For people with prediabetes and diabetes, fibre is an essential dietary component.iStockPhoto / Getty Images
Diets plentiful in fibre have been tied to a lower risk of heart disease, stroke, Type 2 diabetes, colorectal cancer, breast cancer and diverticulitis.
A high-fibre diet has also consistently been shown to promote a healthy gut microbiome, which plays a crucial role in overall health.
And for people with prediabetes and diabetes, fibre is an essential dietary component that helps control blood glucose levels.
Here’s what to know about fibre and blood sugar, plus a list of fibre- and nutrient-packed foods that, as part of a healthy diet, can help stabilize glucose levels.
How fibre helps control blood glucose
There are two types of dietary fibre: soluble and insoluble. Both are present in varying proportions in different foods, but some foods can be rich in one or the other.
While both support blood glucose control, studies suggest the metabolic benefit is greatest for viscous (sticky) soluble fibre.
A 2019 review of 28 clinical trials conducted by Canadian researchers found that consuming an average of 13 grams of soluble fibre daily significantly reduced hemoglobin A1c levels in people with Type 2 diabetes.
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A hemoglobin A1c test measures your average blood glucose level over the past three months. It’s used to diagnose prediabetes and diabetes, as well as help guide diabetes management.
Once consumed, viscous soluble fibre dissolves in water to form a gel-like substance in your stomach, slowing the rate food is emptied into the small intestine.
Doing so, in turn, delays the absorption of carbohydrates (glucose) into the bloodstream, which helps prevent blood sugar spikes after eating.
Soluble fibre is also fermented by gut microbes, which leads to the production of short chain fatty acids, beneficial compounds shown to improve hemoglobin A1c and the secretion of insulin.
How much fibre?
Health Canada recommends adults, ages 19 to 50, consume 25 g (women) and 38 g (men) of total fibre each day. Older women and men are advised to consume 21 g and 30 g daily, respectively.
More recent research has suggested that consuming at least 30 g of fibre per day is needed to guard against heart disease, stroke, Type 2 diabetes and colorectal cancer.
Aim to include at least 10 g of fibre in each meal.
Fibre-rich foods to support blood glucose control
Foods high in viscous soluble fibre include oats, barley, pulses, carrots, okra, eggplant, berries, citrus fruit, apples and pears. Psyllium husk powder is also an excellent source.
In addition, consider adding the following five foods to your regular diet. Besides lots of fibre, they supply other key nutrients that play a role in balancing blood sugar.
Lentils. One cup of cooked lentils provides 15.6 g of fibre, both soluble and insoluble, along with 18 g of satiating protein, low glycemic carbohydrates and a decent amount of magnesium, a mineral that helps regulate insulin secretion.
A cup of lentils also delivers 90 per cent of a day’s worth of the B vitamin folate. Studies conducted in people with Type 2 diabetes suggest folate helps improve the body’s ability to effectively respond to insulin.
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Blackberries. This dark coloured berry provides 7.5 g of fibre per one cup. Because so much of the carbohydrate in blackberries comes from undigested fibre, a one-cup serving provides only 6 g of net carbohydrates. (Net carbs are the amount of carbohydrates that your body can absorb.)
Blackberries are also a good source of vitamin C (30 mg per cup), a nutrient that promotes insulin sensitivity by reducing oxidative stress and inflammation.
Raspberries are a great alternative, providing nearly identical amounts of fibre, net carbs and vitamin C.
Chia seeds. Two tablespoons of these tiny seeds deliver 10 g of fibre, 5 g of protein and 95 mg of blood-sugar-regulating magnesium. (Women and men need 320 mg and 420 mg of magnesium, respectively.)
Chia seeds are also an outstanding source of alpha linolenic acid (ALA), an anti-inflammatory omega-3 fat; you’ll find more than one day’s worth in a tablespoon.
Ground flaxseed, also a food source of fibre and ALA, provides more soluble fibre than chia seeds.
Green peas. Per one cup, these legumes offer 9 g of fibre, nearly one-third of it soluble fibre, and 8.5 g of protein. Thanks to their fibre and protein content, green peas are ranked low on the glycemic index scale.
Plus, they’re good sources of several nutrients that support insulin sensitivity, including magnesium, zinc, folate and vitamin C.
Artichoke hearts. One half-cup of artichoke hearts contains 5 g of fibre, including a good amount of inulin, a viscous soluble fibre. Inulin also acts as a prebiotic, feeding beneficial gut bacteria.
You’ll also find folate and magnesium – and only 5 g of net carbs – in a half-cup of artichoke hearts.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on X @LeslieBeckRD
