Calcium Supplements May be Harmful for Some Older Adults
There is no question that consuming enough calcium is essential for keeping bones healthy and strong, but a new study sheds doubt on the benefits of calcium supplements for post-menopausal women.
Researchers at the University of Auckland in New Zealand examined results from 11 randomized controlled trials involving nearly 12,000 patients. The trials, which lasted an average of four years, involved giving half the participants calcium supplements (which did not contain vitamin D) or a placebo. They found that among the women who took the calcium supplements, there was a 31 percent increase in the risk of heart attack.
Although the exact mechanism is still unclear, researchers believe that, unlike calcium ingested from food, supplements can boost blood levels of calcium, thereby increasing one’s risk of a heart attack.
While the researchers acknowledge the increase in risk is relatively small, the widespread use of calcium supplements significantly increases the number of women who could be adversely affected. Although additional studies are needed, some cardiologists are recommending that patients with osteoporosis should not be treated with calcium supplements. It is still important, however, to consume sufficient calcium from foods such as dairy products and green leafy vegetables.
In an editorial accompanying the study published in the British Medical Journal, cardiologist Dr. John Cleland wrote, “It is not clear whether [calcium supplements] really increase the risk of heart attacks or strokes.” However, he continued, “they do appear to be a waste of time and effort, and we should probably stop using them.”
Sources: Bolland, M.J., et al. (2010). Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. British Medical Journal, 341: c3691
Cleland, J. G. F., Witte, K. and Steel, S. (2010). Calcium supplements in people with osteoporosis. British Medical Journal, 341: c3856–c3856
Glucosamine Offers Little Relief for Osteoarthritis Sufferers
The shelves of vitamin and health-food stores are packed with products containing glucosamine—a natural compound found in healthy cartilage—with labels promising relief from back and joint pain. Despite little evidence to support these claims, sales of glucosamine in 2008 totaled $872 million in the U.S. and $2 billion worldwide.
The results of a new study, however, could put a damper on those big sales. In what has been called the largest and longest trial of glucosamine, participants experienced no change in their levels of pain, disability and quality of life after taking the supplement for six months.
Researchers from Oslo University Hospital in Norway gave 125 patients with lower-back pain and osteoarthritis 1,500 milligrams of oral glucosamine. A second group took a placebo for the same time period. All participants were evaluated at the beginning of the study and again at six weeks, three months, six months and one year. Neither group reported any reduction in pain or improvement in quality of life.
Therefore, researchers concluded, glucosamine offers little benefit for individuals with chronic pain from osteoarthritis.
Source: Wilkins, P., et al. (2010). Effect of Glucosamine on Pain-Related Disability in Patients With Chronic Low Back Pain and Degenerative Lumbar Osteoarthritis. Journal of the American Medical Association, 304, 1, 45–52.
Overweight Want to Eat More…But Don’t Always Eat More
For some us, just the thought of a favorite food can prompt us to start salivating and plotting our next meal. And according to a new study, just how strongly people respond to food cues—thoughts, smell and sight—may be affected by whether or not they are overweight.
Danielle Ferriday, a graduate student at the University of Bristol in the United Kingdom, and her faculty advisor Dr. Jeffrey Brunstrom devised a study to determine if overweight and lean people respond differently to food cues. They recruited 52 normal weight and 52 overweight women and exposed them to the sight and smell of pizza. In addition to monitoring their psychological responses, they tracked how much the women salivated when they smelled the pizza and again when it was placed in front of them.
The lean participants salivated about the same amount when smelling and then seeing the pizza. The overweight women, however, salivated about one-third more once the pizza was actually placed in front of them. And compared to the lean women, the overweight women also expressed a greater desire to eat the pizza. However, despite this increased desire, they didn’t eat anymore than the lean women, even though both groups were told to eat as much as they wanted to.
Ferriday and Brunstrom theorize that the overweight women’s heightened sensitivity to food cues may not make them want to eat more in a single sitting, but may spur them to eat more frequently and develop unhealthy eating habits that lead to weight gain. What is less clear is how this heightened sensitivity develops in some people and not others. For example, are people born with a greater desire for food or is this a learned behavior? Additional studies are needed to answer these questions.
Furthermore, although this study involved women, “we suspect that the findings would apply to men too,” says Ferriday.
Source: Ferriday, D. and Brunstrom, J.M. (2010). ‘I just can’t help myself’: effects of food-cue exposure in overweight and lean individuals. International Journal of Obesity, advance online publication 15 June 2010; doi: 10.1038/ijo.2010.117