Nutritional Psychiatry is a fascinating area of practice combining clinical psychiatry with nutritional science to improve symptoms of mental health disorders, such as depression and anxiety, PTSD, OCD, and many others.
The Nutritional and Lifestyle Psychiatry program at Massachusetts General Hospital is the first of its kind in the United States and is spearheaded by Dr. Uma Naidoo, a Harvard-trained psychiatrist, a nutritionist, and a culinary chef. Talk about a triple threat! She is the author of This is Your Brain on Food, an indispensable guide to the foods, nutrients, and supplements that help fight many common mental health conditions.
But why is Nutritional Psychiatry important and why should you care? On a societal level, 46 percent of Americans will meet the criteria for a diagnosable mental health condition sometime in their life.1 That is almost half the American population! Not only that, 37 percent of Americans are obese and an additional 32.5 percent are overweight, making almost 70 percent of the population above an optimal weight (1).
One in ten Americans have diabetes and 1 out of 3 Americans have pre-diabetes according to the 2020 CDC National Diabetes Statistics Report. (2) Even more shocking is the fact that 1 person dies every 36 seconds in the United States from cardiovascular disease. (3) These diseases are a direct result of the Standard American Diet (SAD) which consists of highly processed foods that have little resemblance to our evolutionary diet.
Even though these statistics paint a dismal picture of the health of our nation, you probably still won't care unless these numbers have direct meaning to you. Meaning comes from having been touched personally or have experienced a mental health condition yourself or have a family member or friend suffer from mental illness, diabetes, or cardiovascular disease, almost everybody falls into this category, and that is why you should care. So read on!
Food & Mood: The Gut-Brain Connection
During embryonic development, special cells called "neural crest cells" form the central nervous system (CNS), which is the brain and the spinal cord. These exact same cells migrate throughout the embryo to form the enteric nervous system (ENS) in the gut. So in fact, the CNS and the ENS are made of the same cells of origin and though the two systems seem to be separate they are connected so intricately the gut is sometimes called "the second brain".
The CNS and the ENS are actually physically connected to each other by way of the Vagus Nerve. The vagus nerve originates in the brain stem and travels all the way to the gut providing a direct connection. Once the vagus nerve reaches the gut it spreads out in all directions to wrap the entire gut in a web of neurons. Its main function is to communicate signals between the gut and the brain in both directions. So it would make sense that what you put into your gut has a big impact on how your brain functions.
Traveling along this two-way street are chemicals that carry the detailed and specific messages back and forth between the brain and the gut. These chemicals are called neurotransmitters and some common ones made in the central nervous system are dopamine, serotonin, and acetylcholine which are key chemicals in regulating mood and processing thought and emotions.
There are many more chemicals such as epinepherine and norepinepherine and even more systems such as the autonomic nervous system and the hypothalamic-pituitary-adrenal axis, but we won't get into them here. Just know that chemical signaling within the human body is an intricately complex system with a built-in system of checks and balances, and when that system of checks and balances is off-kilter, that is when you will see mood disorders, immunologic disorders, gastrointestinal disorders, and a whole host of other symptoms and disorders.
The good news is, the field of nutritional psychiatry and the emerging research and evidence has shown that there are many areas of intervention to bring the balance of neurotransmitters and hormones back into balance to alleviate symptoms caused by an imbalance of these chemicals, in addition to or in place of allopathic western medicine.
Another important piece of this puzzle is the gut microbiome also called the gut microbiota, which is made up of almost a thousand different species of bacteria. There are "good" bacteria and "bad" bacteria, and in a healthy gut there are mostly "good" bacteria and some "bad" bacteria and these two groups have an understanding between each other and live with each other in balance.
However, stress, anxiety and depression can change the composition of the bacteria in your gut (4), coupled with other physiological changes such as increased acid secretion and decreased bicarbonate secretion makes the protective lining of the gut more vulnerable. As a result, food and nutrients are not properly absorbed, leading to deficiencies and suboptimal functioning of both the gut and the brain.
