Calcium supplements and heart risk
Sitting increases mortality
Resveratrol, inflammation, oxidation
Resveratrol protects brain and memory
Exercise helps asthma
CT scan risks
Many people take calcium supplements to protect bone density, but taken by itself it is apparently not without risk. A recent review of studies shows that calcium supplements (but not calcium from foods) are associated with an increased risk heart attacks. This meta-analysis (a summary of the results of other studies) reviewed 15 studies with a total of 20,172 participants over 40 years old who took at least 500 mg of calcium daily.
The average duration of the studies was about four years. Those subjects who took the calcium had a 27 to 31 percent higher risk of heart attacks than those who did not take calcium. (Bolland MJ, et al., Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ. 2010 Jul 29;341:c3691. doi: 10.1136/bmj. c3691.) They also found an increase in the risk of strokes and overall mortality, but these were not statistically significant.
This higher risk was consistent and was unrelated to sex, age, or the kind of calcium supplement. The authors also noted that calcium supplements were not very effective in reducing the risk of bone fractures (although this might be different if the supplements are taken in combination with vitamin D, this is not evaluated in this study.) Also, this data is slightly different from my recent report on calcium and vitamin D not causing calcification of the coronary arteries.
To protect the heart, it is important to be sure to have enough magnesium intake to balance any calcium. Calcium supplements might interfere with the absorption of magnesium, and this might account for the risk observed in this meta-analysis. I always recommend at least as much magnesium as calcium. Older recommendations to take twice as much calcium as magnesium are outdated. (I take 500 mg of calcium and 700-900 mg of magnesium.)
Animals are usually quite physically active, and as part of our animal nature we also need an active lifestyle to maintain health. It is well known that obesity and sedentary lifestyles are associated with an increased risk of heart disease and diabetes. New information also suggests that independent of obesity and diabetes, time spent sitting is associated with a higher risk of mortality. This is somewhat disconcerting to those of us who, in spite of being very physically active, spend a lot of time at our desks or computers (or sitting down to play music, or read a book, or numerous other activities). I am not sure whether reclining would be included in the definition of “sitting.”
As a part of the Cancer Prevention II study of 123,216 men and women with no history of cancer, heart disease, stroke, or lung disease were followed from 1993 to 2006 and evaluated for obesity, physical activity, time spent sitting, and overall mortality. Women who spent more than six hours a day sitting, had a 37 percent higher mortality than those who sat fewer than three hours per day. For men, the risk was 18 percent higher.
The situation was even worse for those who were otherwise physically inactive in addition to spending so much time sitting. Inactive women who sat over 6 hours had a 94 percent higher mortality, and for men the increase was 48 percent. These associations were more related to mortality from heart disease than cancer. (Patel AV, et al., Leisure time spent sitting in relation to total mortality in a prospective cohort of US adults. Am J Epidemiol. 2010 Jul 22. [Epub ahead of print]). I do wonder how the hours spent sitting were evaluated. If subjects self reported their sitting, sedentary people might have underestimated those hours skewing the data.
Apparently, sitting can have consequences even in people who are otherwise active, influencing triglyceride levels, blood pressure, cholesterol, blood sugar, and leptin, all biomarkers of obesity and heart disease. The message is that even if you have a regular exercise program, it is important to keep moving at other times, rather than spending too much time at the desk or in front of the TV (and now I think I’ll get up from the computer and tend the garden).
Resveratrol is a plant compound produced by several plants when attacked by bacteria or fungus. Many studies show its beneficial effects in yeasts and lower animals, suppressing inflammation and oxidative damage. A new study shows that resveratrol also has these same benefits in humans. Two groups of 10 subjects were given either a placebo or 40 mg of resveratrol for six weeks and blood samples were taken at one, three, and six weeks. (Ghanim H, et al., An antiinflammatory and reactive oxygen species suppressive effects of an extract of Polygonum cuspidatum containing resveratrol. J Clin Endocrinol Metab. 2010 Jun 9. [Epub ahead of print]
In those taking the active supplement, the blood specimens revealed the reduction of numerous markers of inflammation, including TNF-alpha, interleukin-6, and C-reactive protein (CRP). It also lowered all of the markers that they evaluated that reflect oxidative stress. They noted that these markers were also associated with the development of insulin resistance and diabetes, so reducing them could have widespread benefits, lowering the risk of stroke, diabetes, and heart disease, and slowing the aging process.
