Ahanu, forty years old, had recently been promoted to senior sales leader at a Fortune 500 company. His new role was exciting but stressful, involving a vast amount of air travel across the globe and a breakneck schedule that often meant long hours every day of the week. While he had steeled himself for pressure and hard work, Ahanu hadn’t expected mounting symptoms of anxiety. He was finding himself on the brink of panic attacks during his frequent travel, which he had never experienced before. Even routine interactions at work, like chatting with colleagues in the break room, greeting his boss, and simply deciding how to dress for work, were causing him to spend hours obsessing about what he said and how he acted, costing him sleep and leaving him feeling constantly jumpy and irritable.
When Ahanu came to my clinic for a consultation, we discussed the difficulties of adjusting to the stress and pressure of his new job and talked about the possibility that imposter syndrome was rearing its head. And, of course, we evaluated his diet. Ahanu came from Native American roots and was the first in his family to work in the corporate world. He grew up on his family’s farm and was used to eating a traditional diet based mostly on low-fat, high-protein, complex carbohydrate–based foods like heirloom varieties of corn, field beans, squash, root crops, and native berries.
Early in his career, Ahanu had largely maintained his traditional diet as a way to stay connected to his upbringing and heritage—and simply because it was a delicious and familiar way to sustain himself. But as his star rose in the company, it was harder to make the time to shop and cook. When he was on the road, he was relying on airport pastries and lavish client dinners designed to be decadent and impressive rather than nourishing. When he was home with the kids, he was tired and wanted to treat them, so they would end up going out for pizza and fast-food meals rather than cooking. I explained to Ahanu that the macronutrients in his diet had gotten twisted around. Instead of eating a largely plant-based diet full of fiber-rich beans and low-glycemic-index carbs from locally grown vegetables, he was eating doughnuts and porterhouse drenched in butter.
I started Ahanu on an SSRI to help ease his anxiety, but I also encouraged him to find ways to get back to his old eating patterns. We talked about how he could make preparing traditional meals a fun activity to do with his family when he was between trips, as well as how to prepare food in advance that he could take with him during his travels. I encouraged a plant-rich diet, adding back the beans and root vegetables he grew up with, as well as exploring some new styles of cooking. Easy meals became his go-to dinners for the family and gave him healthy leftovers for lunch the next day—for instance, oven-baked salmon with my Miso-Infused Cipollini Onions and Green Beans (here). He also made a five-bean stew—loaded with vegetables—in the crockpot and served it with a side of seasoned wild rice. When he traveled, he ate large salads with the dressing on the side. While client meals were part of the job, he decided he would nudge plans out of fancier fine-dining options (with few to no calming dishes) and toward healthier wow-factor meals like sushi. And when that wasn’t possible, he opted for baked or grilled fish, rather than an anxiety-inducing meal.
Before long, Ahanu told me that he was feeling more at ease in his new role, staying focused on his professional goals. Returning to his traditional diet also deepened his bond with his family and helped him reconnect with his heritage. Changing the biggest components of his diet—macronutrients—changed his life.
In this chapter, we’ll study the ways in which fat, carbohydrates, and protein can exacerbate or alleviate anxiety.
Macronutrients—fat, carbohydrates, and protein—are the biggest components of the food we eat. Most healthy diets consist of some proportion of all three. Of course, the devil is in the details. What is the right balance? What are the best and worst sources of each? And how do they factor into anxiety?
Those questions don’t always have easy answers, and changing attitudes about macronutrients can lead to shifting sands of advice. Take fat, for example. Starting in the late 1940s, when much of the foundation of modern nutritional thought was forming, researchers found associations between high-fat diets and high cholesterol, a metabolic risk factor that was correlated with a greater risk of heart disease. Thus, a low-fat diet was assumed to lower cholesterol and lead to better heart health. At first, low-fat diets were recommended only for those at risk of heart disease, but through the fifties and sixties, they became a prescription for everyone. In the eighties and nineties, a fully-fledged lifestyle blossomed that promoted low-fat diets not only for heart health but also weight loss. Doctors, governments, and public sentiment agreed that fat consumption should be as low as possible, and that the healthiest fat to consume was vegetable oil. Margarine replaced butter. Chicken—especially boneless, skinless chicken breasts—replaced fattier meats. Skim milk was king. Brands labeled every possible food as “low-fat” and “heart-healthy,” even if they were packed with calories and sugar.1
In the 2000s, the pendulum started to swing the other way. After years of certainty that fat was at the root of bad health and excess weight, negative attention turned to a different macronutrient: carbohydrates. While low-carb diets had been used for weight loss since the nineteenth century, they rose to new prominence as wave after wave of trendy diets that cut carbs started to take over the popular health consciousness.2 Today, diets recommending an eighties- or nineties-style low-fat approach are much less common, but there are still plenty of diets predicated on low carb intake, including the popular ketogenic diet, which we will discuss in chapter 11.
