Last partial update: August 2022 - Please read disclaimer before proceeding.
Maintaining an adequate calcium intake
Up to 75 per cent of Australian women have calcium intakes less than that recommended by the National Health and Medical Research Council and around 15 per cent have a severely low intake level of less than 300mg per day.
The amount of calcium absorbed from the diet decreases with age and thus dietary intake needs to increase with age. The accompanying table shows the recommended calcium intake for men and women.
Advised calcium intake |
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Person |
Estimated average requirement* |
Recommended dietary intake* |
Males |
|
|
Boys 1 to 3 years |
360 |
500 |
Boys 3 to 8 years |
520 |
700 |
Boys 9 to 11 years |
800 |
1000 |
Boys 12 to 18 years |
1050 |
1300 |
Men 19 to 69 years |
840 |
1000 |
Men 70 years and over |
1100 |
1300 |
Females |
|
|
Girls 1 to 3 years |
360 |
500 |
Girls 3 to 8 years |
520 |
700 |
Girls 9 to 11 years |
800 |
1000 |
Girls 12 to 18 years |
1050 |
1300 |
Females 18 to menopause |
840 |
1000 |
Menopause to 69 years |
1100 |
1300 |
Women 70 years and over |
1100 |
1300 |
Females - Pregnant or lactating |
|
|
14 to 18 |
1050 |
1300 |
19 to 50 |
840 |
1000 |
Maximum intake for all people – 2500mg per day. |
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* The estimated average requirement is the amount of calcium that an average person requires. It is calculated for a 76kg man and a 61kg woman. (Larger people would need more and smaller less..) |
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Source: NHMRC Publication: Nutrient Reference Values for Australia and New Zealand |
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Those at most risk of having an inadequate calcium intake are the following.
- The elderly (Calcium absoption from the bowel decreases with age and this is often made worse by low vitamin D levels in this age group. Also, most elderly people have reduced food intake compared with younger adults and this makes achieving an intake of 1300mg of calcium through diet alone difficult.)
- Socially isolated people
- Post-menopausal women (Reduced sex hormone levels in post-menopausal women deceases calcium absorption from the bowel.)
- Other women with sex hormone deficiency
- People taking steroid medication
- People with intestinal disease. (Such disease disrupts calcium absorption)
- Growing children. Childhood is the most important time during life for increasing bone stores and adequate calcium intake and exercise during this time are vital in achieving maximum adult bone mass / strength. (The bone tissue stored by a girl from age 11 to 13 equals the amount that is lost in the 30 years following menopause.)
Food sources of calcium
As well as being the best source of dietary calcium, dairy products also provide calcium that is the most easily absorbed from the intestine. To achieve adequate calcium intake from diet alone, most people need diary products of some sort. The best way to achieve this is with at least two (three in the elderly) serves of calcium enriched foods per day; good choices are a 250 ml glass of calcium enriched low-fat milk or a serving of calcium enriched low-fat yoghurt, both of which provide about 400 mg of calcium. There are also other calcium-enriched foods available, for example soy products. Using reduced-fat cheeses as a daily calcium source is a less desirable choice as they still have a relatively high fat content and much of this is saturated fat. Soy products with added calcium are a good alternative if you can’t have diary products.
Calcium supplements - Not effective in reducing fractures
UNtil recently it was thought that calcium supplements reduced the incidence of fractures in people with inadequate intake who had osteoporosis. Unfortunately recent reviews of the research on this topic has shown that this is not the case and that suppl;ements are ineffective in reducing fractures.
Additionally, research has shown that supplements increase the risk of heart disease. This is a particular problem as heart disease is common in older people with osteoporosis. Thus, supplemets are not commonly recommended and people are advised to get the calcium they need from food sources.
Some foods affect calcium absorption
Calcium absorption can be affected by foods eaten. Substances that can decrease absorption include tannins in tea, iron, caffeine, excess alcohol, the phosphate in soft drinks, and phylates that are present in fibre. High protein diets, a low vitamin D level and smoking can also reduce levels. Tablets containing calcium carbonate are best absorbed in an acidic stomach environment and thus should be taken with food. (They do however interfere with iron absorption from the diet.) Tablets containing calcium lactate, citrate and gluconate can be taken at any time.
