Summer is the season for picnics with punnets of strawberries, BBQs with fresh fruit side salads and chins streaked with watermelon juice.

Most of us absentmindedly munch away on summer’s fruits and veggies, but nature isn’t dishing them out and simply saying, “Here’s some pleasant poolside snacking”. Pleasant yes, but also prudent: eating certain foods is, in a sense, eating sunscreen.

We all know the dangers of foolhardy sun exposure: studies have shown this ranges from premature aging to skin cancer.

Most of us are quick to grab a tube of SPF to arm ourselves, but diet plays an important role in preventing, and perhaps even reversing, any damage.

Ultraviolet radiation from the sun generates “free radicals” in the skin. Free radicals are unstable molecules that are missing at least one unpaired electron – and they’re not happy about it. While “stealing” electrons from nearby molecules, they wreak havoc, damaging fats, proteins (such as collagen) and DNA in the process.

This oxidative stress has been linked to a number of adverse health effects and shows up in our skin as wrinkles, sagging and age spots.

When we slather sunscreen all over ourselves, its active ingredients reduce the amount of radiation that penetrates the skin and, therefore, the number of free radicals that form.

Some studies have shown, however, that sunscreens themselves, both chemical and physical (or mineral), also create free radicals in the skin.

In addition to limiting exposure in the first place, it seems the best way to safeguard our skin and health from the dark side of the sun is with a combination of sunscreen, protective clothing and a diet rich in antioxidants.

These “free radical scavengers” neutralise the volatile molecules before they cause damage, and some may even reduce the wrinkles and discolouration that come with aging.

Studies have shown that antioxidants like lycopene, vitamins C and E, beta-carotene and selenium can help boost your natural SPF.

Tomatoes and watermelon are rich in lycopene, the carotenoid or pigment that makes these fruits red.

In a study published in the British Journal of Dermatology, 10 women ate 55g (about five tablespoons) of tomato paste in olive oil every day for 12 weeks. Ten others consumed just the olive oil. All of the women, aged between 21 and 47, were exposed to UV rays before and after.

The volunteers who ate the tomato paste experienced a 33 per cent increase in protection against sunburn, as well as much higher levels of procollagen, a molecule that keeps the skin firm. The study concluded that lycopene was responsible.

The body can best absorb this potent antioxidant from tomatoes when they are cooked, so throw some roasted tomatoes on your morning eggs and don’t pass up a pasta dish.

Berries (particularly strawberries), oranges and bell peppers are in season and full of vitamin C, which in addition to fighting free radicals plays a critical role in the production of collagen. Studies suggest it may also have some anti-inflammatory effects.

Vitamin E is another antioxidant that may help with inflammation, which occurs when the skin suffers UV damage (it’s the reason we go red when we burn).

Nuts and seeds, particularly almonds and sunflower seeds, vegetable oils and leafy greens are where you can find this one.

Carrots and sweet potatoes are veggies rich in beta-carotene, and good sources of selenium, which also helps to preserve tissue elasticity.

So bring on the sunscreen and the broad-brimmed hats, but don’t underestimate the power of your food. Beauty really does come from within.

kharris@irishtimes.com