Mushrooms can reduce the risk of breast cancer by 64 per cent—as WDDTY's March issue revealed—and they can also keep you mentally sharp as you get older. Two servings a week reduce the risk of mild cognitive decline (MCI)—such as occasional memory loss or concentration lapses—by around 50 per cent. MCI is generally seen as early-stage dementia. Although nobody is quite sure why mushrooms have such a therapeutic effect, researchers think it's to do with a compound called ergothioneine that is in most types of mushroom. Researchers from the National University of Singapore tested various mushrooms—such as golden, oyster, shiitake and white button—on a group of 600 people aged 60 and older for six years. The researchers tested the group on a range of cognitive, language and visuospatial skills after they had eaten different amounts, and types, of mushrooms. They discovered the optimum amount for MCI protection was one serving, which equates to three-quarters of a cup of cooked mushrooms or 150 g, twice a week. The mushrooms' protective effects were "surprising and encouraging", the researchers said.