A study from the Cleveland Clinic found that people with mild to moderate calcification of their aortic valves who took calcium pills were at double risk for dying from heart disease and three times more likely to need surgery to replace their heart valve than the participants who did not take calcium pills (BMJ Heart, April 25, 2022). This study involved 2657 patients, average age 74, and followed them for almost six years. Several other studies have shown that people who take calcium pills are at increased risk for calcification of arteries and the aortic heart valve which is the main blood outflow valve of the heart (JACC: Cardiovascular Imaging, Jan 2021;14(1):259-268). When the aortic valve is covered with calcium, it becomes narrow and stiff and blocks blood flow from the heart into the aorta that supplies blood to the rest of your body. This can increase risk for death from heart failure. Five percent of people over 75 will develop calcified aortic valves, and when the valve becomes narrower than half an inch, a person is at significant risk for heart failure and death.

This calcification of aortic valves (which is harmful) is not the same as the calcium found in arterial plaques that helps to stabilize them (which is beneficial). Heart attacks are caused by plaques breaking off from the inner lining of arteries, followed by bleeding and clotting that extends to block all flow of blood to part of the heart muscle. That part of the heart muscle then completely lacks oxygen and dies. Plaques that have a thick layer of calcium on their inner walls where blood flows are more stable and less likely to break off. Plaques form in arteries from an unhealthful diet or undesirable genes, or both. Exercise does not prevent plaques from forming, but it appears to help to stabilize plaques so that they are less likely to break off to cause heart attacks. See Stable Plaques: Why Exercisers Have Fewer Heart Attacks

Why So Many Calcium Pills?
In 1994, the U.S. Congress passed a law that allowed manufacturers of calcium and vitamin D pills to advertise and sell their pills without having to supply evidence that their products have any health benefits whatsoever. In North America today, more than $6 billion of calcium pills and $2.5 billion of vitamin D are sold each year.

All people develop weaker bones as they age, so many doctors recommend that seniors take calcium pills. Researchers at Johns Hopkins followed 2700 people who took calcium pills for ten years and found that they had a 22 percent increased risk of arteriosclerotic plaques forming in the arteries leading to their hearts, compared to those who did not take calcium pills (J American Heart Association, October 11, 2016). People who took in large amounts of calcium from food (>1400 milligrams per day) were 27 percent less likely to have plaques. This suggests that calcium in pills may be handled differently from calcium in foods, to accumulate in body tissues and increase risk for heart attacks (J Clin Hypertens (Greenwich), May 2, 2017) and strokes (J American Heart Association, Oct. 11, 2016). Calcium pills can also increase risk for forming kidney stones in susceptible people (Am J Clin Nutr, July 2011;94(1):270-277).

An earlier review of 33 studies showed that calcium and vitamin D pills do not prevent fractures, regardless of dose (JAMA, Dec 26, 2017;318(24):2466). Other reviews of 59 studies and 50 studies showed that neither calcium pills nor foods rich in calcium prevent bone fractures (British Medical Journal, September 29, 2015;351:h4183 ). An editorial in the same issue of JAMA stated that the evidence is so overwhelming that extra calcium does not prevent fractures that we have to ask ourselves why these products are still so widely used.

Calcium from Foods
The recommended daily allowance (RDA) for women up to age 50 is 1000 mg of calcium per day, and 1200 mg per day for women over 50. If you are not sure if you are meeting your RDA for calcium, keep a food diary for a few days and then check for the calcium content of each portion using a google search. You may be surprised to find that virtually every unprocessed or minimally processed food you eat contains some calcium — fruits, vegetables, all types of seeds, all animal products and so forth. If you think you may not be getting enough calcium in your diet, consider eating more of these foods:
• Dairy (I recommend fermented dairy products including cheese, yogurt and kefir)
• Seafood, particularly canned fish with edible bones such as salmon or sardines
• Green vegetables such as kale, collard greens, broccoli, sprouts, bok choy
• Beans and lentils, including soybeans, edamame, tofu and other soybean products
• Nuts and other seeds

If you and your doctor decide that you should add calcium pills, consider one of the popular brands that have a recommended dose of two small pills totaling 400 mg (25-30 percent of RDA), with the balance of your RDA coming from your food.

Avoid Overweight and Diabetes
Since obese people often have big bones, doctors used to think that excess weight would help to strengthen bones, but it does not. Excess weight is associated with increased risk for harmful high blood sugar levels after eating. When blood sugar levels rise too high, sugar sticks to the outer membranes of cells and destroys them. This applies to bone cells and explains why diabetes is a major risk factor for osteoporosis (World J Diabetes, Aug 15, 2013;4 (4): 101–113). All risk factors for diabetes are also risk factors for osteoporosis: excess belly fat, insulin resistance, high blood sugar levels, and lack of exercise (Clinical Endocrinology, April 15, 2019). The bones of diabetics are significantly weaker than those of non-diabetics (Bone, Dec 2015;81:152-160). Overweight diabetics have a very high rate of osteoporosis (Diabetes & Metabolism, June 2008;34(3):193-205) and bone fractures (J Bone and Min Res, November 2012;27(11):2231–2237).

Exercise for Stronger Bones
Everything that causes you to lose muscle size and strength also causes you to lose bone size and strength (Am J Clin Nutr, May 2008;87(5):1567S-1570S). Anything that enlarges muscles also makes bones larger and stronger. Try to exercise regularly against increasing resistance and do weight-bearing aerobic exercise such as walking, jogging, dancing or playing tennis. See Strength Training to Help Prevent and Treat Osteoporosis

My Recommendations
At this time, the best ways to keep your bones strong are:
• eat a plant-based anti-inflammatory diet with a variety of calcium sources
• try to exercise regularly against increasing resistance
• restrict alcohol
• do not smoke and avoid second-hand smoke
• keep blood levels of hydroxy vitamin D over 30 ng/mL. Sunlight is the best source of vitamin D, but if that is not an option, use vitamin D pills.
If you have evidence of osteoporosis, discuss the various bone-strengthening drugs with your doctor.