Diet and Mental Health

Estimates now show us that one in five people struggle with mood and mental health issues, making it a growing public health concern. They can affect how people feel, think, and function. Despite advances in treatment, many people still struggle with symptoms every day.

Commonly seen alongside these issues are poor diet, increasing nutrient deficiencies, and other conditions like obesity, and this relationship is often two-way. Another interesting parallel is the connection between high levels of stress and cardiovascular disease, which can be related to diet. We don’t fully understand why these things tend to occur together, but we know nutrition can be important.

Studies show that what we eat, especially in early life, can affect our brain health and how well we think. More recently, health providers have started to recommend lifestyle changes including nutrition interventions to help improve mood and mental health. 

Below, we dive into the research on the connections between what you eat and your mental health, and possible ways to help you improve when it comes to managing these through diet.

Note: This article is to raise awareness that nutrition can contribute to your mental health. Keep in mind mental health issues can involve multiple factors beyond just food. While we encourage everyone to eat better and explore a healthy diet, you should always consult your qualified healthcare provider about treatment for any diseases or conditions. 

How Does Diet Affect Mental Health?

Did you know that the food you eat and your nutrient status can play a big role in your mental health? Certain nutrients, like omega-3 fatty acids, vitamins B and D, and minerals like zinc and magnesium, are critical for brain health.

Inflammatory foods, like processed meats, refined sugars, and trans-fats can promote inflammation. Conversely, a diet high in fruits and vegetables and healthy fats might actually benefit brain health.

There is also a strong connection between the brain and the gut, which we call the gut-brain-microbiota axis. The axis includes various ways that the three players affect each other. For example, your stress levels and mental state affect your gut flora composition. 

Conversely, your gut flora can control your mood, stress response, and cravings. The status of your gut lining health can also influence your gut flora. All of these are involved in regulating mood and cognition.

An unhealthy diet will show in your body’s weakest link, depending on your genetic predisposition. For some people, that is their brain and mental health. But keep in mind that nutrition is not the only factor in mental health. Here are some other examples of things that can impact mental health:

• Past traumas, especially those that are unresolved, can increase your risk for mental health issues. And, an unhealthy diet might also exacerbate the effects of trauma, by impacting brain function and emotional regulation.

• Poor sleep quality, or not enough sleep, can impact cognitive function, mood regulation, and overall mental well-being. We know that caffeine can also impact sleep, which can exacerbate sleep-related mental health issues.

• Chronic stress is harmful to the whole body, but especially mental health. Stress can increase the risk for conditions like depression and anxiety. Some people turn to comfort foods to help cope, which can further worsen symptoms.

• Loneliness and social isolation are linked to both depression and anxiety. Those who experience this might be more prone to turning to unhealthy food habits, which can make mental health worse.

• Lack of physical activity not only impacts physical health but also affects mental health. An unhealthy diet coupled with a sedentary lifestyle can increase the risk of weight gain, reduce energy levels, and increase the risk of depression and anxiety.

So, while an unhealthy diet can really impact mental health, it also often interacts with other factors. Combined, these can produce more pronounced impacts.

But how do these impact mental health issues? Let’s break down some of these mechanisms:

Poor Blood Sugar Control Is Linked to Brain and Mental Health Issues (Or Make Existing Conditions Worse)

The brain has the highest energy demands compared to all other organs. It relies primarily on glucose, a type of simple sugar, to carry out its functions. Therefore, having a steady supply of glucose or a steady blood sugar is crucial for your brain health. 

Counterintuitively, high carbs or high-sugar foods tend to cause big fluctuations in blood sugar levels. Whereas, protein and complex carbs, especially legumes, are better at stabilizing blood sugar. Therefore, high consumption of simple sugars such as in soda, pastry, other sweet foods, or refined carbohydrates tends to lead to poor blood sugar control. 

When the body experiences big fluctuations in blood sugar, it can disrupt the supply of glucose to the brain. This can cause changes in mental clarity, mood swings, and other symptoms. A more intense situation, called hypoglycemia (when blood sugar gets too low), can actually impair brain function because not enough glucose is available for it to use.

