Mushrooms may soon be weapons in the fight against dementia and Alzheimer's disease. Many of them contain bioactive compounds that may increase nerve growth in the brain and protect against inflammation and other neurotoxins.

A study published in the Journal of Medicinal Food explained that previous research has examined the benefits of mushrooms in fighting cancer and cardiometabolic disease, such as diabetes.

Researchers found evidence indicating a potential role of mushrooms as functional foods — a food that has a positive effect on health beyond its basic nutrition — to reduce or delay development of age-related neurodegeneration.

"Very few studies have focused on food that may benefit neurodegenerative diseases," says Journal of Medicinal Food Editor-in-Chief Sampath Parthasarathy, Ph.D. "The current study might stimulate the identification of more food materials that are neuroprotective."

The study's authors said that mushrooms contain "diverse, yet exclusive, bioactive compounds that are not found in plants. It is very likely that a dietary intake of mushroom or mushroom-based extracts might have beneficial effects on human health and improve brain function."

"A number of edible mushrooms have been shown to contain rare and exotic compounds that exhibit positive effects on brain cells both in vitro and in vivo," they wrote.

The discovered that the extract of lion's mane mushroom (H. erinaceus) had positive effects on brain cells without being toxic, and also helped brain cells recover from damage and injury, especially in the early stages of recovery. One study found that taking H. erinaceus for four months improved the cognitive function of aging Japanese men and women who suffered with mild cognitive impairment.

Researchers at Taiwan's Chang Gung University studied the mushroom Ganoderma lucidum, known to Chinese herbalists as Lingzhi and in Japan as reishi, and found it slows weight gain. Mice that were fed a high-fat diet weighed 42 grams after two months. But mice who were fed the same high-fat diet as well as the mushroom extract weighed only 35 grams.

Mushrooms have also been found to boost the immune system — and ordinary white button mushrooms are as effective as exotic Asian varieties. A study from Tufts University found that button mushrooms contain polysaccharides along with other substances that jump-start the immune system. Besides boosting immunity, the study showed they raise levels of cytokines, which are hormone-like proteins that help defend against viruses and tumors.

Mushrooms have been used in folk medicine for thousands of years to treat asthma, diabetes, and heart problems.