What does calcium do?
This key mineral does much more than keep your teeth and bones strong. Dietician Carrie Ruxton gives the lowdown
What is it?
Calcium is the most abundant mineral in our bodies, making up around 2% of our body weight. It’s mostly stored in bones and teeth, where it acts as natural scaffolding. But this mineral is also vital for muscle contractions, protein metabolism, blood pressure and clotting, and nervous function. If levels in the blood are too low, our bones are ‘raided’ to make up the deficit. This is why we need to keep it topped up. Teenagers and women often have poor calcium intake. Experts think this may be because they’re more likely to skip breakfast (which often contains milk). Worryingly, one in five teen girls don’t get enough, putting them at risk of low bone density.
What is it good for?
LOWER CANCER RISK
There is evidence calcium protects against some cancers, particularly colon and breast. Cancer Research UK says ‘several studies show a lower risk of breast cancer for women with high calcium intake or blood levels’. One such study, of nearly 50,000 Norwegian women, found those who drank milk as both children and adults had a lower risk of developing breast cancer. And in a Korean study, those with higher intake were 16% less likely to develop colon cancer.
STRONG BONES AND TEETH
By our early 20s, 90% of our bone mass has been laid down, so our childhood diet is crucial. You build bone density by eating plenty of calcium-rich foods, alongside vitamin D, which helps calcium absorption and transportation into bones. Later in life, bone mass declines due to hormonal changes, and a good calcium intake can mean the difference between healthy and fragile bones. Researchers reviewed 22 trials: in 16, combining calcium and vitamin D improved bone density. Calcium also combines with phosphate to make hydroxyapatite, the hard substance in teeth. Again, these nutrients are vital in early life as teeth form in the womb. In one study, by age 12, children whose mothers took calcium in pregnancy had a 27% reduced risk of tooth decay compared to those whose mothers took a dummy pill.
Studies show that a higher calcium intake (usually via low-fat dairy) may help reduce ‘bad’ LDL cholesterol levels. It may also have a beneficial impact on blood pressure, which reduces risk of coronary heart disease. Babies of pregnant women who consume calcium have been found to have healthy blood pressure in later life.
How do I get it?
Rich sources include dairy, green leafy vegetables, fortified plant milks and canned fish containing bones, such as sardines. Or try supplements, usually around 800mg to 1200mg per dose. If you’re taking calcium to help preserve bone mass, combine with vitamin D (10-25mcg daily) for optimal absorption.
How much do I need daily?
Teen boys should have 1000mg a day, teen girls need 800mg. Younger children should have 350-525mg; adult men and women 700mg. Breast-feeding women should get 1250mg, as making milk depletes levels.