Dangers of Calcium Supplements
If you’ve been a regular reader of my articles, you’d have noticed that my main thrust has always been and still is the prevention of chronic diseases through low carb and other similar diets.
I’ve even stressed the importance of certain supplements that will help us remain in robust health and even help us reclaim our health should we fall sick.
Today I’m going to take a slightly different route: I’m going to tell you to AVOID this supplement because of the potential damage it can do to your body.
Are You Taking Calcium Supplements?
Calcium is one of the most popular supplements because of the widely belief that megadoses of this mineral are essential for building strong and healthy bones and to prevent osteoporosis.
This is why for years many people especially women who are nearing menopause have been taking calcium supplements in the hope of preventing bone fractures that are a result of osteoporosis.
However studies in recent years have brought up shocking evidence that calcium supplements are not only not needed in preventing osteoporosis, they can be downright harmful to health.
No Benefits from High Intake of Calcium through Supplements
A 2012 observational study by the University of North Carolina and published in the Journal of Clinical Endocrinology and Metabolism showed that high intakes of calcium beyond the recommended daily allowance, typically from calcium supplements did not improve hip and lumbar bone density for seniors.
The researchers surveyed 1384 women and men aged 50 to 70 years of age, took their average intake of calcium and tested against their lumbar and neck femoral bone mineral densities. The results showed that a usual high calcium intake beyond the recommended dietary allowance of elderly women and men, most commonly achieved by calcium supplements, did not provide any benefit for hip or lumbar BMD (bone mineral density). A dietary intake of calcium approaching or meeting the current recommendations was not related to higher BMD of the hip or lumbar spine in late life compared with lower intakes of calcium in older adults.
Another 2007 mega analysis of 7 cohort studies involving over 170,000 women and published in the American Journal of Clinical Nutrition showed that not only was calcium supplements ineffective in preventing fractures in older women, they may even increase the risk of hip fractures.
The researchers concluded that pooled results from randomized controlled trials show no reduction in hip fracture risk with calcium supplementation, and an increased risk is possible.
Supplemental Calcium increases Heart Disease Risk
Although dietary calcium from whole foods has been linked to lower cardiovascular risk factors, the opposite is true for supplemental calcium.
A 2012 huge 11-year joint German and Swiss study involving 24,000 men and women aged between 35 to 64 years of age and published in the British Medical Journal found that increased dietary calcium intake from supplements had a 139% increase in heart attack while calcium intake from food did not increase risk.
Calcium supplements are often recommended to the elderly and postmenopausal women to protect against osteoporosis. Calcium supplements, which might raise MI (myocardial infarction or heart attack) risk, should be taken with caution, said the researchers.
The researchers’ conclusion was that total, dairy or non-dairy calcium intake did not have an overall statistically significant inverse association with cardiovascular risk, except for a likely reduction of MI (myocardial infarction or heart attack) risk associated with a moderately higher dairy calcium intake. However, this study also suggests that MI risk might be substantially increased by taking calcium supplements.
A smaller 2007 mega analysis of over 12,000 participants and also published in the British Medical Journal found that calcium supplements increase heart attack risk by 31%, stroke by 20% and death from all causes by 9%.
Another huge 12-year 2013 study by The National Institutes of Health on 388,229 men and women aged 50 to 71 years and published in the JAMA Internal Medicine found that calcium supplementation was linked to a higher risk of heart disease.
Nearly 12,000 or 3% of the participants died of heart disease in the 12-year study. The researchers found that men who took at least 1,000 mg of supplemental calcium a day had an increased 20% higher chance of dying from heart disease than those who didn’t take any calcium supplements.
The chief researcher, Dr. Qian Xiao wrote: Supplemental calcium intake was related to a significantly elevated risk of total CVD (cardiovascular disease) and heart disease mortality among men. Compared with nonusers, men with an intake of supplemental calcium of more than 1000 mg/d had a significantly higher risk of total CVD death.
And yet another 19-year Swedish study involving over 61,000 women and published in The British Medical Journal in 2012 found that high intake of calcium i.e. 1,400 mg and higher had a 40% higher risk of death from all causes and heart disease. If the women took a 500 mg calcium supplement daily, their risk of dying increased to 157%!
New Zealand researchers suspect that with supplements, a huge dose of calcium at one shot increases the calcification of the arteries which leads to atherosclerosis. On the other hand, natural calcium from whole foods is absorbed at smaller and lower rates from that of supplements.
High Calcium Intake linked to Prostate Cancer
There have been studies linking high levels of calcium to prostate cancer although most of these studies are population based and observational.
A 1998 mega analysis by the Harvard Medical School and Brigham and Women’s Hospital in Boston of 47,781 men from the Health Professionals Follow-Up Study showed that high intake of calcium especially from supplements were positively correlated with increased prostate cancer risk. The researchers wrote that they support increased fruit consumption and avoidance of high calcium intake to reduce the risk of advanced prostate cancer.
Surprisingly, a 2001 follow up to the Physicians’ Health Study by the Harvard School of Public Health in Boston showed that a high intake of calcium from dairy sources increased prostate cancer risk. They found that men who consumed 600 mg or more of calcium a day from dairy sources had a 32% increased risk of prostate cancer then those who consumed 150 mg. The researchers concluded that these results support the hypothesis that dairy products and calcium are associated with a greater risk of prostate cancer.
