Science-y Stuff

Psyllium fibre is a prebiotic. Prebiotics are non-digestible compounds that are food for healthy colonies of probiotics (good bacteria) that grow in the gut (1).

A thriving community of good gut bacteria is essential for healthy immune function. Your body is better able to fight infection, reduce inflammation, and maintain healthy tissue cells.

Gut bacteria can ferment a small portion of psyllium fibre which can produce short chain-fatty acids (SCFA), including butyrate. Research has linked SFCAs with a broad range of health benefits including reduced inflammation, maintenance of a healthy intestinal lining (to avoid leaky gut), and as a protective for intestinal cancers (3, 4).

In fact, treatment with psyllium for 4 months helped reduce digestive symptoms by a difference of 45% in people with inflammatory bowel disease (ulcerative colitis (UC)) compared to the placebo (1).

All types of fibre can be good for the heart. The American Heart Association (AHA) say that dietary fibre can improve cholesterol, and lower the risk of heart disease, stroke, type 2 diabetes, and obesity (1).

Water soluble fibres, including psyllium, could help reduce blood triglicerides, blood pressure and the risk of heart disease (1, 2).

A review of 28 trials found that taking a median of 10.2g of psyllium husk per day could effectively improve markers of heart health, including lowering LDL cholesterol. This can help reduce the risk of heart disease (1).

A 2020 review of 11 trials reported that psyllium could reduce systolic blood pressure by 2.04 mmHg. The authors recommend using psyllium to help treat hypertension (1). 

Psyllium is a bulk forming laxative. It works by absorbing water in the intestine helping to increase the size and moisture of stools. Psyllium is a double whammy for constipation relief and the treatment of diarrhoea (1, 2), and has demonstrated to be more effective than wheat bran on improving the moisture, total weight, and texture of stools (1).

One study showed that taking 5.1g of psyllium twice a day for two weeks significantly increased the water content and weight of stools, as well as the total number of bowel movements, in 170 individuals with chronic constipation (1). In another study, researchers treated eight people who had lactulose-induced diarrhoea with 3.5g of psyllium husk three times daily. Doing so increased their stomach emptying time from 69 to 87 minutes, with accompanied slowing in the colon, which meant fewer bowel movements (1).

Psyllium can both prevent constipation and reduce diarrhoea, effectively helping to normalise bowel movements. 

Psyllium binds to fat and bile acids, helping the body to excrete them. In the process of replacing these lost bile acids, the liver uses cholesterol to produce more. As a result, blood cholesterol levels decrease (1).

In one study, 47 healthy participants experienced a 6% reduction in LDL ("bad") cholesterol after taking 6g of psyllium each day for 6 weeks (1). In another study, reserachers showed taking 5.1g of psyllium twice a day for 8 weeks resulted in a decrease in total and LDL cholesterol, as well as in increase in HDL ("good") cholesterol in 49 people with type 2 diabetes (1).

Interestingly, a review of 21 studies reported that reductions in total and LDL cholesterol are dose dependent. This means greater results were observed with treatments of 20.4g of psyllium per day than 3.0g per day (1).

Fibres that form viscous compounds, including psyllium, can help control appetite and aid weight loss (1, 2). Psyllium may aid appetite control by slowing down stomach emptying and reducing appetite. Decreased appetite and calorie intake may support weight loss.

One study found that taking up to 10.2g of psyllium before breakfast and lunch led to significant reductions in hunger, desire to eat, and increased fullness between meals compared to a placebo (1). Another study showed that psyllium supplementation on its own, as well as paired with a fibre-rich diet, resulted in a significant reduction of weight, body mass index, and percentage of body fat (1).