificance compared to the amount we can make from sun exposure and is generally required for optimal levels of vitamin D in the body.
Vitamin D supplementation represents a practical option, and dosages required to make significant difference to bloodvitamin D levels are usually in the order of several thousand international units (IU) per day. In practice I’ve found that about 1,000 IU (25 micrograms) of daily supplementation with vitamin D3 usually raises blood levels by 10 ng/ml (25 nmol/l) over time.
Children, just like adults, need vitamin D too, something that is highlighted by the recent resurgence in rickets. Again, ideally levels should be checked, but approximate appropriate supplementation levels are 1,000 IU for children under the age of 1 year, and 1,000 IU for each 25 lbs (11 kg) of body weight for older children. Pregnant women in the UK are recommended to supplement with 400 IU of vitamin D each day as a matter of course.
Hi! Glad to see you getting mainstream attention. I read somewhere recently that in fact darker skins do not mean lower production of vitamin D. Sorry I can’t remember where this was, but I thought it was interesting. I just assumed it was an issue but the article claimed that the discovery brought into question the current understanding about the mechanism of vitamin D production through sun exposure. Thought you might be interested.
hello dr briffa,
interesting post. you reach the big media,that is great.
i am italian, i live in the heart of the dolomites mountain range. last summer i had a great exposure to sunshine in the mid hours of the day, i can say an average of 1 1/2 hours a day , thanks to the weather and my lunch breaks in the park, from may through to september.
i see that vitamin d can be stored in the body, but i cannot find anywhere for how long it could be: weeks or months? what your insight?
btw, i follow your blog and i find some of your posts really interesting.
Bravo! Excellent report and recommendations. I always educate my clients about the role of vitamin D and sunlight in overall health. And I encourage them and give them ways to spend more time outdoors all year round. Still, in the winter, who could possibly get enough D in many latitudes without supplementation? I’ve blogged about this too!
I have just tested low for vitamin D and my gp has started me on 800 iu of D3. I have had ME/CFS for five years and have always suffered from terrible pain in my lower legs. I will be interested to see if this deficiency has played any part in my pain.
Vitamin D is stored in the blood as 25(OH)D which has a half life of about 20 days. You cannot make vitamin d from sunlight in mainland Europe at this time of year.
Dr Briffa, I would have liked you to mention whether those with Vitiligo have severe shortages of vitamin D as at the height of a summer’s sunshine day one is covered with creams and or staying in shade.
Outstanding article! Can you furnish references?
Any notion of whether. Vitamin D received by sunlight superior to supplementation?
I always try to get at least an hour in the garden in the mid day sunshine from March onwards until the sun leaves my garden at the beginning of October BUT this year with the absolutely appalling bad weather in London that has only been possible on comparatively few occasions. Apart from the actual health benefits sunbathing also makes me feel enormously better all round. I have never used sunscreens or in fact any creams for being in the sun since the menopause but seem to have had no ill-effects whatsoever, quite the opposite.
This winter though it might be advisable to take a vitamin D supplement ? There’s a long dark winter still to come.
@ Jo darker skins do not mean lower production of vitamin D
The mechanics of Vitamin D3 production as the result of UVB exposure of 7 dehydrocholesterol molecules in skin, is really quite well documented as here
The effect of ultraviolet radiation on serum 25-hydroxyvitamin D(3) levels
Overall there is inverse correlation between skin pigmentation and latitude in humans resulting from the evolutionary advantages pale skins provided away from the Equator, such as increased Vitamin D3 production, enabling greater vitamin D production for use overwinter and improved fertility & fecundity in spring.
However there are many factors that affect the amount of Vitamin D produced as a result of exposure of skin to UVB.
The basics are detailed here Ultraviolet-B radiation increases serum 25-hydroxyvitamin D levels: the effect of UVB dose and skin color.
There is a huge range of response to the same UVB exposure or the same daily supplemental intake. Urban/rural atmospheres differ in the amount of UVB reaching ground level. Ethic background, skin colour, clothing, religion, other traditions, immigration, gender, medications, BMI, age, total cholesterol and the amount of stress we endure all come into the equation.