Blood sugar fluctuations can also impact neurotransmitter levels in the brain, especially one called serotonin, known as your happy hormone. This is why low blood sugar can lead to low mood, anxiety, and irritability. Insulin also helps regulate neurotransmitters in your brain. Therefore, poor blood sugar control can disrupt insulin signaling, and lead to imbalances in neurotransmitters including serotonin, dopamine, and norepinephrine.

These constant blood sugar fluctuations stimulate the release of stress hormones like cortisol and adrenaline. This can further contribute to feelings of anxiety and tension. In fact, chronic stress and dysregulated cortisol levels are linked to a variety of mental health disorders, like depression and PTSD.

High blood sugar levels can also promote inflammation and oxidative stress throughout the body, including the brain. These mechanisms are linked to the development of neurodegenerative diseases, mood disorders, and cognitive decline. Brain inflammation can also impair neurotransmitter production and disrupt neural circuits that regulate mood and cognitive function.

Prolonged exposure to high blood sugar levels can lead to structural changes in the brain. We see this in cases of poorly controlled diabetes. These structural changes can include reduced volume in certain brain regions involved in memory and cognitive function and might even increase the risk for memory issues and other conditions over time. 

It can also lead to changes in how the blood-brain barrier functions, which is important for preventing harmful molecules from crossing into the brain.

Finally, having poor blood sugar control can impact how well blood flows in the brain, impacting the delivery of oxygen and nutrients to brain cells. All these factors can have big impacts on brain function and mental health by disrupting energy metabolism, neurotransmitter balance, stress response, and blood flow.

In those who have pre-existing mental health issues, having poor blood sugar control can also make symptoms worse. And, it can even impact how well some medications function to reduce symptoms.

Common Nutrient Deficiencies Contribute to Mental Health Issues

Zinc

Zinc is a mineral that helps neurotransmitters function. Studies consistently show that those with depression have lower zinc levels. There is some evidence to suggest that increasing zinc through supplementation can help improve mood, even in the cases of treatment-resistant depression. 

Zinc seems to impact depression by influencing a special protein, called brain-derived neurotrophic factor (BDNF). This protein helps grow and differentiate brain cells. In humans, lower levels of BDNF are linked to more depressive symptoms.

Zinc also helps control a receptor called NMDA, which helps brain cells communicate. Zinc can inhibit NMDA activity, reducing the amount of calcium that enters cells and keeping brain activity in check. It also seems to stimulate the release of another chemical called GABA, which calms down brain activity.

Low zinc levels may be more common due to low absorption in people with suboptimal stomach acid levels, vegetarians, and due to some medications. For example, oral contraceptives can significantly increase serum copper, while lowering zinc levels.

Magnesium

Magnesium is another important mineral linked to mood and mental health. Magnesium does two important things in the brain: it blocks a receptor called NMDA and activates another called GABA. These actions might be why it seems to help with tension and relaxation. 

Studies find that increasing magnesium levels in the brain might improve memory and brain plasticity, which are important for mental health.

Iron

Iron plays a big role in mental health. It is involved in the production and function of neurotransmitters like dopamine and serotonin, which help regulate mood and cognition. Iron is also critical for the proper function of the myelin sheath, which is a protective layer that surrounds nerve cells and helps neurons communicate. 

Low iron is linked to depression, fatigue, and even memory issues. In one study, researchers found that people who had low iron levels had a higher risk for anxiety, depression, sleep issues, and other mental health disorders. When supplemented, these risks were reduced.

B Vitamins

B vitamins are crucial for brain function. We know this because neurological and psychiatric symptoms are linked with their deficiency. For instance, a lack of vitamin B6 can lead to depression, cognitive decline, and dementia, while vitamin B12 deficiency often shows neurological symptoms before affecting blood health. 

Interestingly, deficiencies in folate or vitamin B12 can cause mental health symptoms even if they do not cause anemia, which can happen if you do not get enough B12 in your diet.

B vitamins are involved in neurotransmitter synthesis and methylation processes in the brain, and supplementation with B vitamins has shown promise in improving mood and cognitive function. 

One study investigating the link between dietary intake of B vitamins and psychological health in adults found that higher intake of biotin was associated with lower odds of depression, anxiety, and stress. Similarly, moderate intake of other B vitamins like B6, thiamin, niacin, and pantothenic acid was linked to reduced risk of anxiety and depression.

