- A new study from Penn State finds an association between eating mushrooms every day and a lower likelihood of experiencing depression.
- Mushrooms contain several substances reported to have antidepressant qualities.
- This research sets the stage for further study regarding a causal link between the consumption of mushrooms and a reduced risk of depression.
Researchers at Penn State College of Medicine in Hershey, PA, have been investigating the potential health benefits of eating mushrooms.
In May 2021, they published a study that suggested a connection between mushroom consumption and a lower risk of cancer. They also published a study that found an association between eating mushrooms and being less likely to experience premature death. The researchers have now published a third mushroom study.
The study suggests that people who eat moderate amounts of mushrooms are less likely to experience depression.
There has been little research into mushrooms’ possible antidepressant properties. Previous studies were small clinical trials involving fewer than 100 participants.
According to study co-author Dr. Joshua Muscat, Ph.D., M.P.H., an epidemiologist at Penn State Cancer Institute, “The study adds to the growing list of possible health benefits of eating mushrooms.” Dr. Muscat also told Medical News Today, “We had the opportunity to look at this in a larger, nationally representative study.”
Dr. David Crepaz-Keay, from the Mental Health Foundation, was not involved in the recent study but assessed it for MNT.
He reported: “The authors have a strong track record in research in this area, using an important dataset for interesting research. The study is high quality, and the conclusions are measured and reasonable. But the area of food and mental health is still a difficult one.”
The study now appears in the Journal of Affective Disorders.
What the investigation found
For the study, each of the 24,699 participants completed questionnaires on two occasions. For these questionnaires, they recalled all the foods they had eaten during the previous 24 hours.
The participants who were most likely to be mushroom eaters were college-educated, non-Hispanic white women.
The overall incidence of depression among the entire study cohort was 5.9%.
Mushroom eaters constituted 5.2% of the participants. The researchers divided these mushroom eaters into three groups according to the extent of their mushroom consumption.
Those who ate a median amount of mushrooms (4.9 grams [g] per day) were the only group to experience a reduction in the likelihood of depression.
Curiously, the researchers did not observe a similar reduction in depression for those who ate the most mushrooms (19.6 g each day), suggesting that a median intake constitutes the sweet spot for relief from depression.
On the other hand, Dr. Muscat speculated, “The number of study participants [who] consumed a half-a-serving size of mushrooms or more was quite small, so it could just be statistical variation.”
“Alternatively,” he added, “if mushrooms prevented depression, you would expect to see a greater effect in those who consumed the most, so either the protective effect in the middle consumption group is not real, or there are other factors that are obscuring the association in the highest tertile that we just don’t know about.”
Possible underlying mechanisms
The researchers hypothesize that the antidepressant properties of mushrooms may be related to specific compounds present in the fungi.
As lead study author Dr. Djibril Ba, Ph.D., M.P.H., suggests: “Mushrooms are the highest dietary source of the amino acid ergothioneine — an anti-inflammatory, which cannot be synthesized by humans. Having high levels of this may lower the risk of oxidative stress, which could also reduce the symptoms of depression.”
Mushrooms also contain antioxidants, which — according to the authors of the study — some believe have antidepressant qualities.
Another possible influence may be the presence of potassium. This is present in button mushrooms, which are the most popular mushroom variety in the United States. Some research links potassium to a reduction in anxiety.
The researchers also explain that some mushrooms, such as lion’s mane, or Hericium erinaceus, “can stimulate the expression of neurotrophic factors, such as nerve growth factor (NGF) synthesis, which could have a potential impact on preventing neuropsychiatric disorders including major depression.”
MNT spoke with Dr. Uma Naidoo, a Harvard-trained nutritional psychiatrist, professional chef, nutrition specialist, and author of the national bestseller This is Your Brain on Food. We asked Dr. Naidoo, who was not involved in the study, which other foods can support mental health.
She replied, “In regard to depression, the three key nutrients or foods to be included in the diet are folate, omega-3s, and fermented foods.”
“Additionally,” said Dr. Naidoo, “I encourage everyone to be getting plenty of fiber in their diet through a variety of colorful vegetables and berries, and to be cooking with herbs and spices, for overall improved mental health and reduced risk of cognitive decline with age.”
The researchers’ caveats
The researchers cite a few limitations of their study.
First, the analyzed data did not capture exactly which mushrooms people were consuming, eliminating any chance of identifying the relative antidepressant value of individual mushroom types.
Second, the participants’ mushroom intakes were calculated using U.S. Department of Agriculture (USDA) recipe codes, which may or may not accurately reflect the participants’ own recipes. According to the study authors, “This includes misclassification of mushrooms as vegetables and inaccurate assessment of mushroom content in the mixed dishes.”
Finally, the dependence on 24-hour self-reported food intakes may or may not have been sufficiently accurate, say the researchers. “Such non-differential measurement error may have underestimated the association between mushroom intake and risk of depression,” they note.
Still, the study has value. “We get the best scientific evidence from highly controlled randomized trials that compare intervention groups [with] control groups over a period of time,” Dr. Naidoo told MNT.
“This study is certainly a starting point in better understanding the impact of dietary mushrooms on improving symptoms of depression. [It] helps enforce the idea that plant foods rich in vitamins, minerals, and antioxidants are associated with positive mental health, and it opens up new directions for higher level research.”
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