A team of researchers at Penn State University in the US has found that mushrooms contain unusually high amounts of two antioxidants that could help fight ageing and bolster health.

The study showed that mushrooms have high amounts of ergothioneine and glutathione, both important antioxidants, said Robert Beelman, professor emeritus of food science and director of the Penn State Center for Plant and Mushroom Products for Health.

"We found that, without a doubt, mushrooms are the highest dietary source of these two antioxidants taken together, and some types are really packed with both of them," said Beelman.

Beelman said when the body uses food to produce energy, it also causes oxidative stress because some free radicals – which cause damage to cells, proteins and DNA – are produced.

"There's a theory — the free radical theory of ageing — that's been around for a long time that says when we oxidise our food to produce energy there are a number of free radicals that are produced which are side-products of that action and many of these are quite toxic," said Beelman.

"The body has mechanisms to control most of them, including ergothioneine and glutathione, but eventually enough accrue to cause damage, which has been associated with many of the diseases of ageing, like cancer, coronary heart disease and Alzheimer's."

According to the researchers, whose findings have been published in Food Chemistry, the amounts of ergothioneine and glutathione in mushrooms vary by species, with the porcini mushroom containing the highest level. The more common mushroom types, such as the white button, had less of the antioxidants but higher amounts than most other foods. Cooking mushrooms did not seem to significantly affect the compounds.

Beelman said future research may look at any role that ergothioneine and glutathione have in decreasing the likelihood of neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease.

"It's preliminary, but you can see that countries that have more ergothioneine in their diets – countries like France and Italy – also have lower incidences of neurodegenerative diseases, while people in countries like the US, which has low amounts of ergothioneine in the diet, have a higher probability of diseases like Parkinson's Disease and Alzheimer's," said Beelman.

"Whether that's just a correlation or causative, we don't know, but it's something to look into, especially because the difference between the countries with low rates of neurodegenerative diseases is about three milligrams per day, which is about five button mushrooms each day."