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Could eating a fiber-rich apple a day keep the neurologist away, reducing your risk of stroke? That's the finding of eight epidemiologists at a research center in Great Britain who used a statistical tool called meta-analysis to consolidate the findings of eight clinical trials conducted in the UK, USA, and Australia between 1990 and 2012.
The researchers found general agreement among studies that eating just 4 grams of fiber every day offers significant protection against first stroke, and that the benefits of fiber for stroke prevention "kick in" at about 7 grams per day.
The British researchers, however, were reviewing the literature to find the minimum amount of fiber needed in a healthy diet for just one aspect of cardiovascular protection. Other studies have found that the maximum amount of fiber that confers additional disease protection is probably about 20 grams a day, the equivalent of 3 or 4 servings of high-fiber foods. (There's no reason not to eat more if you want to eat more, however.) This protects against many more diseases than just stroke.
- Choosing foods higher in fiber and lower on the glycemic index offers clear benefits for the prevention of type 2 diabetes in people who are obese or overweight, although the associations between glycemic index and diabetes prevention and fiber consumption and diabetes prevention are not clear in studies of normal-weight individuals.
- Researchers at the University of Tromsø in Norway have found a 23% reduction in the risk of heart disease in people who consume "fruits, vegetables, fish, and polyunsaturated fat" as a pattern of healthy eating.
- A specific kind of fiber known as beta-glucan lowers blood pressure and mitigates insulin resistance, the underlying metabolic problem in type 2 diabetes, high cholesterol, high triglycerides, hypertension, and diabetes.
- A number of studies suggest that including the kinds of fiber on which probiotic bacteria can feed into the diet helps prevent asthma, eczema, allergies, and ear infections in children.
- Insoluble fiber, the kind of fiber found in whole grains, is indigestible but absorbs water as it passes through the colon. This adds bulk to the stool and relieves constipation, while indirectly reducing the risk of colon cancer.
- Soluble fiber, the kind of fiber found in fruits and vegetables, has remarkable effects on the immune system. Some kinds of modified citrus pectin have demonstrated benefit in supporting remission from breast cancer and prostate cancer.
- Most kinds of soluble fiber lower cholesterol naturally by binding the cholesterol digested from food so it cannot pass into the bloodstream. Sometimes high-fiber diets lower LDL cholesterol by as much as 25%, although the benefit from adding fiber to the diet to control total cholesterol is usually limited to about 10%.
Eating more fiber usually does not, however, help dieters control their appetites.