Fibre and Psyllium Husks Explained Simply

1. What Is Dietary Fibre and Psyllium?

Fibres are components of plant foods that the body cannot break down. Psyllium husk is the outer layer of the seeds of a plantain species. It swells strongly in water and forms a gel-like mass. Both are mostly used to support digestion and are added to foods.

2. Where Is It Found, and What Is It Made From?

Psyllium husk is contained in the seeds of Plantago ovata, a plantain species. It is the swellable portion of these seeds. Fibres occur in all plant foods. They are especially abundant in whole grains, legumes, vegetables, fruit, nuts and seeds. The husks are obtained by separating them from the seeds and grinding them.

3. What Does Dietary Fibre and Psyllium Do? What Research Shows

Gut Microbiome

Several controlled studies (with a comparison group) show that fibres change the gut flora. The frequency of individual bacterial groups shifts 31354143. The findings come predominantly from isolated fibre powders and fibre-rich foods. On psyllium husk itself there are only few studies, with mixed results 5033. The studies are mostly small and short.

Blood Lipids and Cholesterol

Several controlled studies and reviews show improvements in blood lipids and cholesterol. In several studies, psyllium husk lowered LDL cholesterol 614232646. In a review, oats and isolated beta-glucan lowered total and LDL cholesterol 8. In a review, inulin-type fructans lowered LDL cholesterol and triglycerides 5. However, some studies found no difference in LDL cholesterol 122845.

Blood Glucose and Insulin

In review articles, psyllium husks lowered fasting blood glucose and long-term blood glucose levels more than the control 1114. In review articles, isolated fibre supplements lowered fasting insulin and insulin resistance, meaning how poorly the body responds to insulin, in people with overweight 79. In healthy people, oat products blunted the rise in blood glucose after a meal more than white rice 48. In people with type-2 diabetes, cookies with psyllium husks lowered long-term blood glucose levels more than the same cookies without psyllium husks 44.

Satiety and Body Weight

The picture is mixed for satiety and body weight. Several reviews found an improvement in weight and body mass index from isolated soluble fibre powders 57910. In a review, psyllium husk also improved weight, body mass index and waist circumference 16. By contrast, reviews on psyllium husk in diabetes and on quinoa found no difference in weight and body mass index 1418.

Irritable Bowel Syndrome and Digestive Complaints

Psyllium husks lowered the severity of irritable bowel syndrome more than a dummy treatment (placebo), in adults 27 as well as in children 49. In children with functional abdominal pain, they relieved the pain and improved quality of life more than placebo 32. In adults with irritable bowel syndrome, quality of life did not differ from the placebo group 27. The form matters: in one study, bran did not lower the severity of symptoms, unlike psyllium husks 27.

Bowel Function and Stool Habits

Psyllium husk reduced the number of episodes in faecal incontinence more than placebo 29 and worked similarly to a common anti-diarrhoeal 38. In type 2 diabetes with chronic constipation, biscuits with psyllium husk relieved the complaints 44. Inulin increased stool frequency in functional constipation more than placebo 47. A review in older people found no difference in stool frequency, but less use of laxatives 19.

Tolerance and Adverse Effects

Tolerability was examined in several controlled studies, and the results are mixed. One study reported a bloated abdomen, bloating and discomfort with psyllium husk 45. With beta-glucan tablets, one of three dose groups had gastrointestinal complaints more often than the placebo group 28. A fibre-rich diet increased the risk of bloating 24. Little is known about how tolerability behaves with longer administration.

Other Investigations

In several studies with a comparison group, improvements were seen in some inflammatory values in the blood. For instance, certain inflammatory messengers fell in overweight adolescents who took psyllium husk 34. In women with a hormonal disorder of the ovaries, an inflammatory value improved with inulin 39. In women with migraine, attacks became less frequent, shorter and less severe with inulin, and depressive complaints improved more than with placebo 37. Many of these studies were small and short.

4. How Was Dietary Fibre and Psyllium Taken in the Studies?

In the studies, psyllium husk was examined as whole or ground husks, as granules and as a stirred-in powder. Foods enriched with psyllium husk such as biscuits were also used 2644. In addition, isolated fibres such as inulin, resistant starch, beta-glucan and fructo-oligosaccharides were included 8304142. Fibre-rich foods such as oats, avocado, almonds or a fibre-rich diet were also investigated 20243648. The forms and preparations examined are not interchangeable.

5. Is Dietary Fibre and Psyllium Safe? Side Effects in the Studies

In a placebo-controlled study in elevated cholesterol, psyllium husk was well tolerated 25. Other studies found no differences in intestinal complaints or adverse events 293640. The strength of evidence on tolerability is low. Little is known about longer administration and different dosages.

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