Updated: Nov 20, 2019
Fibre has been getting some interesting backlash in nutrition headlines lately. Some people encourage a lot of fibre while others are saying to never eat fibre because it's detrimental to human health. Let's dig in and see what nutritional science has to say about fibre.
Fibre is a type of carbohydrate, that the body CAN'T digest, therefore it goes through the body undigested. Fibre is found in plant foods such as vegetables, whole grains, fruit, beans and legumes. There are 3 types of fibre. Soluble, insoluble and resistant starch.
Insoluble fibre absorbs water, to help soften the contents of the bowels and helps to support regular bowel movements. It helps to keep us full and healthy.
Soluble fibre is the bulking fibre, it does not absorb water, I like to call it the broom. It draws water out of the gut and helps elimination run smoothly. It cleans everything up!
Resistant starch assists in the production of good bacteria in the large intestine and improves bowel health. Basically, your gut bacteria need to be fed and resistant starch is their food. As you can see fibre has a big job in relation to our gut and overall health. It keeps our bowel movements in check and running smoothly. Fiber appears to reduce the risk of developing various conditions, including heart disease, diabetes, high cholesterol, diverticulitis and in some cases constipation. Often fibre can get a bad reputation in the nutrition world because people like to point out that fibre rich foods, AKA plant foods contain anti-nutrients, which can be hard to digest for some people. Like in the book "Plant Paradox" or by many people who advocate for a plant-free diet. Here is a great video explaining why a lectin-free diet is unnecessary. Now, this super scary word is nothing to be scared of at all. More on anti-nutrients like lectins and phytic acid here and how to cook and prepare plant foods to get the most nutritionally. Now lets get to the data! There are many studies that show how effective a diet high is fibre is at reducing coronary heart disease and type 2 diabetes. There was a study done on men that showed a diet high in whole grains was associate with a reduce risk of type 2 diabetes. Similarly, a study that followed 75,521 women aged 38-63 for 10 years, showed that eating a diet high in refined carbohydrates with very little fibre, increased their risk of coronary heart disease. Another study showed that over a 6-10 year follow up, total dietary fiber was associated with a 14% decrease in risk of all coronary events and a 27% decrease in risk of coronary death for both men and women. In a Harvard study of over 40,000 male health professionals, researchers found that a high total dietary fiber intake was linked to a 40 percent lower risk of coronary heart disease. A related Harvard study of female nurses produced quite similar findings.
Fibre has been show to reduce cholesterol, in a meta-analysis of 67 controlled trials various soluble fibers were shown to reduce total and LDL cholesterol by similar amounts. A common age related disorder is diverticulitis which is inflammation of the intestine. One study analyzed 43,881 US male health professionals, 40-75 years of age. Their findings showed that a diet high in dietary fiber decreases the risk for diverticular disease by 40%. That is quite a large reduction! Another awesome benefit to fibre is that it has been shown to greatly reduces the risk of colon cancer. There are many studies that show the correlation in a high fibre diet and lower colorectal cancers this like this study and this one. Now where things get a little tricky is when we talk about constipation, which is one of the most common digestive issues people in the western world face. A common thought has always been that one of the major reasons for constipation, is a low fibre diet. Fibre that increases the water content of stool has a laxative effect meaning it will help to move the elimination process. Where fibre that does not increase the water content of the stool may have a constipating effect. Some studies show that increasing fiber can improve symptoms of constipation, but other studies show that removing fiber improves constipation. The effects depend on the type of fiber. Prunes and psyllium husk are great options for any one dealing with constipation. In one preliminary study of 63 people with chronic constipation showed that going on a low fibre diet fixed their constipation while the people who didn't change their diet continued to have the same issues. Every body is different and some people will benefit from a diet full of fibre rich foods like legumes, vegetables and fruits and others will have a harder time digesting large amounts of them. As you can see there are many benefits to including fibre in your diet in a way that feels best for your body. I have yet to find a study that shows that fibre is detrimental to one's health.
Plant foods are some of the healthiest foods you can consume, not only do the contain fibre but they also contain phytonutrients, vitamins and minerals that are essential for optimal health!