Pig trotters in sweet vinegar is a traditional dish loved by many Chinese. Aside from its rich flavour, the dish is popular for another reason: the trotters contain very little meat and fat, but plenty of collagen.
Those obsessed with looking forever young have gone from having collagen injected and slathered on skin, to eating it to keep age at bay. Collagen, a fibrous protein that connects and supports tissues in the body, is found naturally in trotters, shark's fin, and chicken and fish skin. But these days, thanks to a craze originating in Japan, it's being added to all kinds of food - from marshmallows and jam to ramen and soft drinks.
Collagen makes up about one quarter of the body's protein and occurs naturally in humans and animals. Derived from the Greek words 'kolla' (glue) and 'gennao' (to produce), collagen is needed for healthy skin, bones, organs and connective tissue. Collagen production decreases naturally with age. It is also affected by free radicals formed through sun exposure, pollution, smoking, stress and alcohol use.
Its reduction is most obvious in the skin. 'Healthy collagen fibres act as little springs inside the skin, giving it elasticity, suppleness and firmness,' says Dr Tinny Ho, a dermatologist at SkinCentral. 'Loss of collagen causes wrinkles, sagging and a thin, crepey look to the skin.'
Secretary Paulina Chan, 30, swears by collagen supplements. Chan downs a collagen drink once a day in a bid to keep her face wrinkle-free. 'I think it has made my skin more radiant, and I have fewer pimples. People tend to think I'm younger than I really am,' she says.
Eating collagen may help the overall formation of collagen in the body, according to a paper published in the Archives of Dermatological Research in 2008. Research published a year later by Tokyo University suggested that eating collagen could reverse the effects of sun-related skin ageing.
Other experts, however, are not convinced. The British Skin Foundation asserts that there is no evidence to show that eating collagen is beneficial for the skin in any way. 'Very few oral supplements have good published studies to prove their effectiveness,' Ho says. 'In general, dermatologists do not regard oral supplements as an effective way of boosting the collagen in the skin.'