How your lifestyle is vital to healthy bones

The Friday Science Lecture by Dr Clive Hunt, School of Applied Sciences, University of Huddersfield — University Campus Oldham’s degree partner

WE tend not to think much about our bones, unless they break!

But we shouldn’t take them for granted.

Bones are not static, once formed they have a blood supply and a constant turnover of minerals flowing in and out.

There are two main types of cell responsible for this: osteoblasts, which help to form bone, and osteoclasts, which cause bone breakdown and resorption.

When we are children and adolescents, there will be a net balance towards bone formation, whereas adults need formation and breakdown to balance.

There are two types of bone: compact (cortical) and spongy (trabecular). The spongy bone forms the interior “scaffolding” of the skeleton. The spaces in between the bone mesh contain red and yellow marrow and other tissue.

However, this spongy bone can become too porous by excessive loss of minerals, which can lead to the condition known as osteoporosis.

Regions of the skeleton that contain a high proportion of spongy bone such as the hip, spine and wrist are the most susceptible to fracture.

Osteoporotic fractures are common in older people (over 50), particularly in women. Approximately 30 per cent of women and 10 per cent of men are affected, translating to over 200,000 fractures per year in the UK.

So, how can we reduce risk of porous bones?

There are both dietary and non-dietary risk factors to consider. Non-dietary includes genetics, which obviously we can’t do anything about, but also lack of physical activity, which we can.

Load-bearing exercise, such as walking and running, throughout life can help protect our bones by encouraging mineral deposition over loss, whereas an inactive lifestyle will do the opposite.

Smoking is also a risk factor, so osteoporosis is another reason to avoid it.

Excessive alcohol consumption also does not help, ie regular intake over the recommended levels of 14 units per week for women and 21 for men. But what about other dietary factors?

Peak bone mass (PBM) is achieved in our teens and into our 20s. The better your PBM then the less chance of porous bones later in life.

A good intake of calcium and vitamin D is important for both growth and maintenance of bones. Some teenagers (particularly girls) who diet excessively and avoid dairy products (good sources of calcium) are putting themselves at risk.

However, generally, women have some protection up to the menopause via the hormone oestrogen.

After the menopause this protection is lost because oestrogen production is reduced. So exercise and diet become all the more important.

Also, exposure to sunlight helps to maintain vitamin D levels, because sunlight promotes synthesis of vitamin D in the skin. Housebound elderly are therefore at particular risk and need good food sources such as fortified margarine, oily fish and eggs.

Other nutrients may also be involved in bone health such as potassium and vitamin K. Fortunately, various fruits and vegetables are good sources of both, so make sure that you eat at least the recommended five a day.

Overall, a balanced diet and regular exercise, and avoidance of smoking and excessive alcohol, can help to maintain healthy bones throughout our lives and into old age.

Another reason to keep up that healthy lifestyle!