Soluble or insoluble? Fibre of any type is not a glamorous topic, but lowly fibre is essential for gastrointestinal health, and it provides many other health benefits.
Often described as “roughage,” fibre was considered to be an inert part of food that simply passed through our intestinal tracts undigested, with little to offer in the way of nutrition. Over time, research has shown that fibre is an essential nutrient with widespread health benefits, making it a vital part of healthy eating. ?
What’s so great about fibre?
Many of us know fibre is important, but we may still be confused about exactly what it is and how it benefits us.
In the field of dietary research, several studies point to the intake of high fibre, particularly from whole grains, as an important dietary intervention for health maintenance. Whole grain foods are an excellent source of fibre, an indigestible carbohydrate, containing many bioactive compounds that offer protection from disease.
The fibre hypothesis
Interest in fibre’s health benefits began in the 1970s when physicians Burkitt and Trowell identified differences between disease patterns in Africa and the Western world. They observed that the Africans studied had a lower prevalence of heart disease, diabetes, and cancer than did Westerners. The researchers attributed this to the plant-based diet eaten by the African population, giving rise to the “fibre hypothesis” suggesting that whole grains, fruits, and vegetables provide fibre that is necessary for optimal health.
According to Canadian guidelines, healthy adults need 21 to 38 g of fibre daily. The average intake is currently about 14 g daily.
For improved health and digestion, both soluble and insoluble fibre should be consumed.
This type of fibre attracts water and turns to gel during digestion, which slows down the digestive process. This decreases the absorption of nutrients such as starch and sugar, resulting in lower cholesterol levels over time, as well as improved glucose tolerance.
On the other hand, insoluble fibre gives stool its bulk and speeds its passage through the gut. Like a sponge, it absorbs many times its weight in water, swelling up and eliminating feces, thereby regulating bowel function.
Benefits of consuming fibre
Fibre-rich foods contain antioxidants, magnesium, selenium, vitamin E, and phytic acid, which help maintain glucose and insulin homeostasis, while also suppressing oxidative damage and reducing inflammation.
Recent research indicates that a generous intake of dietary fibre reduces the risk of developing
- cardiovascular disease (CVD)
- certain gastrointestinal disorders
Multiple observational studies substantiate the protective effects of fibre on heart health. Seven cohort studies comprising over 158,000 individuals indicate that CVD prevalence is 29 percent lower in individuals with the highest intake of dietary fibre compared to those with the lowest intake.
Studies on the effects of increasing oat fibre intake on blood pressure resulted in a modest to moderate reduction in systolic and diastolic blood pressure.
Ischemic stroke has been shown to be reduced by 26 percent in other studies.
Hardening of the arteries
In one study of 229 postmenopausal women, six or more servings of whole grain products per week decreased coronary atherosclerotic progression, commonly called hardening of the arteries, by 40 percent.
Soluble fibres have significant cholesterol-lowering effects, as shown in studies using psyllium or oat beta glucan, where LDL (“bad”) cholesterol is reduced without affecting HDL (“good”) cholesterol. In the small intestine, these fibres increase viscosity and bind bile acids, decreasing their absorption and reducing the amount of cholesterol available for LDL synthesis.
Elevated blood lipid levels along with high insulin levels, excess abdominal fat, and high blood pressure are a constellation of factors describing metabolic syndrome. This condition has been shown to improve when fibre intake is increased.
The incidence of diabetes continues to rise worldwide. A wealth of evidence links high fibre intake with reduced glucose and insulin responses and increased insulin sensitivity. Recently, the Finnish Diabetes Prevention Study reported a trial in which individuals with the highest level of fibre consumption had a 62 percent reduction in the progression from prediabetes to diabetes over a four-year period compared to those with the lowest fibre intake.
Furthermore, glycemic control has been shown to improve in diabetics, reducing the need for medication and insulin in these individuals. Findings from a systematic review indicated a 26 percent reduction in the development of type 2 diabetes among individuals consuming three to five servings of fibre daily.
Whole foods are digested more slowly, allowing for greater nutrient absorption, and make us feel full sooner than processed foods do. Given that approximately 80 percent of people with type 2 diabetes are obese, weight loss is a high priority for diabetes management. A large French cross-sectional study of 5,961 subjects revealed that low fibre intake was associated with elevated body mass index and higher waist-to-hip ratios.
Dietary fibres elicit a wide variety of actions in the gastrointestinal tract, which is also our largest immune organ. In the colon, fermentable fibres interact with gut flora to promote healthy bacteria such as lactobacilli and bifidobacteria. These generate short-chain fatty acids that stimulate the immune system, aid in digestion, and facilitate the absorption of nutrients.
Constipation, acid reflux, and hemorrhoids are commonly prevented and treated with high fibre intake. Evidence also supports a reduced risk for developing colorectal cancer when a high fibre diet is consumed. The protective effects are due to the ability of fibre to dilute fecal carcinogens and bind carcinogenic bile acids, allowing for their excretion.
It’s abundantly clear that fibre-rich foods have health-protective benefits. These foods often have a low fat content, are rich in micronutrients, and exert a significant impact on the prevention and treatment of various diseases.
Drink more water
For optimal health, we should consume at least 25 g of fibre daily. Of equal importance when consuming more fibre is to drink eight to 10 glasses of water per day, as fibre absorbs water. Increase fibre consumption gradually to avoid bloating and abdominal cramps.
Research confirms the benefits of fibre. Incorporating this simple nutrient into our diet is a simple way to maintain good health.
Benefits of whole grains
Whole grains consist of bran, germ, and endosperm components. Refined carbohydrates typically retain the endosperm, but remove other biologically active agents such as fibre, vitamins, minerals, antioxidants, plant compounds such as lignans and phytosterols, as well as the bran and germ. It is these components, however, that benefit health through their effects on glucose balance, lipid and lipoprotein reduction, endothelial function, and other mechanisms.