Calcium is one of the essential nutrients necessary for healthy bone development. Adequate calcium intake is necessary for the attainment of peak bone mass in the late teens (i.e. the highest level of bone strength which occurs at completion of growth) and therefore strong healthy bones, which will sustain the effects of ageing on the skeleton.

It is important to have a well-balanced diet with adequate amounts of dairy products, which are the primary source of foods rich in calcium.

Not only is calcium important to bones, it is also important for the function of various organs within the body and a certain amount of calcium circulates within the blood. If blood calcium levels fall as may occur with inadequate calcium intake in the diet, the body will compensate for this by drawing calcium out of bones and putting it into the blood.

Calcium is also excreted by the body daily. Hence it is important to have an adequate daily intake of calcium through the diet, so that bone mineral strength is not compromised.

Calcium requirements through life

There are critical times in life when it is vital to ensure that calcium intake through food and/or supplements is adequate and meets the recommended requirements for age and sex.

Childhood and adolescence

During childhood and adolescence, when the skeleton is actively growing it is essential that calcium intake meets the requirements of the growing skeleton. It is during this growth phase that the foundations for the attainment of peak bone mass are laid.

The majority of bone mass is laid down shortly after the teenage years. The age at which peak bone mass is achieved is somewhere between the age of 18 and 30. Peak bone mass generally represents a time when the bones are at their ‘strongest’. The higher the peak bone mass, the greater protection the skeleton has against the effects of ageing.

It is important to realize that the peak bone mass achieved varies from one individual to the next. It primarily reflects hereditary factors in addition to hormonal and life style factors. during childhood and adolescence. Hence an individual who has had adequate intake of calcium, plenty of exercise and not been subjected to any sex hormone deficiencies (i.e. interruption to menstrual periods) during childhood and adolescence will likely achieve a high peak bone mass as compared to an individual who has not had favourable circumstances for bone development.

20s to 40s

Between the ages of 20 and 35 years bone gain and loss is quite stable. It is important to maintain a healthy lifestyle during these years for good bone health.

From the mid-30s onwards, bone loss starts to increase more than bone gain. It is part of the normal ageing process that bones lose their mineral (calcium) and protein (collagen) content. For women this process of bone loss is also accelerated further at the time of menopause. If an individual achieves a high peak bone mass, their risk of osteoporosis in later life is reduced.

Midlife - 50s to 65

When women go through menopause, there is a rapid loss of bone that is primarily due to oestrogen deficiency and this process may last from 4 to 8 years after menopause.⁴ After this period of time the rate of bone loss is comparatively reduced and stabilises.

It is also known that women generally start to lose bone even in the years leading up to menopause due to the fact that oestrogen levels are already starting to drop even though menstrual periods may still be occurring.⁵

The gastrointestinal system and kidney become less efficient at absorbing and conserving calcium in the body. This creates a state of potential calcium loss in the blood, and the body compensates for this by drawing calcium out of the bones.⁴

Older years - over 65

In the years beyond menopause the rate of bone loss as a consequence of oestrogen deficiency slows down. In the older age group calcium and vitamin D deficiency becomes more common as a result of dietary changes, reduced sunlight exposure and reduced absorption of calcium through the gut. There are also other important factors for increased fractures in the older age group such as increased frailty and risk of falls. 

Pregnant and breastfeeding women

Pregnant women and breastfeeding women need to ensure that they have adequate calcium intake. In pregnancy, the increased calcium requirement (to provide for skeletal growth in the foetus) is met through increased absorption in the mother’s gastrointestinal system. Women who breastfeed also have higher requirements for calcium, which is provided mainly from the mother’s skeleton. Normal pregnancy and breastfeeding is associated with a certain amount of bone mineral loss, which generally recovers 6- 12 months after the cessation of pregnancy and/or breast feeding.³

Calcium counter

Daily calcium requirements need not come necessarily from dairy products. If you choose alternative calcium sources, note carefully the quantity of calcium found within the particular food source. 

Other dietary factors

Overall it is important to have a well-balanced diet.

Protein intake is important for bone development as it provides the necessary building blocks in bone.

However, it has been found that diets that are very high in protein, salt, caffeine and phosphorus may adversely affects the body’s calcium balance, although this affect may not be that significant in an individual with an adequate calcium intake.^13,14

Further resources

Fact sheets

 Bone Health - Preventing Osteoporosis 98.64 Kb

 Healthy Eating for You 116.18 Kb

Content updated July 27, 2011