Sun Exposure and Vitamin D
We are constantly told to cover up, avoid the mid-day sun, and to use creams containing high sun protection factors (SPF) if exposed to the sun to reduce our risk of developing skin cancers such as melanoma. Even school children in rather gloomy parts of the UK are obliged to wear caps with neck flaps whilst out playing to protect them from the sun. And many moisturisers, body lotions and foundations now include a sun protection factor as standard. All this hysteria is coupled with a rising tide of cancers and particularly melanomas - one of the most deadly cancers.
However, much new research now indicates that this advice although well intentioned is quite ill-advised and that the cancers may be being caused by chronic Vitamin D deficiency brought about through a lack of sun exposure. After all, we have supposedly evolved over millions of years wearing little more than our birthday suits under the African sun, and yet now the message is that the sun is dangerous and something to be fearful of.
If you live in the Northern Hemisphere, then these summer months are your opportunity to get out in the sun.
So what is the best thing to do?
Sources of Vitamin D
Although some Vitamin D can be obtained in the diet mostly through fortified foods and oily fish, or in fish oils or multimineral/vitamin supplements, for most people the vast majority of their Vitamin D is synthesised in the skin upon exposure to sunlight.
However, for many who live in the more northerly or southerly latitudes such as the UK, Canada or New Zealand the sunlight is not strong enough to promote Vitamin D synthesis for at least 7 months of the year. Our livers are able to keep a limited store of Vitamin D which is estimated to last no more than 3 months, but many if not most people are now found to be chronically deficient in Vitamin D.
In a recent UK study all the subjects were found to have low levels of Vitamin D in the winter and spring, half to have low levels during the summer and one in six were classified as severely deficient - even at the low minimum levels set by the UK authorities.
The incidence of the Vitamin D deficiency disease, rickets, has also risen by 90% in recent years. This is particularly an issue in immigrant Asian communities where the women in particular wear traditional dress suited to the hot sun of India, for example, and tend to spend a lot of time indoors.
Another issue with immigrant communities moving to more northerly or southerly latitudes is that darker skin makes Vitamin D much less efficiently than paler skins. And this too may account for the higher incidence of some illnesses in African-Americans when compared to their Caucasian counterparts, for example.
In addition, many of the food sources of Vitamin D are animal in origin so vegetarians and vegans are particularly at risk of deficiency. And as a society we are all generally eating much less fish (which is a good source of Vitamin D) than used to be the case.
The kidneys are also involved in converting Vitamin D into its active form and this process can slow with age putting the elderly at risk of Vitamin D deficiency too.
In addition, some drugs may also contribute to Vitamin D deficiency. These include some anticonvulsants, cholesterol lowering drugs, corticosteroids and barbiturates. Pesticides too being fat soluble can act as steroid hormone disruptors and make Vitamin D deficiency worse. And some digestive disorders such as coeliac disease, food allergies and dysbiosis may promote Vitamin D deficiency by compromising absorption.
The actions of Vitamin D
Scientists have known since the 1920s that Vitamin D was essential in helping to utilise the calcium and phosphorus in food to build healthy bones preventing rickets and osteomalacia. However, the last 30 years have brought a huge expansion in our knowledge about the many different functions of Vitamin D.
Although classified as a vitamin because it has vitamin-like actions, many now think that Vitamin D is really in a class of its own. This is because it produces a metabolic product, calcitriol, which acts as a steroid hormone and Vitamin D is also a potent antioxidant. Calcitriol regulates the expression of over 2,000 genes which is about 10% of the human genome. In addition, Vitamin D regulates cell differentiation thus preventing cancer and also promotes insulin secretion by the pancreas.
Almost all body tissues have been shown to have Vitamin D receptors and it has been identified in at least 38 different tissues to date and is probably present in all cells to a greater or lesser extent.
Emeritus Professor of biochemistry, Anthony Norman of the University of California, Riverside, has spent nearly 50 years studying the subject. He says that Vitamin D has been shown to play an important role in the immune system, the heart and blood vessels, the pancreas, muscle development and strength, and brain development.
A growing body of research is now linking Vitamin D deficiency with a host of diverse diseases as outlined below.
Growth and development and Vitamin D
Vitamin D is known to be important during pregnancy and to growth and development in the early years of life. Researchers at the University of South Carolina found that pregnant women taking very high daily doses of Vitamin D were less likely to experience preeclampsia and gestational diabetes than those on the lowest dose. Vitamin D deficiency is known to cause delayed development and osteomalacia (rickets) in children.
Cancer incidence and Vitamin D
Over 200 epidemiological studies and 2,500 laboratory studies have now linked Vitamin D deficiency to the development of cancer. In fact, Vitamin D appears to play a particularly significant role in the prevention of female cancers such as breast and ovarian cancer, the most dangerous form of skin cancer, melanoma, and in bladder, colon and prostate cancers.
Current research has implicated Vitamin D as a major factor in the pathology of at least 17 different varieties of abnormal cellular growth. Its actions include reducing the growth of new blood vessels from pre-existing ones, which is an important step in the growth of cancerous tumours. It also reduces the spread and reproduction of cancer cells and promotes cell differentiation (cancer cells are often undifferentiated). Vitamin D also appears to increase the destruction of mutated cells by the immune system.
