Penn State professor emeritus of food science and director of the Center for Plant and Mushroom Foods for Health Robert B. Beelman, Ph.D., has spent much of his career paying attention to mushrooms — in particular, how eating them might protect the human brain from dementia and other forms of cognitive decline. “It may be possible to decrease the incidence of neurological diseases by increasing mushroom consumption,” he wrote last year in The Conversation. His latest paper, published earlier this year inNutrition Today, further highlights the connection.
Beelman is careful to say there is no proven causative link between mushroom consumption and protection against dementia and other chronic neurodegenerative diseases, although a 2017 study showed that “frequent mushroom consumption is significantly associated with a lower risk of incident dementia,” and earlier this year another study found that participants who consumed mushrooms had “reduced odds of having mild cognitive impairment.” The week of our interview, an additional study found that eating mushrooms “may reduce the risk of memory problems,” as the New York Times’ coverage put it.
I spoke with Beelman, 75, who is now “retired” but still doing research through collaborations, about what the latest research means and whether mushroom coffee is worth considering.
How would you summarize the potential cognitive or neurological benefits of eating mushrooms?
I should say that none of this is totally proven. But I’m mainly interested in some of the micronutrients that are in mushrooms — the ones that are either already there or the ones that can be caused, like if you UV-treat mushrooms to produce vitamin D.
But the big micronutrient they contain, and what especially interests me regarding neurological benefits, is this antioxidant called ergothioneine.
Yeah, that’s what made me want to talk to you. What is it?
It’s a naturally occurring chemical compound. As far as we know, it’s only made in nature by fungi, blue-green algae, and a few soil-borne bacteria. And of course mushrooms are just a big ball of fungus. So mushrooms have a lot of ergothioneine in them — far more than any other food we know of.
I got interested in ergothioneine and its potential to mitigate chronic neurodegenerative disease for a number of reasons, but one of them was that the biochemist Barry Halliwell and his group at the University of Singapore had published a different paper a few years ago, in which they showed that as people aged, the levels of ergothioneine in their blood dropped significantly. He found that people who had the steepest decline in ergothioneine had the highest incidence of cognitive impairment.
A similar study was done with people with Parkinson’s disease, and it also found that people with Parkinson’s disease have a lower level of ergothioneine in their blood than age-matched normal people. So things started to point to the brain. And we do know that this compound passes the blood-brain barrier, which a lot of other things don’t do.
A big breakthrough occurred back in 2005, when a German pharmacology professor at the University of Cologne discovered that all mammals make a genetically coded, highly specific transport protein for this molecule.
For the ergothioneine.
Right. Including humans. As soon as ergothioneine is consumed, let’s say in mushrooms, within an hour the ergothioneine is in your red blood cells. And then it gets distributed around the body, and it generally accumulates in the tissues that are in the highest oxidative stress. Being an antioxidant, that makes sense.
I just published a paper in the journal Nutrition Today about the micronutrients and bioactive compounds in mushrooms. I don’t know if you’ve seen that.
Right, so there was another paper that came out a couple of years ago, where they estimated the ergothioneine consumption in people from five different countries: the United States, Finland, Ireland, France, and Italy. I don’t know why they chose those five, but they took their data and calculated how much ergo that would amount to on average for the average person — how many milligrams per day were consumed by an average 150-pound person. It came out like the United States was 1.1 and Finland was 1.3, and the highest was Italy with 4.6, and the other two countries were in between.
It made me want to find data on the incidence of neurodegenerative diseases by country, and sure enough you can get that. In this case, I got data on Parkinson’s and Alzheimer’s/dementia. When you compare the amount of ergothioneine consumption estimated versus the incidence of these diseases, you get this curve where the United States and Finland are up very high as far as the rate of disease, and low in the ergo consumption. And it just sweeps right down, with Italy at the highest ergo consumption and lowest incidence of these diseases. So it looks like there could be a relationship there.
I also did it for Japan, and it fits the curve. And then if you do life expectancy, you get the opposite kind of curve. Finland and the United States have the lowest life expectancy of the countries considered, and it increases with ergo consumption, with Italy being the highest of the group and Japan being even higher. So again, this doesn’t really prove anything, it’s definitely not conclusively cause and effect, but it makes you wonder if there’s something there.
There are some epidemiological studies that have been done, with the one in Singapore being the latest. There are three of those now, involving large numbers of people, and they show that as people consume more mushrooms, they have lower levels of either cognitive impairment or dementia.
All of these point to the same kind of hypothesis that we’re proposing here. Of course, the epidemiological studies were done with whole-mushroom consumption and not ergothioneine in isolation, but it seems to probably be one of the primary bioactive components in the mushrooms that are causing this effect.
What would be the next move to figure out more of this?
What I want to see is a human clinical trial. I’m pretty sure Halliwell’s group in Singapore is doing something exactly like that with pure synthetic ergothioneine. Most scientists follow a reductionist philosophy, where they want to know exactly what’s causing something. In other words, what’s the silver bullet in the mushrooms? So they want to use the pure compound. And I understand that philosophy. But being a food scientist, I usually take the whole-food approach. And so I’d like to do the same thing but with some high-ergothioneine mushrooms and then make powders out of them, and then you could capsulize them or something like that.
