Which?, the consumer watchdog magazine, has criticised several skincare companies for making claims that are confusing and incomprehensible – even to trained scientists with a PhD in genetics.

One science-based charity yesterday told The Scotsman that major firms such as L'Oréal, whose adverts are fronted by Penélope Cruz, and Garnier – advertised by Sex and the City star Sarah Jessica Parker – were wilfully using "scientific bamboozlement" to try to sell their skincare ranges.

Which? wanted to check out popular product adverts that promise to, among other things, "refuel surface skin cells" and give skin "a dewy glow", and asked firms to provide scientific rationale to back their claims.

The magazine questioned the maunfacturers of Garnier Nutritionist Omega Skin, Olay Regenerist and L'Oréal Derma Genesis, which make much of the fact they contain ingredients the average consumer knows little about.

A spokesman for Which? explained: "Pentapeptides, hyaluronic acid and omega 3 may sound impressive, but scratch beneath the surface of the glossy cosmetic adverts and the claims of some companies don't make a whole lot of sense."

In its attempts to see whether the public could get a better explanation of these claims, Which? even contacted customer-services departments at companies such as Garnier and L'Oréal. Posing as a consumer, a researcher asked how ingredients such as hyaluronic acid and pentapeptides actually worked on the skin.

Then Which? showed the results of its research to Sense About Science, a charity that promotes good science, to see what it thought of the information it had received. The charity said it thought that staff were often fobbing off customers with pseudo-science that either exaggerated claims or made no sense whatsoever.

After reading Which's transcripts, the scientists were no wiser about how pentapeptides, lipopeptides or omega 3 managed to "help with the signs of ageing" or "improve the appearance of your skin". One psychologist, who did not wish to be named, said such terms were manna to marketing experts, explaining: "The average consumer takes these phrases as gospel. They don't question the claims; they don't even understand them. But then, part of them doesn't want to understand. They trust big brands. It may be seen by some as underhand, but it's part of our consumer culture: the shops and the manufacturers know best."

Dr Aarathi Prasad, a spokeswoman for Sense About Science, said such an approach was grossly flawed. She said: "It is insulting to people's intelligence to expect customers to accept these explanations. They are taking the real science out of context so it becomes bad science.

"It's hard to gauge just how misleading the adverts are, but the problem is they don't present a full and frank explanation of the chemicals and how they work. For example, some face-cream products claim to stimulate the skin and they do, but only when used to treat people with arthritis.

"Some other products use nanogold, tiny particles which react with the skin to energise it. But the only way nanogold can become reactive is with radiotherapy treatment in cancer therapy; it doesn't work if it's just in a pot of cream."

Of those three brands singled out in the study, none stood up to firm scrutiny. A Which? researcher attempted to glean further information from L'Oréal's customer-services department regarding the precise chemical process involved in its Derma Genesis products, a range endorsed by Ms Cruz, the Oscar-nominated Spanish actress. Viewers have seen Ms Cruz boast that L'Oréal is the only cosmetics company to use "hyaluronic acid", a factor that leaves her skin, apparently, "plumped-up" and "tautened".

However, when Which? inquired how this was the case, the customer adviser was unable even to pronounce hyaluronic acid, let alone expound its scientific merits. It was, Dr Prasad concluded, "marketing speak that appears to be cloaked in science".

L'Oréal has previously fallen foul of advertising rules when marketing its goods. Earlier this year, the Advertising Standards Authority (ASA) ordered L'Oréal to remove television and press adverts for its telescopic mascara, after it transpired that Ms Cruz had been wearing a few individual false lashes to fill in gaps in her natural lashes.

The second product examined by the magazine, Garnier Nutritionist Omega Skin, is advertised by Ms Parker relaying how it helps to "refuel surface skin cells". Again, when Which? called the company's customer-advice line, no-one was able to explain how.

The adverts were further singled out for their use of words like "feel" or "appear", rather than presenting definitive facts. "It's a sign that there's no empirical measure of how good these products are, or how robust the claims that are made," said Dr Prasad.

The third cosmetics product, Olay Regenerist, also used confusing terminology. Fronted by Nadine Baggott, the health and beauty editor of Hello! magazine, the television advertisements for the cream are routinely mocked for their reliance on complex scientific terms.

Chief among them is Ms Baggott's assertion that the Olay product, which purportedly helps anti-ageing, benefits from the inclusion of pentapeptides as an ingredient. Again, Which? found Olay was unable to give a detailed answer as to how the pentapeptides work.

Dr Prasad said the customer-service teams at firms such as Olay were not to blame. Instead, she said, their marketing departments ought to be held accountable. She said: "They use these fancy words that give the product that extra 'oomph'. It's never going to go away as long as there's real scientific innovation, which is something we should all encourage and appreciate. The problem is when marketing departments get involved and the science gets twisted or deliberately obscured."

While some consumers may find such claims grossly misrepresentative, they do not flout the regulations of the ASA and do not require the same testing for efficacy and quality control as is required for medicines.

Nevertheless, Dr Prasad, who has a PhD in genetics, added that numerous adverts do not allow shoppers to make conscious decisions. "You can't regulate everything, but this form of claptrap science always slips through," she said. "It's only scientists in our field who have the education and critical eye to pick up on it. The reality is, if it sounds too good to be true, it probably is."

FANCIFUL FINDINGS

THE cosmetics industry is not alone in being criticised for a reliance on pseudo-science in its marketing campaigns.

Sense About Science, the independent science charity, has also drawn attention to a range of goods, from sandwiches to spa accessories, which promote unfounded claims.

For instance, Pret a Manger, the sandwich-and-coffee-shop chain, claims that it eschews compounds such as sodium benzoate and minimises the use of food additives tagged as E numbers in its products.

However, sodium benzoate occurs naturally in apples and cranberries, and Sense About Science says the company uses E250, or sodium nitrite, and E500, an ingredient of baking powder.

In its promotional literature, meanwhile, food giant Nestlé has said its Ski Activ8 yoghurt, "combined with a healthy diet, lifestyle and exercise… can help recharge our batteries".

However, the yoghurt's "unique blend of eight B vitamins and minerals" would do nothing to improve energy levels, but would simply be excreted, says Sense About Science.