We’ve all heard the adage: “You are what you eat.” It’s a common proverb that originated in the 19th century by Jean Anthelme Brillat-Savarin, who is largely credited as the founding father of the gastronomy bible. His pièce de résistance was the book, “The Physiology of Taste: Or Meditations on Transcendental Gastronomy,” in which he stated, “Tell me what you eat, and I will tell you what you are.”
Since then, the proverb has entered our general consciousness, but it wasn’t until recently that scientists and researchers began to investigate the deeper meaning behind it, specifically looking into how food affects our health.
What we put into our bodies is key in both promoting good health and preventing diseases, such as cancer, Type 2 diabetes and heart disease. Case in point: The Mediterranean diet has clinically shown time and time again that an eating pattern high in fresh fruits, vegetables, whole grains, healthy fats and fish is good for our physical health.
However, nutritional psychiatry adds another dimension to that notion of “you are what you eat” and posits that food not only impacts the body, but also the brain.
What Is Nutritional Psychiatry?
Nutritional psychiatry is an emerging field of medicine that is based on the idea that food plays a role in mental health, including mood, mental well-being and mental disorders.
“Nutritional psychiatry is the use of food choices to help optimize mental health and help our patients have better, healthier, happier lives,” explains Dr. Drew Ramsey, assistant clinical professor of psychiatry at Columbia University College of Physicians & Surgeons in New York City. “Everything we need for mental health comes from our food, whether it’s iron, B12 or omega-3 fats. The only molecule in our brain that we don’t eat is oxygen. There’s this foundational connection between mental health and food.”
While a majority of clinical research has focused on the link between food and depression, a growing body of evidence shows that diet also affects anxiety, bipolar disorder, attention-deficit/hyperactivity disorder and other mental health disorders, leading researchers to zero in on dietary interventions.
“(Nutritional psychiatry) is meant to work synergistically with everything else you’re doing to support your overall mental health by being an additional tool in your toolbox for you to use,” explains Dr. Uma Naidoo, a nutritional psychiatrist and director of nutritional and lifestyle psychiatry at Massachusetts General Hospital, the first hospital-based program of its kind in the country. “By speaking about how we eat, it helps people to improve their health and to think more carefully about the choices they make.”
It’s no wonder, then, that the answers to our mental health can be found at the intersection of the gut and the brain.
The Body’s Second Brain
While the human brain contains approximately 86 billion neurons, the human gut contains the second largest collection, with more than 100 million neurons lining the gastrointestinal tract, earning it the nickname of the body’s second brain.
The brain gets most of the credit for regulating memory, learning and mood. But the gut plays a critical role in supporting our physiological and mental processes. For example, the gut produces approximately 95% of the body’s serotonin – a neurotransmitter that helps regulate mood, emotions, sleep and digestion – and contains more than 90% of its receptors.
But to understand how the gut and brain work together, it’s important to understand their shared origin story. Although it’s true that they are two different organs within the body, they actually originate from the exact same cells in the human embryo. As the embryo grows, the cells develop and form two separate organs – the brain and the gut – but remain connected throughout our lives thanks to the 10th cranial nerve, also known as the vagus nerve.
The vagus nerve acts as a two-way text messaging system for this connection, sending neurochemicals back and forth between the brain and the gut, bidirectionally. By staying connected through the vagus nerve, the two organs remain physiologically and biochemically intertwined.
“The gut-brain connection explains the food-mood connection,” Naidoo says.
How Food Influences the Brain
The gut microbiome houses trillions of microorganisms – including bacteria, viruses and fungi – that help support various physiological and mental functions, including our circadian rhythms, immunity, infection, hormone production, cognition and, yes, our mood.
When you consume a healthy diet, your gut breaks down the foods and produces short-chain fatty acids, which are beneficial to regulating the immune system, protecting the heart and brain and fighting inflammation. Its anti-inflammatory effects are important because inflammation has been identified as one of the biggest drivers of several mental health and psychiatric conditions, including depression, bipolar disorder, post-traumatic stress disorder and obsessive compulsive disorder.
