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News and Research
Vitamin C helps prevent heart disease
HELSINKI, FINLAND. A new international cohort study sheds further light on the long-standing debate about the
role of vitamin C in coronary heart disease (CHD). The study combined the results of nine prospective studies
on intakes of vitamin C, carotenoids and vitamin E.
The authors found that while intake of these vitamins through diet only slightly reduced CHD risk, vitamin C
supplementation was associated with significantly lower CHD rates in both men and women. In recent decades,
many studies have suggested that vitamin C and other essential nutrients play a role in heart health, possibly by
preventing atherosclerosis (hardening of the arteries) that can contribute to CHD. Led by Dr Paul Knekt of the
National Public Health Institute in Helsinki, the researchers analyzed data from nearly 300,000 participants and
looked at all major CHD events and CHD mortality over a ten-year follow-up period.
Dietary intake of the carotenoid lutein was linked to slightly reduced CHD risk in the first two years of follow-up,
as was vitamin E intake in women, but overall the effect of dietary vitamin E and carotenoids on CHD risk after
adjustment for other risk factors was small.
However, taking high doses of vitamin C (more than 700 mg daily) lowered the risk of major CHD events by 25
percent. As vitamin C supplementation could merely act as an indicator of a generally "healthy" lifestyle, fiber
and fat intake were taken into account, but the association remained just as strong. The results are supported
by several previous studies suggesting a reduced CHD risk with vitamin C intake over 500 mg per day. On the
other hand, no CHD benefit was found from vitamin E supplementation.
An interaction between vitamins C and E was expected, as vitamin C can help regenerate oxidized vitamin E,
but the effect was not observed in this study. Despite the significant results concerning vitamin C, the authors
conclude that the study does not provide unqualified support for high dose supplementation; they say the
effects are not as yet fully understood.
Knekt P, et al. Antioxidant vitamins and coronary heart disease risk: a pooled analysis of 9 cohorts. American Journal of
Clinical Nutrition, Vol. 80, December 2004, pp. 1508-1520 |
Guns in the home - a dangerous situation
ATLANTA, GEORGIA. Homicides and suicides are among the leading causes of death in the USA and 60% of
them are committed with a firearm. Despite several studies demonstrating an association between the access to firearms and homicides/suicides, it is estimated that about 40% of all American adults keep a gun at home.
A recent study carried out by the Centers for Disease Control and Prevention confirms that having a firearm at
home markedly increases the risk of a violent death occurring in the home. A total of 2,074 death certificates (490 homicides, 1,049 suicides, and 535 "other") were obtained and proxy interviews were conducted with the deceased individual's next of kin or another person familiar with the deceased's life history. Results showed that a firearm was used in 68% of homicides and suicides, and having a gun in the home was associated with an increased risk of firearm homicide and firearm suicide in the home regardless of storage practice, type of gun, or number of firearms. Gun owners had a 90% greater risk of dying from a homicide in the home and they were also at greater risk of dying from a firearm homicide than were non-owners. More than 75% of homicide victims knew their assailant, and almost a third of homicides occurred during a family argument.
Men with a gun in the home were 10 times more likely to commit suicide than were men without, and persons
with firearms in the home who committed suicide were 31 times more likely to have done so using a gun rather than another method. The researchers conclude that having a firearm at home is associated with a greater risk of a homicide/suicide occurring in the home.
Dahlberg, LL, et al. Guns in the home and risk of a violent death in the home: findings from a national study. American
Journal of Epidemiology, Vol. 160, November 15, 2004, pp. 929-36 |
Prostate cancer linked to inflammation
BALTIMORE, MARYLAND. Several cancers have been linked to inflammation or viral infection. Stomach cancer has been linked to an infection with Helicobacter pylori. Liver cancer is associated with hepatitis (inflammation of the liver), and cervical cancer with a human papilloma virus infection. Now researchers at the Johns Hopkins University School of Medicine suggest that prostate cancer may also have its origin in inflammation or viral infection.
It is quite clear that prostate cancer risk is related to diet, with animal fats promoting it and antioxidant-rich fruits and vegetables preventing it. Also, it is clear that some anti-inflammatory agents such as aspirin and COX-2 inhibitors help prevent prostate cancer, especially among older men. There is also substantial evidence that antioxidants such as vitamin E (especially gamma-tocopherol) and selenium exert a strong protective effect against prostate cancer.
Furthermore, there is clear evidence that the inflammation associated with sexually transmitted infections is associated with increased prostate cancer risk. Close examination of prostate cells obtained from biopsies have shown a strong presence of inflamed cells close to cancer cells, and signs of prostatitis (prostate inflammation) are found in almost all older men in the developed world even though symptoms may be absent. Finally, it has recently been discovered that prostate cancer is associated with silencing of the gene responsible for the production of glutathione S-transferase, one of the body's most important antioxidants.
Putting all this information together, the Johns Hopkins researchers conclude that inflammation of the prostate (prostatitis) may contribute to the development of prostate cancer.
Nelson, WG, et al. The role of inflammation in the pathogenesis of prostate cancer. Journal of Urology, Vol. 172, November 2004, pp. S6-S12 |
Pros and cons of folic acid
TORONTO, CANADA. A folic acid deficiency has been linked to an increased risk of giving birth to a baby with neural tube defects (NTDs), or spina bifida. In 1998, Canada, the US, and Chile passed a law mandating that all flour and uncooked cereal-grain products be fortified with folic acid (140 micrograms/100 grams). Since 1998, the number of babies born with NTDs has decreased by anywhere from 15-50% in the US, Canada, and Chile. Clearly, a superb example of the benefits of active cooperation between science and public health policy - or maybe not?
