The benefits of sunshine

It's summer and the media is rife with warnings about the danger the sun poses. Get sunburnt and you'll likely get skin cancer! Don't underestimate the sun, it will make your skin age prematurely! You'd be forgiven for thinking that it's best to chuck that holiday in the Med and stay at home applying sunscreen in a dark room.

What these sensible warnings about the potential consequences of excessive sun exposure overlook is that our body needs the sun - because exposure to the sun leads our skin to produce vitamin D, which has many positive effects on our health.

Here is what you need to know about vitamin D: How you get it and what beneficial effect it has on your body.

Lack of vitamin D

Low levels of vitamin D have been shown to play a role in several conditions, from the body's inability to absorb calcium, which leads to brittle bones, to more serious consequences.

Adults who lack vitamin D may experience pains or muscle weakness.

Children who are low in vitamin D see their development stunted, and may suffer from weaker bones.

Crohn's disease, a condition for which there is no known cure, has been found to be associated with a vitamin D deficiency. Crohn's disease produces inflammation of the intestine, and is linked to both genetic and environmental factors.

Interestingly, Crohn's disease is known to be more prevalent in northern countries where there are fewer hours of sunlight.

Not getting enough sunshine can increase the risk of a heart attack or stroke according to recent studies. People with low levels of vitamin D are over 60% more likely to suffer cardiac disease.

Britain's long, dark winters mean 15% of Britons have dangerously low levels of vitamin D and more than 80% have levels below those considered healthy.

Sun exposure

For most individuals, the sun is the main source of vitamin D. In fact, about 90 per cent of your vitamin D comes from sunshine, so experts recommend sensible sun exposure in the summer.

You might need as little as 30 minutes of sun twice a week, using no sunscreen. This would be enough to provide the body with adequate vitamin D.

A deficiency of vitamin D occurs when its levels in the blood drop to 12ng/ml (nanograms/millilitre) or less. The normal level of vitamin D in the blood is usually around 25-50ng/ml.

Diet

Vitamin D can also be obtained through diet, most specifically through oily fish, liver, eggs, butter and milk. It boosts your immune system and enables your body to absorb the calcium needed for healthy bones and teeth.

Vitamin D levels often fall in the winter months when we need our immune systems to be at their best. This is where a diet rich in vitamin D comes into play.

Oily fish such as salmon, mackerel, sardines, herring (and cod liver oil) can provide you a dose of vitamin D in the cold winter months.

Some foods are also fortified with vitamin D, such as breakfast cereals, margarines and other spreads.

Having a diet rich in vitamin D is especially important for older people, as they are housebound and less likely to get enough exposure to sunlight.

Pregnant women also need a good supply of vitamin D to ensure that their baby is born with good strong bones, while strict vegetarians should bolster their diet with vitamin D supplements because of the absence of fish from their diet.

Nutritionists recommend a diet that involves two to three portions of oily fish per week, as well as five portions of fruit and vegetables.

Benefits of vitamin D

For a start, getting a healthy dose of sunshine and eating enough oily fish can boost your brain's performance.

In tests carried out on middle aged and older men, those with high levels of vitamin D in their blood performed "consistently better" in neuropsychological tests designed to assess mental agility, and were able to process information faster.

For men, a good amount of vitamin D also contributes to testosterone levels, which is a hormone that plays a part in male libido and energy levels.

Vitamin D has been found to play a vital role in helping the body fight off infections, by triggering the body's T cells to fight off invading bacteria and viruses which can cause disease.

Vitamin D and heart disease and diabetes

Recent research found that vitamin D deficiency is strongly linked with metabolic syndrome, a combination of medical and metabolic disorders that increase the risk of developing cardiovascular disease and diabetes.

Older people with high levels of vitamin D cut their their chances of developing heart disease or diabetes by nearly half.

Vitamin D helps fight against cancers

Spending too much time in the sun and on sunbeds has been implicated as a major factor in the growth of skin cancer. But new research suggests that high levels of vitamin D – produced by the skin from sunlight – may actually help improve survival rates of people with skin cancer and bowel cancer.

Two separate studies found that people with higher levels of vitamin D at the time they were diagnosed with either of the two cancers were more likely to survive. Results showed that bowel cancer patients with the higher vitamin D scores at diagnosis were 50% less likely to die from the disease compared to those with the lower scores.

Perhaps more surprisingly, results from the second study showed that malignant melanoma patients with the lowest levels of vitamin D in their blood at the time of diagnosis were 30% more likely to relapse from the disease than those with the highest levels.

This article was published on Fri 20 August 2010