In recent years, a growing body of research has supported the connection between nutrition and mental health.
What we eat not only affects our physical well-being but also plays a crucial role in our cognitive function, mood regulation, and overall mental health.
This article will explore the essential nutrients vital for maintaining good mental health, the connection between the gut and the brain, and various dietary patterns. We will also discuss a few basic counseling tips to help your clients achieve the best possible results.
Table of Contents
The Connection Between Nutrition and Mental Health
Research dedicated to the link between nutrition and behavioral health is relatively new.
The SMILES trial was the first intervention study to examine dietary patterns and symptoms of depression. And it was published in 2017!
Though a pretty small study (n-64), it showed consistently positive results in depression symptoms when nutrition interventions emphasized a Mediterranean-style dietary pattern.
Since then, we’ve seen rapid research on different dietary patterns, the influence of single nutrient manipulation, and the influence of gut health on mental health.
It’s easy to get excited about these studies. I know I do! But, despite all the positive information, we must remember that this is a new area of research, and more information is constantly coming out. This means we must try to maintain an open mind, be flexible in our counseling, and ensure we know how to evaluate research as it comes out.
Like in every other field, not all research is done with the same standards.
Additionally, much of the research that has been done has focused only on Major Depressive Disorder and Generalized Anxiety Disorder. This leaves quite a gap in information regarding other psychiatric diagnoses.
Essential Nutrients for Mental Health
The following section will cover research on individual nutrients. While there is some pretty interesting research in this area, one caveat is not discussed enough.
For any intervention focused on a particular nutrient to work, the individual you are working with must be well-fed, meaning adequate calories, protein, fat, and carbohydrates must be consumed.
No amount of supplementation, correction of deficiencies, or changes in dietary patterns will help if the individual is not eating enough.
A body not getting enough energy will conserve and prioritize, and a person’s mood is less important than their heartbeat. Neither is progress with their therapist.
Omega-3 Fatty Acids
Omega-3 Fatty Acids, particularly those found in fish, have been showing pretty exciting results.
Studies have shown that high doses of EPA supplementation (about 1 g) not only have similar efficacy as fluoxetine but it also enhances the response to fluoxetine.
EPA is one of the few nutrients we will discuss that shows benefits in mega-dosing.
Additionally, EPA is one of the few nutrition interventions showing measurable improvements in anxiety symptoms.
It is believed that the anti-inflammatory effects of omega-3 fatty acids are responsible for this improvement in symptoms.
B Vitamins
All of the B vitamins play roles in energy production and neurotransmitter formation and function and thus have an impact on depression. I try to pay particular attention to B12 and folate, as deficiencies in both have been correlated with various psychiatric disorders, and deficiencies are relatively common.
Vitamin B12 is readily available in the diet but difficult to absorb unless your gut is healthy. Since gut conditions, depression, and anxiety have a high rate of co-morbidity, this is always something to pay attention to.
Even in vegetarians, primary deficiency of B12 isn’t very common. Secondary conditions can occur due to all gastrointestinal disorders, substance (including alcohol) abuse, pernicious anemia, some medications (Metformin, acid-reducers, statins, and gout medications), GI surgery (including bariatric surgery), and more can all inhibit B12 absorption.
I am of the strong opinion that anyone experiencing mental health struggles or GI conditions should have their vitamin B12 status checked at least annually.
Folate has also been strongly correlated to worsening symptoms of mental illness, and repletion does appear to reduce or eliminate some of these symptoms. Foods high in folate also tend to be poorly consumed, whether due to access or preference.
Vitamin D
Vitamin D is only loosely associated with depression and psychiatric disorders, according to the research.
Those who suffer from Major Depressive Disorder have lower rates of mortality when serum vitamin D levels are within the normal range. The recurrence of depressive episodes also seems to reduce.
However, results are mixed when researchers look at repleting Vitamin D status on the actual symptoms of depression and the correlation between low serum vitamin D and rates of depression.
Individuals living far from the equator may experience Seasonal Affective Disorder. This condition does improve with vitamin D supplementation or light therapy.
At this time, vitamin D supplementation is not considered a treatment for depression symptoms. However, due to the high deficiency rate in the American population, annual testing is warranted. The decision to supplement should be based on serum levels, not symptoms.
Statistically, the prevalence of vitamin D deficiency in the United States is about 25%, and vitamin D insufficiency is about 50%.
However, in my experience, the only individuals I see who don’t have low serum vitamin D are those who are already taking a supplement. Take that anecdotal statement however you want!
