- Two recently published studies have suggested a link between vegetarianism and depression.
- The study focused on a Brazilian population, while the other involved a large group of Britons.
- However, both studies have limitations worth noting and more research is needed before firm conclusions can be drawn.
Two recent studies have suggested a link between meatless diets and depression, but some experts believe further research is needed to confirm these findings.
The only study published this month in Journal of affective disordersfound that vegetarians experienced depressive episodes twice as often as meat eaters. The findings were based on a survey that analyzed responses from just over 14,200 people between the ages of 35 and 74 in Brazil.
A questionnaire was used to determine if people followed a meatless diet, while a diagnostic tool, called the Clinical Interview Schedule-Revised (CIS-R), was used to determine if people had episodes of depression.
The link, the researchers wrote, was independent of lifestyle and socioeconomic factors, such as physical activity, smoking, alcohol consumption and body mass index (BMI). The exact reason for these findings is unclear.
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“Depressive episodes are more frequent in people who do not eat meat… The nature of the association remains unclear and longitudinal data are needed to clarify the causal relationship,” they wrote.
The authors hypothesized that the link may be due in part to nutrient deficiency, as previous research has shown it to be the most common cause of a depressed immune system.
For example, researchers from a The 2020 study noted that “The health of the immune system is greatly affected by a person’s nutritional status.” Certain foods, including excessive consumption of sugar and allergenic foods, can depress immune function, they said, while dietary factors that enhance immune function include all essential nutrients, antioxidants, carotenoids and flavonoids.
But in the recent study, the team did not find this association.
the second studio
In another study, also recently published and Journal of affective disordersthe researchers found that “beef consumption may causally reduce the risk of major depression.”
The study included health data on more than 440,000 people in the UK, 45,000 of whom had depression. Beef was the only food linked to a lower risk of depression.
The team of psychiatrists, from National Taiwan University, Massachusetts General Hospital and other centers, said how beef might protect against depression isn’t exactly clear, but they suggested that nutrients found in beef, including protein, iron, zinc, and B vitamins are known to help brain function and may be behind the protective effect.
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However, they also noted that “potential mechanisms need to be investigated further to support our new findings.”
But researchers at Harvard University in 2017 reported that “A dietary pattern characterized by high consumption of fruits, vegetables, whole grains, fish, olive oil, low-fat dairy, and antioxidants and low consumption of animal-source foods was apparently associated with a lower risk of depression.”
However, a diet rich in red or processed meats, refined grains, sweets, high-fat dairy products, butter, potatoes and high-fat sauces, and a low intake of fruits and vegetables were associated with an increased risk of depression. , they added.
Experts disagree
The most recent research has led some experts to question the findings and methodologies.
Mary Mosquera-Cochran, a registered dietitian at The Ohio State University Wexner Medical Center, told Healthline that Because the researchers in the Brazilian study analyzed the data, rather than conducting a controlled experiment, it’s hard to say with any firmness that a vegetarian diet causes depression.
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“The researchers found that diet quality was somewhat associated with higher rates of depression, but did not fully explain the association,” said Cochran, who was not involved in the study.
In addition, he noted that the same study sample had a very small percentage of people who were actually vegetarians: only 82 people out of about 14,200 people.
“The authors note that it is currently estimated that between 5% and 14% of Brazilians follow a vegetarian-style diet, so this sample may not reflect all vegetarians in Brazil either,” Cochran said.
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While the team found no link between nutrient deficiencies and depression in this study, another expert told Healthline that it was certainly possible.
“Any time a person excludes an entire food group—in this case, sources of protein and fat—and fails to replace it with equally nutritionally adequate options, it will affect a range of systemic and physiological functions, such as human health. cognitive,” said Monique Richard. , spokesperson for the Academy of Nutrition and Dietetics. She explained that it was important to delve into the dietary patterns of these people to confidently exclude nutrient deficiencies.
“If a person doesn’t have adequate intake of nutrients like B12, omega-3 fatty acids, and protein, certain enzymes and proteins can be compromised, disrupting specific pathways in the body,” Richard said. “This could affect mood, anxiety, memory, perceived stress, sleep, etc.”
