Sometimes it seems that as soon as we take one health message to heart, we run into another problem as a result.
The importance of year-round sunscreen to protect against skin cancer is getting through to people and, in a spin-off, many brands of moisturiser and make-up now like to boast of their “built-in” sun protection. Those really paranoid – of wrinkles at least – like to cover up at all times.
Yet there is now concern about inadequate levels of the so-called “sunshine vitamin” D among the Irish population. Sunlight on the skin is an important source of this vitamin, which is vital for healthy bones and teeth, among other things.
Statistics
An estimated 500,000 people in Ireland, or 12 per cent of the population, have vitamin D deficiency, according to a study by University College Cork's (UCC's) centre for nutrition research, the results of which were published earlier this year. And a research paper, that is due to come out later this year, shows that overweight children here "have extremely low vitamin D levels – among the lowest in the world", according to its author, Dr Aoife Carroll of the Children's University Hospital in Temple Street, Dublin.
An earlier study she carried out at the hospital found that, generally, more than half of children had less than the optimal level of vitamin D.
It is only at this time of year that we in Ireland have any hope of getting a sufficiency of this vitamin through sunlight; from October to March our latitude means our skin can’t synthesise it. So how do we weigh up skin cancer protection for ourselves and our children with the need for a natural healthy dose of vitamin D when the sun shines?
"Small amounts of ultraviolet [UV] radiation emitted by the sun are essential for the production of vitamin D in people," says Kevin O'Hagan, cancer prevention manager at the Irish Cancer Society.
“Therefore, the Irish Cancer Society does not advise people to stay out of the sun or avoid it but rather to take care and protect the skin from damaging UV rays when in the sun.”
The 81 per cent increase in skin cancer in Ireland since 1994 is primarily the result of over-exposure to ultraviolet rays from the sun and sun beds and not from avoiding all contact from the sun, he explains.
The society suggests people follow the World Health Organisation’s recommendation, under its Intersun programme, to get five to 15 minutes of casual sun exposure to hands, face and arms two to three times a week during the summer months.
However, it also advises people not to let their skin redden or burn in their pursuit of vitamin D and to take extra care if you have fair skin.
Food
O’Hagan also refers to the importance of making sure to eat plenty of foods that contain vitamin D. It’s because relatively few foods naturally have significant levels of vitamin D – oily fish is the best source – that fortification of food, such as milk, breakfast cereals, yogurts, margarine and fruit juices, is becoming more important.
Mother Nature, it seems, reckoned we would get enough vitamin D from being outdoors, but she wasn't to know that we would develop into such an indoor-living species and also damage the earth's ozone layer to the extent that this source is no longer entirely safe.
It is almost counter-intuitive to learn that breastfed babies are more at risk of vitamin D deficiency than those fed on formula. That’s because most formula manufacturers now fortify their milk with extra vitamin D.
Cases of rickets
It was the alarming re-emergence of cases of rickets in children in Ireland in the early 2000s – a bone-disorder that it was believed had been eradicated here with better nutrition after the second World War. This led to the Food Safety Authority of Ireland (FSAI) calling for a national policy on vitamin D supplements for infants in 2007.
Since 2010, the Health Service Executive (HSE) has recommended that all babies aged 0 to 12 months – a time of rapid growth – are given 5 micrograms (5µg) of vitamin D3 (cholecalciferol) in liquid form daily. As their skin is so sensitive at that age they should not be exposed to direct sunlight, so will not be able to make vitamin D safely.
The 5 micrograms (equivalent to 200 international units) is conservative – the recommended supplement is double that in the US and Canada for breastfed babies. But since the advised dose applies to all babies here, and those on formula milk are already likely to be getting extra vitamin D, it avoids any risk of excess.
In Ireland, before ozone depletion, infants were supposed to get some exposure to the sun, says Mary Flynn, chief specialist in public health nutrition at the FSAI. “Now you can’t do that because of skin cancer; you absolutely can’t.”
But then at age one, their vitamin D requirements “don’t just vanish”, she says. Indeed, the data is there to indicate that the problem of insufficient vitamin D is widespread throughout the population.
The FSAI may well push for an extension of the national recommendations on a supplement for other “at risk” groups, such as pregnant women, children aged one to four and older schoolchildren.