Magnesium
On average, Magnesium intake is notoriously much lower than the RDA. And research seems to indicate that the RDA may be currently set too low.
With over 300 metabolic responsibilities, adequate magnesium intake is very important, and deficiency symptoms are frustratingly non-specific.
Increasing magnesium intake is particularly effective in trials of mood disorders, depression symptoms, and mania in Bipolar Disorder. However, improvement is most effective when intake is increased with diet, not supplementation.
This is one reason I encourage at least one serving of nuts or seeds daily. Whole grains, beans, spinach, and yogurt are also good sources.
Increasing magnesium intake does not appear to improve anxiety.
It is postulated that magnesium’s efficacy in reducing symptoms of depression is due to its anti-inflammatory properties.
Zinc
Zinc and magnesium are often studied together regarding mental health and nutrition. They seem to be similarly correlated to worsening symptoms and are effective via regulating the same inflammatory pathways.
Vegetarianism, sickle cell disease, and alcohol abuse disorder all significantly increase the risk of zinc deficiency.
Luckily, regarding client education, zinc and magnesium share many common food sources, such as nuts, seeds, beans, dairy, and whole grains. Though most Americans tend to get their zinc from beef and poultry.
Others:
Vitamins C and E, selenium, and iron have small studies that correlate them to symptoms of depression as well. The antioxidant properties of vitamin C, vitamin E, and selenium may impact mental health.
Iron deficiency anemia can also impact and mimic depression.
The Gut-Brain Axis – A Very Brief Overview
The enteric and central nervous systems constantly communicate via the vagus nerve. This is a bi-directional communication pathway, meaning what’s going on in the gut can impact the brain and vice versa.
This can create a negative loop for individuals with GI distress or behavioral health disorders.
Fortunately, dietitians are in a perfect position to positively impact the gut, which can improve mental health.
There is so much to discuss on this topic that I plan on creating its own category of articles!
The most significant factor in improving this communication is the gut microbiota. While probiotic supplementation can help in some cases, we should really plan to strengthen the microbiome diversity through diet.
This means encouraging a wide variety of fibers, resistant starches, phytochemicals, and unsaturated fats. I’ve found the most success with my clients when focusing on adding things to the diet.
I rarely encourage goals of reducing or eliminating foods. Instead, as we add more of what we need, the excessive amounts of other foods are reduced to a moderate level, and the client doesn’t feel deprived.
Dietary Patterns for Mental Health
By far, the most researched diet for mental health (or really, for everything) is the Mediterranean Diet. And, while it almost always has positive results in improving whatever health marker is the focus of the study, I have THOUGHTS.
No one is arguing that the Mediterranean diet isn’t a healthy diet pattern. However, it is not the ONLY healthy diet pattern, and it is not culturally appropriate for many of your clients.
You’ll never positively impact your client by suggesting a complete overhaul and encouraging them to avoid their customs. So, let’s look at what the research has to say so far and how we can adapt the research to each individual.
Mediterranean Diet
First off, remember that the Mediterranean isn’t just one or two countries. It covers parts of Europe, from the Atlantic Ocean to the Middle East and the northern part of the African continent. That’s a lot of different cuisines!
What we’re really talking about is a dietary pattern that includes protein primarily from fish, poultry, beans, and yogurt, as well as lots of fruits, veggies, whole grains, nuts, and seeds, with olive oil as the primary cooking oil. But beyond food, the Mediterranean region emphasizes a physically active lifestyle and plenty of socializing, particularly around meals.
That gets left out of the conversation most of the time, but it is very important.
So, what does the research say?
Well, the SMILES trial mentioned above demonstrated an improvement in depression and anxiety, as well as a reduction in food costs.
A 2019 meta-analysis involving >56,000 people revealed mixed results on the risk of depression. Nine studies showed a 28% reduction in the risk of depression when following a Mediterranean-style diet, and 4 showed no change in risk.
However, a reanalysis of the data in 2023 revealed a significant inverse relationship between adherence to the Mediterranean Diet pattern and the risk of depression, with a 95% confidence interval. The re-look at adherence to the diet is likely what caused the change.
And if someone has already experienced depression? Those on a Mediterranean-style diet had lower recurrence rates than those who ate a Standard American Diet (35% vs 50%).
Traditional Japanese Diet
Characterized by high intakes of fruits, vegetables, soy, fish, and green tea, it’s easy to see similarities in this dietary pattern to the Mediterranean Diet, even if the foods themselves are different.