Vitamin D

Vitamin D plays a role in brain development, neurotransmitter synthesis, hormones, and immune function . Low vitamin D levels are linked to depression, seasonal affective disorder (SAD), and other mood disorders.

One review study found that there’s a lot of evidence suggesting that having enough vitamin D might be beneficial for mental health. The included studies looked at various mental health aspects such as behavior problems, anxiety, depression, aggression, and more. 

Supplementation has also shown positive benefits in certain conditions, including depression. Another review study looked at 41 different studies involving over 53,000 participants. The results showed that overall, vitamin D had a positive effect on depressive symptoms, meaning it seemed to help improve mood.

Finally, studies looking at the gut-brain axis hint that vitamin D might influence gut bacteria and serotonin production, which could play a role in mental health.

Amino Acids

Amino acids are precursors to neurotransmitters like serotonin, dopamine, and norepinephrine – almost acting like building blocks to their production. Depression has long been linked to lower levels of serotonin and dopamine. 

Studies find that increasing amino acids, like tryptophan and tyrosine, can improve mood disorders by boosting these chemicals. So, deficiencies in these amino acids can disrupt neurotransmitter balance and might even contribute to mood disorders like depression and anxiety.

Omega-3 Fatty Acids

Omega-3 fatty acids, found in fish oil, play a crucial role in both physical and mental health. The two most important ones – eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) – are particularly important for brain function. 

Studies suggest that low intake of omega-3s is associated with various mental health issues, and several trials have shown potential benefits, especially when EPA is added to existing medication.

Inflammatory Food and Gut Inflammation Causing Sickness Behavior/Depression

Animal studies suggest that inflammation, such as from an infection, can cause sickness behavior. This represents a set of symptoms such as lower motivation, social withdrawal, inactivity, and lower appetite. These symptoms make sense if you’re sick and want to rest to recover from an infection. 

Some modern lifestyle factors can increase inflammation even if you don’t have an infection. These include some unhealthy foods, inflammatory foods, poor blood sugar control, and even increased oxidative stress. Research has suggested that some people may be more susceptible to mood issues like sickness behavior due to lifestyle-related inflammation more than others.

Poor Diets Feed Unhealthy Gut Flora

There is emerging research linking mental health issues to gut imbalances. The microbiome can directly or indirectly affect brain function by producing substances like vitamins and short-chain fatty acids. 

Studies on mice without gut microbes have revealed their critical role in brain development, particularly in areas like the hippocampus and microglial cells. These mice also showed abnormalities in their immune, brain, and digestive functions. So, early exposure to gut microbes seems crucial for normal brain development and stress response.

An unhealthy diet can cause leaky gut and throw off the gut flora. When the integrity of the gut lining is compromised, it can allow harmful substances to enter the bloodstream, and cause inflammation and immune responses. These states have been linked to mental health disorders.

Diets rich in processed foods and refined sugars, and low in fiber, can reduce our gut bacteria diversity and even promote the abundance of suboptimal bacteria. Conversely, diets high in fiber, polyphenols, omega-3, and monounsaturated fats, like the Mediterranean diet, promote beneficial gut bacteria that produce anti-inflammatory compounds, potentially improving mental health.

Nutritional Psychiatry: How Food and Corrective Supplementation Can Support Mental Health Issues

What Is Nutritional Psychiatry?

Nutritional psychiatry is a relatively new field of study that focuses on the relationship between diet and mental health. It explores how dietary patterns, specific nutrients, and nutritional interventions can influence brain function, mood disorders, and other mental health conditions. It then applies these principles in the treatment of mental health conditions, to help improve outcomes.

Nutritional psychiatrists may also use orthomolecular medicine, which relies on high doses of nutritional supplements to treat certain conditions. More recently, genetic testing allows better targeted prescription of nutrients and even medications. 

Can Diets Help With Mental Health Issues?

So, if poor diets are linked to mental health issues, can correcting them with nutrition improve symptoms? While the effects can vary between people, we know that diets do have significant roles when it comes to supporting mental health. 

