Antioxidant-Rich Diet May Reduce the Risk of Stroke in Smokers
Smokers are at increased risk of having a ]]>stroke]]> . Various substances found in tobacco smoke, including nicotine and carbon monoxide, can harm the brain in a number of ways. By diminishing the capacity of red blood cells to carry oxygen, and by contributing to the buildup of ]]>atherosclerosis]]> , these toxic substances reduce oxygen supply to the brain. They can also cause direct harm to cells in the brain by increasing their exposure to “oxidative stress”.
Some research has shown that foods rich in antioxidants can help reduce the risk of cancer, heart attacks, and strokes by preventing oxidative damage to cells. Dietary antioxidants include ]]>vitamins C]]> and ]]>E]]> , ]]>beta-carotene]]> , and flavonoids. Antioxidants are abundant in fruits, vegetables, and vegetable oils. Since smokers are exposed to increased oxidative stress, some researchers theorize that antioxidants may be particularly beneficial to smokers.
A new study in the November 2003 issue of Neurology found that people who consumed a diet high in vitamin C were 34% less likely to have a stroke. This effect was most pronounced in smokers, who also benefited from a diet rich in vitamin E.
About the Study
This study included 5,197 participants aged 55 and older, who were part of the Rotterdam Study in the Netherlands. The Rotterdam Study is an ongoing, population-based study of people living in a suburb of Rotterdam, the Netherlands. The participants had intact cognitive functioning, were living independently, and had not had a stroke when the study began.
Before the study, the participants completed food frequency questionnaires, which included intake of antioxidant-rich foods. The participants were divided into low, medium, and high intake groups for each of the following antioxidant-rich foods:
- Vitamin C (found in fruits, salads, and vegetables)
- Vitamin E (found in vegetable oils and margarine)
- Beta-carotene (found in carrots, leafy vegetables, yellow and red fruits, margarine, and dairy product colorants)
- Flavonoids (found in tea, red wine, onions, broccoli, soya beans, legumes, apples, cherries, berries, citrus fruits, parsley, and thyme)
The researchers analyzed the participants who took antioxidant supplements separately. They followed the participants for 6.4 years, keeping track of who had strokes. Then they calculated the affect of antioxidant intake on the risk of having a stroke.
During the study, 253 participants had strokes.
Overall, medium and high intake of foods rich in vitamin C reduced the risk of stroke by approximately a third. This result was mostly due to the affect on smokers. For smokers, the risk of stroke dropped by 62% in the medium intake group and 73% in the high intake group. When nonsmokers were analyzed separately, the intake of vitamin C-rich foods had no significant affect on the risk of stroke.
While foods rich in vitamin E had no significant affect on the study group as a whole, higher intake of these foods was associated with a decreased risk of stroke in smokers.
Foods rich in beta-carotene and flavonoids, and antioxidant supplement intake did not significantly impact the risk of stroke.
How Does This Affect You?
These findings suggest that foods rich in vitamin C and possibly vitamin E may help reduce the risk of stroke, especially in smokers.
How can you increase your intake of vitamins C and E? Try incorporating some of these antioxidant-rich foods and oils into your diet:
- Black currants
- Citrus fruits
- Green peppers
- Mustard greens
- Broccoli tops
- Brussels sprouts
- Wheat germ oil
- Sunflower seed oil
- Cottonseed oil
- Safflower oil
- Palm oil
- Rapeseed oil
Another interesting finding, which is consistent with many other antioxidant studies, is that while foods containing certain antioxidants were protective, antioxidant supplements were not. Does this mean that antioxidants in pills aren’t as effective as those in foods? It’s certainly possible that something in these foods in addition to antioxidants provided the protection. The authors raise another theory: it might be important to be exposed to antioxidants for long periods of time, before buildup of atherosclerosis begins in the arteries. While a person's diet tends to change little over time, many people take supplements only for short periods. Also, the participants who were taking supplements may have been doing so because they were already at higher risk of having a stroke. On the other hand, maybe it was something other than the antioxidants themselves that provided the protection—perhaps the combined benefits of a healthful diet.
It’s important to keep in mind, of course, that a far better way to reduce your risk of a stroke, and countless other bad health outcomes, is to stop smoking if you do. Smoking is the third leading cause of death and the leading cause of preventable death in the United States. Your doctor can help recommend programs and medications to help you quit smoking.
American Dietetic Association
American Stroke Association
Brain basics: preventing stroke. National Institute of Neurological Disorders and Stroke website. Available at: http://www.ninds.nih.gov/health_and_medical/pubs/preventing_stroke.htm . Accessed November 11, 2003.
Cigarettes and other nicotine products. National Institute on Drug Abuse website. Available at: http://www.drugabuse.gov/Infofax/tobacco.html . Accessed November 11, 2003.
Stroke risk factors. American Stroke Association website. Available at: http://www.strokeassociation.org/presenter.jhtml?identifier=4716 . Accessed November 11, 2003.
Voko Z, Hollander M, Hofman A, Koudstaal PJ, Breteler MMB. Dietary antioxidants and the risk of ischemic stroke: the Rotterdam Study. Neurology . 2003;61:1273-1275.
Last reviewed Nov 14, 2003 by ]]>Richard Glickman-Simon, MD]]>
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