Calcium, vitamin D and heart disease. What’s the 4-11?

Posted by on May 2, 2011 in bone health, heart disease | 5 comments

“Calcium supplements cause heart attacks in postmenopausal women.”

Whoa! What?!

If you saw the headlines last week, you may be wondering what’s up with calcium supplementation. Afterall, don’t medical professionals advise the use of supplements to stave off bone loss associated with osteoporosis? And as a result, the Centers for Disease Control reports that over 50% of adults currently use calcium supplements and more than 60% of women over age 60.

It’s important to get away from the sensational headline and take a closer look at what the research shows and what you need to know.

Previous studies have suggested that there may be a link between use of calcium supplements (without vitamin D) and heart attack; in fact, as Reuters‘ reported last year, calcium supplements were shown to increase the risk of heart attack by as much as 31%, possibly as a result of plaque formation in blood vessels. However, is the risk the same if calcium is used alone versus if it is used in conjunction with vitamin D?  In the Women’s Health Initiative study, the use of calcium and vitamin D did not appear to influence heart disease risk at all.

However, researchers decided to take another look at the data because they say that in this trial, more than half of participants were taking ‘personal calcium’ (i.e. not regulated or standardized to all trial participants) and almost half were also adding Vitamin D.

In this reanalysis, published just last week in the British Medical Journal, the researchers discounted the women who were characterized as personal users of calcium supplements and instead, limited their evaluation to a group of women who were not using personal calcium supplements at the study’s start and previously unpublished data from the trial. The findings? The use of calcium with or without vitamin D appeared to cause a 25% to 30% increase in the risk for heart attack and a 15% to 20% increased risk for stroke. However, the researchers say that even small increases in the incidence in heart disease may manifest substantially, especially in the elderly. They add that if you take a look at the risk-benefit ratio, it is unfavourable, meaning that taking calcium with or without vitamin D for five years would cause twice as many heart attacks or strokes than then numbers of fractures that would be prevented.  Additionally, the data analysis suggests that dosing is not a factor, and that the total amount of calcium taken daily is less important than the abrupt changes in blood calcium levels immediately following supplementation.

Although this research answers a few questions about potential risks about calcium supplementation, it also leaves a key question unanswered:  how does the addition of magnesium and vitamin K, which are often included in commercially-available calcium supplements, affect these findings? Data suggest that these minerals and vitamins are added to keep calcium in the bones where it belongs and out the arteries where it does not.

The best guideline, as always, is to visit a physician to assess your bone health and come up with a plan that works specifically for you. Although calcium supplementation appears to be risky, more data are needed before leading organizations start to change their tune about calcium and bone health. Meanwhile, stay ahead of the headlines and try to focus on increasing the amount of calcium-rich foods in your diet:

Table 2: Selected Food Sources of Calcium [Source: National Institutes of Health]
Food Milligrams (mg)
per serving
Percent DV*
Yogurt, plain, low fat, 8 ounces 415 42
Sardines, canned in oil, with bones, 3 ounces 324 32
Cheddar cheese, 1.5 ounces 306 31
Milk, nonfat, 8 ounces 302 30
Milk, reduced-fat (2% milk fat), 8 ounces 297 30
Milk, lactose-reduced, 8 ounces** 285–302 29–30
Milk, whole (3.25% milk fat), 8 ounces 291 29
Milk, buttermilk, 8 ounces 285 29
Mozzarella, part skim, 1.5 ounces 275 28
Yogurt, fruit, low fat, 8 ounces 245–384 25–38
Orange juice, calcium-fortified, 6 ounces 200–260 20–26
Tofu, firm, made with calcium sulfate, ½ cup*** 204 20
Salmon, pink, canned, solids with bone, 3 ounces 181 18
Pudding, chocolate, instant, made with 2% milk, ½ cup 153 15
Cottage cheese, 1% milk fat, 1 cup unpacked 138 14
Tofu, soft, made with calcium sulfate, ½ cup*** 138 14
Spinach, cooked, ½ cup 120 12
Ready-to-eat cereal, calcium-fortified, 1 cup 100–1,000 10–100
Instant breakfast drink, various flavors and brands, powder prepared with water, 8 ounces 105–250 10–25
Frozen yogurt, vanilla, soft serve, ½ cup 103 10
Turnip greens, boiled, ½ cup 99 10
Kale, cooked, 1 cup 94 9
Kale, raw, 1 cup 90 9
Ice cream, vanilla, ½ cup 85 8.5
Soy beverage, calcium-fortified, 8 ounces 80–500 8–50
Chinese cabbage, raw, 1 cup 74 7
Tortilla, corn, ready-to-bake/fry, 1 medium 42 4
Tortilla, flour, ready-to-bake/fry, one 6″ diameter 37 4
Sour cream, reduced fat, cultured, 2 tablespoons 32 3
Bread, white, 1 ounce 31 3
Broccoli, raw, ½ cup 21 2
Bread, whole-wheat, 1 slice 20 2
Cheese, cream, regular, 1 tablespoon 12 1

* DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration to help consumers compare the nutrient contents among products within the context of a total daily diet. The DV for calcium is 1,000 mg for adults and children aged 4 years and older. Foods providing 20% of more of the DV are considered to be high sources of a nutrient, but foods providing lower percentages of the DV also contribute to a healthful diet. The U.S. Department of Agriculture’s Nutrient Database Web site lists the nutrient content of many foods. It also provides a comprehensive list of foods containing calcium.
** Calcium content varies slightly by fat content; the more fat, the less calcium the food contains.
*** Calcium content is for tofu processed with a calcium salt. Tofu processed with other salts does not provide significant amounts of calcium.

5 Comments

  1. 5-2-2011

    We very much agree here (http://womensvoicesforchange.org/do-we-really-need-calcium-vitamin-d-supplements.htm), but also it’s important that these new guidelines serve as a launching pad for more rigorous research studies.

  2. 5-2-2011

    Working with your doc is the key here. Remember to always always ask lots of questions, b/c there are options. This video was helpful for me: http://whatstherealcost.org/video.php?post=five-questions

    • 5-4-2011

      Thanks so much Susan!

  3. 5-2-2011

    Thanks for putting this together! The calcium/bone density/heart risk discussion is a perfect example of why “one size fits all” strategies aren’t always sensible. I spoke with my Gyn about this when the studies first started cropping up — and, after discussing my regular eating habits — came up with a “calcium intake” plan that I am comfortable with (and this chart makes it even easier to follow!!!)

    • 5-4-2011

      The key thing in your comment Laura is that you and your gyn came up with a calcium intake plan. That’s great! Thanks for sharing!

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