A diet high in sodium (salt), caffeine or protein foods can increase calcium loss via the kidneys / urine and thus reduce body calcium stores.
Inadequate vitamin D is very uncommon in Australia and supplements are rarely necessary.
Vitamin D is needed for the body to be able to absorb dietary calcium from the bowel and helps with calcium deposition into bone. It actually acts as a hormone . Vitamin D deficiency is not a problem for the vast majority of Australians.
Recent research has shown that there is no benefit in taking vitamin D supplements even if your levels are relatively low. Major large randomised studies showed taking vitamin D supplements had no effect on longevity or any major disease including heart disease and cancer; and particularly there was no effect on the incidence of fractures; This was the case whether blood levels were normal or low.
The reason is that the vitamin D a person consumes is a pro-hormone that is used by the body to make the active version of vitamin D. The body tightly controls the level of this active hormone but needs relatively little of the pro- hormone to achieve adequate levels. Thus deficiency is very unusual and only occurs when there is a severe deficiency where it causes osteomalacia in adults and rickets in children. Vitamin D levels probably need to be quite low, less than 10nmol/, for these lesions to occur and a level of 20nmol/L or more is safe. (this level was previously considered low.)
For this reason vitamin D testing is not recommended unless the person has a specific medical issue that might cause a very low vitamin D level. (See below.) This includes people with intestinal malabsorption problems, people who take medication that reduces vitamin D and people who get very little sunlight.
Food sources of vitamin D
Vitamin D is found in small quantities in oily fish, eggs and milk products and some foods are fortified with vitamin D, including some types of margarine and milk. The recommended daily intake of vitamin D is 400 to 800IU (10 to 20 micrograms) per day. Some other countries, especially those in northern Europe, fortify foods with vitamin D. This does not occur in Australia as the population gets enough vitamin D from sunlight.
Sunlight is the best source of vitamin D in Australia
By far the best way to source required vitamin D intake is by exposure to UVB radiation from sunlight, which converts a vitamin D precursor (7-dehydrocholesterol) to active vitamin D in the skin. Almost all Australians get suffcient active vitamin D from sunlight.
The amount of sunlight exposure required to produce adequate vitamin D depends on the amount of skin exposed, skin colour, and the intensity of the sunlight, which varies according to the latitude, the time of year and the time of day, and cloud cover. It is unfortunate that UVB radiation is also responsible for sunburn and skin cancers, which are a huge health problem in Australia and for this reason it is important to avoid excessive sunlight exposure. Luckily, adequate vitamin D production in the skin requires small amounts of sun exposure with exposure of about 15 per cent of the skin to a very modest amount of sunlight being adequate. This equates to about 33 per cent of the sunlight (i.e. UVB radiation) which would cause even the faintest redness in the skin. The table below gives the recommended guidelines regarding the sun exposure required to produce adequate vitamin D. As mentioned in the table, people with dark coloured skin need a sunlight exposure that is three to four times greater than those mentioned to create the required amount of vitamin D. Older people also need slightly longer exposure than that mentioned in the table.
Who is most at risk of having vitamin D deficiency?
Those at most risk of having an inadequate vitamin D levels are the following.
- The house-bound elderly or those in institutions. (These people usually require calcium and vitamin D supplements.)
- Other elderly people unable to go outside.
- People who have limited sunlight exposure due to covering most of their skin with clothes; for example, Islamic women who wear the hejab.
- The breastfed infants of pregnant women who are dark skinned or whose clothing covers most of their skin.
- People on certain medications that lower vitamin D (e.g. some anti-epileptic medications)
- People with malabsorption due to gastrointestinal disease
Vitamin D supplements - No benefit for the vast majority of the population
It was previously thought that the use of vitamin D supplements in people with low levels vitamin D reduced the incidence of fractures and reducerd falls by improving muscle strength and mobility.
As stated above, recent reviews of the body of research on this topic have shown that there is no such benefit.