In most cases, a knowledgeable psychiatrist will incorporate both conventional treatments (like medication & psychotherapy) and nutritional interventions into treatment plans for mental health conditions. This integrated approach recognizes how important it is to address biological and psychosocial factors together in managing mental health disorders.

Excess body weight is a big problem worldwide, and it might also be a big contributor to mental health issues [R42]. Generally, we’re eating more processed, high-energy foods lacking in nutrients, which leads to both obesity and nutrient deficiencies. 

Our diets often lack important vitamins and minerals that are crucial for our nervous system to function properly, like B vitamins, zinc, and magnesium. We’re also not eating enough fiber and nutrient-rich foods like vegetables and whole grains, which make things worse and can contribute to mental health issues like depression.

The MIND diet, which combines elements of the Mediterranean and DASH diets, focuses on high intake of vegetables, fruits, nuts, whole grains, olive oil, fish, and seafood, along with moderate red wine consumption [R8]. It has been linked to a lower risk of developing neurological disorders like Alzheimer’s disease and can also slow cognitive decline with age. 

Adhering to the MIND diet is associated with reduced chances of depression and psychological distress, and its emphasis on plant-based foods and limited intake of animal and high-fat foods may be the big reasons.

The ketogenic diet, known for its high-fat content, has been proven effective in treating epilepsy by altering brain metabolism and neurotransmitter function. After being used for over 100 years for epilepsy, Dr. Christopher Palmer’s group is now exploring it for mental illnesses like schizophrenia and depression. 

These conditions share similar biological pathways involving issues like low glucose metabolism, imbalanced neurotransmitters, and inflammation. In many cases, Dr. Palmer’s patients lost a significant amount of weight and had excellent outcomes on their mental health conditions. 

Potentially, stabilizing the blood sugar, keeping the brain fueled, and supporting healthy mitochondrial function with ketosis could be a very promising approach to mental health.  

Do Diets Have Placebo Effects That Improve Mental Health?

The placebo effect is a phenomenon when someone’s health appears to improve after doing an intervention solely due to their expectation or belief. For any drugs to get approved, researchers would have to compare the drugs with a placebo. Yet, for diet and nutrition studies, a perfect placebo is very difficult to design. 

Mental health issues seem to improve well with placebos, and in nutrition research, it is often difficult to separate actual impacts from placebo effects. One of the challenges with scientific studies to confirm the benefit of diet with mental health is that dietary changes do have placebo effects, especially when certain diets have spiritual links or provide a sense of purpose and belonging.  

If someone believes that a particular diet or nutrition intervention will improve their health, they may experience benefits simply because they have the expectation that it will. These positive beliefs and attitudes can enhance its perceived impact. While we don’t completely understand why this happens, we have some ideas.

Participating in an intervention might provide social support, a sense of belonging, and even opportunities for self-care or self-improvement. All of these can have a positive impact on mood and well-being. 

The act of simply following a structured plan and monitoring food intake can also provide a sense of control and empowerment. These can help trigger actual physiological responses, such as the release of endorphins (which make you feel good), which can help improve feelings of overall well-being. 

And, the context that an intervention is administered can also influence its perceived effects. These can include things like the credibility of the healthcare provider, the setting where the intervention takes place, and the amount of attention and care received, which can all promote positive responses independent of the effects of the food.

What is also important though, is something called the mind-body connection. This idea plays a significant role in mental health. We know that adopting an improved diet might lead to improved physical health outcomes (like weight loss or better energy), and these can positively impact mood and psychological well-being.

It is also important to recognize that while placebo effects might not address underlying biological mechanisms or root causes of mental health issues, they can lead to substantial and subjective improvements. This makes them still meaningful and valuable, especially when combined with a comprehensive treatment approach.

Conclusion

We still have a lot to learn when it comes to the relationship between diet and mental health, but there is growing evidence to suggest that it does play a role. Mental health problems vary a lot between people and at different ages. Our genes, culture, and environment are all significant. So, finding the right diet recommendations for mental health is challenging, but important. 

Also, mental health conditions can make it very difficult to stick to a restrictive dietary and supplementation regimen without additional logistical support. We recommend seeking out nutrition-oriented psychiatrists who partner with a health coach to get your journey started.

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