Mushrooms are a source of many important vitamins and minerals including B vitamins, iron, potassium and selenium.
Recent research has also discovered that they are a prime natural source of the powerful antioxidant L-Ergothioneine. Led by Professor Robert Beelman, researchers at Pennsylvania State University found that just a handful of white button mushrooms have about 12 times more of the antioxidant than wheat germ and four times more than chicken liver which were previously thought to the be the best sources. L-Ergothioneine scavenges free radicals and protects the body’s DNA from damage. As a result of this research, the university advocated that white mushrooms be elevated to 'superfood' status.
Mushrooms are in fact one of the highest antioxidant vegetables in the world, in the same league as the red capsicum and spinach. Research led by Joy Dubost, also at Pennsylvania State University, found that cultivated mushrooms contain another antioxidant polyphenol which plays a role in protecting the body’s DNA against free radicals.
The white button mushroom is often considered to be the poor relation to its more exotic cousins. But new research from The French Institute of Agricultural Research which compared the antioxidant activity of button mushrooms and the exotic maitake and matsutake mushrooms, found that the white button mushroom has as much, and in some cases more antioxidant properties than more exotic varieties. (Published in the SCI's Journal of the Science of Food and Agriculture, October 2007)
Meanwhile, research published by Hanyang University in South Korea found eating mushrooms may lower the risk of breast cancer. The research was based on more than 700 women, half of whom had the disease. The group who had mushrooms everyday were estimated to have an 80 per cent reduced risk of cancer. It was thought the fungi interfered with the action of aromatase, an enzyme that helps the body make oestrogen. White button mushrooms had the strongest effect.
A similar study on mice by researchers at the City of Hope, California (published December 2006) found that when the rodents were fed mushroom extract they had a 58 per cent reduction in breast cancer growth. White flat mushrooms had the strongest effect, with shiitake, white button, Portabello and crimini mushrooms also having significant inhibitory effects on aromatase, even when cooked.
The Glycaemic Index (GI) of mushrooms is so low it can’t even be measured. In fact, to get a GI measurement in mushrooms you would need to eat 1.2kg in less than 10 minutes! Mushrooms are also a useful source of protein for vegetarians.
An 80g serving, around 14 baby button mushrooms, four large closed cup mushrooms or one large flat mushroom counts towards the 5-A-DAY target.