Who was right, the anti-fat crusaders or the anti-carb crusaders? Both of them. And neither of them. Despite what some diet evangelists will tell you, no one macronutrient should be totally ostracized, and there isn’t a definitive balance of macronutrients that is better than all others. Consider how diets heavy in different macronutrients affect conditions like T2D, which has a strong correlation with anxiety. The traditional approach to treating T2D through diet is to eat a low-fat, low-calorie diet in order to normalize blood sugar and other metabolic indicators—a similar line of thinking to the original low-fat recommendations from the fifties. But recently, low-carb diets like the ketogenic diet have gained prominence in treating T2D and have shown that they can be even more effective, reducing the need for diabetic medications and even forcing T2D into remission.3 However, recent research showed that a high-starch, plant-based diet from the BROAD study—which has a very different macronutrient makeup than a keto diet—was extremely effective at helping study participants with T2D lose weight and improve cholesterol and other metabolic risk factors.4 Rather than insisting that there must be a single optimal dietary treatment for T2D, it’s better to recognize that several different approaches can be effective and that methods can be tailored to patient preference and situation. This is part of a broader movement to a much more personalized form of medicine in all medical specialties, but it’s particularly important when considering dietary interventions.
There are also many ways in which the balance of macronutrients in your diet can improve or worsen anxiety directly. Much of the low-fat-versus-low-carb debate happened before we really understood the connection between food and mental health, but with our current knowledge, we are beginning to see that prioritizing one macronutrient over the others can risk worsening anxiety. For example, a low-fat diet might leave you short of valuable omega-3 fatty acids, which are hugely important in fighting anxiety. A low-carb diet might make it hard to get proper amounts of dietary fiber, which plays a crucial role in regulating the gut microbiome. A low-protein diet (or one that doesn’t include a diverse selection of proteins) could result in a lack of essential amino acids like tryptophan.
In other words, when making recommendations for my patients, I try to keep from getting wrapped up in absolutes—there is no one type of macronutrient that can be eliminated to cure anxiety. But just because I don’t think fat or carbs are an all-or-nothing proposition, that doesn’t mean that macronutrient balance and quality don’t matter. I am glad we have left behind the era of demonizing all fat, but I certainly acknowledge the importance of reducing or eliminating unhealthy fats, as well as promoting healthy fats. The same is true of carbs. While a low-carb lifestyle isn’t a guaranteed ticket to a calm mind, there are certain types of carbs that should be avoided and others prioritized. When it comes to protein, proponents of a vegan diet are vocal about avoiding animal protein at all costs, while ardent meat eaters will claim that you can never be truly healthy on a totally plant-based diet. In reality, it’s possible to reduce anxiety as a vegan or a meat eater, as long as you make conscious, informed choices about the proteins you eat.
Spending time on social media, watching morning shows, and even discussing food with your friends and family can quickly induce anxiety as you encounter strong, often conflicting opinions. But by understanding macronutrients, you’ll be better equipped to determine the best ways to eat for your brain and body—and your anxiety.
The negative connotations surrounding the word “fat” tend to cloud discussions about the important role of fat in your body and diet. Between the demonization of dietary fat in the late twentieth century and harmful body standards that encourage burning fat at all costs, it’s easy to see why it is such a loaded term. But fat is necessary for a healthy life. In chapter 5, we learned how your adipose tissue is actually an advanced endocrine organ that helps manage your body’s long-term energy needs. Fat is also a crucial part of your diet, providing a great source of energy, helping you dissolve and absorb nutrients, and supplying you with essential fatty acids that your body can’t make on its own. Essential fatty acids are particularly important for mental health, since your brain is nearly 60 percent fat and relies on a steady supply of dietary fats to maintain proper function.5
Of course, not all fats are created equal. Let’s break down the different kinds of fats and learn which ones to prioritize and which to avoid as you make antianxiety eating choices.
