Tanning: a herb and a fruit studied to protect you from harmful UV rays

Sun exposure: balancing benefits and risks

Exposure of the skin to the sun's UV rays is the main route for synthesising vitamin D — on average, diet alone provides only 15-30% of our needs.

This vitamin (which should more accurately be called a hormone) plays a key role in our bodies, contributing to normal immune function, the normal absorption and use of calcium and phosphorus and, by extension, the maintenance of normal teeth and bones (1).

Even so, you don't need to lie in the sun for hours on end: a short exposure to the sun (around 15 to 20 minutes) in the late morning or afternoon is more than enough.

On the other hand, prolonged (or unprotected) exposure to ultraviolet rays, in particular UVA and UVB rays, accelerates skin ageing. This phenomenon, known as photoageing, is the result of excessive production of free radicals, which induces oxidative stress in skin cells (2). This typically results in a visible loss of elasticity, the early appearance of wrinkles or brown spots, and even deep-seated changes to dermal tissue that can lead to skin cancer (melanoma) (3).

To avoid such damage, it's a good idea to follow the basic recommendations, which are now well known: avoid exposure during the hottest part of the day (typically between 12:00 and 16:00), wear clothes that cover you up and apply a suitable sun cream (4). But can you go even further to protect yourself from the harmful effects of UV rays and still have a lovely, tanned complexion by the end of the summer?

Herbs and fruit to combat photoageing

Could certain plants enhance our skin's natural resilience to UV?

This is the avenue that experts in photoprotection have been exploring for several years. After intensive research, two potential candidates have especially caught their attention: rosemary and grapefruit.

Used for centuries in phytotherapy, rosemary is a hardy aromatic plant from the Lamiaceae family native to the Mediterranean basin.

Widely recognised for its immunostimulant, hepatoprotective and digestive properties, this 'plant shield' contains rosmarinic acid, which is thought to have a powerful antioxidant action.

A study suggests that combining it with UVB filters in sun protection products reduces oxidative stress levels in the stratum corneum (the superficial part of the epidermis) (5).

As for grapefruit, it concentrates a whole range of bioactive nutrients, including vitamin C (which helps to maintain normal skin by enabling normal collagen synthesis); carotenoids (including beta-carotene, a precursor to vitamin A, which contributes to skin health); and, above all, polyphenols from the flavonoid family, including naringenin and hesperidin, which are thought to have both anti-inflammatory and anti-free radical properties (6).

Rosemary and grapefruit: better together for photoprotection?

Research carried out on both skin cells and human subjects seems to confirm the efficacy of the rosemary-grapefruit combination for photoprotection (7).

This confirms the legitimacy of synergistic compounds such as Nutroxsun®, a registered extract of rosemary and grapefruit standardised to 35% polyphenols.

A double study of Nutroxsun® sheds further light on the biological mechanisms at work (8).

After 2 weeks of supplementation, a reduction was observed in ultraviolet-induced redness and UVA-stimulated skin lipid peroxidation (which 'attacks' the fatty acids in cell membranes).

An increase in skin elasticity and a reduction in the depth of wrinkles were also reported.

Researchers attribute this supposed dual photoprotective and anti-ageing action to the inhibition of UV-induced reactive oxygen species and inflammatory markers such as cytokines, as well as to changes in the cell signalling pathways that control the breakdown of the extracellular matrix (the assembly of proteins that 'bind' cells together).

Tanning: the best compounds to prepare and protect your skin

There are other natural compounds capable of stimulating tanning and/or reducing the harmful effects of UV rays.

These include molecules from the carotenoid family, renowned for their healthy glow: lutein, astaxanthin, lycopene and, of course, beta-carotene, a plant precursor of vitamin A that contributes to good skin health.

Studies have also highlighted their role in neutralising the photooxidative reactions that affect the integrity of skin cells (9).

The most effective sun-preparation supplements are based on synergistic combinations.

They aim to enhance the complexion (whether to start a pre-tan, tan more effectively or even prolong the tan) while offering the highest level of skin protection (in addition to the usual preventive measures).

Some manufacturers have chosen to capitalise on Nutroxsun® by including it in their formulation and combining it with carotenoids (this is the case with Solar Prep Formula, which also contains zinc, SOD, biotin, etc.) (10-11).