EGCG in green tea can help improve depressive symptoms, glycemic control, and binge eating. Green tea is also known to reduce stress and anxiety.
Studies regarding the efficacy of the Traditional Japanese Diet at improving mental health have varied, from no change to marked improvement.
Soy and green tea, along with high intakes of fruits and vegetables, are often credited with improving depressive symptoms when eating a Traditional Japanese Diet.
Vegetarian Diets
Vegetarians report better moods than omnivores despite their low intake of EPA/DHA. Vegans have mixed results, with some studies showing lower rates of depression than the general population and others showing higher rates.
There may be a “chicken or egg” situation at play here. Are people who are prone to mood disorders more likely to become vegan, or does the diet potentially worsen mental health? Right now, we don’t really know.
A well-balanced vegetarian diet has been shown consistently to be nutritionally adequate. However, when not well-balanced, some nutrient deficiencies are common in vegetarians, the same ones that can lead to worsened mood.
Zinc, vitamin B12, magnesium, and iron can all be low on a veg*n diet. Additionally, vegetarians are just as likely to not eat enough fruits and vegetables as omnivores!
Vegetarians looking to improve their mental health through diet should focus on balance, eat enough produce, and eat plenty of nuts and seeds. They should also consider using algal oil, which contains structurally identical EPA and DHA found in fish oil.
Intermittent Fasting
This has been a doozy of flawed research and interpretation from diet and wellness influencers in the last few years! The TDLR version? There’s not enough research to prove or disprove Intermittent Fasting as a means to improve mental health. Or any other claim, really.
A 2021 Meta-Analysis found lower anxiety and depression without fatigue.
However, we have to look at this critically, as even though it was a meta-analysis, it only included 1,436 participants. And none of the participants were actually diagnosed with Major Depressive Disorder or Generalized Anxiety Disorder!
The researchers did note that the IF protocols were deemed safe for all participants, including those with Type 2 Diabetes.
A small study (n=31) showed that in aging men IF combined with calorie restriction was associated with weight loss as well as significant decreases in tension, anger, confusion, and total mood disturbances.
In 2023, a study involving men on an 8-day water fast showed increased resting heart rate, cortisol, and beta-hydroxybutyrate. However, the researchers concluded, “The study confirmed the beneficial effect of 8 days of water-only fasting on physiological variables without affecting mental well-being,” though “the authors are aware of the numerous limitations of this study.”
Everything about this study seems wrong to me. This seems like a scientific way to induce an eating disorder. Moreover, signs of anxiety include an increase in resting heart rate as well as elevated cortisol and beta-hydroxybutyrate, precisely what was seen in the participants.
Low glucose was also seen in the participants (duh), which is also known to cause symptoms of anxiety.
I’d love to hear everyone’s take on this!
Research on intermittent fasting is highly variable, partly because every study has its definition of what intermittent fasting is.
If I have a client who is interested in trying IF, I often discuss the potential of fluctuating glucose worsening symptoms of anxiety as well as the potential for nutrient deficiencies.
However, unless the client displays disordered eating habits or has a history of an eating disorder, I often encourage them to experiment. During that time, I ask them to monitor their mood, energy, and concentration throughout the day. We also talk about how their nutrition needs don’t change just because they are intermittent fasting.
Anecdotally, most of my clients don’t stick with an IF pattern. Sometimes, it’s because scheduling is difficult, but often, it’s because they notice poor concentration at work or low energy after work.
Western Diet Pattern (AKA Standard American Diet – SAD)
SAD is characterized by a high intake of saturated fat, salt, and sugar and a low intake of unsaturated fat, fruits, vegetables, and whole grains.
This dietary pattern is essentially the opposite of any dietary intervention that improves symptoms of mental illness.
If this dietary pattern leads to metabolic syndrome, the risk of worsening mental health increases.
There is also a bit of “chicken and egg” here. Does the diet lead to depression, or does depression lead to the diet? In reality, it’s probably both.
This is a good time to reiterate that “fed is best.” If fast food is all a person can manage when in a depressive episode, that is the best food for them!
I often recommend clients write a “contingency plan” for use when they are low on spoons.
By this, I mean a list of easy-to-prep and eat foods that they can send to a support person to make feeding themselves as easy as possible. This can include grape tomatoes, baby carrots, rotisserie chicken, whole grain crackers, cheese sticks, etc. Everything on the list should be something the individual likes, is easy to eat, and is willing to eat.
Convenience foods, such as precut fruit and veggies and canned or frozen fish and meat, are also great for this.
