We associate sunshine with cancer, but a new study has demonstrated that it can be a life-saver for people who already have breast cancer
Think sunshine and you probably think skin cancer, or malignant melanoma. So effective has the UK's SunSmart campaign been that few of us think that the sun, and the vitamin D it generates in our bodies, can help safeguard us against a host of chronic diseases and even save our lives.
Yet a new study this month has proven just that: women who are deficient in the vitamin are twice as likely to die from their breast cancer as women with higher levels of the vitamin. The discovery was so compelling-and so important-that the researchers stopped their study early just to announce that vitamin D supplements should become part of the daily regimen of every woman suffering from breast cancer.1
Taking 4,000 IU (100 mg) of vitamin D supplements every day should be enough to protect the breast cancer sufferer and stop the disease from becoming a killer, say researchers at the University of California and Naval Health Research Center at San Diego.
They made their discovery when they reanalyzed the evidence from five studies involving 4,443 breast cancer patients. The women who had 30 nanograms of vitamin D per millilitre (ng/mL) of blood were twice as likely to survive their breast cancer as those with just 17 ng/mL, which is the average level of vitamin D in the blood in the US.
Vitamin D also works as a preventative. Women who had 50 ng/mL levels of the vitamin in their blood serum had a 50 per cent lower risk of developing the cancer.
Earlier studies have also found that the vitamin can protect against diabetes, arthritis, heart disease, multiple sclerosis (MS), Crohn's disease, psoriasis and a range of cancers, including the 'big four'-breast, bowel, prostate and colon tumours.
Although there is plenty of evidence to show that vitamin D helps prevent breast cancer, the San Diego researchers were among the first to discover it could prevent death in women who already have the disease. They reckon that high levels of vitamin D can stop tumours from growing and spreading by improving communication between healthy cells.
Now the researchers want others to take up their work and test vitamin D at the upper safe limits of 10,000 IU (250 mg) a day to see how effective a cancer-fighter that is.
But their recommendations take vitamin D requirements to far higher levels than other scientists currently believe are necessary for maintaining health. The RDA (recommended daily allowance) is currently set at just 600 IU (15 mg) for most people, and 800 IU (20 mg) for those aged over 70, and pregnant women and nursing mothers.
And this is where the sun comes in: unless you supplement, you just can't get such high levels of the vitamin from diet alone. The healthy balanced diet gives us just 10 per cent of our vitamin D requirements-eggs, oily fish and oysters have high levels of the vitamin-but most people eat a poorer diet than this and get just 5 per cent of their needs from food.
The current guidelines on supplement levels are hopelessly wrong, says medical researcher Oliver Gillie, who reckons the current RDA is out by a factor of 10. The RDA is based on taking a teaspoon of cod liver oil, the traditional way from Victorian times of getting your vitamin D and still one of the richest sources after the sun. However, says Gillie, our body needs between 2,000 (50 mg) and 4,000 IU (100 mg) a day-as the San Diego researchers suggest-and even more in cases of pregnancy and nursing mothers.2
As few of us could down 10 teaspoons of cod liver oil every day, the obvious and natural source of the vitamin is sunshine. But we have become so frightened of exposing our skin to any sunshine that we are seriously deficient in vitamin D, says Gillie. But even if we do indulge in sunbathing, the sunshine in the northern hemisphere is invariably too weak except for the couple of months of summer. That's why the death rate from cancer is much higher in the northerly states of the US, which have the lowest ultraviolet B (UVB) radiation from the sun, say the California researchers.
Absorbing the sun's rays is also a natural way for us to process vitamin D. The complex chain reaction starts when a chemical on our skin, 7-dehydrocholesterol, changes to vitamin D3 on exposure to sunlight. This is carried by the circulation to the liver, where it is changed into 25(OH)D; from there, the kidneys transform 25(OH)D into active vitamin D (1,25-dihydroxyvitamin D3, or calcitriol, a powerful hormonally active form of the vitamin).
In effect, vitamin D isn't a vitamin at all, but a steroid hormone that regulates growth in more than 30 different tissues throughout the body. It controls calcium absorption for healthy bones and triggers apoptosis (natural programmed cell death), a vital process that prevents cancer. It also restricts cancer growth by stopping the formation of new blood vessels that feed tumours.
Although there's no denying the importance of vitamin D, our health guardians-including the UK's Department of Health and the World Health Organization (WHO)-reckon that no one under the age of 50 even has to think about vitamin D deficiency.
If you do supplement, they recommend that you don't take more than 25 mg a day, as higher doses can cause hypercalcaemia, or a buildup of too much calcium in the blood.
While this is true, hypercalcaemia is very rare, and only those with liver or kidney problems may be vulnerable. As for the rest of us, says the Mayo Clinic, the only cases among healthy people have been seen with mega-doses of 1,250 mg (50,000 IU) a day-that's 50 times greater than the Department of Health's 'safe dose'-and even then, only when taken continuously for several months.
The other piece of advice-that no one under 50 needs to even think about vitamin D deficiency-flies in the face of the facts. Optimal levels of vitamin D are around 100-150 nmol/L of blood serum, yet children in the UK have an average level of just 52 nmol/L in winter, which rises to 80 nmol/L in summer, while the elderly have average levels of 35 nmol/L in summer and just 23 nmol/L during winter, a level so low that rickets, heart attack, reduced muscle strength and the risk of falls become a real possibility.
Anticancer Res, 2014; 34: 1163-6
Gillie O. Sunlight robbery: Vitamin D and public health. Annual Caroline Walker Lecture, 16 November 2010, Kensington Town Hall, London; online at www.healthresearchforum.org.uk/reports/public_health.pdf
Stay in the sun long enough for your skin to redden, but not so long that you begin to burn: that seems to be the simple maxim for safe sunbathing.
Medical researcher Oliver Gillie, who is campaigning for a more sensible SunSmart policy, says the current guidelines have gone way too far and have frightened everyone from going out into the sun. The guidelines have almost exactly copied those for Australia, and are wholly inappropriate for northern climes, where sunshine is rare and often weak.
Here are some of the major differences between the current UK SunSmart policy and Gillie's own Sunsafe advice.
Stay in the shade between
11 am and 3 pm
Get into the sun in the
middle of the day
Cover up with a T-shirt and hat
Expose as much skin as you can
Use factor 15+ sunscreen
Only use sunscreen when beginning to burn
Don't burn; tanning is healthy
What about skin cancer?
Skin cancer, or malignant melanoma, is the most common form of cancer, accounting for 75 per cent of all cancer diagnoses-and sunshine is the "only known environmental risk factor" for malignant melanoma, the deadliest form, according to researchers at the Memorial Sloan-Kettering Cancer Center in New York. While that's certainly true, sunshine accounts for only 10 per cent of cases.1
This peculiar fact is borne out by other studies showing that people who are regularly exposed to the sun-perhaps because of their occupations-are no more likely to develop malignant melanoma than those who live and work mainly indoors.2
And those who do develop skin cancer often do so in parts of the body that aren't generally exposed to the sun. Melanomas are most commonly found on the backs of men and upper legs of women,3 and on the soles of the feet in black people.4
Other risk factors for skin cancer-and ones that are almost never mentioned-include obesity, lack of exercise and poor diet, including the consumption of fast food and high-fat snacks.5 Drinking large amounts of alcohol may also increase the risk,6 and women who suffer from endometriosis-when cells from the womb become deposited and grow in other tissues of the body-are twice as likely to develop melanoma.7
Haller DG et al., eds. Cancer Management: A Multidisciplinary Approach, 14th edn; online only
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