Why You Need To Get More Fibre
The Standard American Diet is dangerously low in fibre, and yet no one seems to be too concerned. They should be. Learn all about fibre and why YOU (yes, you) need to be eating more of it in today's blog post!
WHAT IS FIBRE?
Fibre is the structural component of plants (the equivalent of an animal's muscles and bones) that humans cannot digest, often known as roughage. Any transformation that occurs to the fibre we eat is due to the bacteria in our guts, rather than our own digestive system. There are two types of fibre: soluble and insoluble.
Soluble fibre is found in oats, legumes, vegetables, barley, and fruits and is great for reducing blood glucose and cholesterol in the body as well as preventing diarrhea.
Insoluble fibre is found in whole grains, nuts, fruits, and vegetables. This type of fibre prevents constipation and certain types of cancer.
WHY DO WE NEED IT?
Fibre is a necessity for a healthy diet. It:
- helps to control blood glucose;
- reduces the risk of obesity due to its ability to increase satiation;
- regulates bowel movements;
- manages blood pressure and cholesterol (reducing the risk of heart disease), and;
- reduces the risk of cancer.
Not too shabby, eh?
Fibre and Heart Disease
Fibre is inversely associated with the incidence of coronary heart disease, in other words, the more fibre you eat the less likely you are to suffer from heart disease. This is due to fibre's positive impact on heart health by reducing bad cholesterol (LDL) and managing blood pressure.
How does fibre reduce cholesterol? Viscous soluble fibre (found in barley, oats, sea vegetables, shiitake mushrooms, cherries, grapes, berries, citrus fruits, and other foods) has the ability to bind with cholesterol in the intestine, preventing its assimilation into the body by eliminating it in the stool instead.
Check out this study for more detail!
Fibre and Diabetes
From the Canadian Diabetes Association website:
'Soluble fibre may help control blood sugar by delaying gastric (stomach) emptying, retarding the entry of glucose into the bloodstream and lessening the postprandial (post-meal) rise in blood sugar. It may lessen insulin requirements in those with type 1 diabetes. Because fibre slows the digestion of foods, it can help blunt the sudden spikes in blood glucose (sugar) that may occur after a low-fibre meal. Such blood sugar peaks stimulate the pancreas to pump out more insulin. Some researchers believe that a lifetime of blood glucose (sugar) spikes could contribute to type 2 diabetes, which typically strikes after the age of 40, and more than doubles the risk of stroke and heart disease.'
Another great aspect of high-fibre meals? Their positive impact on blood sugar levels can continue for hours, even after other meals have been eaten. And there's something else - high fibre meals have been shown to significantly increase production of the blood sugar reducing hormone glucogon-like peptide 1 (GLP-1). This GLP-1 response is triggered not by the presence of soluble fibre, but by the products created through the fermentation of fibre by bacteria in the large intestine.
Essentially, if you want to control your blood sugar, you want to eat more fibre.
Fibre and Obesity
Fibre is well-known to increase satiety without adding calories and therefore encourages the maintenance of a healthy weight. This is largely due to fibre's effect of the speed of gastric emptying, in other words, fibre slows down the digestion process, keeping you full for longer. It also lowers the caloric density of the diet, meaning that a higher volume of food can be consumed for the same amount of calories.
Another benefit of fibre-rich foods for satiation? They often require more chewing than low-fibre foods - and the more you chew, the more satiated you feel. Cool, right?
Fibre and Colon and Bowel Health
It's time to talk about soluble and insoluble fibre again! You can't get off THAT easily.
Soluble fibre is broken down in the gut by colonic bacteria resulting in energy and gas. This type of fibre produces a gel-like substance in stool which binds to other substances (such as cholesterol) and removes them when the stool is eliminated. It also slows and regulates gastric emptying (as I previously mentioned) which results in more regular bowel movements.
Insoluble fibre is not so easily broken down in the gut, however it holds water extremely well (up to 15x its weight) and therefore aids in increasing the weight and size of stool as well speeding up the rate of food passage through the digestive system.
Consuming the right types of fibre in the proper amounts can aid in reducing the symptoms of IBS including abdominal pain, constipation, diarrhea, incomplete evacuation, and excessive gas. Learn which types of fibre aid in resolving each symptom here.
What about colon health?
Fibre aids our colons by directly fuelling the good bacteria in our gut. When you eat a low-fibre diet you are literally starving your gut bacteria, which you need to stay healthy. Different species of bacteria feed on different types of fibre, so eating a wide variety of plant foods is imperative for bacterial balance.
Another way that fibre supports the health of our colon is in their digestion by bacteria. This results in short-chain fatty acids which are then used by the cells of our large intestinal wall as fuel. Without this fuel the cells lining our colon cannot carry out their metabolic activities, and cannot support normal intestinal function.
Fibre and Cancer
A study conducted in 2010 (among others, such as this one) found a clear inverse-association between dietary fibre intake and colorectal cancer risk, meaning the more fibre that was consumed by the subjects, the lower their risk of developing colorectal cancers.
But why does fibre have this effect?
Well, we're not yet entirely sure. What we do know is that scientific evidence for this phenomenon has been accumulating since the 1970s, when the hypothesis was proposed by Denis Parson Burkitt, an Irish surgeon, that dietary fibre reduces the risk of colorectal cancer. This was based on his observation that rural Africans eating a high-fibre diet had low rates of these cancers.
'Several plausible mechanisms have been proposed to explain the hypothesis, including increased stool bulk and dilution of carcinogens in the colonic lumen, reduced transit time, and bacterial fermentation of fibre to short chain fatty acids.' (From the introduction of this 2011 study.)
More and more researchers are delving into this field of study, giving us hope that a definitive answer will be found soon!
HOW MUCH DO WE NEED?
You already know where you can get fibre. It is not found in any animal foods, but is present in abundance in plant foods such as vegetables, fruit, legumes, nuts, seeds, and unprocessed grains.
How much we need, however, is a slightly more complicated question. It is, in fact, possible to ingest too much fibre (which can lead to bloating, abdominal pain, increased gas, and diarrhea), but how much is too much? The conservative recommendation for dietary fibre consumption is 25-30g per day, but as a person on a whole foods plant based diet I eat more in the range of 70-80g of fibre a day (while experiencing none of the aforementioned side-effects of too much dietary fibre).
Many experts in the plant based nutrition field see this daily recommendation as more of a bare minimum than an optimal range, and as there has been no upper limit of safe dietary fibre consumption set, see it as a 'more is better' type of situation. I tend to agree with them. The best way to know if you're ingesting too much fibre is to be in tune with your own body and watch for the signals it gives you. However, from my extensive research I have come to the conclusion that it would be VERY difficult indeed to ingest too much dietary fibre without vastly surpassing your daily calorie needs.
In other words, have at it!
I hope you enjoyed this post and learned a little more about fibre than you knew before!
Until next time,
How much fibre do you get in a typical day? Have I convinced you to up that amount?
SOURCES & FURTHER READING