Flawed Calcium and Heart Attack Study Misleads Consumers

On July 29, 2010, the British Medical Journal ^[1] published a flawed study of the usage of calcium supplements and associated risk of heart attack ^[2]. The study misleadingly concluded that use of calcium supplements increases the risk of heart attacks by 27% and has no significant effect on overall mortality. The authors advise that the use of calcium supplements in treating or preventing osteoporosis should be reconsidered. Some in the media are broadcasting this study as a reason to stop using calcium supplements.

Please don’t stop your calcium supplements before reading more about the serious flaws in this study!

A major problem with this study is that it excluded people taking vitamin D, magnesium, and other common ingredients in bone protection products. As a result, the study participants generally had low levels of nutrients that are associated with lower risk of diseases such as atherosclerosis and cardiovascular disease and are directly tied how calcium is used in the body. These nutrients all work together to keep calcium in the bones where it belongs, rather than building up calcium deposits in the vascular system and heart that can contribute to cardiovascular disease and heart attacks.

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Vitamin D Deficiency

The study participants had low levels of vitamin D from about 18.0 ng/mL to 37.2 ng/mL. These levels are all below generally accepted optimal levels for vitamin D around 50 ng/mL to 80 ng/mL. They are also below the levels of approximately 39 ng/mL to 45 ng/mL associated with a 25% to 50% reduction in fractures ^[5]. (This reduction is computed compared to 25 ng/mL as a reference level.)

Adjusting vitamin D to optimal levels ^[6] nearly always requires supplementation and testing. That’s because individuals respond to vitamin D levels in widely varying fashions. Some people attain optimal levels with 1000 IU per day of vitamin D3, others can take 10,000 IU or more per day and still not achieve optimal levels.

Effects of Magnesium

Magnesium has the effect of a calcium channel blocker, helping to keep calcium from building up in the arteries. It also helps prevent diabetes and related blood sugar and lipid problems, conditions which are believed to contribute to cardiovascular disease including heart attacks.

(from Magnesium: Widespread Deficiency with Deadly Consequences ^[7])

The benefits of magnesium for cardiovascular health are already extraordinary, given its protective role against metabolic syndrome and diabetes, two major factors that threaten heart and vascular health. But its heart-healthy benefits do not end there—research reveals that magnesium may offer a wealth of other cardiovascular benefits.

For example, the Honolulu Heart Program tracked the relationship between magnesium intake and the incidence of illness and death from coronary heart disease among Japanese men living in Hawaii. After adjustment for numerous cardiovascular disease risk factors, a lower level of magnesium intake increased the risk of coronary heart disease by 50-80%.

Low levels of magnesium are also believed to adversely affect some of the functions of vitamin D.

Magnesium deficiency is believed to be more common in the United States than in some nations because bottled water commonly sold in the US has generally had its magnesium content removed.

(from Is Your Bottled Water Killing You? ^[8])

The present-day enthusiasm for bottled water has further compounded the problem. Americans consumed nearly 8 billion gallons of bottled water last year. The mineral content of these products varies widely. While some mineral waters, particularly those from Europe, contain a moderate amount of magnesium, other brands of bottled water contain little or none.

The upshot of all this is that we cannot rely on drinking water to provide adequate magnesium. The recommended dietary allowance (RDA) for magnesium—that is, the amount required to prevent severe deficiency—is 420 mg a day for men and 320 mg a day for women. In cities with the highest magnesium water content, only 30% of the RDA can be obtained by drinking two liters of tap water a day. In most cities, only a meager 10-20% of the daily requirement can be obtained. That leaves 70–90% of the daily magnesium requirement that must be obtained from other sources. Since many people’s diets are also low in magnesium, the average American ingests substantially less magnesium than the RDA.

Detecting anything less than a severe magnesium deficiency may be difficult. The human body will deplete its magnesium reserves in bones to keep the magnesium level in blood steady. So you can be suffering from low magnesium levels potentially for years, with your body losing bone integrity, yet the deficiency may not show up in common blood tests.