Because the number of permutations is so great, it’s important, whatever regime we adopt, we all test 25(OH)D regularly so we are able to predict the 25(OH)D result and understand how our individual body responds to sun and/or supplements.
Good stuff about vitamin D and great you reached big media. I was tested low on vitamin D in September and my GP suggested 2000 IU per day or 10 000 per week. But to up my levels i’ve taken 5000 IU per day and feel great.
It is worth remembering the importance of complimenting any supplementation with vitamin D with supplementation of magnesium. The two work together in the body – any increase in synthetic vitamin D may well require a corresponding increase in magnesium Otherwise you could become prone to the sympthoms magnesium deficiency, as I did when I started supplemeting with vitamin D (following Dr Briffa’s advice) two years ago.. Magnesium deficiency is not nice – e.g. difficulty sleeping, difficulty swallowing and breathlessness. (Dr Briffa: i really think you should be mentioning the close connection between these two nutrients in your articles on vitamin D). I recommend that anyone who decides to take vitamin D supplements should reserach the magnesium connection and be aware of the possible consequences of taking high doeses of vitamin D without also addressing magnesium.
@ MikeS Beneficial effects of UV radiation other than via vitamin D production
I think using all sources of vitamin D is better than just using supplementation alone.
If you look at the cholesterol metabolism pathway you’ll see the precursor molecule to cholesterol is 7 dehydrocholesterol, which when exposed to UVB is converted to Cholecalciferol, vitamin D3.
In summer when we are outside UVB converts some of that 7 dehydrocholesterol to vit d which is used and so isn’t boosting Total Cholesterol numbers. So when Autumn/Winter comes we see a rise in Total Cholesterol, LDL-C and Trigs and also a rise in coronary heart disease, cerebrovascular disease and respiratory disease with a summer trough in the same. In England and Wales, the winter peak in coronary and cerebrovascular disease accounts for 20,000 extra deaths.
Vitamin D works best as an anti-inflammatory agent at 125nmol/l 50ng/ml.
If we could use all sources of Vitamin D3, including UVB exposure, to keep inflammation under control throughout the year, with regular 25(OH)D testing to keep Vitamin D levels high and stable throughout the year, maybe some of those 20,000 extra deaths could be avoided?
I’d be interested to know more about the difference in d2 and d3 supplements – i heard d2 is bad? Also what about synthetic vs. natural sources? Surely natural is the way to go. I take a vit d supplement made out of mushroom extract!
@ Jayne “my gp has started me on 800 iu of D3. I have had ME/CFS for five years and have always suffered from terrible pain in my lower legs. I will be interested to see if this deficiency has played any part in my pain.”
I’m afraid 800iu /daily vitamin D3 is not equivalent to the amount of vitamin D3 human bodies naturally create given full body non-burning summer sun exposure.
Naturally our bodies create/absorb about 10,000iu~20,000 given summer sun exposure.
If you go to the Vitamin D charity GRASSROOTSHEALTH you will see in their banner a graph of typical USA responses to different daily vitamin D supplement intakes. (remember USA is nearer the equator than the UK)
You will see from that graph that to be sure that MOST people get 25(OH)D above 50ng/ml or 125nmol/l significantly more than 800iu/daily/D3 will be required.
5000iu/daily is a reasonable starting point but 1000iu/daily for each 25lbs weight is better for people who are overweight.
Retesting 25(OH)D 3~5months later will show if that is an adequate amount.
If below target by 25nmol/l then add 1000iu/daily and if above 150nmol/l then reduce daily intake by 1000iu daily.
You will only discover if vitamin D supplementation can help your body cope better with chronic inflammation and fatigue if you provide more than adequate resources to control inflammation and the inflammatory response.
It is important both the amount of 25(OH)D (calcidiol) circulating in plasma is adequate but also we maintain reserves of Vitamin D3 in tissue that can be used to elevate local 1,25(OH)2D3 in response to local inflammation.