A concrete example of this is shown in those who have irritable bowel syndrome or inflammatory bowel disease also have mood changes due to gut bacterial populations being drastically altered (5). Another example is the changes in the proportions of Escherichia, Bacillus, Lactococcus, Lactobacillus and Streptococcus can change dopamine levels and can predispose one to Parkinson's and Alzheimer's disease (6).
The link between the gut and the brain is strong and fortunately can be researched and tested by science to allow us to move forward in the field of Nutritional Psychiatry with confidence.
The Science Behind Nutritional Psychiatry
The saying "You Are What You Eat" is a simple truth. The food that you put into your body literally becomes a part of your body and affects how every system in your body functions. When food consumption is thought about in this way, it is hard to justify putting into our bodies toxins and substances we know are detrimental to our health, but yet we do.
That discussion is a loaded topic for another time, but the basics of it are, that food is a form of energy used by all our body's organ systems in order to keep us alive and functioning metabolically and mentally. The type of food matters and there is a science to prove it!
The Link Between Depression & The Gut
A study done in 2019 by a psychiatrist named Stephanie Cheung, examined gut health in patients with major depressive disorder. It showed that these patients had at least 50 types of bacterial species in their gut microbiome that were different than those control patients without a major depressive disorder (7). This is not earth-shattering news, but it is evidence that what is happening in the gut affects mood and gives us a place to start making some changes.
What changes are we talking about here? Increasing probiotics and prebiotics in your diet is what we are talking about. Everybody has heard of probiotics, but maybe you haven't heard of prebiotics.
Prebiotics are essentially FOOD for the "good" bacteria living in your gut.
There are types of fiber that the human digestive system itself cannot digest but the bacteria living in the gut can. The bacteria in the gut break down the prebiotics into short-chain fatty acids to reduce gut inflammation and block the growth of cancerous cells. Just as we need high-quality food to function, the bacteria living in our gut need the right foods to function too, so that we can digest and absorb all the nutrients, minerals, and vitamins our bodies need.
Some examples of prebiotic foods are beans, bananas, berries, garlic, onions, asparagus, artichokes, and leeks. Try having a banana a day in the form of this delicious Chocolate, Banana, Peanut Butter smoothie that I have almost every day.
Chocolate, Banana, Peanut Butter, Prebiotic Rich Smoothie
1 banana
1 cup almond milk (or your favorite non-dairy milk)
2 TBSP raw cacao powder (NOT cocoa powder - cocoa is raw cacao cooked at high heat and destroys some of the beneficial nutrients)
2 TBSP peanut butter
1 cup ice
Optional scoop of Green Superfoods Powder and/or 1 tsp Maca Root Powder (gelatinized NOT raw)
How Effective Are Probiotics For Mood Disorders?
Now onto Probiotics. A study done in 2010 assigned its participants to receive either a daily probiotic supplement or placebo for thirty days. The outcomes measured were a self-assessment of mood symptoms and measured cortisol (a stress hormone) levels in the urine. Compared to the placebo group, the probiotic group reported less depression AND had lower levels of cortisol in their urine (8).
This can be explained by the ability of certain species of gut bacteria to be able to boost levels of brain chemicals like gamma-aminobutyric acid, which may provide relief from depression and other mental health conditions (9).
While you can certainly take a probiotic supplement, if you can get your probiotics from food sources first, that is always the preferred way. Yogurt with live active cultures is one of the best sources of probiotics. Other sources include kombucha, kefir, kimchi, sauerkraut, and fermented soybean products like miso, tempeh, and natto. It can be hard to make sure you are incorporating these foods into your daily life, or you might not particularly like these types of foods, if that is the case, consider taking a probiotic in supplement form. Another option is to take the supplement on days that you were not able to get probiotics in your diet from a food source.
Prebiotics and probiotics is just one example of the many nutritional interventions that can be made to enhance mood and depression just one of many mental health conditions that this intervention may benefit. For each specific mental health diagnosis, there will be many nutritional interventions that overlap and there will be some nutritional interventions that are more specific to the condition.
