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Almost all the calcium found in the body is stored in our bones and teeth; just one percent is found in our blood and other body tissues.
But how do we get the calcium we need, and how much do we need?
How The Body Gets Calcium
The best way to get calcium is to eat calcium-rich foods, including dairy products (milk, yogurt, cottage cheese), dark leafy greens (particularly spinach, kale, bok choy and morogo), broccoli, green peas, beans (like broad beans and black-eyed beans), avocado pears, salmon and sardines, oranges, sesame seeds, and almonds.
According to the Mayo Clinic, many people who appear to be eating a healthy and balanced diet don’t get enough calcium. They include:
- Vegans, because they don’t eat dairy products
- Those who have lactose intolerance or who limit their intake of dairy products
- Anyone who eats a lot of protein or sodium (salt) because this can result in the body excreting calcium
- People suffering from osteoporosis
- Those receiving corticosteroid treatment long term
- People with certain digestive or bowel diseases (including celiac and inflammatory bowel disease) that decrease the body’s ability to absorb calcium
These are the people who probably need to take calcium supplements, though the Clinic warns that it should be under the guidance or care of a doctor or dietician.
There are numerous calcium supplements available, many of which also contain vitamin D, which is vital for bone health as well, and which seems to work best when paired with calcium. Some supplements also contain magnesium, a mineral that is also essential for good bone health.
The two main types of calcium supplement are calcium carbonate (which contains 40 percent elemental calcium, the actual amount of the mineral contained in a unit) and citrate (which contains 21 percent.) The photograph on the next page shows 500 mg calcium carbonate supplement tablets.
When the body doesn’t get enough calcium, it has to rely on the calcium stored in the bones. When people under about 30 years are healthy, any calcium “borrowed” from the bones will be replaced at a later stage. But when people don’t get enough calcium, and don’t do enough exercise, this doesn’t always happen.
As a recent Harvard School of Public Health report states: While bone production is greater than “bone destruction,” until the age of about 30, thereafter the opposite is true. So it is perfectly normal for people to lose bone as they get older, even if they are taking the recommended amount of calcium every day.
The challenge is to maximize bone stores early in life, which will help to minimize osteoporosis and other low bone mass problems. However, even this won’t necessarily do anything to lessen the risks of fracture, particularly in later life as research has found (see next page.)
How Much Calcium Do We Need?
The Institute of Medicine’s National Academy of Sciences recommendations start at 200 mg for those up to six months rising to 1,200 for those over 70; 1,000 mg for ages 19-50 and pregnant or lactating women, and those from 4 to 8 years; and 1,200 mg for women aged 50 plus.
In some countries including Japan, India and Peru, the general daily intake of calcium is remarkably less than a third of the US recommendation, yet the recorded incidence of bone fractures is relatively low. Researchers at Harvard think this might be due to additional factors including the degree of physical activity people generally get as well as the amount of sunlight (and therefore vitamin D) they are exposed to.