Dr. Young-In Kim of the University of Toronto now suggests that, while folic acid fortification has been an unqualified success in reducing NTDs, it may have created other problems. In other words, what is good for a relatively small proportion of the overall population (pregnant women) may be detrimental to a much larger part of the population. Dr. Kim points out that, while folic acid is effective in preventing the initiation of many forms of cancer, it may actually accelerate the growth of already existing cancers. Folate plays a very important role in DNA synthesis and replication, which is great when it comes to healthy cells, but not when it comes to cancerous cells. Rapid replication and proliferation is the last thing you want in the case of cancer cells. As a matter of fact, experiments have shown that inducing a folate deficiency inhibits tumor growth and at least two chemotherapy agents (methotrexate and 5-fluorouracil) owe their effect to the fact that they counteract the cell proliferation effect of folic acid.
Dr. Kim concludes that, "The potential cancer-promoting effect of folic acid fortification in the vast majority of the US population, who are not at risk of NTDs, but have unintentionally been exposed to high amounts of folic acid, is a legitimate public health concern and needs careful monitoring."
Kim, YI. Will mandatory folic acid fortification prevent or promote cancer? American Journal of Clinical Nutrition, Vol. 80, November 2004, pp. 1123-28 |
Even a little exercise helps
There is substantial evidence that regular exercise improves health and increases longevity. What is less clear is whether less frequent, but more vigorous activity is equally beneficial. Researchers at the Harvard School of Public Health recently reported that "weekend warriors", that is men who only engage in vigorous activity once or twice a week, do benefit. Their study included 8,421 men (enrolled in 1988 and 1993). The men were classified as sedentary (expending less than 500 kcal/week), insufficiently active (500-999 kcal/week), weekend warriors (more than 1,000 kcal from sports/recreation 1-2 times a week), and regularly active (more than 1,000 kcal/week).
Between 1988 and 1997, 1,234 of the study participants died. Men who were physically active on a regular basis had a 36% lower mortality than did sedentary men, while weekend warriors had a 15% lower risk of dying. However, when limiting the analysis to men without major risk factors, weekend warriors were found to have a 59% lower mortality than sedentary men. The researchers conclude that vigorous exercise once or twice a week can extend life significantly in men with no major risk factors such as smoking, hypertension, high cholesterol, etc.
American Journal of Epidemiology, Vol. 160, October 1, 2004, pp. 636-41 |
Footwear linked to risk of falls
SEATTLE, WASHINGTON. Having a fall is the most common cause of fatal injury among older Americans. Non-fatal falls are also common with about one third of live-at-home, older adults experiencing one each year. Overall health status and physical activity level are not significantly related to risk of falling; however, older adults with low hand grip strength and difficulty in getting up from a bed or chair do have a higher risk. The use of walking aids and gait abnormality also increase the risk of a fall.
Researchers at the University of Seattle now report that footwear type is perhaps the most important factor when it comes to preventing falls. The researchers monitored a group of 1,371 adults aged 65 years or older for a two-year period. During this time 327 falls to the ground occurred that met the criteria of being unintentional, not being associated with a loss of consciousness, and not resulting from being hit or pushed. Most falls occurred in or around the home with about 62% taking place while walking on a level surface, 23% occurring at a change of level such as stairs, steps or a curb, and 13% taking place on a slope. About 50% of the falls occurred between noon and 6:00 pm. Only 2% of all falls occurred during vigorous physical exercise as compared to 43% while walking outdoors and 31% while walking indoors.
The researchers compared the type of footwear worn by the fall victim at the time of the fall with the type worn by non-falling controls engaged in a similar activity at a similar time. They observed a strong correlation between footwear type and the risk of falling. The safest footwear, by far, would seem to be athletic shoes and canvas shoes (sneakers). Being barefoot or in stocking feet was associated with an 11 times higher risk of falling when compared to wearing athletic shoes. Other shoe styles, such as high heels and shoes without heels, increased falling risk by a factor of 2 or more. The researchers conclude that wearing athletic or canvas shoes may be a useful component in intervention programs designed to prevent falls.
Koepsell, TD, et al. Footwear style and risk of falls in older adults. Journal of the American Geriatrics Society, Vol. 52, September 2004, pp. 1495-1501 |
Warfarin-related bleeding incidence on the rise
BOSTON, MASSACHUSETTS. Warfarin (Coumadin) therapy is a major cause of internal bleeding and hemorrhagic stroke. The risk increases substantially with higher doses (elevated INR or international normalized ratio value) and with the concomitant use of other anticoagulants or medications that potentiate warfarin's action. Researchers at the Harvard Medical School now report that the incidence of warfarin-related major bleeding and intracranial hemorrhage (hemorrhagic stroke) among patients admitted to the Brigham and Women's Hospital has increased substantially, from the 4-year period 1995-1998, to the 4-year period 1999-2002. Among the highlights of the findings are:
- The annual incidence of warfarin-related bleeding increased by 22% between the two time periods.
- The proportion of patients with major bleeding increased from 20.2% to 33.3% and that of intracranial bleeding from 1.9% to 7.8%.
- The proportion of warfarin-treated patients who had an INR value higher than the intended range was 57% in the first time period and 59% in the second.
Sixty-two per cent of the warfarin-treated patients also received medications that are known to potentiate the effect of warfarin. Among the more common ones were quinolone antibiotics (32%), levothyroxine (15%), simvastatin (10%), and amiodarone (10%). The use of more than one potentiating medication increased from 24% in the first period to 41% in the second period. If aspirin, clopidogrel and other antiplatelet agents and anticoagulants are included, then a full 86.6% of warfarin-treated patients received one or more medications that would increase the effect of warfarin and make them susceptible to major bleeding.
Kucher, N, et al. Time trends in warfarin-associated hemorrhage. American Journal of Cardiology, Vol. 94, August 1, 2004, pp. 403-06 |
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