The clinical practice of Nutritional Psychiatry will show more benefit in the mild to moderate mentally ill categories and will not be the first line of therapy for more severe mental health conditions such as acute psychosis, suicidal ideations or psychiatric emergencies. Even still, the correlation between nutrition and mental health is promising and as more research emerges, the hope is to see nutrition as a pillar in the treatment plan of psychiatric disorders.
The Link Between Anxiety & The Gut
When you feel anxious or nervous, how does that manifest in your physical body? Some common symptoms are fast heart rate, excessive sweating, shakiness, a knot in your stomach, or even nausea. This again is evidence of the bidirectional relationship between the brain and the gut.
Data from a study done in 2018 compared the microbiota of people with a generalized anxiety disorder (GAD) to those to healthy controls and found that the patient's with GAD had a much less diverse population of bacteria and the "good" bacteria the ones that produce short-chain fatty acids, a sign of a healthy gut was sparse and there was an overgrowth of "bad" bacteria.10 Furthermore, treating the anxiety disorder with medication did not correct the imbalance, leading us to conclude that to address the root cause of the problem you have to target the gut microbiota (10).
Irregularities in the microbiome can weaken the gut wall, which serves as a protective barrier between the gut and the bloodstream. When the gut wall is weak, bacteria can leak through the gut wall lining and enter the blood circulation and even the brain, which is called leaky gut syndrome and can cause serious illnesses like sepsis and bacteremia (infection of the bloodstream) (9).
60 percent of patients with anxiety have irritable bowel syndrome (IBS), a chronic disorder that can manifest as abdominal pain, diarrhea, constipation, bloating and painful gas (11). The more severe the anxiety the more severe the IBS (12). The reverse relationship is also true, patient who have IBS have been shown to have decreased functioning in the areas of the brain responsible for executive function and feeling emotions (13).
So it's great to know all this information but how does this translate to everyday practical life? What can you do in your life to decrease your symptoms of anxiety and experience a little more calm in your life? Before we get into what to EAT, it will be beneficial to dive into what NOT to eat, as making these shifts first will go a long way in helping to decrease anxiety symptoms before we even add in the good stuff!
What NOT to Eat — The Standard American Diet (SAD)
It's so fitting that the acronym for The Standard American Diet is SAD because it is extremely sad that the food (if you can call it that) in the SAD are the very things that are making Americans sick.
Saturated and trans fats, polyunsaturated fats used for deep frying, high glycemic index carbohydrates, refined processed foods, sweetened drinks, especially those with high-fructose corn syrup, and overconsumption of red meat. These things are literally killing Americans and wreaking havoc on the mental health of the American population.
It may not land well with people when they are told NOT to eat something they really like, framing it as a reduction or limited consumption may be more helpful, because really who doesn't love french fries or falafel every now and then! There are foods that should be more strictly eliminated or reduced and there are ones that a cognizant reduction or limitation is encouraged to help decrease anxiety and depression.
The foods that should be eliminated or significantly reduced are:
saturated and trans fat such as red meat and refined processed foods
high glycemic index carbohydrates such as flour and sugar, especially high-fructose corn syrup
Foods that should be reduced, limited, and consumed in moderation are:
Caffeine - Caffeine overstimulates the areas of the brain that perceive a threat and can worsen anxiety. Studies have shown that 100 mg of caffeine (1 cup of coffee) has little to no effect on anxiety. While 100 - 400 mg of caffeine a day shows mixed results, more studies showed increased anxiety and some showed no effect. And greater than 400 mg of caffeine a day showed a significant increase in anxiety (13). A good rule of thumb is no more than 4 cups of coffee a day. Other strategies to decrease caffeine can be to switch to decaf or half-caf, half-decaf, or switch to black or green tea which has half the amount of caffeine per cup, 50 mg.
