Heatwaves: how grapes protect your skin from the Sun

Summer has not even begun, yet we are already struggling through a brutal heatwave that is putting our bodies under severe strain. Every possible measure is worth taking to limit its effects - starting with grapes, a remarkably effective fruit for helping to protect you from the Sun’s harmful effects.

Yesterday, 26 May, France experienced one of the hottest days ever recorded for the month of May. Temperatures reached 37.1 °C near Hossegor, 33.5 °C in Lyon and 33 °C in Paris and Bordeaux alike. Even Brittany was not spared, with temperatures climbing above 30 °C across much of the region. This severe heatwave has sadly been linked to the deaths of seven people and, according to forecasts, is expected to continue into next week.

During periods like this, the usual precautions are essential: avoid going out during the hottest hours whenever possible, drink enough fluids, cool yourself down by any means available, wear lightweight clothing, and look out for others - especially vulnerable people, including children and older adults. One lesser-known recommendation can be added to the list: eat grapes. They may not really be in season, but alongside their flavour and nutritional benefits, they can strengthen your skin’s natural defences, which are heavily affected by extreme heat.

Grapes: a skin ally during heatwaves

Grapes contain high levels of catechins and resveratrols, two groups of polyphenols. These organic compounds are naturally produced by plants and, among other roles, help them defend themselves against external threats such as UV radiation, pathogens, environmental stress and heavy metals. When eaten, these compounds enter the bloodstream and reach skin cells, where they activate genes involved in producing proteins that build and reinforce your skin’s protective barrier.

As well as this photoprotective effect, regularly eating grapes supports two biological processes at the same time: keratinisation and cornification. These are the two stages of one continuous cycle: the constant renewal of your skin.

How grapes strengthen the skin barrier

Epidermal cells are created in the deepest layers of the epidermis, then gradually move towards the surface as they mature. Along the way, they build up keratin - a rigid, water-resistant protein also found in nails and hair - until they lose their nucleus and die. Once at the surface, these dead cells flatten into thin layers that stack on top of one another, creating a dense, waterproof covering known as the stratum corneum. This layered structure determines how resistant your skin is to external aggressors, including UV rays.

The thicker and better formed this layer is, the more effectively it can absorb or deflect radiation before it reaches the living cells underneath, where it can damage DNA. Grapes speed up this cycle and increase the density of the skin barrier.

Antioxidants in grapes and UV exposure

Grapes also provide an antioxidant effect that counteracts UV radiation, which triggers the production of free radicals in skin cells. These unstable molecules set off a chain oxidation reaction: they take electrons from membrane lipids and DNA, weakening cells from within. The polyphenols in grapes chemically neutralise them before this cascade gets out of control.

Allow for around 400 grams a day - the equivalent of two medium-sized bunches - for two weeks before these effects become established. If you are determined to eat only seasonal fruit, or simply do not like grapes, you can buy grape seed extracts from a pharmacy. Although they cost more, they contain the same polyphenols at a far higher concentration. It is probably unnecessary to say that grapes are no substitute for a good SPF 30 or SPF 50 sunscreen: this remains your main defence against UV rays, as it is the only one that stops them before they even reach your skin.