“If you’re eating the standard American diet, over time, your gut is going to develop inflammation,” Naidoo says. “Because the gut and brain are connected, that inflammation is also going to be transmitted through this connected ecosystem to the brain.”
Another way food influences our mental health is by either improving or impairing expression of the brain-derived neurotrophic factor (BDNF) gene, which is responsible for making key proteins that support neuroplasticity, learning and memory.
Healthy, well-balanced diets that are rich in whole, nutritious foods promote BDNF levels in the brain, thereby improving brain growth and repair, whereas eating unhealthy, processed foods can decrease BDNF levels.
“To really do the good work, the deep work, the necessary work that so many people need to do to address their depression, addiction or trauma, it takes a well-nourished mind,” says Ramsey, who authored the book, “Eat to Beat Depression and Anxiety.”
Foods and Beverages to Eat and Drink
It may come as a surprise to some people, but eating high-fat, sugary comfort foods – like ice cream, pizza and pastas – during times of stress, anxiety or sadness isn’t going to bring you out of your funk.
In fact, certain foods have been shown to have both an anxiolytic effect, meaning they may reduce anxiety, and depression-relieving properties.
Experts encourage people to eat a well-balanced diet of whole, nutrient-dense foods to improve their mental well-being.
Examples include:
To improve the diversity of good bacteria in your microbiome, which is one of the main indicators of good gut health, people should incorporate more fermented foods.
The fermentation process kills off the bad bacteria in food while promoting the growth of various good bacteria – such as lactobacillus, bifidobacterium, bacillus and pediococcus – that help digestion and restore balance to our gut.
The most common fermented foods that are rich in probiotics include:
- Raw apple cider vinegar.
- Yogurt.
- Kefir.
- Kimchi.
- Kombucha.
- Sauerkraut.
- Pickles.
- Miso.
“What we’re hoping to do is move people away from the probiotic (supplement) aisle toward the foods people have always eaten for probiotics. These are live fermented foods (that) need to be refrigerated because they contain live bacteria,” Ramsey says.
However, not all fermented foods are created equal. Certain fermented foods – such as beer, wine, sourdough bread and canned sauerkraut – are exposed to high heat from blanching, canning or cooking during production that destroy both good and bad bacteria.
To reap the benefits of probiotics, be sure to look for items that contain live and active cultures.
“Every culture has a fermented food, so I ask my patients to lean into that and add a little bit to each meal because those fermented foods are helping you beat that inflammation,” Naidoo says.
Fish and seafood
Fish and seafood contain high amounts of DHA and EPA omega-3 fatty acids, which proffer anti-inflammatory benefits and promote serotonin synthesis, both of which are important for good mental health. In fact, studies have shown that people who consume fish have a 20% reduced risk of depression compared to those who do not.
Plus, seafood contains high concentrations of vitamin B12, vitamin D, iodine, magnesium and other key vitamins and minerals. Zinc, which is found in high concentrations in oysters, has been linked to reduced anxiety in preclinical studies.
Some examples of good seafood to include in your diet are:
- Wild-caught salmon.
- Tuna.
- Sardines.
- Mackerel.
- Clams.
- Oysters.
Greens, particularly dark leafy greens, are packed with fiber, folate, carotenoids, vitamins C and K, iron and calcium, but the star nutrient for brain health is magnesium. Research, including a 2017 study and 2021 study, suggests foods packed with magnesium may help reduce anxiety and depression.
- Kale.
- Spinach.
- Bok choy.
- Collard greens.
- Arugula.
- Swiss chard.
- Asparagus.
Asparagus has long been used in traditional Chinese medicine as a tonic, but studies show that the vegetable has an anxiolytic effect and can decrease cortisol secretion.
To sneak more greens into your diet, Ramsey suggests getting creative with your dishes. For example, instead of a traditional basil pesto, he encourages people to incorporate spinach or kale into the sauce.
