The skin is a phenomenal organ, allowing the body to stretch and retain its original shape afterwards. The reason this is possible is because of the collagen and elastin in naturally healthy skin.
Collagen makes up around 75% of the skin’s dry weight and hold the skin together. Collagen provides the main structural element of skin. Elastin fibres are the reason why skin is stretchy. These fibres are able to stretch to one and a half times their relaxed length without breaking.
Overstretching of the skin results in the dermis tearing and produces red striae that later fade to silvery stretch marks. These stretch marks can occur in pregnancy, at puberty, with rapid or excessive weight gain, and with trauma to the body. It is possible to reduce the severity of stretch marks but there will always be limits to the stretchiness of the skin.
Collagen is one type of connective tissue, the most abundant of all tissues in the body. The word itself is derived from the Greek ‘kolla’ which means glue and some animal tissues (traditionally horse flesh) are still used to produce glue from their collagen.
Collagen is essential for the structure of the skin and conditions affecting collagen production will lead to cracked skin, slow or impaired wound healing, scarring and bleeding gums, as well as increased exposure to skin infections. Scurvy is one such condition as vitamin C is vital for collagen production due to its role in forming hydroxyproline, a key protein in collagen.
The bundles of protein fibres making up collagen lend the skin its rigidity and these fibres are not very stretchy and become even less flexible with age. Sun exposure, lack of vitamin C, and other lifestyle and dietary challenges can all contribute to poor collagen production and resulting skin problems.
Smokers are particularly at risk of poor skin health, partly because vitamin C is used up in protecting the body’s cells from the oxidising effects of smoking rather than in producing collagen. Scarring, poor wound-healing, saggy and lacklustre skin are all common findings in long-time smokers.
Elastin is the stretchy component of the skin, again made up of protein fibres but able, in this case, to stretch considerably without snapping or tearing. Elastin lends the skin suppleness and strength and is essential for the constant processes of expansion and contraction in bodily tissues such as the lungs and blood vessels.
Both elastin and collagen are present in the skin in a solution comprising water and other other substances. Dehydration, therefore, makes the skin less stretchy and impairs its ability to retain its shape, as does oxidative damage that accumulates with age.
This can be demonstrated by lightly pinching the skin on the back of the hand in someone young, someone elderly, and in those who are well hydrated or dehydrate; the former, in both cases, will likely see their skin spring back into shape almost immediately, whereas the latter may have a ridge of skin that takes several minutes to return to form.