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(Diane Labombarbe/iStockphoto)
(Diane Labombarbe/iStockphoto)

Leslie Beck

Can extra calcium hurt your heart? Add to ...

Last week, calcium supplements were called into question after a report concluded that regularly taking them might increase the risk of heart attack.

The report - a combined review of 11 studies conducted in the past 20 years - linked calcium supplements to a 30 per cent greater risk of heart attack, especially among people who also consumed high amounts of the mineral from their diet.

Based on their findings - and the fact that taking calcium only modestly reduces the risk of bone fracture - the study authors called for a reassessment of the role of calcium supplements in the prevention and treatment of osteoporosis.

Does this mean it's time to trade in your calcium pill for a glass of milk? It's too soon to say. Not one of the studies included in the analysis focused on heart attack or other cardiovascular events. The studies were designed to assess the relationship between calcium and bone health or colon polyps.

What's more, the researchers chose to exclude trials that gave participants calcium combined with vitamin D. The large U.S. Women's Health Initiative, for example, reported that calcium and vitamin D supplements had no effect on the risk of heart disease.

Vitamin D deficiency has been shown to boost the risk of heart disease and heart attack. The nutrient helps keep heart cells healthy, maintains normal blood pressure and reduces inflammation.

Interestingly, among the trials included in the analysis that did measure the vitamin D status of participants, two reported blood vitamin D levels considered insufficient. (The researchers are currently conducting further research that will look at vitamin D with calcium supplements. The findings are expected to be published later this year.)

Last week's findings certainly shouldn't dissuade you from meeting your daily calcium requirements.

An adequate intake of calcium - from food and supplements - has repeatedly been shown to preserve bone density in older adults. Studies have revealed that age-related bone loss is more pronounced when dietary calcium is low, which is the case for many Canadians.

A low calcium diet is a risk factor for osteoporosis, a silent disease characterized by low bone mass making bones fragile and more likely to break.

Adults aren't the only ones who need calcium for bone health. Adequate calcium is also vital for kids to build strong bones and teeth. In fact, our bones continue building mass until sometime in our twenties, when they stop and natural bone loss begins.

Getting enough calcium also helps keep blood pressure in check. Several studies have found that increasing calcium intake from food and supplements reduces blood pressure in people with and without hypertension.

Calcium-rich dairy products are key components of the DASH diet, an eating pattern proven to dramatically lower elevated blood pressure in people. (DASH stands for Dietary Approaches to Stop Hypertension.)

Research also suggests that getting enough calcium can lower the risk of colorectal cancer. Randomized controlled trials have shown calcium supplementation to reduce the recurrence of colorectal adenomas, polyps that can develop into cancer.

Studies in the lab have demonstrated the ability of calcium to slow the growth of - and kill - certain cancer cells. It's also thought that calcium, once it is consumed, binds to certain compounds in the intestinal tract, preventing their toxic effects on colon cells.

Meeting your daily calcium requirements is also an important strategy to prevent kidney stones made from calcium oxalate. Once consumed, calcium binds to oxalate, a natural compound found in foods, in the intestinal tract. This reduces the amount of oxalate that gets absorbed and makes its way to the urine where it can form stones.

So don't give up on calcium. It's very important to consume adequate - though not excessive - calcium to meet daily requirements. And if your diet falls short, a calcium supplement can bridge the gap.

Adults aged 19 to 50 need 1,000 milligrams of calcium per day. After age 50, Osteoporosis Canada advises a daily intake of 1,500 milligrams. Kids aged 9 to 13 require 1,300 milligrams of calcium each day; 4 to 8 year-olds need 800 milligrams and younger children should get 500 milligrams.

For most adults, these numbers translate into three or four dairy servings per day. One cup (250 ml) of milk or yogurt delivers roughly 300 milligrams of calcium, as does 1.5 ounces (45 grams) of hard cheese. Calcium-enriched beverages such as soy, rice and almond milk and orange juice also provide about 300 milligrams per 250 ml serving.

Cooked green vegetables, legumes, almonds, tofu and canned salmon with the bones also provide some calcium.

Food is the best source of calcium. If you're getting what you need from your diet, you don't need a calcium supplement.

But not everyone can meet their daily requirement from foods alone. If you do need to supplement your diet, choose a calcium product with vitamin D. (The Canadian Cancer Society advises a daily vitamin D intake of 1000 international units (IU), an amount that can't be obtained in the diet or from sunlight in the fall and winter.)

If you need to take more than 500 milligrams from a supplement, divide your dose over two or three meals. (The amount of calcium your body absorbs decreases as the dose in a supplement increases.)

For women and children over one year, the safe upper daily limit for calcium is 2,500 milligrams. An excessive calcium intake can cause elevated blood levels of calcium, impaired kidney function and decreased absorption of other minerals.

Keep in mind the study reported last week found no increased risk of heart attack among supplement users who consumed less than 800 milligrams of calcium from their diet.

Leslie Beck, a Toronto-based dietitian at the Medcan Clinic, is on CTV's Canada AM every Wednesday. Her website is lesliebeck.com.

Follow on Twitter: @lesliebeckrd

 

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