Dietary fiber comes from plants, the part that our body does not absorb when digesting food. Fiber can be insoluble or soluble (dissolves in water). No fiber can be digested. However, soluble fiber as it goes through the digestive tract, changes its form when it is fermented by bacteria. Soluble fiber absorbs water and becomes gelatinous as it does so. However, the form of insoluble fiber remains unchanged as it goes through the gut.
According to prior studies, dietary fiber can help reduce some of the risk factors associated with stroke, including hypertension and high blood levels of LDL (low-density lipoprotein), also known as "bad cholesterol".
In this latest study, the team found that for every seven-grams more fiber we consume daily, our risk of first time stroke goes down 7%. Seven grams of pasta may be found in one serving of whole wheat pasta plus two servings of vegetables or fruit.
Co-author, Diane Threapleton, M.Sc., and Ph.D. candidate, said:
"Greater intake of fiber-rich foods - such as whole-grains, fruits, vegetables and nuts - are important for everyone, and especially for those with stroke risk factors like being overweight, smoking and having high blood pressure."
The researchers gathered and analyzed data from eight studies published between 1990 and 2012. Four of the studies focused on ischemic stroke, which occurs when a blood clot blocks the flow of oxygen-rich blood to the brain. Three focused on hemorrhagic stroke, when a blood vessel leaks blood into the brain or on its surface.
The authors combined the findings from the eight studies and factored in variables that may influence stroke risk, such as smoking and age.
The American Heart Association and UK health authorities recommend that adults consume 25+ grams of dietary fiber each day. Americans eat much less than this. The average British adult only consumes 14 grams of fiber per day.
In order to get your twenty-five plus grams, you need to consume 6 to 8 servings of grains and 8 to 10 servings of vegetables and fruits daily.
"Most people do not get the recommended level of fiber, and increasing fiber may contribute to lower risk for strokes. We must educate consumers on the continued importance of increasing fiber intake and help them learn how to increase fiber in their diet."
Stroke in the USA - stroke is directly connected to 137,000 deaths each year in the USA. It is the fourth leading cause of death in the country. Stroke is also a leading cause of disability among those who survive strokes.
Stroke in the UK - approximately 150,000 people in the UK have a stroke each year. It is the third most common cause of death. And as in the USA, it is a leading cause of disability among survivors.
Apart from consuming an adequate amount of dietary fiber each day, the American Heart Association recommends that people get plenty of exercise and not smoke if they want to minimize their risk of stroke and other heart and vascular diseases.
Study leader, Dr. Victoria Burley, from the School of Food Science and Nutrition, University of Leeds, said "Increasing your fiber intake doesn't necessarily mean wholesale change to your diet. It might just mean switching from white bread to wholemeal (whole grain), or from corn flakes to bran flakes. It's a simple measure with a lot of benefits."
The study was funded by The Department of Health (England) and Kellogg Marketing and Sales (UK) Limited.
Fruits, vegetables, nuts and whole grains are important for adequate dietary fiber intake
In an Abstract in the journal, the authors concluded:
"Greater dietary fiber intake is significantly associated with lower risk of first stroke. Overall, findings support dietary recommendations to increase intake of total dietary fiber. However, a paucity of data on fiber from different foods precludes conclusions regarding the association between fiber type and stroke. There is a need for future studies to focus on fiber type and to examine risk for ischemic and hemorrhagic strokes separately."
Plant sources of fiberSome edible plant products are high in both soluble and insoluble fiber. For example, the skins of plums and prunes are a good source of insoluble fiber, while their pulps are rich in soluble fiber.
The following are good sources of soluble fiber:
- Legumes, including beans, lupins, peas, etc.
- Oats, barley, rye and chia
- Some fruits, such as the pulp of apples and pears, plums, berries, bananas (ripe), prunes (and prune juice)
- Some vegetables, including carrots, broccoli, and Brussels sprouts
- Root vegetables and tubers, including onions and sweet potatoes
- Some seeds, such as psyllium seed husk and flax seeds
- Nuts, e.g. almonds are very high in soluble fiber
- Whole grains
- Wheat and corn bran
- Legumes, including peas and beans
- Seeds and nuts
- Potato skins
- Some vegetables, including celery, nopal (a Mexican cactus), zucchini (courgettes), cauliflower, and green beans
- Some fruits, such as bananas (unripe)
- The skin of some fruits, such as tomatoes (they are fruits) and kiwifruits
Other benefits of a high-fiber dietStudies over the last couple of decades have demonstrated a range of health benefits associated with high-fiber diets. Below are some examples:
Eating a high-fiber diet, especially whole grans and cereal, is associated with a lower risk of colorectal cancer, researchers from Denmark and Great Britain reported in the BMJ.
The authors gathered and examined data from 25 prospective studies involving nearly two million participants. Their findings showed a clear gradient in risk associated with the amount of dietary fiber intake.
Women can lower their risk of breast cancer if they increase their dietary fiber intake, scientists from the Department of Nutrition and Food Hygiene, School of Radiation Medicine and Public Health, Soochow University, Suzhou, China, reported in the American Journal of Clinical Nutrition.
They found that women who ate the most dietary fiber had an 11% lower risk of breast cancer compared to their counterparts who at the least. They added that it appears that a high fiber diet is linked to better overall health, and it is the better health that reduces the cancer risk, rather than just the fiber itself.
- Your risk of dying for any reason is reduced if you follow a high-fiber diet, researchers from the National cancer Institute explained in Archives of Internal Medicine.
They added that a high fiber diet helps reduce the risk of death from respiratory, infectious and cardiovascular diseases.
- A team of scientists from the University of Scranton, Pennsylvania found that popcorn is rich in antioxidants and fiber. It is unusual that snack foods get the health vote, but it appears that popcorn contains significant amounts of fiber and polyphenol, a type of antioxidant known to lower the risk of heart disease, cancer and other diseases.
- A team from Northwestern Medicine demonstrated that a high-fiber diet could be a vital heart-healthy lifestyle change for young and middle-aged adults to make. The researchers, who presented their findings at the American Heart Association's Nutrition, Physical Activity and Metabolism/Cardiovascular Disease Epidemiology and Prevention Scientific Sessions 2011 in Atlanta, Georgia, in March 2011, found that people aged from 20 to 59 years with the highest fiber consumption had a considerably lower estimated lifetime risk of cardiovascular disease compared to individuals who ate the least fiber.
Dietary fiber boosts the immune system - investigators from the University of Illinois found that a diet high in fiber reduces inflammation linked to obesity-related diseases and strengthens the immune system.
Professor Gregory Freund said "Soluble fiber changes the personality of immune cells - they go from being pro-inflammatory, angry cells to anti-inflammatory, healing cells that help us recover faster from infection."