Keto and Other Low Carb Diets
The use of ketogenic diets in mental illness isn’t well-studied. For the general population, I generally do not recommend any low-carbohydrate diet.
This is because, for most people, a low-carb diet translates into a low-fiber diet, which worsens gut health and, therefore, mental health. Also, carbohydrates carry the nutrients that later become serotonin and melatonin into the brain.
Depending on the person, we may need to moderate carbohydrates, but I generally adhere to the AMDR for carbs unless I have a compelling reason to change that.
Don’t get me wrong, ketogenic and other low-carbohydrate diets do have their place, particularly in neurodegenerative and other neurological disorders, such as epilepsy.
However, the studies I’ve seen that show improvement in depression and anxiety from a ketogenic diet have been very poorly designed.
In researching this article, I came across a news release from April 2024 that I found interesting. A very small study looked at a ketogenic diet and its effect on severe mental illness.
The study followed 21 participants with either schizophrenia or bipolar disorder who were on anti-psychotic medications AND had a metabolic abnormality. This is a step up from many studies, as most that I’ve seen involving keto and mental illness exclude individuals who have received a diagnosis!
Additionally, participants received nutrition education, a keto cookbook, and access to a health coach. Most keto studies I looked at had the participants state whether they were following a keto diet or not!
Anyway, 14 participants adhered to the ketogenic diet until the end of the study. They showed an improvement in triglycerides, serum glucose, and insulin resistance and an average improvement of 31% on a psychiatrist rating.
The participants noted improved mood, sleep quality, energy, and quality of life.
Given the high rate of metabolic abnormalities in patients on anti-psychotic medication, this is a super promising study. However, considering this intervention, we must consider the individuals’ access to care, cooking ability, and more.
For my practice, I’d have to see a lot larger, repeatable studies before I start recommending a ketogenic diet to anyone.
Practical Tips for Dietitians
When first considering nutrition for mental health, it is best to start with basic nutrition recommendations. Increase fruits, vegetables, whole grains, nuts, and seeds. Add fish. Reduce intake of sugar and unsaturated fats.
Make sure they are eating enough.
The biggest takeaway is to really get to know your client. Have they been screened for substance abuse or an eating disorder? Are they able to afford the type of nutrition you are recommending? Is it culturally relevant? Are they willing to make the changes you suggest?
I often spend quite a bit of time bringing people back down. They hear that nutrition can help their mental health and want to know what supplements they should take. However, no supplement will outperform a well-balanced diet, and some are harmful.
And no supplement will improve your patient’s mood and energy level if they are only eating 1000 kcal per day!
Counseling Tips
Almost across the board, clients will react better to adding foods to their diet rather than taking foods away. No one feels good when restricted, even if they do it to themselves.
For many clients, this means adding vegetables to their day, often a side salad with dinner. But on occasion, they are already eating a lot of veggies. So we add fruit or nuts. Or we add fermented foods, such as yogurt. Or they’re not eating enough protein, so we need to add fish, beans, and poultry.
I am also a big fan of introducing mindful eating early in our relationship, often in the first session. It used to amaze me how many people could not tell when they were hungry or full. Almost every one of my clients chooses to focus on mindfulness around food as one of their first goals, even if it isn’t their primary focus.
But beyond hunger and fullness, who do they eat with? Are they working while they eat? Do they enjoy their food? How do they feel before and after the meal? Do they have more energy throughout the day when they eat breakfast? Do they sleep better if they have a snack before bed?
How’s their anxiety when they have that 2nd or 3rd cup of coffee?
Are they less irritable or more concentrated when eating throughout the day?
Encourage your client to start with small goals, then increase them as they are comfortable. They may need help brainstorming if they don’t meet their goals. Or they may need to switch tacts and find another goal.
Prioritizing nutrition is key to supporting mental health and overall well-being. Individuals can positively impact their mood, cognitive function, and emotional resilience by incorporating a balanced diet rich in nutrients such as omega-3 fatty acids, antioxidants, vitamins, and minerals.
Maintaining a healthy gut microbiome through probiotic-rich foods can enhance mental health outcomes.
Ultimately, making conscious choices about what we eat can profoundly affect your client’s or patient’s mental health and quality of life. By investing in our bodies through proper nutrition, we empower ourselves to better manage stress, anxiety, depression, and other mental health challenges.
Further Reading
- Brain Changers by Felice Jacka
- The Psychobiotic Revolution by Scott Anderson and John Cryan
- Take the free email course!
