Biology of Humans 6th Edition by Judith Goodenough,Betty McGuire

Exercise 5

Women, especially postmenopausal women, are often encouraged to take daily calcium supplements to keep their bones dense. However, as we will see in Chapter 6, calcium is also important in muscle contraction, including that of heart muscle. For this reason, Mark Bolland and his colleagues investigated the effect of calcium supplements on cardiovascular disease. In this study1, the participants were randomly assigned to a placebo group or to a group that took calcium and vitamin D supplements. The authors conclude, "Calcium supplements (without coadministered vitamin D) are associated with an increased risk of myocardial infarction [heart attack]. As calcium supplements are widely used these modest increases in risk of cardiovascular disease might translate into a large burden of disease in the population. A reassessment of the role of calcium supplements in the management of osteoporosis is warranted."
Some researchers have claimed that calcium supplements reduce cancer risk. Use reliable references to understand the basis for this claim. Consider the design of the research study when you decide whether these claims are valid. Cite your sources.