“I really encourage people, clinically, to move beyond the salad. Salads are wonderful, and I love a nice salad, but work in other ways to use greens in your diet,” Ramsey says.
Nuts and seeds
Eating raw, unsalted nuts and seeds is a great way to nourish your gut and mind.
“Nuts are really the perfect snack in my mind,” Ramsey says. “You get everything that signals fullness to the body – fat, protein and fiber.”
Nuts and seeds to add to your diet include:
- Almonds.
- Pistachios.
- Macadamias.
- Hazelnuts.
- Sunflower seeds.
- Chia seeds.
- Walnuts.
Not only do walnuts look a lot like the brain, but they are also one of the best nuts for the brain, containing more antioxidants and omega-3s than other nuts. In a 2019 study published in Nutrients, researchers evaluated the relationship between consuming walnuts and depression. After analyzing survey data from 26,656 participants who reported their nut consumption, researchers found that people who ate nuts – particularly walnuts – had lower depression scores than people who did not consume nuts. In fact, those who consumed walnuts had a 26% lower risk of depression than the other groups.
Beans and legumes
Beans, beans, the magical fruit. That’s because they contain prebiotic fiber, which is the type of fiber that helps the good bacteria in the gut thrive, so it’s in your best interest to add more of these mighty beans into your diet. After all, a healthy gut is a happy mind.
Other high-prebiotic foods include bananas, berries, asparagus and dandelion greens.
Dark chocolate
If you need any other reason to satisfy your dark chocolate craving, here it is: Natural dark chocolate, not the candy bar style, has been shown to lower the risk of depression.
In a 2019 study, researchers evaluated more than 13,000 adults in the U.S. and found that people who consumed dark chocolate in the past day were 70% less likely to experience depression. To be clear, dark chocolate used in the study consisted of 45% or more cocoa. The effects were not observed in people who ate milk chocolate.
Dark chocolate contains flavanols, antioxidants linked to mood and cognition; theobromine, which boosts focus and cognition; N-acylethanolamines, a fatty acid that contains anti-inflammatory properties; and phenylethylamine, which increases dopamine production in the brain.
Herbs and spices
There are various herbs and spices that researchers have investigated and identified as beneficial for our mental health, including:
- Saffron. Numerous clinical trials, including a 2017 study and 2021 study, demonstrated that saffron supplements improved mood, alleviated stress and reduced anxiety. In addition, study participants reported improved depression, sleep quality and overall quality of life.
- Turmeric. Curcumin, the active ingredient in turmeric, contains polyphenols that increase BDNF levels and fight inflammation. To get the most out of turmeric, add a pinch of black pepper and a healthy fat – such as olive oil or avocado oil – to increase the bioavailability of the spice.
- Oregano. Studies show oregano extract increases BDNF levels and improves anxiety, cognitive function and depression.
- Lavender. While smelling lavender essential oils can decrease depression, anxiety and stress, ingesting lavender oil has clinically shown to be effective in treating anxiety and depression disorders, according to studies on Silexan, an 80-milligram capsule of lavender oil.
- Chamomile. Widely known for its calming and sedative properties, chamomile contains properties that may have an antidepressant and anti-anxiety effect thanks to apigenin, a flavonoid with sedative, anti-inflammatory and neuroprotective properties.
Water
There are no fancy ingredients in water – just good ol’ H2O. Considering water makes up approximately 75% of the human brain, it’s no wonder hydration plays such a critical role in our mental health and well-being. Dehydration affects our function and health and has been associated with lower cognitive function and fatigue – both of which can affect your mood and mental wellness.
The National Academies of Sciences, Engineering, and Medicine recommends a daily fluid intake of approximately 15.5 cups for men and 11.5 cups for women. However, it’s important to adjust your intake depending on your physical activity level, environment and any health conditions that may require you to drink more.
Foods and Beverages to Limit or Avoid
On the flip side, there are certainly foods and beverages you should limit or avoid if you want to improve your mental health.
“Bad microbes feed off of sugar and processed ingredients,” Naidoo explains. “When they thrive, they upset the delicate balance in the gut microbiome.”
