Calcium and Atherosclerosis

 

This is the current issue of the journal OBG Management and, as you can see, the cover story is by Dr. Goldstein. It is an update in bone health specifically addressing calcium supplements and their role in cardiovascular disease.

In 2001 a National Institutes of Health (NIH) consensus panel on osteoporosis concluded that calcium intake is indeed crucial to maintain bone mass and should be maintained at 1,000-1,500 mg/day in older adults. That panel felt that the majority of older adults were not meeting recommended intake from dietary sources and, therefore, recommended calcium supplements. It is well known that calcium supplements are one of the most commonly used dietary supplements in America. Various surveys have shown that they are used by the majority of older women in the United States.

More recently, however, large, randomized placebo-controlled trials (the gold standard of clinical research) involving calcium supplements have demonstrated some concerns about their safety as well as their efficiency in possible fracture prevention. Several studies over the last few years have suggested that calcium supplements can increase the risk of kidney stones as well as cardiovascular events in healthy older women. It is important to note that not all research has shown these detrimental effects of calcium supplementation but none of them has shown a positive benefit.

Thus, many of you are aware and I have spoken to many of my patients as well, about the importance of trying to obtain adequate calcium (I recommend 1,200 mg/day) from dietary sources. At the end of this email, I have attached a list of foods and the amount of calcium contained within those various foods. My other problem with calcium supplements is that 1) they are often extremely constipating 2) they do not deliver the amount of elemental calcium listed on the label. For instance, calcium supplements have elemental calcium that is bound to a negative ion (the medical term for this is “salt”). Thus, calcium oxalate in Oscal or calcium citrate in Citrical have the calcium bound to oxalate or the calcium bound to citrate. When it dissolves into your blood stream, the amount of elemental calcium is, at best, forty percent of what is on the label. Thus, a 500 mg Oscal will give you, at best, 200 mg of elemental calcium.

This cover story article that I have written for OBG Management entitled, “Calcium and Atherosclerosis?” reviews several more recent studies that indicated that women who took calcium supplementation had higher calcium artery calcification (CAC scores) on CT scan. This is a surrogate marker that is felt to represent risk for heart disease. Women on calcium supplementation also manifested higher small increases in blood pressure compared to women who obtained their calcium from diet alone.

Most recently the United States Preventative Services Taskforce recommended against calcium supplements for the primary prevention of fractures in postmenopausal women (unless they were institutionalized).

I realize that when contradictory information comes out many patients lose faith in the medical establishment, in general. This is indeed unfortunate. Realize that changes that are then promulgated in the media are often the result of an increase in our understanding of the science. Indulge me for a moment and understand the evolution of lipids (better known as cholesterol). In 1959 when my father had his first heart attack, they barely understood the importance of saturated fats and cholesterol as a molecule. This was three years before even the President’s Council on Physical Fitness was developed. In those days, heart attack victims were told to, “not eat red meat and substitute blue fish,” as well as not to exercise for fear of, “stressing their heart.” The understanding about cholesterol then divided into HDL (the good) and LDL (the bad) came along next. For quite some time it was felt that the higher your good cholesterol the better. Later, people often looked at the ratio between good and bad cholesterol. More recently, the science has indicated that the most important factor is how low is your bad cholesterol. It cannot be too low from a risk point of view. Such changes in opinion are simply the function of more scientific knowledge and a better understanding of physiology.

Thus, do not be disheartened that in 2001, women were told to take calcium supplements and now in 2017, we are telling women to get their calcium from their diet and not from supplementation. It is simply better knowledge. And while we’re at it, don’t forget you need 1,000-2,000 IU/day of vitamin D. I advise that as a supplement since most vitamin D comes from sunlight and we have ruined the ozone layer and if you do go out in the sun, you will be wearing SPF for protection against skin cancers.