(Dec 1) THE only 'natural' protection against aging skin is regular, consistent use of sunscreen, skin experts say. When it comes to the sun, prevention is the best cure. 'Sun exposure has been always regarded to be the major cause for skin damage, the UV rays from the sun trigger excessive melanin secretion from melanocytes manifesting in pigmentation,' says Sudhir Gandhi, regional director of Mega Lifesciences (Australia) Pte Ltd.

Mega Lifesciences developed Pynocare, the first oral depigmentation solution to manage melasma, commonly known as pigmentation. Its belief is that the root cause of pigmentation is inner turmoil that goes on inside the skin - hormonal changes, metabolic changes, lifestyle stress and genetic factors.

'So complete protection can only be achieved when sunscreens are combined with oral treatment,' he says.

But, meanwhile, if you don't think you need oral medication to reduce the sizes of your pigmentation spots yet, try simple prevention.

'You have to use dedicated sunscreen for that, not make-up with SPF content. They're just not strong enough,' advises Girish S Munvalli, a US-based dermatologist, who was in town this week for the launch of a new laser light treatment, Aesthera's PPx.

He recommends dedicated sunscreens of SPF30 which block out 92 per cent of the sun's rays. 'The difference between the higher numbers is that SPF45 blocks out 96 per cent, and SPF60 blocks out 98 per cent, so the effect is negligible while the cream gets too thick for comfort,' he notes.

It's a big leap from SPF15 to SPF30 however, as SPF15 blocks out only about 80 per cent of the sun's rays.

Also, with companies like L'Oreal undertaking research and development avidly in this major area, new ingredients are being added to sunscreens.

Mexoryl is an organic compound, the first new sunscreen filter that's approved by the US Food and Drug Administration since 1988. What makes sunscreens work are the chemical compounds in them, which are either organic (Mexoryl, Padimate O, Avobenzone) or mineral (titanium dioxide and zinc oxide).

Mexoryl is the first sun filter available in a photo-stable form designed to protect the skin from the harmful short UVA waves (320-340 nms) of the sun, explains Didier Saint-Leger, director, L'Oreal R&D China.

UVA waves account for up to 95 per cent of the UV radiation that reaches the Earth's surface, but traditionally, sunscreens have been able to block out UVB rays rather than UVA.

Mexoryl is particularly effective against short UVA waves, and being photo-stable means it doesn't degrade when it is exposed to the sun for long periods of time.

L'Oreal brands that use Mexoryl in their formulation include Lancôme and Biotherm (in the luxury division), L'Oreal Paris and Garnier (in the consumer products division), and Vichy and La Roche Posay in the active cosmetics division.

The other thing to note is that UVB rays cause sunburns, as they remain primarily at the surface layers of the skin.

UVA rays, on the other hand, penetrate more deeply into the skin and have also been linked to skin cancer. UVA rays have the additional capability of being able to pass through glass and occasionally through clothing while UVB rays do not.

And then the amount of solar energy depends on latitude (there's more UVA in the tropics than in the Northern Hemisphere for example), altitude (if you're skiing), the time of day (highest at 11am to 3pm, the zenith being 2pm and not noon), and then other variables like clouds or pollution, and reflection of ground or sea, or sand and snow.

Not everyone burns the same way, points out Mr Saint-Leger. Chinese, for example, are mostly phototypes III and IV - which burn moderately or slightly but tan easily. So why is it important to protect against UVA rays at all times?

'Because they're present as soon as the sun rises, and on cloudy days as well. Plus, they pass through glass, penetrate deeper through the skin and are a major contribution to dermal damage,' he says. Plus accounting for over 80 per cent of skin aging.

In his research on Asian skin, Mr Saint-Leger has noted that high UVA levels lead to durable pigmentation. It's also necessary for darker skin to have more protection in UVA to avoid the darkening effect.

Meanwhile, in case you think that applying a sunblock SPF15 and then a foundation with SPF15 means that you're SPF30 protected, you're not.

'This does not add up arithmetically. You will still be SPF15 protected,' replies Mr Gandhi.

So go with the right sunscreen with the right SPF, and find out more about the active ingredients that are actually effective in blocking out the relevant rays.