As a result, the bad microbes outnumber and overpower the healthy microbes, causing a cascade of negative effects that wreak havoc on the body and mind.
The worst foods to consume for your mental health include:
If you want to boost your mental health, put down the bag of chips and french fries. Ultra-processed and fried foods aren’t doing your brain any favors.
“Nutritional psychiatry is not about complex meal plans or macronutrient ratios,” Ramsey says. “It’s about addressing the number one problem that people have when it comes to food choices in America: the choice of ultra-processed foods over real whole foods.”
In a recent 2023 study published in PNAS, researchers found that frequently consuming fried food is strongly associated with a higher risk of anxiety and depression because of a particular culprit: acrylamide, a chemical byproduct found in foods that are cooked, fried, roasted or baked at high temperatures. Long-term exposure to acrylamide causes disturbances to the lipid metabolism and inflammation within the brain that have shown to induce anxiety and depressive symptoms.
In fact, acrylamide is a neurotoxin that can also infiltrate the blood-brain barrier, causing neurodegeneration and impairing the nervous system functions.
“If you imagine your brain has a layer of cells that protect and separate it from the rest of the body, the junctions between the cells are the glue that holds that wall together,” Ramsey says. “The proteins that make that glue get downregulated when you eat a lot of fried foods.”
As a result, the blood-brain barrier becomes compromised. Inflammatory molecules penetrate the brain, leaving the brain vulnerable to mental health and psychiatric disorders, including schizophrenia, autism spectrum disorder and mood disorders.
Sugar
The truth about sugar isn’t so sweet. This ingredient has been implicated in high blood pressure, inflammation, weight gain, diabetes and other physical health conditions, but it’s also bad for our mental health.
“This won’t be a surprise, but it will be a surprise from the perspective of your brain,” Naidoo says. “(People) think about it as affecting their waistline or family history of Type 2 diabetes, but sugar actually affects the neurons in your brain, so those added sugars that you have in foods you don’t realize are not helping.”
Artificial sweeteners – including aspartame and sucralose – aren’t any better. A recent 2023 study determined that a chemical found in sucralose, sucralose-6-acetate, causes DNA damage, increases inflammation and disrupts the gut microbiome.
Unfortunately, artificial sweeteners and sugar substitutes are found virtually everywhere, hiding in yogurts, beverages, cereal, ketchup, pasta sauces, white bread and other foods.
Alcohol
Relaxing with a nice glass of wine may sound beneficial, and you may tell yourself that the cabernet sauvignon you just poured is full of antioxidants and heart-healthy benefits. It may lull you into a calmer state of mind, but experts warn that is only a short-term benefit. For people who are already experiencing depression and/or anxiety, drinking alcohol may worsen their mental health. With increasing use, alcohol can cause and exacerbate depression, anxiety, psychosis and antisocial behaviors, according to psychiatrists.
“Alcohol is a great tool for covering our feelings and numbing them, but there’s no evidence that it’s helpful in mental health at all,” Ramsey says. “It’s one of the major challenges to our public mental health.”
The Bottom Line
While nutritional psychiatry has demonstrated that food plays an integral role in our mental well-being, it’s important to note that our dietary choices are not the be-all and end-all for our mental health. Eating a spear of asparagus isn’t going to magically ameliorate your anxiety or depression, nor will eating one croissant ruin your mood. Mental health, like all of health, is driven by a mosaic of factors: genetics, environment, family history and other external forces, such as trauma.
“It’s not that every good mood or bad mood is because of the food,” Ramsey says. “That’s certainly not the case, but treating our mind and our body with respect and giving it the nutrients and fuel it needs to function optimally can have a very empowering feeling.”
Ultimately, food – and how we choose to nourish our bodies – is one piece of the puzzle to how we care for our minds.
“Food is medicine,” Naidoo says. “We want people to be thoughtful when they put something in their mouth because it actually is potentially very helpful for their body, but also very important for their brain.”