Another 2003 study by the American Cancer Society in Atlanta, Georgia in the Cancer Prevention Study II Nutrition Cohort found that high calcium intake i.e. 2,000 mg or more a day was associated with an increased prostate cancer risk compared to those taking lower intakes. However the researchers pointed out that dairy intake was not associated with prostate cancer risk. Their conclusion: Our results support the hypothesis that very high calcium intake, above the recommended intake for men, may modestly increase risk of prostate cancer.
In yet another study, led by the University of Southern California and published in 2011 in Medical News Today also linked high calcium intake to prostate cancer in African American men.
Dr. Sue Ann Ingles, associate professor of preventive medicine at the Keck School of Medicine of USC together with a team from the Wake Forest Baptist Medical Center and the Cancer Prevention Institute of California studied 783 African American men living in the San Francisco and Los Angeles areas. Of these 533 were diagnosed with prostate cancer.
The study which was published by the Journal of Bone and Mineral Research found that men who reported the highest intake of calcium were two times more likely to have localized and advanced prostate cancer than those who reported the lowest. Men with a genotype associated with poor calcium absorption were 59 percent less likely to have been diagnosed with advanced prostate cancer than men who genetically were the best absorbers of calcium. And, among men with calcium intake below the median, genetically poor absorbers had a 50 percent decreased risk of having advanced prostate cancer than the best absorbers.
One of the other researchers Dr. Gary G. Schwartz, associate professor of cancer biology and epidemiology and prevention at Wake Forest Baptist said, “We now have a better understanding of why calcium in diet may increase the risk for prostate cancer and who is at increased risk, if our results are confirmed, it gives much better insight into the preventable causes of prostate cancer. So if I know I’m a good absorber of calcium, I may want to be careful about the use of calcium supplements.”
Calcium Supplements Increase Kidney Stones Risk
High calcium intake particularly from calcium supplements has been linked to increased risks of getting kidney stones.
A 1997 joint analysis of the Nurses’ Health Study 1 by the Brigham and Women’s Hospital, Harvard Medical School, Harvard School of Public Health and the Massachusetts General Hospital in Boston and published in Annals of Internal Medicine found that intake of dietary calcium was inversely associated with risk for kidney stones and intake of supplemental calcium was positively associated with risk.
In that study, the researchers found that in 67% of women who took supplemental calcium, the calcium either was not consumed with a meal or was consumed with meals whose oxalate content was probably low. Their conclusion was that high intake of dietary calcium appears to decrease risk for symptomatic kidney stones, whereas intake of supplemental calcium may increase risk. Because dietary calcium reduces the absorption of oxalate, the apparently different effects caused by the type of calcium may be associated with the timing of calcium ingestion relative to the amount of oxalate consumed.
In another 2006 large scale 7-year study involving over 36,000 post-menopausal women between 50 to 79 years of age, the researchers also found that calcium supplements increased the risk of kidney stones.
The participants of the study were either given a daily supplement containing 1,000 mg of calcium and 400 IU of vitamin D or a placebo pill. Not only did the women had their risk of getting kidney stones increased, the supplementation didn’t lower their risk of hip fractures although there was an increase in the overall bone density.
Yet another 2011 huge study by the Institute of Medicine, it was found that total (calcium) intakes (diet plus supplements) above 2,000 mg/day may increase the risk for kidney stones, and demonstrate no increase in benefits relative to bone health. There is also some limited evidence that the long-term use of calcium supplements may increase the risk for cardiovascular disease.
In the American Society of Nephrology or ASN Kidney Week 2015 November 3 – 8 held in San Diego, California, Christopher Loftus, MD candidate from the Cleveland Clinic Lerner College of Medicine and his colleagues presented a research paper which stated that calcium supplements could increase the risk of kidney stones.
Loftus and his team identified over 6,000 patients with histories kidney stones. Of these 1,486 patients were given calcium supplements, 417 were given vitamin D supplements and 158 with no supplements at all.
Patients who took calcium supplements had lower total calcium and oxalate (which are components of kidney stones) in their urine while blood levels were unaffected. However, these patients also had a faster rate of kidney stone growth suggesting that the mechanism of calcium supplementation on stone formation may not be straightforward.
Loftus conclusion was, “While taking supplemental calcium has associated positive effects, these results suggest that supplemental, as compared with dietary, calcium may worsen stone disease for patients who are known to form kidney stones.”
Dietary Sources of Calcium Rich Whole Foods
So, with all these negative connotations which are mostly linked to calcium supplements, how do we ensure we get enough calcium to prevent osteoporosis and yet not risk having all these other chronic conditions?
The answer is calcium from whole foods, and some are not necessarily from dairy sources.
What I’ve done is listed the foods that are rich in calcium so that you can get enough of this important mineral through natural dietary sources:
- Chia and sesame seeds.
- Canned salmon.
- Tofu, edamame and soy milk.
- Leafy greens such as kale, spinach and collard greens.
- Beans and lentils.
- Dried figs.
- Black-eye peas.
In a future article, I’ll go in-depth as to why these whole foods are not only much preferred than calcium supplements, they also have other health benefits as well.