DR MARGA BOYANI explains why we need a constant supply of calcium throughout our lives
Calcium is the most abundant mineral in your body. Of this, 99 per cent is in the bones and teeth and one per cent in the blood, muscles and other soft tissues.
Every cell in the body uses calcium. It keeps bones and teeth strong, maintains normal nerve and muscle function, regulates the heart’s rhythm and is necessary for blood clotting.
The body gets the calcium it needs in two ways: Through food such as milk, which has one of the highest concentrations per serving, or by ‘borrowing’ it from the bones. Throughout your lifetime, calcium is ‘deposited’ in and ‘withdrawn’ from the bone bank depending on your needs.
If you are a healthy adult, you lose 500 milligrams of calcium from your bones every day to maintain a precise level of calcium in the blood at all times.
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At that rate, it would not take long for your bones to become powder if you do not replace this calcium back every day. That is why you need a constant supply of calcium throughout your life.
The amount you need depends on your age. You need a lot of calcium during your growing years to build strong bones, a little less in the middle years to keep your bones strong, and much more later in life to prevent bone loss.
Building and maintaining strong bones depends on calcium, vitamin D and physical activity as exercise keeps calcium in bones.
Recommended amount of calcium for women
• Ages 19 to 50, pregnant or not — 1,000mg per day.
• Teenage girls up to age 18 — 1,300mg daily.
• Post-menopausal women — 1,500mg per day.
For bone health, vitamin D is no less important than calcium because it is used to transport calcium to your bones. When blood levels of calcium drop, vitamin D travels to the intestines to encourage more calcium absorption and to the kidneys to minimise calcium loss in the urine.
Vitamin D is called the ‘sunshine vitamin’ because your body can make its own in the skin from the sun. Foods such as milk and eggs also contain vitamin D.
For fair skinned individuals, 15 minutes of sunlight will produce enough Vitamin D to last for several days, even when wearing light clothing. It takes a little longer for this to happen with dark-skinned people. Vitamin D is also present in fish, fortified milk and some cereals.
Do you need to take calcium supplements?
Though calcium supplements do have their place, food is the best source of calcium because it provides other important nutrients.
Three glasses of milk provide about 900mg of elemental calcium. Elemental calcium is the actual amount of calcium available to your body.
When your dietary calcium intake is too low, your body will ‘withdraw’ the calcium it needs from your bones. Over time, if more calcium is taken out of your bones than is put in, the result is thin, weak bones that break easily. If this continues, you develop osteoporosis.
Increasing calcium in your diet
• Add cheese to salads and milk to casseroles and soups.
• Use skimmed milk, which has a higher content of calcium than full-fat milk.
• Try and get most of your protein from plants rather than from animal protein because as your body digests these proteins, it releases acids into the bloodstream, which have to be neutralised by drawing calcium from the bones. This is then flushed out in urine.
• Avoid excess salt because the sodium in salt greatly increases calcium loss through the kidneys into urine.
• Do not smoke to avoid losing calcium.
• Keep caffeine to not more than four cups a day.
• Get enough vitamin A because it directs the process of borrowing and redepositing calcium in the bones.
• A sunscreen lotion of 8 SPF or higher prevents the formation of vitamin D in the skin so if you’re fair-skinned, wait 15 minutes before applying sunscreen lotion when sun bathing.
