To D Or Not To D: That Is The Question
14 November 2005
To D Or Not To D: That Is The Question
There is no question excessive exposure to ultraviolet radiation (UV radiation) can be damaging to health and is the cause of more than 90 percent of all skin cancer cases.
On the other hand, adequate vitamin D, the main source of which in New Zealand is exposure to sunlight, is essential for general health – bone, joint, muscle and neurological function. The link between sunlight exposure, vitamin D levels and osteoporosis and rickets in children is well established.
So, on the most simplistic level, do we lie in the sun and get skin cancer? Or do we hide away indoors and develop (brittle or deformed bones)? Or is it possible to gain adequate vitamin D and still protect ourselves from the danger of UV radiation?
This was the dilemma debated recently when an Expert Advisory Group met for the first time; a meeting convened by the SunSmart Partnership (the Health Sponsorship Council and the Cancer Society).
The result of their discussions is a national position statement that examines the risks and benefits of sun exposure in New Zealand.
Its release on the SunSmart website http://www.sunsmart.co.nz/sunvitamind.asp coincides with SunSmart Week (November 13-19).
Spokesperson for the group, Wendy Billingsley from the Health Sponsorship Council and Cancer Society, says the group agreed that in most situations, sun protection is warranted to prevent skin cancer and sun damage to the skin during times when the ultraviolet index is high (higher than or equal to 3).
“It’s unlikely to put people at risk of vitamin D deficiency,” Ms Billingsley says. “During summer, most people should be able to achieve adequate vitamin D levels through normal coming and going outdoors”
Someone who burns easily in the sun may only need five minutes of daily summer sun exposure before 11am and after 4pm (to the face, hands and forearms) to achieve adequate vitamin D levels. Someone who tans more easily or who has darker skin will need more time, for example up to 20 minutes.
But the position statement emphasises that deliberate exposure at peak UV times (between 11am and 4pm) is not recommended as this increases the risk of skin cancer, eye damage and photo-aging.
During winter, particularly in Southern New Zealand, where UV radiation levels are dramatically lower, vitamin D status may drop below adequate levels.
“Additional measures to achieve adequate vitamin D may be needed, especially for those at risk of vitamin D deficiency. Summer levels of vitamin D influence winter levels because body stores decline in winter,” Ms Billingsley says.
The group who are at increased risk of vitamin D deficiency include the elderly, babies of vitamin D deficient mothers, people who are housebound or in institutional care, people with darker skin types and those who cover their skin for cultural reasons.
The fact people who have darker skin types are at higher risk of vitamin D deficiency (and at lower risk of skin cancer), may have implications for the health of Maori, Asian and Pacific communities, especially those living further south, the group advises.
“People with a higher risk of vitamin D deficiency should discuss this with their medical practitioner,” Ms Billingsley says.
While it is unlikely that adequate vitamin D can be gained through dietary means alone, there are some food sources such as fatty fish (salmon, sardines and mackerel), meat (especially liver) and eggs.
The expert advisory group comprised representatives from a wide range of organisations including the New Zealand Dermatological Society, the Departments of Medicine and Health Sciences and of Human Nutrition from the University of Otago, University of Auckland, the Te Ropu Rangahau Hauora a Eru Pomare Centre, NIWA, Osteoporosis New Zealand, the Ministry of Health, the Social and Behavioural Research in Cancer Group, the Cancer Society National Health Promotion Committee and the New Zealand Food Safety Authority.