I was involved in a human clinical trial with vitamin D–enriched mushrooms a few years ago at Icahn School of Medicine at Mount Sinai. We were looking to see if we could take vitamin D–deficient people and make them replete with vitamin D by giving them vitamin D–enriched mushrooms.
But we also studied the participants’ ergothioneine levels, too.
How did you do that?
We supplied about 40 people in the NYC area with seven frozen meals a week. They were entrées made by a chef, and each contained 100 grams of mushrooms. So the participants ate 100 grams of mushrooms a day — these were button mushrooms.
How many mushrooms would that be?
That’s about five or six average-size white button mushrooms. And they would have been sliced up and cooked, and then of course these meals were frozen. Anyway, the long and short of it was that between starting the experiment and 16 weeks later, the ergothioneine level in their blood doubled. This was plasma, since we didn’t have any whole blood at the time. It was what we call a retrospective study, since studying the ergothioneine wasn’t the primary goal of the experiment and it was done after the fact.
Anyway, the ergothioneine level doubled during that time, and then it started to drop back down toward normal after they stopped eating the meals with mushrooms. A number of other biomarkers were also measured, and some of the ones that cause inflammation followed the opposite pattern. In other words, their level of these inflammatory compounds decreased during the 16 weeks when the participants were eating mushrooms, and after going off it they went back up.
So it appeared as though something in the mushrooms was reducing the level of these pro-inflammatory compounds. And of course inflammation is what causes basically every chronic disease.
I was especially interested in the study that found a specific transporter in the body that appears to be there only to pick up ergothioneine. Broadly speaking, it seems to suggest that our bodies want or even need us to eat mushrooms, sort of like having a lock for which only mushrooms are the key. I like this lock-and-key image. What do you think?
Well, that’s pretty close.
The transporter is a very specific protein that does lock up to ergothioneine and move it through cell membranes to get into the cells. Ergothioneine is a very water-soluble compound, and normally it wouldn’t be able to pass through the cell membrane because of solubility factors. But when the ergo hooks up with this transporter protein, it’s able to pass through the membrane, then that releases the ergo into the cell. So it’s pretty close to what you’re saying.
You mentioned that ergothioneine levels are high in all mushrooms but that they’re especially high in porcini mushrooms. What are the best mushrooms to eat?
Well, like everything in biology, there’s a lot of variation, although it just so happens that the white button mushroom, which is the most popular mushroom in the United States, has the lowest amount of ergothioneine of all the ones we’ve tested. And porcini, which has the highest amount, can’t be cultivated, as luck would have it. It grows in the wild. As of now, anyway! Ha! Somebody will probably figure that out.
But while button mushrooms always have quite a bit less than some other mushroom varieties, they still have quite a bit more than any other food we’ve been able to test.
So grocery-store button mushrooms are still a good source of this.
Yes, they are.
The other thing I’m interested in is that everyone has ergo in their blood; I’m pretty positive everybody has it in their blood. Half the people don’t eat mushrooms, though, so where are they getting it?
My hypothesis is that fungi and some of the bacteria that make ergo are in the soil, and plants pick it up through their roots. And then of course animals eat the plants, and it gets into the human food chain that way. But the amount that’s in all these other foods, like meat, is quite small compared with the amount that’s in mushrooms. And so I’ve been wondering if our agricultural practices — which are devised to produce as much food as possible as cheaply as possible — have perhaps compromised the populations of these microorganisms in the soil. And if there are therefore fewer of these microorganisms for plants to pick up.
To test this, we did a collaboration with people at the Rodale Institute, which studies organic regenerative agriculture. We compared oats that were grown organically with oats that were grown conventionally — oats are one of the foods that are known to have more ergo than others. And we found that oats grown in no-till soil produced about 25 percent more ergo than the oats grown in conventional, tilled soil. We repeated this again the following year and found the same thing. But a lot more needs to be done.
What does your own mushroom intake look like?
My wife and I eat them maybe about two or three days a week, but I take mushroom-powder capsules every day, and she does as well. I make a lion’s-mane powder, which has gotten a lot of interest now, and she puts some in her coffee.
I think mushroom coffee is taking off a bit, trend-wise. I recently saw a story in The Guardian about mushroom teas and coffees and then another one in Outside. I also saw mention of a mushroom shampoo …
Yeah, I think that’s true. I’ve seen companies that sell all kinds of coffee preparations, and I think it’s catching on.
I was just at a mushroom conference in Orlando three weeks or so ago. Another telling detail was that there were three different investor-type people checking out opportunities, looking at the potential for mushrooms as an investment. And in the last couple of years, there’s been some rather large acquisitions of some of the more prominent mushroom companies by some of these holding companies.
I think if I can hang on a few more years [laughs], there’s going to be a major trend of interest here.