Stroke is a condition caused by a lack of blood supply to the brain or by hemorrhage (bleeding) within the brain.
Stroke is the third leading cause of death in the United States, but most strokes are not fatal. Depending on the area of the brain that is damaged, a stroke can cause coma, reversible or irreversible paralysis, speech problems, visual disturbances, and dementia. Factors that increase the risk of certain types of stroke include hypertension, diabetes, elevated levels of high cholesterol or homocysteine, and atherosclerosis (hardening of the arteries) of the blood vessels that supply the brain
Symptoms of stroke include weakness, numbness, or inability to move an arm or leg; sudden and intense headache; severe dizziness or loss of coordination and balance; difficulty with speaking or understanding; and blurred or decreased vision in one or both eyes. People with stroke may also have seizures, vomiting, drooling, and difficulty swallowing. Some people experience temporary warning episodes of neurologic symptoms called transient ischemic attacks (TIAs) before suffering a complete stroke. People experiencing symptoms suggestive of having suffered a stroke or a TIA require immediate (emergency room) medical attention.
Dietary changes that may be helpful for stroke
Researchers have found an association between diets low in potassium and increased risk of stroke.1 2 3 People who take potassium supplements have been reported to have a low risk of suffering a stroke.4 However, the association of increasing dietary potassium intake and decreasing stroke mortality only occurred in black men and hypertensive men in one study.5 Others have found an association between increased risk of stroke and the combination of low dietary potassium plus high salt intake.6 Increasing dietary potassium has lowered blood pressure in humans, which by itself should reduce the risk of stroke.7 However, some of the protective effect of potassium appears to extend beyond its ability to lower blood pressure.8 Maintaining a high potassium intake is best achieved by eating fruits and vegetables.
Diets high in fruit and/or vegetables are associated with a reduced risk of stroke, according to most studies.9 10 In a large preliminary study, cruciferous and green leafy vegetables, as well as citrus fruit and juice, conferred the highest degree of protection.11 Because it is not clear which components of fruits and vegetables are most responsible for the protective effect against stroke, people wishing to reduce their risk of stroke should rely primarily on eating more fruits and vegetables themselves, rather than taking supplements.
A large study also found that women who eat higher amounts of whole grains are at lower risk of ischemic stroke.12 Those women who ate more than one whole-grain food on an average day (twice the amount of fiber eaten by the average American) had approximately a 35% lower risk of suffering an ischemic stroke compared with women who ate virtually no whole-grain products on an average day. This study fits with previous research showing that women who consume more whole grains are also at reduced risk for heart disease caused by atherosclerosis.
The influence of dietary fat on the risk of stroke is not as clear as it is for heart disease risk. Some recent reports suggest an association between increased fat intake, including saturated fat (primarily found in meat and dairy), and a decreased stroke risk.13 14 These unexpected findings may be due to unique dietary conditions in the country studied (Japan) or to flaws in study design.15 16 17 Other evidence suggests the opposite relationship—that people consuming more saturated fat are at higher risk of stroke.18
Evidence regarding the role of unsaturated fats (primarily found in vegetable oils, cooked and processed foods made with vegetable oils, nuts, and seeds) is equally unclear,19 20 21 suggesting that unsaturated fats may have varying effects on different types of stroke or that some unsaturated fats differ from others in their influence on stroke risk.
Evidence is accumulating in favor of fish consumption, a rich source of omega-3 fatty acids, as a way to help prevent stroke. Eating fish has been linked to reduced stroke risk in most,22 23 24 but not all,25 26 studies.