(from Magnesium: Widespread Deficiency with Deadly Consequences ^[7])

A recent study in animals found that magnesium is so crucial to proper bone growth and development that a 50% reduction in dietary magnesium significantly disrupted bone and mineral metabolism. Interestingly, while serum magnesium levels remained constant, there was a significant reduction in bone mineral content.

Fortunately, correcting a magnesium deficiency is relatively easy by adding inexpensive magnesium supplements or increasing the consumption of certain foods.

(from Magnesium: Widespread Deficiency with Deadly Consequences ^[7])

Dr. Altura says that the best way to correct magnesium deficiency is through diet, especially since many of the foods high in magnesium, such as nuts, dark leafy green vegetables, legumes, whole grains, and some fish, are part of an overall healthy diet. “Any fish that is high in omega-3 fatty acids is also high in magnesium,” he says. Water can also be a source of magnesium but the amount varies wildly depending on the water supply. Since so much of the food Americans consume is processed, which depletes it of its mineral and vitamin content, magnesium is hard to replenish entirely through diet (cooking also removes magnesium from foods). Magnesium supplements may be needed to help fill this void. While the recommended daily allowance of magnesium is 420 mg/day for men and 320 day/women,34 many health experts now advise that adults consume at least 500 mg each day.

If you have kidney problems, you need to be more careful with magnesium supplementation because your kidneys may be unable to remove any excess magnesium.

Effects of Vitamin K

Other nutrients, such as vitamin K, are also commonly deficient in many people. Vitamin K is needed for producing osteocalcin which is responsible for retention of calcium in bones and keeping it out of the vascular system where it can calcify inside arteries, veins, and the heart. Too little osteocalcin may increase the risks for heart attacks and cardiovascular diseases.

Many people do not get enough vitamin K in their diets. Some of the dark leafy green vegetables that tend to have a lot of magnesium are also relatively rich sources of vitamin K1. Some examples of food high in vitamin K include kale, collards, spinach, turnip greens, mustard greens, green leaf lettuce, broccoli, green onions, parsley, asparagus, Brussel sprouts, and cabbage. Unfortunately, the vitamin K1 form common in vegetables is not nearly as effective as the more expensive Vitamin K2 MK4 and MK7 forms produced by bacteria and found in certain dietary supplements.

If you’re taking the common drug warfarin, also called Coumadin, please realize that it is a vitamin K antagonist. It will impair your body’s ability to generate osteocalcin. Conventional doctors today often advise patients taking warfarin to prevent dangerous internal blood clots to avoid eating many vitamin K rich foods so as to keep their blood clotting more consistent as it is also influenced by vitamin K. Unfortunately, warfarin dosing is highly dependent upon diet. It may be a better strategy to supplement with a consistent amount of vitamin K per day and adjust the warfarin dosage upwards or try alternatives such as high dosage fish oil, vitamin E, proteolytics such as bromelain, nattokinase, and serrapeptase to achieve reduced risk of dangerous blood clots while not subjecting yourself to the very much increased risk of arterial calcification caused by warfarin. Ironically, over the long-term, warfarin-induced calcification of the vascular system could increase the risk of a dangerous blood clot because it can cause even smaller clots to block blood vessels and turn into much larger clots.

Better Analysis Requires More Than One Nutrient

It’s reasonably clear that calcium, vitamin D, vitamin K, and magnesium all work together affecting similar organs and biochemical processes. The attempt made to determine the effect of one nutrient, calcium, while the other three were likely deficient in many of the study participants has yielded results that cannot be reliably generalized to people who have adequate levels of all of these nutrients. It is very likely that if this study was repeated in participants who have adequate levels of all four of these nutrients that the results would be far different.

Combining Multiple Nutrients With Testing May Yield Much Better Results

I suggest that you should not stop taking calcium supplements based solely upon this study. If you review the links in this article and in the further reading section below, I think you’ll be reasonably convinced that getting adequate intake of calcium, magnesium, vitamin D, and vitamin K together will likely produce far better effects than taking calcium alone. In you have limited time, I suggest the most important additional reading you can do on this topic is the article Flawed Analysis Misleads Public About Calcium and Heart Attack Risk ^[9].

