As a teenager in the late 1970s, a tan was the mark of a good holiday and the sun’s only role was to turn pale flesh brown. Never mind if your package holiday entailed being stranded in a half-built hotel, delayed in Malaga for 15 hours or a bout or two of food poisoning. Having a tan was all that mattered.
Things have moved on now as we are better informed, yet for many people the desire to tan remains. Aside from the change in colour, exposure to ultraviolet rays causes inflammation of the skin, damages the DNA and suppresses the immune system.
On the other hand UV exposure triggers vitamin D production, a nutrient that is generally deficient in the British population. Reduced levels of vitamin D are implicated in several health conditions such as rickets and osteomalacia, although Dr Google lists many more conditions linked to poor vitamin D status, ranging from muscle weakness to lung, prostate and breast cancers. Indeed many health professionals recommend supplementation and, ironically, one of the contributing factors for low vitamin D status is the use of sunblock.
Holidaymakers generally use lotions with a decent sun protection factor (SPF) when actively getting a tan, but neglect to use something daily when going about our usual business. Needless to say, you can’t avoid the ultraviolet rays that can cause skin damage just because you aren’t laying out with a towel and a swimsuit, and so the advice is to use SPF at all times.
What we eat can play a role in offering a degree of protection against the UVB rays as various elements with antioxidant activity have been shown to delay the onset of burning in the skin when exposed to UV light. While it is generally accepted that dietary plant chemicals such as flavanols and polyphenols can help combat oxidative stress in the skin, many questions still remain unanswered. These chemicals are found in most plants to varying degrees, notably in familiar foods such as green and black tea, cocoa, red wine and apples. Quite how much one would have to eat of any given food and also the levels of protection that this might offer are yet to be determined.
Another class of plant chemicals, carotenoids, has been found to reflect some UV rays, reducing their potential damage. There are several nutrients that belong to the carotenoid family, including lycopene and lutein. Lycopene is rich in tomato but is more easily absorbed in the human body from tomato that has been heated or processed, making tomato juice or passata a more effective source than a raw cherry tomato. Lutein, a first cousin of lycopene, is found in many vegetables such as kale and spinach as well as in egg yolk, olives and avocado.
The manufacture of skin cells is a constant process as those at the deepest layer of the epidermis are especially active, repeatedly dividing themselves to make new skin cells. These fresh cells are then pushed up through the epidermis towards the surface. En route they wither and are filled with keratin, creating a protective surface layer, which is then shed and replaced. It takes at least 30 days for fresh cells to reach the surface but it can take several weeks for dietary antioxidants to be incorporated into skin cells.
Therefore the polyphenols in a glass of red wine enjoyed over the spring bank holiday won’t provide any UV protection until the August bank holiday. In short, there are countless reasons to maintain a good diet, including protection against UV rays, although there are no precise guidelines available. Avoiding the midday sun, limiting sun exposure and sensible use of SPF is far more reliable.