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Calcium… not just for bones
We have more calcium in our bodies than any other mineral, mostly in bones and teeth. You know how important it is for strong bones but you may not know that it’s equally important for strong muscles and a healthy nervous system. Your bones will suffer if your blood levels get too low because your body takes calcium out of your bones to keep your nerves, heart and muscles working. This is a sensible survival mechanism - you can live with weak bones but you’ll die immediately if your heart can’t function.
How much do you need?
Recommended daily intake of calcium
Calcium (mg)
Children & adolescents
1-3 yrs 500
4-8 yrs 700
9-13 yrs 1,000-1,300
14-18 yrs 1,300
Women
19-50 yrs 1,000
51+ yrs 1,300
Pregnancy & lactation
14-18 yrs 1,300
19+ yrs 1.000
Men
19-70 yrs 1.000
71+ yrs 1,300
Source: Commonwealth of Australia Dept. of Health & Ageing, NHMRC, NZ Government Ministry of Health. Nutrient Reference Values for Australia & New Zealand. C’wealth of Aust. 2006
The Australian and New Zealand governments have recently updated the recommended daily intakes and it’s surprising how much the experts say we need, even at quite a young age.
Who is likely to need more calcium?
Children & adolescents - to support growth
Postmenopausal women & elderly people - to make up for increased losses from bones
What about pregnant women?
Although we used to believe that a pregnant woman needs a lot more calcium to support the baby’s bone growth, her ability to absorb calcium increases dramatically so an increase in intake isn’t normally needed.
Our fragile bones - the impact of the osteoporosis epidemic
Osteoporosis (porous bones) is the hard-to-detect progressive loss of bone minerals that weakens bones and leads to bone pain and fractures, usually occurring after menopause and in older age. Crush fractures in the spine are common, in which the vertebrae collapse down, causing pain, curvature of the upper spine and loss of height.
Check your risk of osteoporosis.
Do the following apply to you?
a history of bone fractures from relatively minor injuries
a family history of osteoporosis
no regular weight-bearing exercise
a low intake of dairy or other high calcium foods
post-menopausal or aged over 60
smoker
high coffee or alcohol intake
By the time you are diagnosed it is usually fairly advanced; your first warning sign may, in fact, be a fracture. A hip fracture in old age is particularly serious as recovery is slow and you can have permanent loss of mobility and increased mortality risk.
Osteoporosis affects 2 million Australians and 1 in 2 women and 1 in 3 men aged over 60 years will have a fracture due to osteoporosis, about half of these affecting the spine.1 Prevention is the best way to reduce your risk of this painful and disabling condition.
Look after your bones
Good bone health starts early. Bones develop rapidly during the growth spurt that occurs at puberty and children in the 9-13 year age group can need as much as menopausal women. Bones can be built up in childhood and early adulthood but, after that, bone breakdown tends to balance bone building so it’s harder to accumulate new bone. After menopause and in older age, bone breakdown may exceed bone building and your bones gradually weaken.
The best way to keep your bones strong is to build a healthy bone ‘bank’ by depositing a lot of calcium early in life so that the withdrawals that accompany ageing don’t diminish your bone bank balance to the point of causing fractures.
Is it ever too late to rebuild your bones?
Just increasing your calcium intake may not be enough to strengthen your bones when you are older, especially if you are a woman past menopause when declining oestrogen levels reduce your ability to absorb it. Calcium in bones is in the form of calcium phosphate, also called hydroxyapatite, and magnesium is also part of bone structure so these minerals are all important for healthy bones. Most average diets are high in phosphate but both calcium and magnesium are often inadequate. You also need to make sure that the calcium you take in is absorbed and used efficiently. Vitamin D, formed from sunshine on your skin, is important because it can increase calcium absorption from your diet, reduce losses in urine and help mobilise it from bones to supply your nerves and muscles. Magnesium and boron help maintain calcium levels and vitamin K makes the specialised proteins in bone that hold calcium. Vitamin C, zinc and manganese help build strong connective tissue that gives your bones flexibility and resilience.
It’s hard to tell if your bones are losing calcium.
Check yourself for these other indications that your calcium intake may need a boost…
muscle cramps, spasms, twitches
muscle weakness, muscle pain, loss of balance
nervous tension, irritability, anxiety, insomnia - you will have a shorter fuse if calcium is low and you will find it harder to relax
indigestion - because of nervous tension that makes you eat too quickly, fail to chew thoroughly and swallow air with your food
weak, brittle fingernails
tooth decay, gum disease
menopausal symptoms
Can supplements really help?
The latest review of calcium supplements has concluded that they don’t work for fracture prevention.2 However, this seems to be because many people in the studies didn’t take them regularly. When they looked at those who did, there was a benefit. Why didn’t people keep taking their supplements? The answer may be that most studies use high-dose calcium carbonate, a type of calcium that can cause bowel upsets. Calcium citrate and hydroxyapatite are better choices if you have a sensitive digestive system.
Many studies have shown that calcium and vitamin D supplements used together are effective for improving bone density and Australian researchers have recently recommended daily supplements containing 1,200mg of calcium and 800 IU vitamin D for all people aged over 60 years to prevent hip fractures.3 In a study of elderly women, average age 84 years, loss of bone minerals stopped, their hip bone density increased by nearly 3% and they had a 43% lower risk of hip fractures when they took daily supplements of 1,200mg calcium and 800 IU vitamin D3 (natural vitamin D) for eighteen months.4 Even more interesting, the risk of hip fractures reduced almost straight away, well before their bones showed improvements in mineral density.
References
1. Jean Hailes Foundation for Women’s Health. Bone health for life. Available at: www.bonehealthforlife.org.au
2. Calcium intake and hip fracture risk in men and women: a meta-analysis of prospective cohort studies and randomized controlled trials. Am J Clin Nutr. 2007 Dec;86(6):1780-1790.
3. Tang BM et al. Use of calcium or calcium in combination with vitamin D supplementation to prevent fractures and bone loss in people aged 50 years and older: a meta-analysis. Lancet. 2007 Aug 25;370(9588):657-66.
4. Chapuy MC et al. Vitamin D3 and calcium to prevent hip fractures in the elderly women.N Engl J Med. 1992 Dec 3;327(23):1637-42.
Boosting your vitamin D
Sunlight on bare skin is the best way to make your own vitamin D. But you don’t have to risk sunburn. Ten to fifteen minutes of sun exposure to face, hands, arms, legs or back without sunscreen at least twice a week is generally enough to produce adequate vitamin D in summer. In winter, your body uses stores accumulated in summer. Foods are generally low in vitamin D except for organ meats like liver but these are not recommended in large quantities because of the saturated fat and high vitamin A content. Supplements can help if you can’t get in the sun regularly and if you are older because your ability to make vitamin D declines with age.
The fitness factor
Physical exercise consisting of one hour of moderate activity three times a week has been shown to help prevent bone loss and increase bone mass in postmenopausal women. Walking, jogging and cycling are all helpful but include some weight training to strengthen muscles and bones. Consult your health care practitioner before commencing an exercise program.
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