Fibre & the Glycemic Index/Load
If you’ve ever seen a Registered Dietitian, you’ve likely heard of fibre. Fibre is one of those foods that most health care professionals recommend getting more of because of it’s myraid of benefits including improved bowel regularity & lower cholesterol levels. But what exactly is fibre & where exactly can it be found? Read on for more details!
Fibre is a type of carbohydrate found primarily in plant-based foods that passes through the digestive system unchanged (without being digested or broken down). There are 2 main types of fibre:
- Soluble fibre dissolves in water to form a gel-like substance. This type of fibre helps to lower blood cholesterol levels & improve blood sugar management. For example: oats, legumes, brown rice, psyllium, apples, apricots, oranges, etc.
- Insoluble fibre does not dissolve in water & moves through the digestive tract intact. This type of fibre helps stool move through the digestive tract more quickly to keep bowel movements regular (i.e decreases constipation). For example: wheat bran, whole grains, skin of fruits/vegetables, nuts/seeds, dates, prunes.
In indivuals living with diabetes, aiming to include more fibre in the diet is important as fibre DOES NOT raise blood sugars & helps to delay the digestion of food thereby slowing the rise in blood sugars after a meal. Including more fibre in the diet has also been linked to improved digestive health, decreased cholesterol levels & assists with improved satiety (you feel fuller for longer). A diet that is low in fibre has been linked to constipation, irritable bowel syndrome, heart disease, diabetes, bowel cancer, hemorrhoids & diverticulitis.
How Much Fibre Do I Need?
The amount of fibre that you need in a day varies depending on your age & gender. It is recommended that Canadian women aim for a minimum of 25 g of fibre daily while it is recommended that men aim for closer to 38 g of fibre per day. Many Canadians are only meeting half of this requirement.
Steps to Adding More Fibre to Your Diet:
- Increase fibre intake slowly! Increasing your fibre intake all at once may lead to bloating, gas and/or constipation.
- Increase fluid intake to help prevent bloating & constipation. Aim for 6-8 cups of water per day.
- When reading food labels, look for products made with whole wheat or whole grains (e.g. whole grain bread, brown rice, whole wheat pasta). Try to choose products with more than 4 g of fibre per serving.
- Choose whole fruits & vegetables instead of juice. Even 100% fruit juice does not have as much fibre as whole fruits/vegetables. Try to include more fruits & vegetables at your meals & snacks.
- Try adding beans/lentils to soups, casseroles or salads.
- Consider adding ground flaxseed, chia seeds or wheat bran to cereals or mix in a handful of nuts & seeds.
The Glycemic Index & Glycemic Load:
The Glycemic index (GI) is a tool which ranks food/drink on a scale of 0 to 100 based on how much it raises blood sugars after consumed. Foods that have a high GI increase blood sugars higher & faster compared to foods with a lower GI. Low GI foods are generally higher in fibre & therefore, take longer for the body to break down which leads to inceased satiety. There are 3 GI categories: low GI (55 or less), medium GI (56-69) & high GI (70 or more). There are many factors that can impact glycemic index:
a) Cooking – cooking can increase the GI rating of a food as starch molecules swell & soften making it easier to digest. For example: pasta cooked to el dente has a lower GI compred to pasta that is well cooked.
b) Processed Foods – highly processed foods are digested faster & tend to have a high GI rating. For example: Cornflakes have a higher GI compared to regular oatmeal.
c) Processng – Unprocessed foods have a lower GI rating as it takes longer to digest. For example: pumpernickle bread has a lower GI compared to white bread.
d) Fat/Protein Content of the Food – foods with a higher fat or high protein content have a lower GI rating because both slow down how quickly food is digested. Keep in mind however, higher fat foods are not always the most nutritious option. For example: a baked potato has a higher GI compared to potato chips!
e) Acid Content of the Food – acid present in food slows down how quickly food is digested. For example: sourdough bread.
In general, the more highly processed a food is or the quicker a food is digested, the higher the GI. Following a low GI diet has bee shown to decrease the risk of type 2 diabetes, heart diseas & stroke, helps you to feel fuller longer & may help to maintain or lose weight.
The glycemic load on the other hand is a measure that takes into account the amount of available carbohydrate in a food together with how quickly it raises blood sugar levels. Unlike the GI, the glycemic load takes into account how much fibre is in a food. As mentioned, fibre will not raise blood sugars & prevents blood sugars from rising as quickly after eating. For example: as per the GI, carrots & watermelon are considered high GI foods, however when compared to the glycemic load (taking into account fiber content + portion size), they are ranked as low.
Click here for more information on the glycemic index/glycemic load.