Calcium

What is calcium?

The average adult’s weight is made up of about 2% calcium. Most of this is found in the skeleton and teeth – the rest is stored in the tissues or blood. Calcium is vital for healthy teeth and bones. It also plays a crucial role in other systems of the body, such as the health and functioning of nerves and muscle tissue.

Good sources of calcium include:

• dairy foods – milk, yoghurt and cheese
• calcium-fortified products – for example, plant-based milks like soy milk and rice milk
• breakfast cereals.

People at different life stages need different amounts of calcium – young children, teenagers and women over 50 all have greater than average requirements.

According to the most recent National Nutrition and Physical Activity Survey of 2011-12:

• Over half of all Australians aged 2 years and over consume inadequate levels of calcium from food sources.
• Females are less likely to have adequate intakes of calcium than males.
• 73% of females consume less calcium than recommended.
• 51% of males consume less calcium than recommended.

It is much better to get calcium from foods than from calcium supplements. Be guided by your doctor about whether you need additional supplements. Too much calcium from supplements may cause other health problems.

Role of calcium in the body

Calcium plays a role in:

• strengthening bones and teeth
• regulating muscle functioning, such as contraction and relaxation
• regulating heart functioning
• blood clotting
• transmission of nervous system messages
• enzyme function.

Calcium and dairy food

Australians receive most of their calcium from dairy foods. If milk and milk-based foods are removed from the diet, this can lead to an inadequate intake of calcium. This is of particular concern for children and adolescents, who have high calcium needs.

Calcium deficiency may lead to disorders like osteoporosis, a disease in which bones become fragile and brittle later in life, making them more prone to fractures and breakages. While osteoporosis can affect both men and women, post-menopausal women are at particularly high risk.

Too little calcium can weaken bones

If not enough calcium is circulating in your blood, your body will use hormones to reduce the amount of calcium your kidneys excrete in your urine.

If not enough calcium is absorbed through the gastrointestinal tract, calcium will be taken from the bones.

If your dietary intake of calcium is constantly low, your body will eventually remove so much calcium from the skeleton that your bones will become weak and brittle.

Calcium needs vary throughout life

The recommended dietary intake of calcium is different for people of different ages and life stages.

People with special calcium needs

It is particularly important that people from certain groups meet their calcium needs. These groups include:

• Babies – formula-fed babies are estimated to need more calcium than babies that are breastfed, because the calcium in infant formula may not be absorbed as efficiently as that found in breastmilk.
• Young children – skeletal tissue is constantly growing, so young children have high calcium requirements.
• Pre-teens and teenagers – puberty prompts a growth spurt, which in turn increases calcium requirements. This group also needs more calcium to build peak bone mass. If the skeleton is strengthened with enough calcium during these years, diseases like osteoporosis in the later years are thought to be less likely.
• Elderly people – as we age, the skeleton loses calcium. Women lose more calcium from their bones in the 5 to 10 years around the age of menopause. However, both men and women lose bone mass as they grow older, absorb less calcium and need to make sure they get enough calcium in their diet to offset these losses. While a diet high in calcium cannot reverse age-related bone loss, it can slow down the process.

Caucasian (white) people have larger frame sizes and generally have higher intakes of animal foods, caffeine and salt than non-Caucasian people. It is thought they may need more calcium as a result.

Pregnant and breastfeeding women and calcium

A developing baby needs a lot of calcium. However, there is no need for women to take additional dietary calcium during pregnancy because pregnant women absorb calcium from food more efficiently.

Breastfeeding women do not need to increase their calcium intake, unless they are adolescents.

Good sources of calcium

Good dietary sources of calcium include:

Please note: not all calcium consumed is absorbed by the body. Factors impacting calcium absorption include low vitamin D levels, large amounts of caffeine/alcohol consumption and some medical conditions (such as coeliac or kidney disease).

Calcium supplements

It is much better to get calcium from foods (which also provide other nutrients) than from calcium supplements. But if you have difficulty eating enough foods rich in calcium, you might need to consider a calcium supplement, especially if you are at risk of developing osteoporosis.

Before taking supplements, it’s best to discuss this with your doctor or other registered healthcare professional. Calcium supplements are often taken with vitamin D.

If you do take calcium supplements, make sure you don’t take more than the amount recommended on the bottle. Too much calcium may cause gastrointestinal upsets such as bloating, constipation and, rarely, other complications such as kidney stones.

Calcium supplements – complications

Safety of calcium supplementation has often been debated. High levels have been potentially linked to heart disease.

Although high levels of calcium intake through supplementation may be of concern, calcium supplementation at levels of 500 to 600 mg/day is both safe and effective for reducing the risk fractures in people who don’t get enough calcium from their diet. If you have any concerns about calcium supplements, talk to your doctor or other registered healthcare professional.

Lifestyle can affect bone strength

Poor bone health can be hereditary. However there are some lifestyle factors that can reduce calcium in your bones and lower your bone density (weaken your bones). These include:

• high-salt diet
• more than 4 drinks per day of caffeine-containing drinks - for example, coffee, cola and energy drinks (and, to a lesser extent, tea)
• excessive alcohol intake
• very low body weight
• low levels of physical activity, specifically weight bearing, resistance training and balance exercises
• low levels of vitamin D - people who are housebound or cover their bodies completely when they are outside are at increased risk
• smoking.

Where to get help

• Your GP (doctor)
• Dietitians Australia Tel. 1800 812 942
• Nutrition Australia Tel. (03) 8341 5800
• Healthy Bones Australia
• Australian guide to healthy eating