Teasing out the fibres

Written by Dr Frankie Phillips RD

What is the big deal about fibre?

Fibre is a type of carbohydrate that isn’t broken down in the gut, so it reaches the large intestine (colon) undigested. Research has revealed that eating enough fibre can help to keep the digestive system healthy, but may also help to reduce risk of cardiovascular disease, type 2 diabetes and some cancers, including colon cancer by up to 30%.1

Current recommendations are for adults to eat 30g fibre per day, but surveys including the National Diet and Nutrition Survey reveal that most people eat far less fibre than they should – only about 20g per day.

Fruits, vegetables, nuts, pulses and wholegrains all contain dietary fibre, and it’s now clear that mycoprotein, a sustainably produced, protein-rich, whole food source derived from the fermentation of fungus is also a good source of fibre.

Fill up on fibre facts

Fibre is in fact an umbrella term – there are several types of fibre, found in different amounts in different foods and exerting a range of actions on the body.

In simple terms….
Insoluble fibre adds bulk to stools and promotes the movement of material through the gut. It is found in wholewheat flour, wheat bran, nuts, beans and vegetables such as cauliflower, potatoes with skins and broccoli.
Soluble fibre ‘dissolves’ in water, forming a viscous gel-like substance. It can impact blood cholesterol and glucose levels. Oats, barley, peas, beans, apples, citrus fruits and carrots all provide soluble fibre.

But…dietary fibres can also be further classified as either polysaccharides (non-starch polysaccharides (NSP) and resistant starches) or oligosaccharides including fructo-oligosaccharides (FOS) and galacto-oligosaccharides (GOS) found in onions, garlic, chicory, beans and pulses.

NSP can be further classified as cellulose, which is found in wholegrains, vegetables, fruits, seeds, nuts, bran for example.

Other types of fibre include chitin (found in Quorn mycoprotein and fungi), hemicellulose, lignans (polyphenols), beta-glucans (found in oats/barley/mycoprotein), pectins, gums and mucilages (used in gelling agents, thickeners, stabilisers and emulsifying agents), as well as resistant starches (found in cooled potatoes, bananas, pulses, seeds).

In addition, some types of fibre can influence the types and amounts of bacteria in our gut, the gut ‘microbiome’. The breakdown of fibre in the gut creates more short-chain fatty acids (SCFA) which are a source of fuel (food) for our gut cells keeping the gut lining healthy, another hot topic in nutrition and health research.

Overall, dietitians and nutritionists advise eating a range of fibre-containing foods: a diverse variety of fibre-containing plant-based foods will provided the greatest health benefits.

Fungi fibre vs Plant fibre

Did you know that fungi and plants contain different types of fibre? Fungi contain chitin whereas plants contain cellulose. As a food derived from the fungus Fusarium venenatum, Quorn mycoprotein is high in fibre (containing 6g fibre per 100g). More than 80% of the fibre in Quorn mycoprotein is in the form of beta-glucan, a soluble source of fibre, while the remainder is chitin (an insoluble fibre).

Mycoprotein fibre and health

Studies comparing people who consume mycoprotein against non-consumers show that mycoprotein intake is associated with lower glycaemic markers, higher fibre intake, and higher diet quality scores.2 Recent data also reports improved acute blood sugar control and a potent satiety effect after eating mycoprotein3 . Other studies in humans have shown that mycoprotein consumption can lower circulating cholesterol concentrations.4 It is possible that these beneficial effects are attributable to the amount and type of dietary fibre present in mycoprotein.

Beta-glucan is of great interest, as studies show that beta-glucan in barley and oats seems to have a powerful effect on reducing blood cholesterol (for more information on diet and cholesterol management see HEART UK’s Ultimate Cholesterol Lowering Plan©). More evidence is needed regarding the potential impact of Quorn mycoprotein beta-glucan on circulating lipids as well as the potential for producing short-chain fatty acids- a hot area of investigation, which may give a clue to the mechanisms by which mycoprotein could deliver health benefits.

Less is known about the potential role of the chitin found in mycoprotein fibre. Chitin is not a common feature of Western diets and there have not been many studies investigating the effect of chitin on health, although the soluble fraction of chitin (chitosan) may have an impact on satiety and blood cholesterol levels.5,6

Whilst we wait for more data to become available on the role of mycoprotein in health, it clearly makes sense to consider including this high-fibre high protein food on the menu during fibre February!

1 Mayor, S. (2019). Eating more fibre linked to reduced risk of non-communicable diseases and death, review finds. BMJ, [online] p.l159. Available at: https://www.bmj.com/content/364/bmj.l159
2 Cherta-Murillo, A. and Frost, G.S. (2021). The association of mycoprotein-based food consumption with diet quality, energy intake and non-communicable diseases’ risk in the UK adult population using the National Diet and Nutrition Survey (NDNS) years 2008/2009–2016/2017: a cross-sectional study. British Journal of Nutrition, [online] 127(11), pp.1685–1694. Available at: https://doi.org/10.1017/s000711452100218x.
3 Cherta-Murillo, A., Lett, A., Frampton, J., Chambers, E., Finnigan, T. and Frost, G., 2020. Effects of mycoprotein on glycaemic control and energy intake in humans: a systematic review. British Journal of Nutrition, [online] 123(12), pp.1321-1332. Available at: https://pubmed.ncbi.nlm.nih.gov/32100651.
4 Coelho, M.O.C., Monteyne, A.J., Dirks, M.L., Finnigan, T.J.A., Stephens, F.B. and Wall, B.T. (2020). Daily mycoprotein consumption for 1 week does not affect insulin sensitivity or glycaemic control but modulates the plasma lipidome in healthy adults: a randomised controlled trial. British Journal of Nutrition, [online] 125(2), pp.147–160. Available at: https://doi.org/10.1017/s0007114520002524.
5 Mhurchu, C.N., Poppitt, S.D., McGill, A-T., Leahy, F.E., Bennett, D.A., Lin, R.B., Ormrod, D., Ward, L., Strik, C. and Rodgers, A. (2004). The effect of the dietary supplement, Chitosan, on body weight: a randomised controlled trial in 250 overweight and obese adults. International Journal of Obesity, [online] 28(9), pp.1149–1156. Available at: https://doi.org/10.1038/sj.ijo.0802693.
6 Bokura, H. and Kobayashi, S. (2003). Chitosan decreases total cholesterol in women: a randomized, double-blind, placebo-controlled trial. European Journal of Clinical Nutrition, [online] 57(5), pp.721–725. Available at: https://doi.org/10.1038/sj.ejcn.1601603.

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