In studies, women with higher blood levels of Vitamin D have been shown to have half the breast cancer incidence of those with the lowest levels. And in a study of patients with colon cancer, those with the highest levels of vitamin D were nearly half as likely to die as those with the lowest levels.
In fact according to Dr. William Grant, Ph.D., an expert on Vitamin D, nearly a third of cancer deaths could be prevented with higher levels of Vitamin D. And the evidence linking Vitamin D levels to cancer is such that Professor Angus Dalgleish, an oncologist at St George's Hospital, London is calling for all cancer units to screen all their patient's Vitamin D blood levels.
Melanoma In a complete reversal of what we have been told for decades, it is low Vitamin D levels that appear to pose a major risk of melanoma. Such that the incidence of melanoma actually declines with sun exposure and increases with the use of sunscreens! Melanomas are also more common in indoor rather than outdoor workers, and tend to occur on regions of the body that are rarely exposed to the sun.
One study revealed that melanoma patients who had higher levels of sun exposure were less likely to die than other melanoma patients, and patients who already had melanoma and got a lot of sun exposure were prone to a less aggressive tumour type. Patients with the lowest Vitamin D levels were also 30% more likely to relapse after treatment for melanoma than those with the highest levels.
Poor immunity, allergies and vitamin D
Studies have shown that Vitamin D promotes cytokine production which modulates the immune system and can help to promote inflammation and allergy or fight infection(s). In Danish research conducted at the University of Copenhagen, researchers have found that Vitamin D plays a crucial role in activating immune defences by triggering and arming the body's T cells which destroy invading bacteria and viruses.
American research has also found that supplementing Vitamin D reduced the incidence of colds and flus by 70% over 3 years in Afro-Caribbean people who are more vulnerable to deficiency because of their darker skin.
Asthma And in a Costa Rican study, serum levels of Vitamin D were found to be inversely linked to several indicators of allergy and asthma severity.
Mood and Vitamin D deficiency
Some of the symptoms of Vitamin D deficiency are seen in women only, like mood changes during premenstrual syndrome. Depression and seasonal affective disorder (SAD) have both been linked to low levels of Vitamin D and in the particular case of SAD this may coincide with depletion of the body's stores of Vitamin D in the dark winter months.
Vitamin D deficiency and autoimmune diseases
Several studies have reported reduced levels of Vitamin D in patients with autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus (SLE) and scleroderma. And Vitamin D has been shown to influence the genes associated with the development of autoimmune diseases such as Crohn's disease and type 1 diabetes.
Multiple sclerosis (MS) It has long been recognised that multiple sclerosis rates increase with latitude and decrease towards the equator. In fact, Scotland has one of the highest rates of MS in the world and this may be because the Scots are known to be exposed to the same amount of sunlight as Eskimos within the Arctic Circle, but without the benefit of a high Vitamin D oily fish diet.
Recent research shows that when sun exposure is combined with exposure to the Epstein-Barr virus which causes glandular fever or mononucleosis, the vast majority of MS cases can be explained. In fact, eleven years ago, German researchers demonstrated that all MS patients had antibodies against the Epstein-Barr virus and the authors of the study suggested that the virus might activate the underlying disease process.
Vitamin D has been shown to have a direct effect upon expression of the genes associated with the development of multiple sclerosis and this may be one of the modes of action.
Arthritis Vitamin D deficiency is also commonly associated with joint pain and stiffness and arthritis. In particular, recent research has shown patients with psoriatic arthritis tend to have low blood levels of Vitamin D.
Type I and Type II diabetes Both Type I and Type II diabetes have been linked to low Vitamin D levels. In one study where Vitamin D supplements were given to babies in Finland their risk of Type 1 diabetes was reduced by 80%. And other research has found low Vitamin D levels in children newly diagnosed with diabetes.
A Dutch study found that two-fifths of the older diabetic men tested had low blood levels of Vitamin D and also that the lower the level, the greater the glucose intolerance.
Heart disease, strokes and Vitamin D
Studies of patients with heart disease have shown that the death rate was double in the patients with the lowest blood Vitamin D levels that of the group with the highest blood levels. And, in a report delivered to the 42nd Annual Conference on Cardiovascular Disease and Epidemiology Prevention women who supplement Vitamin D were shown to lower their risk of death from heart disease by one-third.
In other studies, Vitamin D levels and sunlight exposure have been shown to be linked to both hypertension and the risk of having a stroke. The mechanism may be that Vitamin D governs calcium deposition not only in the bones, but also in the arteries according to researchers at UCLA School of Medicine in California.
Strokes Low dietary calcium and Vitamin D intake has been linked to the likelihood of having a stroke. Comparing the diets of healthy women with those who have had strokes, the healthy women were found to have diets containing 38% more Vitamin D and 17% more calcium than the stroke victims.
