Pleuran (Oyster Mushroom Beta-Glucan) for Respiratory Health

Pleuran, an insoluble beta-glucan from oyster mushrooms, has several randomised trials for preventing respiratory infections, though almost all come from one research group. In 175 children with frequent infections, 36% of those taking pleuran with vitamin C stayed infection-free during treatment, compared with 21% on vitamin C alone, and a 2025 trial in 249 children found 15% fewer infections over a winter.

The effect is modest: most children still caught infections, just fewer of them. Adult evidence is thinner, with one trial in athletes and a small study in COPD, and we found no large trials in the general adult population.

Pleuran's branched 1,3/1,6 glucose chains resemble the cell walls of fungi. Researchers describe it as acting through the receptors innate immune cells use to recognise microbes, mainly in the immune tissue of the gut.

In elite athletes, a hard 20-minute exercise bout cut natural killer cell activity by 28% during recovery in the placebo group, but not in those taking 100 mg of pleuran a day for 2 months. Over three months, pleuran also raised the number of circulating natural killer cells in athletes and kept phagocytosis, the engulfing of microbes by immune cells, steady while it fell on placebo. In children, a pleuran, vitamin D and zinc chewable raised salivary IgA within 8 to 10 days.

Immune markers moving in the right direction do not always translate into fewer infections, and the marker studies here were small or uncontrolled. The salivary IgA result, for example, came from a 49-child pilot without a comparison group.

Structure matters too. In endurance athletes, pleuran reduced upper respiratory symptoms while soluble oat beta-glucan did not, so pleuran's results cannot be assumed for other products on our beta-glucans page.

The children's trials dosed pleuran by body weight, 10 mg per 5 kg a day, usually combined with vitamin C. Adult studies used 100 mg a day, for 2 months in elite athletes and for 3 months, with vitamin C and zinc, in people with COPD. In the asthma trial, children aged 7 to 17 took two capsules of pleuran with vitamin C a day for 24 weeks.

Trials ran through the respiratory-infection season, from about 2 to 6 months. In the 2025 children's trial the effect was visible after the first month, and in a post hoc analysis children who started at the beginning of the season had fewer and shorter colds.

In a double-blind trial in 175 children (average age 5.7) who had more than five respiratory infections in the previous year, 36% of those taking pleuran with vitamin C had no respiratory infection during treatment, against 21% taking vitamin C alone, over a 12-month follow-up. Flu-like illness and lower respiratory infections were also less frequent.

A 2025 trial in 249 children with recurrent infections in Slovakia, the Czech Republic and Serbia compared a pleuran chewable with vitamin D and zinc against vitamin D and zinc alone for three winter months. Children on pleuran had 15% fewer infections (2.35 vs 2.77) and about 19% fewer colds, with clearer effects in children over 6 and fewer, shorter episodes of tonsillopharyngitis.

In 50 athletes, three months of pleuran reduced the incidence of upper respiratory symptoms compared with placebo. In an open-label, non-randomised study of 64 people with high-risk COPD, those who added 100 mg of pleuran to vitamin C and zinc for three months had fewer exacerbations (0.7 vs 1.0) that resolved faster (6.7 vs 7.4 days) than matched patients taking vitamin C and zinc alone.

In a randomised trial in 90 people with cold sores, pleuran shortened herpes symptoms. Over a 120-day prevention phase respiratory symptoms were milder, but only cough differed significantly from placebo.

Nearly every trial comes from the same group of researchers and tests branded pleuran products, and we found no independent replication. In the 2025 asthma trial (230 children), fewer respiratory infections appeared only in children aged 12 and over, an age subgroup rather than the whole trial.

Not every result is positive: in a small randomised trial in 27 children with acute gastroenteritis, pleuran did not shorten diarrhoea. Broader reviews are encouraging but not specific to pleuran: a systematic review of 34 trials of fungal beta-glucans reported fewer and milder respiratory infections, and a review of 12 studies in children found 10 that reduced infections, while calling for higher-quality trials.

Pleuran was well tolerated in the trials. In the largest children's trial, compliance was 98.7% and only mild side effects were reported; the asthma trial reported no related serious adverse events over 48 weeks; and a systematic review of 34 trials of fungal beta-glucans found no adverse events caused by them.

Safety in pregnancy and breastfeeding has not been studied. Because pleuran is meant to stimulate immune responses, people on immunosuppressive treatment should not use it without their specialist's agreement.

We found no published interaction studies for pleuran. The main theoretical conflict is with medicines that deliberately suppress the immune system. The vitamin C, vitamin D and zinc given with it in the trials caused no reported problems.