We only begin to store vitamin D ABOVE or = to 40ng/ml ~ 100nmol/l and only at/above 50ng/ml ~ 125nmol/l can significant reserves of Vitamin D3 in tissue be detected.
Dr Davis of the Track Your Plaque and WheatBelly fame has found that even at very high daily vitamin D3 intakes he uses with his patients it MAY take up to 3 years before vitamin D reserves are fully restored.
If we look at the related condition Fibromyalgia and Vitamin D3 we find significant improvement when blood level of 25(OH) D became above or = to 30 ng/mL, (75nmol/l) this improvement became more significant when their blood level of 25(OH) D exceeded 50 ng/ mL. (125nmol/L)
In addition to the magnesium KEVIN mentioned (required to enable switching from circulating (Calcidiol) to active hormonal form of vitamin D3 (Calcitriol) it’s important to check your diet provides the RDA for calcium Other vitamin D Cofactors are Vitamin K, Vitamin A, Zinc and Boron. The omega 3 DHA also helps improve regulation/production of Calcitriol (1,25-dihydroxyvitamin D or 1,25(OH)2D3).
Vitamin D3 is an integral part of our anti-inflammatory resources and should be used with it’s necessary cofactors and together with magnesium, omega 3 repletion + an anti-inflammatory diet and lifestyle.
@ Chloe Brotheridge ” the difference in d2 and d3 supplements – i heard d2 is bad? Also what about synthetic vs. natural sources? Surely natural is the way to go. I take a vit d supplement made out of mushroom extract!”
This article compares the efficiency of D2D3
Meta-analysis looks at efficacy of D2 vs D3
If we look at what actually happens when people use mushroom sourced Vitamin D.
Ergocalciferol from mushrooms or supplements consumed with a standard meal increases 25-hydroxyergocalciferol but decreases 25-hydroxycholecalciferol in the serum of healthy adults.
Our understanding of Vitamin D is developing all the time and there is still much to learn.
It will be interesting to find out more about how human bodies use the
Vitamin D4 in Mushrooms
However, I think until we know for certain D4 is safe for humans, we should base our Vitamin D economy on form of vitamin D3 naturally created in human skin and/or the biologically identical form made by exposing lanolin (by product from the wool industry) which we know acts in the same way.
Thanks – an interesting read.
I agree with Kevin about ensuring you have enough of the other minerals that are needed for Vit D metabolism. I would also add Calcium into that equation but I would start by upping the foods rich in these minerals in your diet rather than relying on supplements. Mother Nature has packaged Magnesium and Calcium conveniently together in dark leafy greens such as spinach, collard greens , swiss chard and turnip greens so if you make sure you are getting a big bowl of dark leafy greens daily you’ll be covering the bases as far as these two minerals are concerned. (For reluctant children – I recommend chopping them up quite finely and sprinkling them into soups, stews, pastas – everything reall 😉 Unfortunately no such neat nutritional solution for Vitamin D though so it’s sun or supplements (good excuse to break up the winter with a trip to a sunny destination – for those who can afford it…..)
By the way – other Mg rich foods are seeds (sunflower and pumpkin) and nuts (cashews and almonds), black beans and molasses, some of which also have decent Ca levels. One of the easiest ways to increase Mg levels is to buy a big bag of Epsom salts (most chemists shd stock it) – chuck a few handfuls in the bath (with a few drops of lavender oil, perhaps) and soak for at least 20mins. Your skin will absob the Mg ions (and the sulphate) boosting levels of both. It can be particularly therapeutic for those with muscle aches or arthritis. Bliss. Oh – and by the way if you do get sunburnt on your winter sun seeking holiday – an Epsom salts bath can help soothe and relieve the inflammation from that too.
You write: “…in the UK vitamin D can only be made from the end of March through to September, and only in the middle of the day.”
As far as I know vitamin D can be made with UVB. In the middle of the day the UVA is very intensive, which has a negative impact on the skin. Thus might it be optimal the sun exposure mornings and afternoons?
