Shedding light on the humble mushroom

Exposing the fungus to ultra-violet rays could provide an important source of vitamin D for sun-starved Irish bodies

COULD LIGHT-TREATED mushrooms help plug the vitamin D gap in the Irish population? An ongoing study at University College Dublin is putting them to the test.

The research is looking at whether eating field mushrooms that have been exposed to ultra-violet light to boost their vitamin D levels can have an effect on a person’s vitamin D status and other biochemical markers in the body.

Vitamin D, also known as the “sunshine vitamin” because we make it in our skin following exposure to the sun, is important for healthy bones, cell growth and the immune system.

But previous research by the nutrition group at UCD’s Institute of Food and Health showed that many Irish adults are lacking in vitamin D, according to Dr Anne Nugent, a lecturer in human nutrition at the institute.

“That work found that approximately half of the adults studied had sub-optimal vitamin D status,” she says. “And we are now looking to see if people with low vitamin D levels have alterations in some of their markers of metabolic and immune function compared to people who have normal vitamin D status.”

One of the issues in Ireland is the poor quality of sunlight in winter months, explains Nugent. “ is one of the most efficient ways the body can make vitamin D. But in Ireland, especially between November and February, it’s not going to happen – the sun isn’t high enough in the sky.”

Vitamin D is present in some foodstuffs, such as oily fish, butter and fortified margarines and milks, and the current study is looking at whether bumping up levels of the vitamin in mushrooms could offer another dietary route to improving vitamin D status in Irish adults.

Working with Monaghan Mushrooms, the approach is to irradiate the fungi with ultra-violet light. This converts ergosterol within the mushrooms to vitamin D2.

Studies in animal models show that eating such UV-treated mushrooms can increase levels of vitamin D circulating in the body, but published studies in humans have been limited to date.

So the UCD researchers are working with 80 volunteers to look at the impact of eating the powdered UV-treated mushrooms every day for four weeks.

“It’s about a half a teaspoon,” explains Nugent, who is working on the project with Prof Mike Gibney and Dr Lorraine Brennan. “Many people choose to sprinkle it on their stir-fry or into a gravy or sauce, or put it into a drinking yogurt.”

Participants, who are aged between 45 and 60, give a blood and urine sample at the start and end of the trial and are divided into groups that take the UV-treated mushrooms, ordinary mushrooms, a vitamin D3-containing capsule or a placebo capsule.

“We are looking at circulating levels of vitamin D and we would also like to look at some other markers,” says Nugent.

Some studies suggest that vitamin D2 – the type in these mushrooms – is not as effective as the vitamin D3 form in humans, but Dr Nugent says the jury is still out on that question.

“We have to look within our own population,” she says. “Our mushrooms are vitamin-D2 enriched but our capsule supplement is vitamin D3, so we will be able to look within our own group and see how they relate to one another.

“I think it’s hard to judge when you are looking at the very different studies, so we will be able to see what’s relevant for our population.”

The dietary intervention study is funded by Monaghan Mushrooms Ltd in collaboration with the Mushrooms and Health Global Initiative.