Does beta-glucan help strengthen your immune system?

Beta-glucan stimulates the cells of your innate immune system, such as macrophages and natural killer cells. This has been measurably and clearly demonstrated in cell and animal research. However, that does not yet tell you how large that effect is in ordinary, healthy people: human studies yield encouraging but mixed results, and large clinical trials are still lacking.

The most compelling mechanism is what researchers call 'trained immunity'. Beta-glucan, particularly from yeast, can reprogram immune cells so that they respond faster and more powerfully to a subsequent infection. This reprogramming is epigenetic: chemical markings are, so to speak, left on the DNA that keep the cell in a more alert state. This has been well described in cell and animal models, and has also been partially confirmed in humans. One controlled human experiment even showed that beta-glucan could 'reactivate' immune cells after they had been put into a kind of numbed state by a previous severe infection.

In mouse studies, beta-glucan reduced the spread of cancer to the lungs and extended survival. It also offered protection against tuberculosis, but exclusively in animal models. Whether those findings translate to cancer patients or people with infectious diseases has not yet been clinically proven. Such mouse results are interesting, but no guarantee that the same will hold true in humans.

Beyond immunity, beta-glucan has also been reported to have beneficial effects on cholesterol, blood sugar and gut bacteria, but that falls outside the scope of the immune question. As a supplement aimed at supporting your immune system, the following applies: the biological mechanism is plausible and has been observed in humans to some extent, but it remains unclear which dosage and which source (oats, barley or yeast) is most effective for healthy adults.