Alcohol - Alcohol is often used by many as a way to relax or to relieve the stress of a hard day. In more severe cases, heavy drinking is used as a way to cope with anxiety, social anxiety disorder or to avoid pain from mental or emotional traumas. While drinking alcohol may feel good in the moment, excessive consumption and habitual consumption can have serious consequences and can make anxiety even worse. Alcohol also causes those with anxiety to sleep poorly, and the day after consequences of jitters and increased anxiety are signs of mild to moderate alcohol withdrawal.
Gluten - While the research on anxiety and celiac disease is somewhat conflicted, there have been studies that have shown that patients with celiac disease who were on a gluten-free diet for one year did have less anxiety (15). A common recommendation is for patients with anxiety to trial a gluten-free diet to see if there is any difference in their symptoms and get tested for celiac disease. Even if celiac disease does not show up, low gluten or gluten-free diet can help manage anxiety symptoms just by way of having a cleaner diet as gluten in the form of flour is often coupled with sugar and that combination can lead to problems that can contribute to a vicious cycle of carbohydrate cravings, emotional eating, guilt, shame which can lead to further mental health issues.
Sugar - Have you ever noticed that when you are feeling down or blue you might crave sugar? And when you are eating the cookie or cupcake you feel GREAT! Not only does it taste good but it also causes an instant release of dopamine and serotonin in the brain that activates your reward center and makes you feel good. If this is a once in a while type of thing, there is nothing wrong with that, but if this happens every day, multiple times a day and you are overindulging in sugary treats, the more sugar you eat the more likely you are to be depressed. The studies have shown that there is a profound and near-perfect correlation between excess sugar and depression (17). The reason is, our brains use glucose as their primary energy source and only need 62 grams of sugar a day, which can easily be achieved by eating a healthy whole diet. When much more sugar is consumed, the excess sugar "floods" the brain causes inflammation, and can result in depression when this happens on a regular basis.
Artificial Sweeteners - Artificial sweeteners such as saccharin, sucralose, stevia, erythritol, and especially aspartame as been proven to be toxic to the brain. Several studies have shown that artificial sweeteners can alter concentrations of mood-regulating neurotransmitters by inhibiting the synthesis of dopamine, noradrenaline, and serotonin and can contribute to mood disorders (16).
Nutritional Approaches to Treat and Prevent Anxiety & Depression
The good news is, there are tons of healthy and delicious ways you can adjust your diet to improve your mood, feel calmer and more energetic. The table below shows you some examples of foods to incorporate into your diet on a daily basis.
Focus on Omega-3 fatty acids from fish and nuts/seeds, increasing vegetables especially dark leafy greens, plant-based protein (small amounts of lean animal protein), high-fiber whole grains, healthy fats like olive oil and avocados, and moderate amounts of fruits.
This diet is basically the Mediterranean Eating Pattern and to say that this way of eating is much healthier than the SAD is an understatement. While it may seem like a "no brainer" the reality is that many Americans do not have access or the resources to eat in this way and that is why among the many challenges we face as a nation the obesity epidemic is one of them.
Inflammation and the Brain
We have already touched on how eating too much sugar can cause inflammation of the brain which can present as having a low, dull mood and brain fog, and how having too many "bad" gut bacteria can trigger metabolic processes that cause brain inflammation as well.
Watch out for these additional foods that can cause brain inflammation and what can be adjusted to decrease inflammation.
Omega-6s - A high omega-6 to omega-3 ratio has been shown to lead to increased levels of anxiety as measured by increased interleukin-6 (an inflammatory marker) (18). You can think of omega-6s as "bad" fatty acids and omega-3s as "good" fatty acids that are anti-inflammatory and neuroprotective. Omega-6s are found in full-fat cheeses, high-fat cuts of red meat, corn oil, and palm oil. Cut down on omega-6s by switching to canola oil and increase omega-3s by eating more fatty fish such as salmon, sardines and mackerel, walnuts, chia seeds, and omega-3 fortified eggs.