Research also suggests that Vitamin D plays a crucial role in dozens of other disorders including obesity, periodontal disease, tooth decay, infertility, endocrine problems (especially thyroid gland disorders) and chronic fatigue syndrome (CFS).
Dietary sources of Vitamin D
Dietary sources alone are unlikely to maintain adequate blood Vitamin D levels unless you are a fish-loving Innuit! However, they can make a contribution towards maintaining total levels. Dietary sources include:
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Vitamin D fortified foods which includes all milk in the USA (100 IU of Vitamin D per 8-ounce serving), some margarines and Kellogg's Special K and Bran Flakes cereals are also currently supplemented with Vitamin D.
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Vitamin D is naturally high in egg yolks, oily fish, fish oils, some cheese, cod liver oil, Brewer's yeast, mushrooms, wheat bran, green leafy vegetables, beef liver, some types of grain and wheat bran. So incorporate these into your diet as much as possible.
Sun exposure and Vitamin D
The best way to optimise your Vitamin D levels is via sun exposure and for this you need to expose large portions of your unprotected skin to the sun as often as possible. The amount required will vary according to factors such as skin colour, the amount of skin exposed, the time of day, altitude, latitude and cloud cover.
For those with Caucasian skins, once your skin starts to turn a pale shade of pink, your body has produced all the Vitamin D it is going to and any further exposure may then result in skin damage including burning and ageing. This is usually somewhere around the 15-20 minute mark so some unprotected exposure little and often seems to be the message. Darker skin will need more sun than lighter skins to make the same amount of Vitamin D.
Contrary to popular belief, the best time to be in the sun for Vitamin D production is actually as near to noon as possible. Whilst the ultraviolet A (UVA) wavelengths penetrate the skin causing free radical damage, it is the ultraviolet B (UVB) wavelengths that promote the production of Vitamin D within the skin. And although the UVA rays are fairly constant throughout the day, the UVB rays are at their maximum around noon. So in terms of Vitamin D production, it is the midday sun that is the most beneficial and effective. Note that sunscreens typically reduce or block the beneficial UVB rays. In the winter, safe tanning beds are also an option for optimising UVB rays.
For natural protection in the sun consider the following:
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Using a sunscreen that contains either zinc or titanium rather than oxybenzone or retinyl palmitate (Vitamin A).
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Eating a diet full of fresh raw foods containing natural antioxidants to combat the free radicals produced by sun exposure.
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Eating an omega 3 rich diet and consider supplementing omega 3 oils to provide some protection against sunburn.
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Supplementing the carotenoid, astaxanthin, which particularly helps to protect your skin from sun damage.
Supplementing Vitamin D
There is a great deal of controversy over the current recommended daily amounts of Vitamin D which were established before the current slew of research and in order to prevent deficiency diseases such as rickets. These are now considered to be hopelessly inadequate by many working in the field.
In the UK the current recommended daily amount is 200 international units (5 mcg) and in the US 400 IU (10 mcg). For comparison, our bodies make about 10,000 IU of Vitamin D during 20 minutes of whole body exposure. This is 50 times the current UK and 25 times the current US government's current recommendations. In addition, those working in the tropics have blood levels 5 times that of the 'normal' UK range.
The UK government currently recommends supplementation of Vitamin D for pregnant and breast feeding mothers, children under 4 years, people over 64 and those with darker skin or those who are not exposed to the sun very much. Older people have a reduced ability to make Vitamin D and people who are obese are also at greater risk of deficiency because Vitamin D is stored in their fat rather than released into their circulation.
Historically, concerns about overdosing on Vitamin D have been expressed because Vitamin D is a fat soluble vitamin and any excess is stored rather than excreted as happens with the water soluble vitamins. However, toxicity is now thought to be much less of an issue than previously thought and you would consistently have to supplement high levels over quite a long period of time for Vitamin D toxicity to be likely.
The symptoms of Vitamin D toxicity include hypercalcaemia (elevated blood calcium), bone pain and headaches. Those at greater risk of Vitamin D toxicity include infants, women over 65 and those with reduced kidney function. Another caution is that Vitamin D may increase absorption of aluminium.
If supplementing consider the following:
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Nearly all experts recommend supplementing Vitamin D throughout the winter, and some also suggest supplementing during the summer at reduced dosages.
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Ensure that you take the active form D3 (cholecalciferol) rather than the D2 form and this has been shown to be much more effective.
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Liquid forms of Vitamin D may be more easily absorbed from the intestines.
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Authorities such as the Canadian Cancer Society recommend supplementing 1,000 IU daily for cancer prevention and some researchers now suggest supplementing anywhere from 4,000 to 10,000 IU's a day. The amount recommended differs with skin colour, age, weight and sun exposure.
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Multimineral/vitamin formulas often contain Vitamin D, so check the amount before supplementing additional Vitamin D.
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Vitamin D can make magnesium deficiency worse and for this reason some experts suggest supplementing magnesium with Vitamin D.
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Some companies now offer fingerprick blood tests for Vitamin D levels, which while not cheap are reasonably priced. If taking high levels of Vitamin D, it is advisable to monitor blood levels.
Further resources
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