There is strong evidence that nutritional patterns can affect later-life brain function; a healthy diet filled with high-quality foods has been linked to reductions in cognitive decline risk, while a poor diet appears to increase cognitive decline along with other health concerns. Mounting evidence suggests that early evaluation and treatment for depression can improve or maintain cognitive function in patients with mild cognitive impairment – the first stage of Alzheimer’s disease. Furthermore, the risk of developing dementia is doubled in older adults with depression, whereas the risk of Alzheimer’s is up to 65% greater. Not only is a healthy diet beneficial for preventing neurological decline, but it can also help address cardiometabolic health conditions such as type 2 diabetes, hypertension, and metabolic disorders.
A recent review published in the European Neuropsychopharmacology journal found evidence linking a poor diet to worsened mood disorders, such as anxiety and depression. Among its findings, the study revealed that a high fat and low carbohydrate diet can help children with epilepsy, vitamin B12 deficiency can contribute to fatigue, poor memory, and depression, and that a Mediterranean diet – high in vegetables and olive oil – can provide protection against mood disorders.
Nutritional Interventions for Mental Health
The comprehensive literature review focuses on elucidating more information about the relationship between nutrition and mental health to gain a clearer understanding of the influence of food on mental health. However, determining a conclusive outcome proved challenging due to the nature of the evidence. Although a number of large cross-sectional population studies reported a link between certain nutrients and mental health, it was not possible to determine whether food was driving these changes. Well-controlled dietary intervention studies, on the other hand, are often conducted on a much smaller scale and only run for short periods of time, making it difficult to generalize their findings.
Improved Wellbeing and Decreased Mental Health Symptoms
Led by Prof. Suzanne Dickson from the University of Gothenburg in Sweden, the authors examined the currently available body of research on nutritional psychiatry and determined strong correlations between a healthy diet and improved mental health. They found strong correlations between a healthy diet and better mental health, many of which were associated with increased consumption of fresh fruits and vegetables.
The review reports relatively strong evidence supporting the benefits of a Mediterranean diet on mental health. Based on results from a total of 20 longitudinal and 21 cross-sectional studies, researchers found compelling evidence that the diet had protective effects against depression. Additionally, the team found adequate evidence revealing that children with drug-resistant epilepsy had fewer seizures when eating a ketogenic diet high in fat and low in carbohydrates.
The review also notes potential positive implications of vitamin B-12 supplementation. Individuals with vitamin B-12 deficiencies tend to experience lethargy, fatigue, and memory problems which have been linked to subsequent psychosis and mania. In these cases, evidence suggests that vitamin B-12 supplementation can significantly improve well-being.
Strong associations were also found in the case of thiamine supplementation for nervous system disorders, folic acid in neurodevelopment in utero and infancy and depression in adults, as well as niacin consumption for the mitigation of dementia symptoms.
Mixed Evidence Supports Need for Further Research
In other cases, evidence was mixed. For example, some research has found that vitamin D supplementation improves working memory and attention in older adults, while other studies have found that vitamin D supplementation may reduce the risk of depression. However, these trials have been small and others have not confirmed any link between vitamin D and mental health. Similarly, research has not conclusively determined whether nutrition plays a role in attention-deficit hyperactivity disorder.
“We can see an increase in the quantity of refined sugar in the diet seems to increase ADHD and hyperactivity, whereas eating more fresh fruit and vegetables seems to protect against these conditions,” Professor Dickson explains, “but there are comparatively few studies, and many of them don’t last long enough to show long-term effects.”
On the other hand, strong correlations indicate that nutritional decisions in early life can affect later-life cognitive function. Although, “at present we lack a detailed understanding of the metabolic and cellular mechanisms that underpin these associations,” the study’s authors write, emphasizing the need for increased research efforts in this field.
Although it is difficult to prove that specific dietary patterns contribute to mental health, or the ways in which they do, this review adds to the growing body of literature supporting the connection between mental health and nutrition. As neuropsychiatric disorders are some of the most pressing societal challenges today, these findings have significant implications for the lives of millions of people and need to be verified before recommendations are made.
The study’s authors warn the medical community against jumping to conclusions on the basis of provisional evidence and underscore the importance of further investigation of the field of nutritional psychiatry. While future research will need to focus on provable dietary causes associated with mental health conditions, the currently available evidence is sufficient to suggest that nutritional interventions in combination with lifestyle modifications can be effectively incorporated into routine clinical care to manage physical comorbidities related to mental illness.