Monosodium Glutamate - Though there is controversy as to whether or not MSG is as toxic as it has historically been made out to be, scientific studies have shown that MSG is safe at ordinary levels (10 gm per average adult)(19). However, in sensitive individuals, particularly those who have PTSD who are vulnerable to excess glutamates, too many glutamates can cause brain inflammation and destruction of brain cells. It would be wise to limit MSG containing foods such as fish sauce, oyster sauce, tomato sauce, savory snacks, chips, ready-to-eat frozen meals for people who have PTSD.
Saturated Fats - Diets high in saturated fats can exacerbate inflammation in the brain and have been linked to cognitive decline and increased risk of developing Alzheimer's disease (20). Inflammation disrupts the chemical pathways involving dopamine and glutamate and their role in memory formation and the nerves become sluggish and information travels much more slowly along the nerves. Swap out using butter to cook with for avocado oil, start viewing red meats and full-fat cheese as a once-in-a-while type of food rather than a daily or multiple-times-a-week type of food. The good news is, damage done by a high-fat diet can be undone with the right dietary changes and exercise.
Micronutrients and the Link Between Deficiencies and Mood
Micronutrients are vitamins and minerals that are essential in allowing our bodies to carry out physiological functions such as metabolism and digestion. Research has shown that deficiencies in key nutrients such as iron, zinc, selenium, vitamin D, and magnesium have been linked to increased depression (1).
My approach is to try and get all the required vitamins and minerals from food sources first. If for a specific reason, getting the required micronutrients is challenging, for example, you are a vegetarian or vegan or you are allergic to fish or nuts, then you can consider a supplement.
If you are feeling a low or dull mood, try incorporating the following foods into your diet and monitor for any difference in mood or improvement of depressive symptoms. If you see no difference, consider talking to your primary care provider and asking to do blood work to check for any deficiencies.
Iron - shellfish, lean red meats, legumes, pumpkin seeds, broccoli, and dark chocolate (the higher the percentage the better)
Magnesium - avocados, nuts/seeds, legumes, whole grains, and some omega-3 rich fish (salmon and mackerel)
Zinc - seafood (especially cooked oysters), lean beef, and poultry. Lower amounts are found in beans, nuts, and whole grains.
Vitamin D - sun exposure, fortified milk, eggs, salmon, and mushrooms
Selenium - Brazil Nuts
Where Do We Go From Here?
Nutritional Psychiatry is going to be a topic that will pop up more commonly as new and exciting research continues to emerge.
There is a wealth of information out there and it can be overwhelming to try and discern and tease out what information is reliable and trustworthy. A good place to start is to start with the basics of nutrition philosophy. Eat a whole, real food, unprocessed plant-based diet.
Don't eat too much. Move your body in any way that feels good to you every day. Be kind and gentle to yourself and others. Anything else on top of that is just "icing on the cake" so to speak!
References:
Naidoo, U. (2020) This is your brain on food. New York, NY. Little, Brown Spark.
https://www.cdc.gov/diabetes/library/features/diabetes-stat-report.html
https://www.cdc.gov/heartdisease/facts.htm
Galley JD, Nelson MC, Yu Z, et al. Exposure to a social stressor disrupts the community structure of the colonic mucosa-associated microbiota. BMC Microbiology. 2014;14(1):189.
Simren M, Barbara G, Flint HJ, et al. Intestinal microbiota in functional bowel disorders: a Rome foundation report. Gut 2012;62(1):159-76.
Giau V, Wu S, Jamerlan A, et al. Gut microbiota and their neuroinflammatory implications in Alzheimer's disease. Nutrients. 2018;10(11)1765.
Cheung SG, Goldenthanl AR, Uhlemann AC, et al. Systematic review of gut microbiota and major depression. Frontiers in Psychiatry. 2019;10:34.
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Kiecolt-Glasser JK, Belury MA, Andridge R, et al. Omega-3 supplementation lowers inflammation and anxiety in medical students: a randomized controlled trial. Brain, Behavior, and Immunity. 2011;25(8):1725-34.
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