High salt intake is associated with both stroke27 and hypertension, a major risk factor for stroke.28 Salt intake may increase stroke risk independent of its effect on blood pressure.29 Among overweight people, an increase in salt consumption of about 1/2 teaspoon (2.3 grams) per day was associated with a 32% increase in stroke incidence and an 89% increase in stroke mortality.30 Reducing salt intake is recommended as a way to reduce the risk of stroke.31
Having one or two drinks per day has lowered stroke risk in most studies,32 33 though some researchers report no protection34 and others find that even light drinking leads to an increased risk of stroke.35 Regular heavy drinking or binge drinking, however, has consistently raised the risk of suffering a stroke by increasing blood pressure and causing heart muscle abnormalities and other effects.36 37 38
Lifestyle changes that may be helpful for stroke
Smoking is associated with a significantly increased risk of stroke.39 40 41 Even secondhand smoke puts nonsmokers at increased risk.42
Exercise reduces the risk of stroke according to most,43 44 45 46 though not all,47 studies. The benefits of exercise are probably due to its effects on body weight, blood pressure, and glucose tolerance.
Obesity has been associated with an increased risk of stroke in most studies.48 49 Excess abdominal fat appears to be more directly linked to increased risk of stroke, compared with fat accumulation in the thighs and buttocks.50 51 52 While losing weight and keeping it off is difficult for most people, normalizing weight with a healthful diet and exercise program is one of the best ways to reduce the risk of many diseases, including stroke.
Nutritional supplements that may be helpful for stroke
Vinpocetine given by intravenous injection has been reported to improve some biochemical measures of brain function in stroke patients.53 54 A controlled trial found intravenous vinpocetine given within 72 hours of a stroke reduced some of the losses in brain function that typically follow a stroke.55 However, the reliability of human stroke research using vinpocetine has been questioned,56 57 and more double-blind trials are needed. No studies using oral vinpocetine for treating acute strokes have been published.
Elevated blood levels of homocysteine, a toxic amino acid byproduct, have been linked to risk of stroke in most studies.58 59 60 What is not clear, however, is whether high homocysteine levels cause strokes or are simply a marker for some other causative factor. Supplementation with folic acid, vitamin B6, and vitamin B12 generally lowers homocysteine levels in humans.61 62 63 Whether lowering homocysteine will result in a decrease in the risk of suffering a stroke, however, remains unknown.
Narrowing of the neck arteries (carotid stenosis) caused by atherosclerosis is a risk factor for stroke. Preliminary diet studies have found that people who eat foods high in antioxidants such as vitamin C and vitamin E have less carotid stenosis.64 65
In a double-blind trial, people with atherosclerosis in the carotid arteries were given a palm oil extract containing 160–240 mg of tocotrienols (a vitamin E-like supplement) and approximately 100–150 IU vitamin E per day. After 18 months, they had significantly less atherosclerosis or less progression of atherosclerosis compared to a group receiving placebo.66 Vitamin E plus aspirin, has been more effective in reducing the risk of strokes and other related events than has aspirin, alone.67 However, most preliminary trials have shown no protective effects from antioxidant supplementation.68 69 70 71 72 73 A large Finnish trial concluded that supplementation with either vitamin E or beta-carotene conferred no protection against stroke in male smokers,74 although a later review of the study found that those smokers who have either hypertension (high blood pressure) or diabetes do appear to have a reduced risk of stroke when taking vitamin E.75
People with high risk for stroke, such as those who have had TIAs or who have a heart condition known as atrial fibrillation,76 are often given aspirin or anticoagulant medication to reduce blood clotting tendencies. Some natural inhibitors of blood clotting such as garlic,77 78 79 fish oil,80 and vitamin E,81 82 may have protective effects, but even large amounts of fish oil are known to be less potent than aspirin.83 Whether any of these substances is an adequate substitute to control risk of stroke in high-risk people is unknown, and anyone taking anticoagulant medication should advise their prescribing doctor before beginning use of these natural substances.
Researchers have found an association between diets low in magnesium and increased risk of stroke, an effect explained partially, but not completely, by the ability of magnesium to reduce high blood pressure.84 Protection from stroke associated with drinking water high in magnesium has also been reported.85 Intravenous magnesium given immediately after a stroke has been proposed as a treatment for reducing stroke deaths,86 but results so far have been inconclusive.87
Are there any side effects or interactions with stroke?
Refer to the individual supplement for information about any side effects or interactions.