There are two main types of unsaturated fats, monounsaturated fats (made up of monounsaturated fatty acids, or MUFAs) and polyunsaturated fats (made up of polyunsaturated fatty acids, or PUFAs). The difference between the two has to do with their chemical structure, with “mono” and “poly” referring to the number of double bonds in their fatty acid chains. An easy way to distinguish unsaturated fats from saturated fats is that unsaturated fats are nearly always liquid at room temperature, whereas saturated fats are solid at room temperature (though certain unsaturated fats, like margarine and vegetable shortening, undergo processing that allows them to be solid at room temperature). MUFAs and PUFAs are generally regarded as healthier than their saturated cousins, but it’s worth considering the details before assuming that all unsaturated fats are perfectly healthy with no danger of increasing anxiety.
MUFAs make up the bulk of fats in olive oil, avocados, most nuts, and some cooking oils. MUFAs are nearly always recognized as being healthy, particularly olive oil and avocado oil. Olive oil is the primary cooking fat of Mediterranean cultures, whose low rates of heart disease inspired nutritionists worldwide to create and recommend the Mediterranean diet, which has also been shown to fight depression and anxiety.6 Avocado oil has many of the same benefits as olive oil, while being better for high-temperature cooking like sautéing and stir-frying.
There are a myriad of studies that show that high-MUFA diets promote gut health,7 fight inflammation,8 and lead to decreased metabolic risk factors9 as well as lower levels of anxiety.10 Not all MUFAs should be eaten in unlimited quantities—for instance, while certain cooking oils like canola and peanut oil contain MUFAs, they tend to be used in deep-frying, which is likely to lead to consuming a ton of calories’ worth of refined carbs. While I suggest my patients limit these cooking oils, I certainly encourage them to eat healthy fats from olive oil, avocados and avocado oil, nuts, and seeds.
PUFAs have two important subsets. Omega-6 PUFAs include most vegetable cooking oils found in processed foods—corn oil, sunflower oil, and safflower oil are all types of PUFAs. Like MUFAs, these fats are regarded as relatively healthy in very small quantities, though it’s important to acknowledge that they are often a major component of unhealthy foods. No fat is healthy when combined in large amounts with high-glycemic-load carbohydrates that practically beg you to stuff yourself with them. In other words, French fries aren’t healthy. While evidence is somewhat mixed, there are signs that omega-6 PUFAs have been linked to anxiety and depression,11 and they can be pro-inflammatory,12 so I generally encourage my patients to limit them, especially in fried, processed, and packaged foods.
On the other hand, omega-3 PUFAs are some of the most important fats for mental health. There are three main types of omega-3 fatty acids: EPA and DHA, which are found in fatty fish like salmon, and ALA, which largely comes from plant sources like seeds, nuts, seaweed, and other types of algae. DHA is particularly crucial in brain development, and babies who don’t get enough DHA can have a variety of troubles as their brains grow. Later in life, omega-3s have powerful anti-inflammatory properties; they are a crucial tool in fighting anxiety-causing neuroinflammation, which we discussed in chapter 4.13 While much of the research surrounding omega-3s’ effect on mental health is centered around depression and neurodegenerative diseases, there is growing evidence that omega-3s directly reduce anxiety as well.14
Given our understanding of the importance of omega-3s, omega-3 supplements are available that give you a certain ratio of EPA, DHA, and ALA as a pill or capsule. While I don’t categorically object to supplements, it’s worth acknowledging that in many studies, dietary sources of omega-3s yielded better results than supplements.15 Additionally, no one enjoys choking down a large capsule of fish oil, but many enjoy eating a well-cooked piece of salmon. For my anxious patients who don’t object to eating fish for other reasons, I heartily recommend that they take the time to learn to cook salmon in order to capitalize on the best source of EPA and DHA. Those who prefer a plant-based diet can eat flaxseeds, chia seeds, and walnuts for ALA, and EPA and DHA are also available via vegan algal oil supplements.
One important way to think about your PUFA intake is to try to eat a proper ratio of omega-6 fats to omega-3 fats. Given how much vegetable oil we consume compared to how little fish we consume, it can be very easy to skew this ratio—with the average American consuming in the vicinity of 15 to 1 omega-6s to omega-3s, according to some estimates. Studies have found that balancing out that ratio, ideally to lower than 5 to 1, yields many health benefits, largely resulting from a reduction in inflammatory conditions.16 Improving this ratio has also been shown to directly decrease anxiety.17 Of course, it’s not always practical or even possible to determine the exact amount of omega-6s and omega-3s in your diet, so I simply encourage patients to try to eat fewer omega-6 fats and more omega-3 fats.
