Calcium is one of the most well-known but misunderstood minerals. It is added to everything from cereal to orange juice, yet there is a lot of evidence that supplements are not effective and may even be harmful…
Calcium Supplements: The Problem
There are several supplements that I personally take daily, even when eating a very high-quality real food diet because it is difficult to get enough of these nutrients from our modern food supply.
Calcium is naturally found in dairy products and is often added to dairy and dairy-substitutes. Calcium is also added to many processed foods, cereals, breads and juices. Many people also take calcium supplements, especially during pregnancy and post-menopause, but recent research calls this practice into question.
Like so many other nutrients, Calcium needs cofactors (other vitamins and minerals) to be absorbed. Without these, calcium supplements are not bioavailable and may be harmful.
A 2012 study published in the British Medical Journal showed that those who took calcium supplements had a 139% higher risk of heart attack, though this increased risk was not present when the same amount of calcium was consumed from whole food sources. (1)
Other studies have shown the same correlation:
- A 2010 meta-analysis showed that calcium supplementation increased the risk of stroke, heart attack and death from all causes (2)
- A study published in JAMA in 2013 showed that supplementation in excess of 1,000mg/day was associated with a 20% increase in risk of death from cardiovascular disease. (3)
- Other studies, like a recent one published in the American Journal of Clinical Nutrition showed that calcium supplementation increased risk of kidney stones and prostate cancer (4)
- Chris Kresser showed that this risk is even higher in women “Additionally, a recent Swedish study reported a 40% higher risk of death among women with high calcium intakes (1400 mg and above), and a 157% higher risk of death if those women were taking a 500 mg supplement daily, compared to women with moderate daily calcium intakes (600-1000 mg).” (5)
So why does it appear that calcium supplementation can increase the risk of heart related problems?
Two possible reasons…
- Researchers speculate that when supplemental calcium is taken, it cannot all be absorbed and the excess is left circulating in the blood, which can lead to calcification in the arteries, or is excreted in urine, which may lead to kidney stones.
- It is very difficult for the body to absorb many forms of calcium, especially when they are taken alone, as it needs cofactors like Vitamin K2, Magnesium and Vitamin D to be properly utilized.
Calcium for Bone Health?
But, what about bone health? Turns out, calcium supplements aren’t the silver bullet for bone health either…
A 2012 study showed that supplemental calcium (above the recommended amount from food) did not increase bone density or reduce fracture rate. (6)
In fact, in 2013, the United States Preventative Services Task Force reviewed 135 studies on calcium and rate of fractures and recommended that post-menopausal women STOP taking supplemental calcium. (7)
Food sources of calcium (like dairy, bone-in meats and certain types of fish) were shown to be beneficial for bone health without the increased risk of cardiovascular and other problems.
Dairy is the most recommended dietary source, but there are some confounding factors. Numerous studies in several countries have shown that dairy consumption reduced the risk of osteoporosis, hypertension and other problems associated with these diseases. (8,9,10)
Some in the natural health community claim that dairy is actually bad for bones because dairy products acidify the body, causing it to pull calcium from the bones to re-alkalize.
Chris Kresser thoroughly explained (and debunked) this theory, and a 2011 study reviewed this theory and found no scientific evidence to substantiate it. (11)
A Better Option: Food Sources of Calcium
The available literature points to the same conclusion that many of us feel intuitively- that food sources are better than supplements whenever possible and this is especially true with calcium.
Dairy is a controversial topic, since many people do not tolerate it or choose not to consume it. Fortunately, while it is the most well-known dietary source of calcium, it is by no means the only source and others may be better. Also, research suggests that the most beneficial part of dairy (especially raw dairy) for bone health may be Vitamin K2, not calcium. More on that below…
Wonderful non-dairy sources of calcium include:
The Importance of Cofactors
Cofactors are also vital for proper calcium absorption and use in the body. In isolation, calcium (and many nutrients) can be harmful, as I explained above, but it is vital and helpful when consumed in proper balance with its cofactors.
There is an excellent book called Vitamin K2 and the Calcium Paradox, which explains in depth how Vitamin K2 is needed for proper utilization of calcium and how calcium consumption without K2 can lead to health problems.
K2 is found in raw dairy from pastured cows, liver, aged cheeses and natto (a fermented soy product). It is also available in supplement form.
Other cofactors for calcium include Vitamin D and Magnesium (among others). In fact, K2, Calcium, Magnesium and D3 are all better utilized when consumed together.
Personally, I prefer to get my Vitamin D from the sun whenever possible and my calcium from food, but I take supplemental forms of Vitamin K2 and use transdermal magnesium to keep my levels in optimal ranges. (This is a great quiz to see if you are deficient in magnesium).
Supplemental calcium is not the panacea for strong bones that it is made out to be. Calcium is certainly important, but it is most beneficial when it comes from food sources and when taken in proper ratio with its cofactors.
Do you take calcium supplements?