Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. Bolland etal, Brit Med Journal 341:c3691, 2010.
These investigators looked at whether calcium supplements increase the risk of cardiovascular events. They included only studies that used calcium supplements alone. If vitamin D or bisphosphonates were also used, the studies were excluded. The studies included a total of almost 20,000 patients over age 40, primarily women but also men, who took calcium 500mg/day or more. The data showed that there was approximately a 30% increase in myocardial infarction (heart attack) in the patients taking calcium; however, there was no increase in strokes or death in those taking calcium. The authors concluded that because calcium supplements are widely used even modest increases in risk of cardiovascular disease might translate into a large burden of disease in the population, and that a reassessment of the role of calcium supplements in the management of osteoporosis is warranted.
Dr. Albrecht’s comments:
It is important to realize that this study only looked at supplemental calcium and not dietary calcium and specifically excluded calcium plus vitamin D. Indeed another recent meta-analysis has not been able to find any evidence of increased cardiovascular risk with calcium and vitamin D supplementation. Higher vitamin D levels are associated with a lower cardiovascular risk. Indeed, evaluation of many of the studies included in the meta-analysis, shows that the levels of vitamin D3 to be 18 to 37 ng/ml significantly below the desired range of 50-80ng/ml.
Moreover, there remain significant anomalies in the theory that higher calcium supplementation increases cardiovascular risk that need to be explained before definitive conclusions can be reached. If an excessive increase in serum calcium is of concern with supplementation then why is calcium alone detrimental but calcium with vitamin D supplementation is not? If vitamin D is considered important at optimizing intestinal calcium absorption then we might anticipate that potentially higher serum calcium levels will be achieved compared to calcium supplementation alone. Furthermore why is high dietary and supplemental calcium protective for cardiovascular disease (Boston Nurses Health Study and Iowa Women’s Health Study) whereas supplemental calcium in this meta-analysis detrimental?
Based on current published data patients taking calcium with vitamin D have little cause for concern. Furthermore anti-resorptive treatment (bisphosphonates) combined with calcium and vitamin D supplementation have demonstrable benefits in fracture prevention and reduction in overall mortality, but the benefits of bisphosphonates are not proven without the concomitant use of calcium supplementation.
It is our recommendation that patients attempt to get their calcium via dietary sources if possible. For patients with osteoporosis or severe osteopenia, we recommend that you get 1000-1200 mg per day. If a patient’s dietary calcium intake is low, then prescribing calcium supplementation based on dietary intake to avoid excess supplementation can be done. To calculate dietary calcium, most people get 300mg/day from NON-dairy foods. There is 300mg of calcium in each cup of milk, cottage cheese, yoghurt or fortified orange juice. The balance can be made up from supplements. We also recommend:
1 adding vitamin D3 (cholecalciferol) at a dose of 800 to 2000 IU/day to maintain adequate levels (50-80 ng/ml).
2 100 micrograms the MK-7 form of vitamin K2, known to remain in the bloodstream longer and reach levels seven- to eight-fold higher compared with other forms of vitamin K.
3 2gm/day of strontium ranelate (680 mg/day dose of strontium).
Regretably, calcium supplements and drugs such as the bisphosphonates are the only options conventional medicine generally offer the millions of older people experiencing bone loss. Nutrition is something we have a fair amount of control over, and its impact is huge. Large amounts protein and carbonated soft drinks leach calcium from your bones. On the other hand, foods such as yogurt, dark leafy greens and other vegetables, prunes, and seeds all help to strengthen bones. Sunshine (because of the production of vitamin D), potassium, magnesium, strontium, vitamin K and omega-3 fatty acids are all proven to support bone health. Dietary sources of calcium, which are the most easily absorbed calcium by the body, are essential. These and other vitamins and minerals work together to create strong bones. One of the most impressive ingredients is strontium, a mineral in the same family as calcium and magnesium. In 1959 the Mayo Clinic found that strontium improved the condition of every single person (all with severe levels of bone loss) in their study. Much more recent studies have also shown benefits. A large multi-center trial known as the strontium ranelate (SR) for treatment of osteoporosis (STRATOS) trial was designed to investigate the efficacy and safety of different doses of strontium in the treatment of postmenopausal osteoporosis. The authors concluded that the 680 mg/day dose of strontium (2gm/day of strontium ranelate) offered the best combination of efficacy and safety. Patients in the strontium group increased lumbar bone mineral density by an average of 14.4 percent and femoral neck BMD an average of 8.3 percent and suffered fewer fractures. For some mysterious reason, strontium dropped off the radar screen as calcium’s popularity grew. This is probably because of the stigma of strontium-90, a highly dangerous, radioactive component of nuclear fallout.