Mushrooms are superfood solution to lack of summer sun

The battle to prevent vitamin-D deficiency during the winter months, when there is not enough sunlight for the skin to make the vital nutrient, has a new ally – the humble button mushroom.

Scientists have found it is possible to boost levels of vitamin D in commercially-grown mushrooms by exposing them to short bursts of ultraviolet light either before or after harvesting. Tests show that vitamin D in the mushroom can be boosted to match levels typically found in vitamin D-rich foods, such as oily fish, liver and egg yolks.

Vitamin D deficiency has recently been implicated in a range of disorders and it is a particular problem for dark-skinned people because their skin cannot make enough of the vitamin in winter and it is difficult to eat enough of the foods that are rich in the nutrient.

Wild mushrooms are rich in vitamin D because they grow in daylight. Wild chanterelle, porcini mushrooms, and shitake mushrooms also contain relatively high levels because of their sunlight exposure. But button mushrooms are usually grown in the dark to preserve their white complexion. Exposure to ultraviolet light increases their vitamin-D levels about a hundredfold.