Taking daily collagen supplements can rejuvenate the skin by boosting elasticity and hydration or moisture - but it won't stop wrinkles, says a new scientific review.

Experts looked at the available evidence and say they are highly confident that collagen pills or powder provide "some legitimate" skin gains if taken over time but are no quick fix.

The supplements may also ease wear and tear, arthritis joint pain and stiffness, according to the results from 113 trials involving nearly 8,000 people.

Collagen is a type of protein made naturally in the body but that declines with age. It supports and strengthens skin, nails, bones and connective tissues, including tendons and cartilage.

'Collagen is not a cure-all'

From early adulthood onwards, the body produces less collagen and existing collagen breaks down at a slightly faster rate.

Smoking and sun damage make this worse.

Around the menopause, when women stop having periods, skin loses even more collagen - about a third, say the researchers who have published their findings in the Aesthetic Surgery Journal Open Forum.

There are several types of supplements people can take, including marine, bovine and vegan collagen. The review was unable to show if certain types worked better than others.

The researchers from Anglia Ruskin University stress that many of the studies conducted with supplements have been funded by the supplement industry, and that "bold claims" have been made about collagen anti-ageing benefits. The review did not have any industry funding.

One of the lead investigators, Prof Lee Smith, said: "This study brings together the strongest evidence to date on collagen supplementation.

"Collagen is not a cure-all, but it does have credible benefits when used consistently over time, particularly for skin and osteoarthritis. Our findings show clear benefits in key areas of healthy ageing, while also dispelling some of the myths surrounding its use."

Collagen may be best positioned not as an anti-wrinkle treatment, but for holistic maintenance for ageing and sun-damaged skin, say the researchers.

Smith says: "If we define anti-ageing as a product or technique designed to prevent the appearance of getting older, then I believe our findings do support this claim for some parameters.

"For example, an improvement in skin tone and moisture is associated with a more youthful-looking appearance."

Skin-friendly diet

Bridget Benelam, a nutrition scientist at the British Nutrition Foundation, said diet was also important for skin health.

"Vitamin C helps with collagen formation and so ensuring you get enough from foods such as citrus fruits, berries, green vegetables, peppers and tomatoes may help. Zinc, found in meat, poultry, cheese, some shellfish, nuts, seeds and wholegrains, also helps the body produce collagen.

"Dietary sources of collagen and many collagen supplements are made from animal products and so not suitable for vegan diets. However, the body makes its own collagen from the amino acids found in dietary protein and so protein from sources such as beans and lentils can provide the amino acids needed for collagen production. There are also vegan supplements available."

Dr Tamara Griffiths, president of the British Association of Dermatologists, welcomed the research but recommended more: "Further data with targeted, robust dermatological studies are required to build on the promise raised by this systematic review."