WeeklySA_AdminCONDITION: Research suggests that diet may play an important role in mental health – particularly one rich in polyphenols and natural whole foods may help regulate cognition, emotion, and mood. However, further research into this relationship is necessary…
By Jessica Caporuscio and Ruth Eagle
Research into the effect of diet on mental health has noted that people who follow a standard Western diet, which includes highly processed foods and added sugars, have a higher risk of developing anxiety and depression.
Although the majority of the research to date has focused on the benefits of the Mediterranean diet, other dietary patterns may also have a positive effect on mental health.
In this article, we review some of the evidence that indicates a healthy diet may improve mental health and help treat or prevent certain conditions. We also explore how food affects a person’s mood.
Can diet help with mental health?
Nutritional psychiatry, also known as psychonutrition, is a new field of study that focuses on the effect of diet on mental health.
Most studies in this area have focused on the effects of the standard Western diet and the Mediterranean diet. A 2022 review looked at the existing body of research on diet, nutrition, and mental health.
The review suggests that a diet heavy in highly processed foods and lacking a variety of natural, plant-based foods may increase the risk of mental health conditions. It also indicates that people who follow a Mediterranean diet or similar diets such as MIND and DASH may be less likely to experience mental health conditions.
Researchers have also looked into how nutrition might affect mental health, focusing on the hippocampus.
The hippocampus is an area of the brain that generates new neurons in a process called neurogenesis. Research has linked neurogenesis in the hippocampus to a person’s mood and cognition.
Factors that can negatively affect neurogenesis in adults include: aging, oxidative stress, diets high in fat and sugar, alcohol and opiates.
Healthy foods and habits appear to promote neurogenesis. These include:
• Diets that include polyunsaturated fatty acids (PUFAs), curcumin, and polyphenols
• A diet that meets calorie needs and avoids overeating or undereating
• Physical activity
• Learning
The foods a person eats during pregnancy may also affect the growth of brain cells in a foetus and may have long-lasting effects on mental health.
Understanding how nutrition impacts neurogenesis is crucial, because it may lead the way to dietary practices that stimulate neurogenesis, potentially alleviating mental health conditions.
Best diets for mental health
There is no specific diet that is “best” for mental health. However, some eating patterns appear to be better than others.
Mediterranean diet
Among common diet plans, the Mediterranean diet has the strongest evidenceTrusted Source supporting its ability to reduce the symptoms of depression. The Dietary Guidelines for Americans 2020–2025Trusted Source also recommend this diet for overall health and well-being.
Compounds in the Mediterranean diet that have links with lower depression rates include: omega-3 fatty acids, vitamin D, methylfolate and s-adenosylmethionine.
The Mediterranean diet consists of: plenty of fruits and vegetables, whole grains, potatoes, cereals, beans and pulses, nuts and seeds, olive oil; low to moderate amounts of dairy products, fish, and poultry; very little red meat; eggs (up to four times per week); and low to moderate amounts of wine.
Low calorie diet
Short-term calorie restriction has shown some promise for treating the symptoms of depression.
A 2023 systematic review and meta-analysis of 25 studies looked at the effect of low calorie diets on depressive symptoms in individuals with overweight or obesity.
The definition of a low calorie diet was a deficit of 500 to 1,500 calories per day or 30% fewer calories than the person used in energy.
The authors found that depression scores were significantly lower after participants followed a low calorie diet. The addition of exercise or behavioral therapy did not significantly affect the reduction in depressive symptoms.
It is vital to note that calorie restriction can sometimes lead to the development of an eating disorder. The practice is also unsafe for people who have an existing eating disorder or have engaged in behaviours relating to disordered eating.
Anyone wishing to try calorie restriction should speak with a doctor or registered dietitian about how to ensure they get enough nutrients.
Intermittent fasting
There is ongoing debate about whether intermittent fasting (IF) can help improve mood and mental well-being. IF is the practice of restricting calorie intake for periods of 12 to 48 hours, followed by periods of eating normally. ssA 2023 review of 23 studies looked at the effects of IF on depression. The authors noted that IF seems to improve brain function in rats by regulating circadian rhythms and increasing neurotrophic factors.
However, the results of human studies showed a wide variety of effects on mood and were too varied to draw any conclusion. This is likely due to variations in fasting regimens and participants. Although IF shows promise in treating depression, higher quality studies are necessary.
As with calorie restriction, IF is not safe for everyone. People with a history of eating disorders or blood sugar issues, such as hypoglycemia, should not attempt IF without a doctor’s guidance.
Polyphenols are plant compounds with antioxidant and anti-inflammatory properties. They are present in many fruits, vegetables, cereals, beverages, and spices. Polyphenols in the diet may have positive effects on anxiety and depression.
A small 2020 study compared the effects of a high polyphenol diet and a low polyphenol diet on the well-being of people with mild high blood pressure.
After eight weeks, participants eating a high polyphenol diet reported fewer depressive symptoms and improved physical and mental health compared with those eating a low polyphenol diet. There were no changes in anxiety, stress, self-esteem, or body image perception.
This may suggest that a diet high in polyphenols could have mental health benefits for people with high blood pressure. More research is necessary to investigate the effects in other groups of people.
Foods or diets to avoid
Several studies have shown that people who follow a Western diet, which includes a lot of unhealthy fats and processed carbohydrates, are more likely to experience problems with cognitive and emotional health. This kind of diet alters the bacteria in the gut, which may affect the brain through the gut-brain connection.
Foods best to avoid or limit include: processed foods; fried foods; refined carbohydrates, such as white bread and pasta; and sugary products and alcohol. Researchers are still determining how diet affects mood.
A Mediterranean diet can positively affect a person’s weight, blood pressure, cholesterol, and other measures of health. Calorie restriction and fasting may positively affect a person’s mental health, but more research is necessary to confirm this idea.
While a nutritious diet may contribute to good mental health, it is best for anyone experiencing symptoms of a mental health condition, such as depression or anxiety, to speak with a doctor. – NMT
