Should we eat mushrooms to prevent cancer?

Wild mushrooms in a pan

A study claims that eating 2 mushrooms a day can halve your risk of cancer. Is the research too good to be true?

From portobello to chestnut, from oyster to shiitake, mushrooms are eaten in many places around the world. High in protein, low in fat and sugar, the humble mushroom also contains fibre, minerals such as potassium and vitamin B.

But do mushrooms prevent cancer?

Exciting mushroom cancer study

Long enjoyed as part of a healthy diet, mushroom sales got a boost earlier this year following the publication of research by Pennsylvania State University. The research showed that people who eat two mushrooms a day (around 18g) have a 45% lower risk of cancer compared with those who do not eat mushrooms.

The research, published in Advances in Nutrition, looked at 17 cancer studies from 1966 to 2020, analysing more than 19,500 people who developed cancer.

But before you reach for the chanterelles, it’s worth considering whether this evidence is strong enough to make you change your diet.

Mushroom type and other unknowns

Although this research is interesting – and further demonstrates what we at World Cancer Research Fund have known for many years: that what we eat has an impact on our cancer risk – much is still unknown, including:

  • Do mushrooms lower risk for all cancers or just some?
  • Is the type of mushroom important?
  • Do raw and cooked mushrooms have the same effect?
  • Does dose (how many mushrooms you eat) matter?

John Richie, who co-authored the research paper, said: “Future studies are needed to better pinpoint the mechanisms involved and specific cancers that may be impacted.”

And that’s the key point – single research papers reveal lots of interesting things, but don’t necessarily prove anything on their own.

To be fair, the Pennsylvania research was a meta-analysis: they looked at research papers published by other people, rather than getting in the laboratory and putting mushrooms under the microscope themselves.

But it’s only when you put all the papers on cancer together – which we do with our Continuous Update Project, a database of scientific papers on many aspects of diet and cancer – that you get the proper picture. And that picture includes both:

  • epidemiological studies: looking at lots of people over many years to see how cancer rates compare between people who eat mushrooms and people who don’t.
  • mechanistic studies: looking at the biology of mushrooms and – much more complex – the biology of humans to see what happens in the body when people eat mushrooms and how that may prevent cancer cells developing.

So are mushrooms a superfood?

We can’t yet be sure whether mushrooms have a significant impact on a person’s risk of cancer. Helen Croker, our Head of Research Interpretation, says: “It’s important to consider mushroom intake within the broader context of a person’s diet and activity regime.

“Our reviews, which are the most comprehensive examinations of the impact of lifestyle factors on cancer risk, find some evidence that consuming fruit and vegetables might reduce the risk of several cancers, and they may also reduce the likelihood of gaining excess weight, which is itself a strong risk for several cancers.”

Our Diet and Cancer Report, which was published in 2018 using more than 20 years of evidence on nutrition and cancer, says it’s unlikely that any single food or drink causes or prevents cancer. Rather, the patterns of what we eat across our lives lower or increase our risk of getting cancer. And that is a message worth getting excited about.

> Fan of fungi? Click here to browse all our mushroom recipes