None of these supplements are expensive. Testing can be used to help confirm you are getting the appropriate levels of each nutrient.

A common CBC test will show you your blood calcium level. You’ve probably already had one recently as it is among the most common blood tests ordered by doctors.

Many CBC tests also include indicators for kidney function, letting you understand if you might be at risk for kidney impairment that could make magnesium supplements more dangerous. If you have impaired kidney function, you should be more careful about magnesium supplementation. Red blood cell (RBC) magnesium may be a more reliable indicator for magnesium levels than blood serum magnesium, but either of these tests may be unable to detect anything less than a severe magnesium deficiency. If you don’t have a kidney impairment or other reason to be in danger of getting too much magnesium, you may be best off adding around 400mg to 500mg of magnesium per day, taken with food to avoid digestive side effects, and periodically recheck your test results.

Vitamin K testing may be a bit more tricky. Direct testing of vitamin K levels may not be as useful as osteocalcin test that measures the osteocalcin protein in the body that keeps calcium out of the arteries and in the bones. Osteocalcin also appears to affect metabolism by causing the pancreas release more insulin and for fat cells to release the insulin sensitizing hormone adiponectin that may help reduce the insulin resistance associated with type 2 diabetes. This means that low osteocalcin levels might contribute to obesity, diabetes, and metabolic syndromes, all conditions that increase cardiovascular disease risk.

If you don’t have enough osteocalcin, you probably need to add more vitamin K to your diet via a combination of vegetables and supplements. Vitamin K2 MK4 and MK7 forms are generally regarded as being far more effective than vitamin K1 supplements.

If you have a limited budget, probably the most useful test related to the supplements I’ve mentioned is for blood serum vitamin D. That’s because it appears there is higher risk of vitamin D deficiency even with supplementation. Further, there is a very high degree of variability to vitamin D supplements that makes it effectively impossible to know if you’re getting an adequate amount without risking overdoing it unless you get tested. As a relatively extreme case, I personally know of one man taking about 13,000 IU per day of vitamin D3 supplements who only tests at 44 ng/mL, still below the lower end of the optimal 50 ng/mL to 80 ng/mL range. While he hasn’t worked out exactly how much vitamin D3 he’ll need to get his test into the middle of the optimal range yet, it is possible it could be even 20,000 IU per day or more. Considering that the RDA for vitamin D3 is only 400 IU, it is clear that there may be vast differences between the levels of vitamin D people are getting versus what they need for optimal health.

This more holistic approach of combining complementary supplements and testing, rather than simply supplementing calcium alone, is likely to lead to much better results both for those wanting to avoid osteoporosis and cardiovascular disease.

Further Reading

Flawed Analysis Misleads Public About Calcium and Heart Attack Risk ^[9]

Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis ^[2]

Calcium supplements in people with osteoporosis ^[10]

Higher Vitamin D Levels Improve Weight Loss and Health ^[11]

Adjusting Your Vitamin D Intake to Optimal Levels ^[6]

Vitamin D Supplementation: Helpful or Hazardous?

Selecting An Omega-3 Fat or Fish Oil Supplement ^[12]

Vitamin D May Help Fight Asthma And Flu ^[13]

Low Vitamin D Common in African-American Asthma Kids ^[14]

Disease Incident Prevention by Serum 25(OH)D Level ^[5]

A new link between skeleton, obesity and insulin resistance: relationships between osteocalcin, leptin and insulin resistance in obese children before and after weight loss ^[15]

Linus Pauling Institute: Vitamin D ^[16]

Linus Pauling Institute: Vitamin K ^[17]

Linus Pauling Institute: Magnesium ^[18]

Linus Pauling Institute: Calcium ^[19]

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These statements have not been evaluated by the Food and Drug Administration. The products mentioned in this post are not intended to diagnose, treat, cure or prevent any disease.