Study results
The study of 250 children that Carroll led at Temple Street, finding that more than half had less than the optimal level of vitamin D, was done five years ago. The results highlighted those most at risk in the Irish population, which includes children with darker skin because it is harder for them to make the vitamin from sunshine.
Paediatric dietitian Ruth Charles says the children she has seen in her private clinics with problems arising from low levels of vitamin D are typically: "Dark-skinned children who are breast fed exclusively [no formula or solids] for longer than six months and whose mother is also dark skinned with her own low vitamin D levels, due to low dietary intake exacerbated by poor exposure to the correct frequency of UV light that Ireland has to offer.
“In extreme cases, I have seen rickets in this group,” she adds.
Carroll says it would be interesting to repeat her research of five years ago, now that more foods are fortified and there is more awareness about the problem. However, she believes it would be useful if there was a discussion at national level about extending the policy on supplements to children beyond a year.
As regards her latest research, which shows that overweight Irish children have some of the lowest vitamin D levels in the world, she explains that this vitamin dissolves in fatty tissue and if you are overweight, “there is a larger area for it to get dissolved into, so the levels are lower”.
You would also have to wonder, she adds, if lifestyle choices among these children have an impact, such as whether they are outside exercising as much as their normal weight peers, or if they are more inclined to cover up their bodies when outside.
Low awareness
The results of an online questionnaire for mothers released earlier this month suggest that awareness of vitamin D issues is still low. Some 82 per cent of respondents in a survey commissioned by Avonmore Super Milk say they have never suspected that a family member might be deficient in it and one in four admits “not knowing anything” about the vitamin.
More than half of those surveyed also believe rickets is the biggest indicator of deficiency. While rickets, and osteomalacia in adults, is caused by extreme vitamin D deficiency, the symptoms of a lack of vitamin D in the diet are often vague and non-specific, such as tiredness or general aches.
Low levels have also been linked through research to various other illnesses, including cancer, diabetes, TB and multiple sclerosis, but no causative effects have been established.
However, lack of vitamin D is definitely a factor in osteoporosis because it is essential to help the body absorb calcium and phosphorus.
If you have low vitamin D, the parathyroid glands become overactive and take calcium from the bones to maintain an adequate level of calcium in the blood, says Prof Moira O’Brien, founder of the Irish Osteoporosis Society. Proper functioning of the heart, nerves and muscles relies on calcium in the blood.
You can get osteoporosis at any age so the most important thing is to prevent it and prevention starts in utero, she stresses. “If the pregnant woman doesn’t have normal levels of vitamin D, then the baby doesn’t get it.”
Taking in sufficient vitamin D is one thing but then the body has to absorb it, she points out. People with coeliac disease or Crohn’s disease, for instance, have severe problems with this.
O’Brien estimates that there are 300,000 people in Ireland with osteoporosis, of whom only about 30 per cent have been diagnosed.
“The chances of getting melanoma are far rarer than the chance of getting osteoporosis,” she says, having pointed out that the risk of getting an osteoporotic fracture is one in two in women over the age of 50 and one in four among men of the same age.
There is a myth, even among some in the medical community, that the bone condition can’t be reversed in patients, she adds. “I would say 5 per cent, if they are lucky, are treated properly.”
The amount of vitamin D needed varies from individual to individual, depending on factors including age, exposure to the sun, the season and how well your body absorbs nutrients. But generally, up to 10 micrograms is what most people require daily.
A low-dose supplement of 5 micrograms, while getting up to another 5 micrograms from food, would suit most people, says Flynn.
Vitamin D can accumulate to toxic levels in the body, although over-dosing is very unlikely through the consumption of food and/or fortified milk. In infants, for instance, harmful effects begin only at levels five times higher than the recommended dose, according to the HSE.
However, the FSAI has had to take action against extremely high-dose supplements on the market, according to Flynn.
“We have got reports of young men taking excessive doses of vitamin D in the mistaken belief that it is going to improve their muscle mass; it absolutely won’t,” she says. In fact, it could calcify your muscles. Just adequate levels are needed to maintain muscle function.
While pregnant women, babies and children are seen as “at risk” groups, so too are grandparents. Older skin isn’t as effective at manufacturing the vitamin, even in exposure to sunlight.
“We probably need to be more mindful of our elderly population in long-stay institutions,” Flynn says.
For more information: fsai.ie; cancer.ie and irishosteoporosis.ie swayman@irishtimes.com
