The Vitamin D Dilemma

Media release: New Zealand Dermatological Society Inc July 6, 2008

The Vitamin D Dilemma - The Wrong Message Could Be Putting Sun-Smart Kiwis At Risk

Recent publicity surrounding the prevalence of vitamin D deficiency in New Zealand may be sending a confusing message and actually encouraging Kiwis to put themselves at unnecessary risk – say skin cancer experts.

Dermatologist Dr Louise Reiche says while lack of vitamin D is associated with a number of serious diseases and health complications, excess lifetime sun exposure is the direct cause of one of our country’s greatest killers- skin cancer. It’s the most commonly occurring cancer in New Zealand and contributes to around 260 deaths each year, she says.

A recent study* in the Bay of Plenty showed up to 1 in 10 New Zealanders may develop melanoma in their life time, says Associate Professor Marius Rademaker.

For other types of skin cancer the risk is even higher with 7 out of 10 people developing a Basal* Cell cancer (BCC) and 3 out of 10 a Squamous* Cell cancer (SCC) in their lifetimes. The biggest risk factor for these skin cancers is sun exposure.

Professor Rademaker says New Zealanders are mistaken if they think that only summer sun-burns cause problems, all sun exposure, even in winter, adds to the cancer risk.

Dr Reiche acknowledges that exposure to appropriate levels of sun is a fine balancing act but is concerned many people will take the vitamin D message too far and literally bake themselves. There is no sense in being reckless in winter as prolonged exposure will just achieve UVA damage rather than boost Vitamin D production, she says

According to Dr Reiche Vitamin D production is maximal at tiny amounts of UVB - this is much less than would be required to make our skin even slightly pink. Ten to 15 minutes of direct summer sun exposure to the face, backs of hands and arms is enough for most people.

“The body has in-built mechanisms to avoid over production of Vitamin D (too much becomes a poison) and so even before the skin becomes red from the sun, excess Vitamin D is inactivated. Thus, more sun means less Vitamin D. A little sun is optimal,” says Dr Reiche.

The commonly quoted UVI (ultraviolet index) is not a perfect measure but gives a guide to the amount of UVB we are exposed to so that individuals can gauge potential benefits and risks from UV exposure she says.

The UVI varies throughout New Zealand at different times of the year. It is strongest in the spring and summer months in the far north (e.g. UVI 14) and lowest in the winter in Southland (e.g. UVI less than 1.4).
Kiwis need sun protection when the UVI is greater than 3, says Dr Reiche. Anything over UVI 10 is considered extreme and means people should stay out of the sun.

Dr Reiche says, as we age (over 50 years of age), our ability to make Vitamin D in the skin declines, particularly if the skin has been sun damaged. Additionally we are more susceptible to skin and other cancers as our immune system ages. Sun protection and oral vitamin D supplementation is therefore even more important. Vitamin D production and absorption also appears to be linked to physical activity.

“Those who exercise outdoors or participate in outdoor sport have highest levels of vitamin D. So sitting outside is insufficient- get out for a walk, do the gardening or other outdoor ‘Push Play’ activities,” says Dr Reiche.

Both Dr Reiche and Professor Rademaker encourage their patients to carry out activities in a “sun smart’ way, they recommend 15-30 minutes outdoor exercise, 4-5 days per week, in the earlier morning or later afternoon.

Apart from sun exposure vitamin D levels can be also be topped up through supplementation from foods such as oily fish, eggs, milk, liver, lamb and fortified foods e.g. margarine and soy milk, and Vitamin D tablets says Dr Reiche.

She suggests most people can maintain healthy levels of vitamin D through a balanced lifestyle and a little bit of common sense.

-Ends-

Written on behalf of The New Zealand Dermatological Society Inc. by Impact PR. For further information or images, please contact Fleur Revell-Devlin fleur@impactpr.co.nz (ph. 021509600) or Mark Devlin, mark@impactpr.co.nz (ph. 021509060).

Notes to editors:

Dr. Louise Reiche: MBChB, FRACP, MD is a specialist physician Dermatologist practising in Palmerston North.
Louise graduated from Otago Medical School in 1985 and completed Dermatology post graduate training (NZ and UK) in 1994 and MD (Otago) in 2002. Louise works privately from Aorangi Hospital in Palmerston North.
In addition to general dermatology clinics, Louise runs specialized eczema allergy testing (patch test), mole screening and melanoma surveillance photographic clinics, and minor surgery.
Louise is a member of the New Zealand Dermatological Society and serves on the executive, and the NZ Cancer Society Vitamin D group.

Associate Professor Marius Rademaker: BM, FRCP(Edin), FRACP, DM is a specialist dermatologist practising in Hamilton.
Marius graduated from Southampton University Medical School in 1980 and completed his dermatology training in Edinburgh, London and Glasgow. He has long been involved in dermatological research and was awarded a MD thesis in 1991. He emigrated to New Zealand in 1992 and works at both Waikato Hospital and Tristram Clinic, Hamilton. He is a member of numerous Australian/New Zealand committees on skin cancer and dermatological research.

The Study
*Salmon PJ, Chan WC, Griffin J, McKenzie R, Rademaker M. Extremely high levels of melanoma in Tauranga, New Zealand: possible causes and comparisons with Australia and the northern hemisphere. Australas J Dermatol. 2007 Nov;48(4):208-16
The objective of the study was to determine the incidence of melanoma in the Tauranga region of New Zealand, to compare these findings within Australasia and the northern hemisphere, and to understand the causes of the relatively high rates in Tauranga. Data were obtained from retrospective review of histology reports from the public and private health systems in greater Tauranga (Tauranga and Western Bay of Plenty Districts). Primary cutaneous melanomas (including both invasive and in situ melanomas) reported during 2003 were included. Age-standardized melanoma rates were calculated for the entire population as well as for the non-Maori population of the region, identified from the 2001 New Zealand Census. The age-standardized incidence of invasive melanoma in the non-Maori population of the greater Tauranga region was 79/100,000. The age-standardized rate for the entire population was 70/100,000. The rate of in situ disease was 78/100,000 for non-Maori and 72/100,000 for the entire population. The Tauranga region of New Zealand has an exceptionally high incidence of invasive and in situ melanomas. This is likely related to environmental, geographical and societal factors, including relatively high levels of UV exacerbated in recent times by ozone depletion, relatively cool summer temperatures which encourage outdoor exposure, and relatively fair skin colouring.

*Basal cell carcinomas arise from cells at the base of the skin, rarely metastastises (spread through body) and are the commonest skin cancer. Squamous cell carcinomas arise from skin cells higher the skin, are the second commonest skin cancer but may spread to other parts of the body.

ENDS

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