In lower animals, resveratrol has been shown to extend life, but this kind of study is difficult to do in humans (as it would take an inordinate amount of time). However, resveratrol increases the activity of the enzyme telomerase, which helps to preserve DNA length during cell division. This has been associated with decreased cell aging and prolongation of life in all the animals studied.
Resveratrol is found in the skin of red grapes and (perhaps more famously) red wine. It is also found in peanuts, blueberries, cranberries, and mulberries. Per ounce, peanuts have about half as much resveratrol as red wine, but some Concord grape products can have quite a bit more than wine. Most supplements are derived from Japanese knotweed. You would have to drink unhealthy amounts of wine to get therapeutic levels of resveratrol, so other sources and supplements are better. (I take 75 mg per day of trans-resveratrol.)
Resveratrol has wider potential for health benefits. It is an activator for a group of enzymes called “sirtuins.” In laboratory and animal studies these enzymes appear to slow the aging process, and new evidence shows that they promote memory and brain agility. The molecular effects of these enzymes are similar to the benefits of caloric restriction in protecting DNA and promoting longevity (without the discipline required and the other sacrifices involved when reducing your food intake).
SIRT1, the mammalian form of this enzyme, plays a role in cardiac function and DNA repair, in addition to its effects on the brain. Activation of SIRT1 improves the plasticity of brain synapses (the connections between neurons) and the formation of memory. In addition to memory and longevity, SIRT1 has a direct role in maintaining normal brain function. (Gao J, et al., A novel pathway regulates memory and plasticity via SIRT1 and miR-134. Nature. 2010 Jul 11. [Epub ahead of print]).
An exercise program can improve asthma control in adults. Even with medication, asthma control is often inadequate, and while exercise can sometimes precipitate asthma attacks, regular physical activity can help reduce symptoms. In a study of 36 subjects, 21 were put on an aerobic training program for 12 weeks, and the other 15 served as controls. They exercised three times a week on a stationary bike, a treadmill, or jogging, and did strength training once a week.
At the end of 12 weeks of supervised training, the exercisers continued on their own for another 12 weeks. In the assessments of asthma symptoms using the Asthma Control Questionnaire (ACQ), the exercisers had significant improvement compared to the controls at both the 12-week and the 24-week evaluations. They also had improved quality of life based on how much the asthma restricted their daily activities. (Dogra S, et al., Exercise is associated with improved asthma control in adults. Eur Respir J. 2010 Jun 7. [Epub ahead of print])
Diet and supplements also help with asthma. Particularly relevant to this study are earlier studies that show that taking vitamin C regularly and prior to exercise (1500 mg or more) can prevent asthma attacks that may be precipitated by physical activity. (Tecklenburg SL, et al., Ascorbic acid supplementation attenuates exercise-induced bronchoconstriction in patients with asthma. Respir Med. 2007 Aug;101(8):1770-8.)
I’ve been following the investigational reporting in the New York Times on the overuse and misuse of CT scans. Their investigations found that patients were getting radiation overdoses and that the scans, even when properly administered could still be risky.
The risk is that ionizing radiation overdoses can cause local symptoms (such as burns, hair loss, and headaches from brain scans) and over time can lead to cancer and brain damage. These are particular problems for the organs of the torso (thyroid down to the bladder) from CT scans of the abdomen.
According to the Times, the problem stems from a combination of manufacturers’ designs and the poor training of technicians. (Bogdanich, W. After stroke scans, patients face serious health risks. NYT, July 31, 2010.)
You should be aware of these risks and always make sure you are getting the appropriate testing, and when possible, ask if you might be able to have ultrasound testing or MRI scans that do not use ionizing radiation.
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