@ Ferri In the middle of the day the UVA is very intensive, which has a negative impact on the skin. Thus might it be optimal the sun exposure mornings and afternoons?
But this is a UK website and in the UK our UVB exposure is only optimal at midday.
Obviously NO ONE SHOULD EVER get sunburnt.
This UK website shows actual UVB readings through the day for different times of the year and there is also an interesting graph showing how UVB concentrations in the UK compare with Alice Springs Australia and Florida USA.
UV Light in Nature: Solar Ultraviolet Light
And there is a calculator here
Calculated Ultraviolet Exposure Levels for 1000 iu increase in Vitamin D Status that you can adjust for your latitude/longitude and altitude that works out exposure required for 1000iu, but bear in mind most people require an EXTRA 5000~10,000iu to reach the 25(OH)D level around 125nmol/l 50ng/ml that Hunter Gatherer’s in East Africa living now as human DNA evolved reach vitamin D equilibrium. (They also have sufficient common sense to stay out of the midday sun)
I think the problem arises because of the inflammatory nature of modern diets and lifestyles results in skins that are very pro-inflammatory.
That can be changed if you take time over winter so in spring/summer your skin is fit for the natural UV exposure it evolved to thrive under.
These links lead to evidence based strategies for improving the natural photo-protection level of your skin.
Skin Texture, Cancer and Dietary Fat- Wholehealthsource
Natural Sunscreen Options Healthyfellow
Eat Your Sunscreen? | Wellness Mama
UV hardening therapy: a novel intervention in patients with photosensitive cutaneous lupus erythematosus.
Do bear in mind that all the suggestions from the above links work best in combination and take time to become effective. 3~4 months preparation is the minimum time to see significant improvements in the resistance to burning from UV exposure.
Much of the damage from UVA comes from the release of iron from blood as a result of inflammation.
If everyone regularly donated blood we would have less free iron available to damage our DNA.
The blood donation service offers a free anti-ageing service for those who wish to slow or delay the ageing process.
Dump your excess iron for free and do something amazingto help others at the same time.
The sooner you start the less chance you have of suffering the consequences of iron overload as a result of iron behaving badly. If you’re approaching 70 then it’s worth knowing you can continue to donate after your 70th birthday if you’ve donated in the 2 years prior to becoming 70 so please don’t lose your opportunity to reduce iron overload.
Iron is one of the metals implicated in the onset/progression of Alzheimer’s.
@Ted, thanks a lot for your helpful response! !
Ted, thank you so much for your advice. I’m going to increase my dose. The gp gave me tablets that are giving me an awful stomach ache so I’m thinking of trying the drops.
@ “a few minutes on a sunbed every 6 wks or so in winter tops up the vit d?”
It depends on the tubes used?
Low pressure lamps that emit a balance of UVA and UVB are needed.
High pressure lamps emit only UVA that penetrates deeper into the skin and causes damage and doesn’t create vitamin D.
You need only a quarter ~ half of the UV exposure required to turn skin “pink” to produce 4000~10,000iu.
Oiling your skin before UV exposure increases penetration of UV so you would need to reduce time exposed.
It’s very important to check 25(OH)D because individual response to UVB is determined by the amount of 7 dehydrocholesterol in your skin which depends on your total cholesterol level.
The lower your total cholesterol the less vitamin d your skin can produce and the amount of UVB the tubes produce declines with the age of the tube and unless the sunbed owner has a UVB monitor there is no way of knowing if the tubes produce sufficient UVB to produce effective amounts of Vitamin D3.
The use of short non-burning UV exposure overwinter is a useful way of keeping the skin hardened to reduce chance of sunburn the following summer but I would prefer everyone to also use supplements to increase Vitamin D3 levels as effective strength Cholecalciferol (Vit D3) supplements are guaranteed to produce an improvement in 25(OH)D whereas UV lights may/may not be effective (too many variables outside your control)
have i read somewhere that a few minutes on a sunbed every 6 wks or so in winter tops up the vit d?