Calcium: Bone’s biggest booster

Calcium is the most plentiful mineral in the human body. It’s found in every cell, most abundantly in the bones of the skeleton, which are a calcium reservoir, harbouring 99 per cent of our entire supply. Calcium plays a big role in building healthy bones and teeth, but it’s essential to just about every part of the body; among other things, it plays a role in blood clotting, helps maintain normal heartbeat and blood pressure, and keeps the nervous system functioning.

Calcium comes entirely from dietary sources, but most of us don’t get enough. The Osteoporosis Society of Canada recommends that, if possible, you meet your calcium requirements from food sources alone, rather than with supplements, because a healthy variety of foods will provide other important nutrients, as well. Milk products, for instance, are an important calcium source, but they also supply vitamin A, phosphorus and magnesium, which contribute to healthy bones, and milk is the top dietary source of vitamin D. If, however, you’re lactose intolerant, or if for any other reason high calcium foods aren’t on your menu, you may have to take a supplement.

To find out where you stand, calculate how much calum you’re already getting in your diet. Girls 10 16 need 1,200 1,400 mg daily; 17 and 18 year olds should have 1,200 mg daily; women between 19 49 need at least 1,000 mg of calcium daily; and women over 50 need 1,000 1,500 mg daily. If you’re washing down a Swiss cheese sandwich and a handful of figs with a litre of milk every day, you’re probably already exceeding your daily calcium requirement. If your numbers don’t add up, consider a supplement.

^Calcium supplements come in tablets, caplets, liquids, chewable and even effervescent tablets; be advised, though, that there’s a big difference in prices and formulations. The most important thing to look for is the amount of elemental calcium per tablet. For instance, only about 40 per cent of a calcium carbonate tablet – the most popular compound – is actually calcium, so a 1,250 mg tablet contains only 500 mg of calcium. Read the label carefully, or ask your pharmacist for advice.

Calcium carbonate (the main ingredient in antacids like Tums and Rolaids) is refined from natural elements, such as limestone, or shell sources, most often oyster. If you find you can’t tolerate calcium carbonate – some people suffer stomach upset, constipation or nausea – try another formulation.

Calcium citrate is the most popular option, though it contains proportionately less calcium (about 200 mg in a 950 mg preparation). Its big advantage is that, unlike calcium carbonate, which should be taken with meals for best absorption, calcium citrate is absorbed at any time, with or without food, though it’s always a good idea to take calcium with a glass of water.

Other formulations include calcium glucoheptonate and calcium gluconate, plus calcium combined with other minerals, such as magnesium, which helps build bone; some experts believe it also aids in calcium absorption. Such combinations, of course, carry a higher price tag. Watch out for formulations made from dolomite or bone meal; they have a higher lead content. Your best bet is to look for a D.I.N. (Drug Identification Number) on the bottle, which means it’s been approved as a drug by the Health Protection Branch of Health Canada, or a U.S.P. (United States Pharmacopoeia) number, which indicates the product meets American standards.

For best absorption of any calcium supplement, take two or more smaller doses throughout the day rather than a single 1,000 mg tablet. Get plenty of regular exercise, and watch your diet: Doubling your protein intake will increase your urinary calcium output by 50 per cent, which means excess protein makes you lose calcium. So do large quantities of caffeine, alcohol and laxatives.

A final note: While it’s best to maximize your calcium contributions to the bone bank early in life, studies have shown that calcium can have positive effects on bone density even very late in life, so keep it coming. Bone has more than a supporting role to play in the body.