Bone health, nutrition
Bones play useful roles in our body — they support it against gravity, provide points of attachment for muscles to facilitate our movement and store calcium. They also protect the brain, liver, lungs, heart, kidneys and the central nervous system.
It is important for us to develop strong bones during childhood and adolescence, and take good steps to ensure their health during adulthood.
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Our bones are continuously changing with old tissues being replaced with new ones. During our young ages, new bone is made faster than it breaks down, leading to an increase in Bone Mass (BM); most people reach their peak BM around 30 years (NB: Bone remodeling continues after that, but we lose more BM than we gain).
Achieving optimal BM during this period minimises the risk of developing osteoporosis (a condition of weak and thin bones) and fractures later on in life.
Bone health
Nutrition is one important factor in the development of BM and the prevention of osteoporosis. The nutrients of obvious importance here are calcium and phosphorus (they constitute 85-90 per cent of the mineral content of bone), together with vitamin D. Other minerals (e.g. zinc, magnesium, iron and fluoride), proteins and vitamins (e.g. A, C, and K) are also worth mentioning.
Drinking excessive alcohol, smoking, having eating disorders, being underweight and/or ill, weaken our bones.
They become weaker with advancing age – considering our actively growing population, with three to five per cent being 65 years and above (PHC, 2022), we must be concerned.
The concentration of calcium in our blood is so critical that the body is very sensitive to it. If it goes too high, the body will mobilise through the intermediacy of vitamin D to deposit the excess in the bones (accretion). This will strengthen the bones.
On the other hand, if the level goes below the threshold, calcium will be withdrawn from the bones (resorption) to make up for the loss. If the latter should occur often, our bones will become prone to fracture.
Bone loss
Too much thyroid hormone can cause bone loss. In women, bone loss increases dramatically at menopause due to reducing oestrogen levels.
The prolonged absence of menstruation (amenorrhea) before menopause also increases the risk of osteoporosis. In men, low testosterone levels can cause BM loss.
Elderly persons, in addition to having relatively lower amounts of calcium from their diet, excrete more urinary calcium than younger people do.
Fractures
The clinical outcome of weak bones is manifest in the incidence of fractures. These can occur as a result of some trauma which could be “low” (e.g. slipping in a bath tub), “moderate” (e.g. being hit by a fast-moving ball while playing), or “high” (the result of heavy impact during boxing, vehicle accidents or a heavy fall).
The parts of the body that we use often naturally develop better than those that we do not. For example, the bones of a professional athlete would be denser than that of, say, a lecturer, of same age and sex, because the former exercises his/her bones (and muscles) regularly through routine training.
Does excess help?
Some epidemiological studies show that the intake of calcium products promotes BM, and protects against fractures. Women (45y+) tend to benefit from calcium supplements (NB: Women are three to four times more likely to develop fractures than men).
During adolescence, females synthesise oestrogen in their fat deposits. After 45 years or so, menstruation ceases and the body would have problems with increased urinary loss of calcium.
It makes sense then, that young women should have reasonable amounts of fat in their body, as a form of “biological insurance” in their postmenopausal stage.
For healthy bones, we need adequate calcium in our diets (e.g. from dairy products, fish with bones, soy products, etc.)
We must pay attention to vitamin D (in fish oils – from salmon and tuna), mushrooms, eggs and fortified foods). We must engage in some physical activity and enjoy being exposed to some amount of sunlight.
The writer is a Harvard-trained freelance writer on science, public health. E-mail: [email protected]
