Mushrooms can provide as much vitamin D as supplements – but only if you put them in the sun before you eat them
Mushrooms transform UV light into vitamin DSun-exposed mushrooms are as effective at boosting and maintaining vitamin D levels as supplements areHave to be in summer sun for 60 minutes to produce vitamin D – cooking doesn't reduce the vitamin level
17:11 GMT, 22 April 2013
21:00 GMT, 22 April 2013
Mushrooms exposed to the sun can provide as much vitamin D as a health supplement, a study has found.
Researchers recommend people take the fungi out of their wrapping and leave them outside for half an hour before eating.
Much like our skin, mushrooms transform ultraviolet light from the sun into the vitamin and continue to do so even after they have been harvested.
Eating mushrooms could provide as much vitamin D as swallowing a supplement – but you need to put them in the sun first
The nutrient is essential for the immune system, strong healthy bones and teeth and the absorption of calcium.
In the study, 30 adults were given a daily capsule for 12 weeks containing either 2,000 units of vitamin D, or sun-exposed mushroom powder with high-levels of the nutrient.
At the end of the trial, there was no significant difference in the participants’ vitamin D levels.
'These results provide evidence that ingesting mushrooms which have been exposed to ultraviolet light and contain vitamin D2, are a good source of vitamin D that can improve the vitamin D status of healthy adults.
'Furthermore we found ingesting mushrooms containing vitamin D2 was as effective in raising and maintaining a healthy adult's vitamin D status as ingesting a supplement that contained either vitamin D2 or vitamin D3,' said lead author Dr Michael Holick.
The findings were presented at the American Society for Biochemistry and Microbiology meeting in Boston and also published in the journal Dermato-Endocrinology.
While growers in the U.S. and Australia are increasingly exposing the fungi to sunshine or UV-light to boost levels of Vitamin D, it is not common practice in Britain.
But Dr Holick says mushrooms continue to produce the nutrient even after they are harvested as long as they are placed in direct sunlight.
Much like our skin, the fungi transform UV light from sunlight into the vitamin and continue to do so even after they are harvested
Consumers are advised to take the mushrooms – any variety will work – out of any wrapping and place them outdoors between the hours of 10am and 3pm for up to 60 minutes during the late spring and summer months.
'Yes, we are talking about regular mushrooms. Just take them out of the packaging and place them in the sunshine. It doesn't matter which way up they are, after about 30 minutes they should produce a good source of vitamin D,' he said.
Adults are recommended to take a maximum 2,000 units of the nutrient daily, according to the researchers.
One portion of the sun-exposed mushrooms provides around 400 units, but greater consumption could boost vitamin levels as much as a supplement.
And cooking does not affect vitamin levels, said Dr Holick. 'Many experts believe that cooking will not damage the vitamin levels, and it is perfectly stable with heat. If anything, it make it far easier to absorb the nutrient.'