Ageing is inevitable but understanding its causes can help slow down the process.

While the outward signs of ageing are well recognised, what is happening at the cellular level is a little more obscure. In basic terms, ageing can be seen when cellular death occurs at a rate at which the cells cannot be replaced.

Numerous theories abound as to what causes the ageing process. Some theories claim ageing is based on a genetically controlled biological timetable, while others attribute ageing to environmental assaults on our systems such as ultraviolet light, cell tissue wear and tear and by-products of metabolic processes. Ageing is most likely a combination of several processes and the widely accepted theory today is that unrepaired accumulated cellular damage, caused by free radicals generated by ongoing normal metabolism and contributed to by environmental sources, is the basis of ageing.

Free radicals and ageing
‘Ageing is a disease,' said Dr Earl Stadtman, a researcher on ageing at the National Institutes of Health in the United States. ‘The human life span simply reflects the level of free radical oxidative damage that accumulates in cells. When enough damage accumulates, cells can't survive properly anymore and they just give up.'

Oxidative damage is a natural chemical process that occurs when oxygen molecules combust within the human body and produce by-products referred to as oxygen free radicals. These highly reactive free radicals, or oxidants, are incomplete molecules that steal electrons from surrounding molecules or donate their remaining electrons to a nearby molecule. In the process, the radicals create molecular instability that damages, disrupts or destroys nearby cells which can cause mutations in the sequence of genetic material and alter the structure of tissues and their functions. The accumulation of these changes is thought to lead to the development of ageing and degenerative diseases.

The body's natural defence mechanisms against free radicals are referred to as antioxidants. They are used to neutralise free radicals before they can cause further damage. Ensuring a daily intake of antioxidants from fresh fruit and vegetables, avoiding smoking and protecting skin from the sun can reduce the risk of degenerative diseases as well as the visual signs of ageing.

How we age
With age, the accumulated effects of free radical damage and the normal wear and wear of cellular life begin to take their toll. Here is a decadal breakdown of some common indicators of ageing.

20s

Accumulated sun damage can begin to show on the face, and there is a mild drop in dermal repair, the immune system and collagen synthesis. These changes can appear as fine lines and an increase in pore size.

Muscles also start to lose fullness and firmness due to shrinkage of muscle fibres. In addition, metabolism, the rate at which the body burns calories at rest, slows down by about 2 percent per decade from the age of 20 and the number of calories the body needs gradually declines.

30s

More fine lines are evident around the eyes and mouth and the first wrinkles start to appear (photo damage). There is a moderate decrease in dermal repair, resulting in less collagen and some loss of elasticity. There is also a significant drop in skin hydration, and the skin's natural process of exfoliation begins to slow. Pigmentation may start to appear in response to a reduction of pigment-producing melanocytes that help protect against ultraviolet radiation.

The decline in cardiovascular fitness also begins in the 30s, and can drop 30 to 40 percent by age 65. Gradual loss of bone strength and density also starts around 35.

From age 30, hair follicles produce less melanin, leading to greying and eventually hair follicles turning white. It is at this age that around 25 percent of men begin to show some signs of baldness.

40s

As the sebaceous glands in the skin cut back production and supportive fibres grow less elastic, skin becomes drier, thinner and more inclined to wrinkle. Signs of photo damage are more visible: freckles, pigmentation, discolouration and changes in skin colour.

The lens in the eye also begins to lose elasticity, making it less able to focus on close objects.
Muscles continue to shrink as fat deposits expand, making it more difficult to control weight. Fat tissues are increasingly deposited towards the centre of the body. Inflammation, pain and stiffness may result from the breakdown of the joint structures and changes in connective tissue.

50s +

By the age of 50, collagen breakdown becomes more noticeable as wrinkles start to appear at the corners of the mouth and skin loosens and sags in the cheeks, jowls and neck. Skin tone becomes more irregular, and thinning skin starts to lose its natural protective barrier and becomes more susceptible to environmental factors.

In addition to the ageing effects on the skin, the decline in oestrogen and progesterone accelerates bone loss and raises cholesterol levels, increasing the risk of osteoporosis, heart attack and stroke. Immunity is also likely to start to weaken, making the body more susceptible to infections and disease.

Bone mass and density is reduced and joints become stiffer and less flexible. Fluid in the joints may decrease and the cartilage may begin to rub together and erode.

The rate of hair growth slows, as hair follicles begin to stop producing new hairs. At the same time, women may notice coarse facial hair, especially on the chin and upper lip.

Ageing is the natural wear and tear of the body's component parts. While it cannot be stopped, a healthy lifestyle that includes a diet rich in antioxidants can help stop or reverse many age-related changes.

ACSM #43