Fiber is a necessary nutrient in the human diet, essential to a properly functioning digestive system. And while it's been known for some time now that a high-fiber diet is good for the heart due to its protective effects against heart disease and obesity, a new study shows that it could actually help people who have experienced a heart attack to live longer.
Researchers from Harvard University and Brigham and Women's Hospital analyzed the reported fiber intake of 2,258 women and 1,840 heart attack survivors, and found that the risk of dying in the nine years post-heart attack was 25 percent lower for those who consumed the most fiber in the study, compared with those who consumed the least.
And when looking solely at deaths from cardiovascular disease (such as heart attack, coronary heart disease, and stroke), the risk of dying over the nine year post-heart attack period was 13 percent lower for those who consumed the most fiber, compared with those who consumed the least.
The findings, published in the British Medical Journal, involved data from the Nurses' Health Study and the Health Professional Follow-up Study, where participants answered questions about lifestyle habits every two years.
Researchers found that fiber from cereal and grains in particular seemed to confer the survival benefits after heart attack.
"Possible mechanisms for the beneficial effects of a high fiber diet on coronary heart disease risk and mortality include reductions in systemic inflammation, lower serum low density lipoprotein cholesterol level, reduced lipid peroxidation, improved insulin sensitivity, overall better glycemic control, and a beneficial gut microbiota environment," the researchers wrote in the study.
In addition, they noted that many foods that are naturally high in fiber -- including whole grains and produce -- also contain a wealth of other nutrients, such as vitamins, antioxidants and phytochemicals, which could also affect health positively.
According to the Institute of Medicine, men age 50 and younger should get 38 grams a day of fiber, while women age 50 and younger should get 25 grams a day of fiber. Meanwhile, men ages 51 and older should get 30 grams a day, and women ages 51 and older should get 21. For an idea of how much fiber is in foods, a cup of black beans has 19.4 grams, while three-quarters of a cup of oatmeal has 7.7.
There are two kinds of fiber: soluble fiber, which dissolves in water and is known to decrease cholesterol levels, and insoluble fiber, which is what helps with stool bulk and promotes digestive movement. Many plant-based foods have both of these kinds of fiber in them, according to the Mayo Clinic.
Need even more reason to up your fiber game? Here are some recent findings linking high-fiber diets to improved health:
More fiber decreases risk of heart disease. A 2013 study in the British Medical Journal showed that upping fiber intake is associated with a lower risk of two kinds of heart disease: coronary heart disease (plaque buildup in the arteries) and cardiovascular disease (including heart attack, stroke, and heart failure). Specifically, increased soluble fiber intake seemed to be especially effective in lowering cardiovascular disease risk, while increased cereal fiber intake seemed to be especially effective in lowering coronary heart disease risk.
Got Type 2 diabetes? Adding fiber to your diet could help you. A meta-analysis published in the Journal of the American Board of Family Medicine showed that increasing intake of dietary fiber seemed to have beneficial effects in reducing fasting blood glucose and HbA1c among people with Type 2 diabetes. (HbA1c is an indicator of diabetes control, and looks at average blood sugar levels.)
Eating a high-fiber diet could protect you from stroke. A 2013 analysis of studies in the journal Stroke showed that the risk of stroke decreased 7 percent for every 7 more grams of fiber a person ate every day.
And overall, eating more fiber seems to be linked with living longer. A large study published in 2011 in the Archives of Internal Medicine examined fiber intake among 388,000 adults who answered questions about the frequency with which they ate 124 kinds of foods. The researchers followed up with them nine years later, and found that those who ate the most fiber over the study period had a 22 percent lower risk of dying in that period from any cause, compared with people who ate the least fiber.