A question of balance

WITH summer here, it’s fair to ask: is sunshine a public-health menace or a saviour?

For the last 30 or 40 years, a loud anti-sunshine message has ruled the day. This has meant gallons of sunblock at the highest available SPF, long sleeves and floppy hats, even wetsuits for kids at the beach — all in the name of preventing skin cancer (and wrinkles).

It was the perfect intervention until, in the past decade or two, the vitamin D enthusiasts stepped forward with a different argument. Vitamin D is produced by sunlight interacting with our skin — and the more the better, they say. It also can be absorbed in food as part of a healthy diet, but the sun-to-skin-to-bloodstream route is the more dependable. Many studies have suggested that vitamin D deficiency leads to countless medical problems, from cancer and heart disease to dementia and arthritis. But as a general rule in medicine, when something is said to be a panacea, it is probably exactly the opposite. As a result, sceptics love to doubt the happy talk about vitamin D, though some health advantages, such as bone and muscle strength, are indisputable.