In Australia, the major food sources of calcium are dairy products — milk, yoghurt, cheese and ice cream. Generally speaking, low-fat dairy products have just as much calcium as regular versions, so you don't miss out on calcium if you're cutting back on fat. Dairy products are the best calcium source, but not the only one. If you need to avoid or prefer not to eat them, there are calcium-enriched non-dairy alternatives.
If you're concerned about how much calcium you eat, you may find it useful to talk to a dietitian about ways to increase calcium in your diet, and check out tips for boosting your calcium intake.
What to avoid
Some substances can reduce your body's ability to make use of calcium. To get the most from calcium in food (or supplements) it's best to avoid having the following things at the same time as food rich in calcium. This won't always be possible, especially if you're vegetarian:
- Oxalates - in spinach, rhubarb, peanuts.
- Phytates - in beans, peas and lentils, and in minimally processed wholegrain and wholemeal cereals.
- Large amounts of fibre.
- Some medications, such as cholestryramine (for treating high cholesterol) and antacids that contain aluminium, can interfere with calcium absorption if taken at the same time. Conversely, taking calcium supplements or eating calcium-rich foods at the same time as some other medications can reduce the effectiveness of the medication -- for example, tetracycline for infections, beta blockers for heart conditions and even the common aspirin tablet.
- Some other minerals (such as iron) tend to compete with calcium for absorption. If you need both iron and calcium supplements it's best to take them at different times of the day.
- Caffeine can also increase your body's calcium needs - but if you get lots of calcium from your diet, caffeine may only have a minor effect. Adding milk to coffee may go part or all of the way to balancing out the effects of the caffeine it contains.
When do you need a supplement?
Dietary surveys in Australia have shown that some people, especially women, are probably not getting enough calcium. While it's preferable to obtain the calcium you need from your diet, supplements may be of benefit if you find it difficult to get enough from food.
Choosing the best calcium supplement
Here are some pointers to help you navigate through the maze of calcium supplements on the market:
- Calcium supplements come in various forms and concentrations. The different chemical forms include calcium carbonate, calcium citrate, calcium lactate, calcium gluconate, calcium phosphate and calcium orotate. Each different chemical form contains a different amount of 'pure' calcium - called the amount of 'elemental' calcium. So unless the label tells you the amount of elemental calcium, it's difficult to compare supplements. CHOICE Online thinks all labels should clearly show the amount of elemental calcium you're paying for.
- If you don't like taking too many pills, calcium carbonate supplements may be a good choice as they're highly concentrated. They commonly contain around 600 mg of calcium in one tablet. Calcium phosphate is also a highly concentrated calcium supplement, but it's perhaps less well absorbed.
- If you choose calcium citrate, calcium lactate or calcium gluconate you may need to take more tablets, as these forms are less concentrated. There is some evidence to suggest that calcium citrate is the most easily absorbed form of calcium supplement. While some manufacturers claim calcium orotate is better absorbed than other forms, these claims are unproven.
- Calcium citrate may be advantageous for people whose stomachs produce less acid, as is common in older people. But taking a more common and cheaper calcium carbonate supplement with a meal or a glass of orange juice may help it dissolve just as well.
- Supplements containing natural sources of calcium such as oyster shell, dolomite and bonemeal may contain contaminating metals such as arsenic, lead or mercury. If you choose this type, check that it has been purified.
- Added extras in a calcium supplement may not be of any use. Vitamin D, often added to calcium supplements, is essential for calcium absorption, but unless you rarely get outside (as may be the case for some elderly people in nursing homes, for example), you're likely to receive plenty of vitamin D from sunlight. Other ingredients are often added, but they don't necessarily influence calcium absorption.
Safe levels and side effects
You're more likely to get too little than too much calcium from your diet. A total daily intake of 2000 mg is considered safe for healthy people. However, if you've had kidney stones in the past, you shouldn't take a calcium supplement without medical advice - consult your doctor. Large doses of the less readily absorbed calcium supplements can lead to constipation. Excess gas and bloating are also possible in some people. Changing the type of calcium supplement may help.
When to take it
If you take one calcium tablet per day, it's probably best taken with or just after your evening meal. After you've eaten the stomach generates more acid, which will help dissolve the tablet. An evening supplement provides calcium through the night when there's none coming from your diet, and your body is still losing calcium through your kidneys. If you take more than one calcium tablet per day, the dosage is best spread over the day to increase absorption.
Bone boosting tips
- Include at least 3 serves of dairy products in your diet each day. This could include milk on your cereal or as a smoothie, a tub of yoghurt and a piece of cheese.
- Snack on almonds during the day - not only will it boost your calcium intake but nuts have many other proven health benefits, including being good for your heart.
- Have a salmon sandwich for lunch a few times a week with salad.
- Choose calcium-enriched foods where possible.
- Stay active, with regular weight bearing exercise.
- Maintain a healthy weight, rather than aiming to be too thin.
- Limit the amount of salt you eat, particularly from highly salted processed foods.
- Don't smoke.
- Avoid too much alcohol.
- Consider a calcium supplement if it's not feasible to get the calcium you need from your diet.
- If you're a woman who is experiencing menopause, you may want to consider discussing hormone replacement therapy with your doctor.