When you think of fatty foods, your mind might drift to the smell of sizzling bacon or the taste of melted butter. These are types of saturated fat, which is largely derived from animal sources. Unlike MUFAs and PUFAs, saturated fat is usually solid at room temperature—the bacon grease and melted butter will turn back into solids as they cool. The few plant sources of saturated fat, like coconut and palm kernel oil, are also solid or semisolid at room temperature.
Saturated fats have a reputation for being unhealthy, and as with all foods, I certainly recommend that my patients moderate their intake of them. Saturated fat has traditionally been considered a factor in heart health, and for years guidance has been to eat as little as possible in order to reduce risk of heart attack and other cardiovascular conditions. High cholesterol due to a diet rich in saturated fat is also one of the pillars of metabolic syndrome, which we learned in chapter 6 is a risk factor for metabolic conditions like T2D. And sure enough, there have been studies linking consumption of saturated fat to increased anxiety,18 as well as anxiety-producing conditions like neuroinflammation.19
However, saturated fats are currently one of the biggest areas of conflict in the study of nutrition. After years of recommending little to no saturated fat intake, studies are now suggesting that saturated fats may not be as harmful as we thought. In a landmark study from 2020, the Journal of the American College of Cardiology found that saturated fat from whole-fat dairy, unprocessed meat, and dark chocolate do not have an effect on heart-disease risk and can actually be protective against conditions like stroke.20 While more research is needed on what these findings mean for mental health conditions like anxiety, it’s becoming clear that saturated fats have also been overly vilified in the past. Upon reviewing the most recent literature on saturated fats, I’ve embraced recommending sensible amounts of full-fat dairy, butter, and some cuts of ethically farmed beef. These foods are quite rich in protein as well as vitamins and minerals, so changes in saturated fat guidelines make them worthy additions to your diet, at least in moderation.
While new scientific research has led to an improvement in saturated fat’s reputation, that is very much not the case for trans fats. Though small amounts of trans fats do occur in natural sources, they’re largely man-made through a process called hydrogenation. Ironically, trans fats proliferated during the low-fat craze of the second half of the twentieth century—given the bad reputation of saturated fats, snack makers looked for a non-saturated fat that was still solid at room temperature. The solution was partially hydrogenated oil, which is a major source of trans fats. It began to appear in butter substitutes like margarine, chips, cakes, cookies, and almost every form of processed snack food.
What was originally pitched as a healthier alternative to saturated fat turned out to be just the opposite. Trans fats have been implicated in increased risk of heart disease, T2D, obesity, and even cancer.21 Many of these ill effects are likely related to its pro-inflammatory tendencies, as trans fats contribute to chronic systemic inflammation.22 Unsurprisingly, trans fats have been directly linked to higher levels of anxiety in both animal23 and human studies.24
During the 2000s, many governments, including the US government, took measures to ban trans fats, which has helped reduce the risk of exposure. However, due to lobbying from the processed-food industry and the slow timeline of advancing legislation, the ban was not actually enacted until 2018, with products produced before the ban allowed to stay on the market until 2020. Even in 2022, it’s possible for older processed foods to contain high levels of trans fats, so that’s another reason I always encourage patients to limit any processed, packaged junk food and fried food from restaurants.
As knowledge about the dangers of trans fats grew, producers of cooking fats like vegetable shortening moved to fully hydrogenated oils, which yield a similar product without the trans fats. However, given how heavily processed shortening is—and given that it is usually used in sweets and processed snacks—I still recommend avoiding it.
When you think of carbohydrates, your mind probably jumps to starches: bread, rice, pasta, potatoes, and other dietary staples. Those are certainly major sources of carbs in traditional diets around the world. But sugar is the simplest form of carb, and it makes up a huge part of the caloric load in many modern diets, especially the standard American diet. More complex carbs come from fruits like apples, vegetables like broccoli, and legumes like lentils. When you think about cutting carbs, are you committing to eliminating broccoli and lentils? I doubt it. That’s why, amid volleys of arguments from different factions in the carb wars, I try to keep a level-headed approach when advising my patients. Treating carbs as a monolithic, universally harmful food group just isn’t useful, and I think it’s time for a more sensible approach.
Most research and discourse surrounding carbs concerns improving metabolic health. But remember, metabolic health is mental health. As we’ll see, the recommendations about carb consumption that improve metabolic health will improve anxiety, too.
Just as we saw with fats, it’s all about eating quality carbs. The idea that your body processes every carbohydrate the same way simply is not true. There is ample evidence that different types of carbs have different metabolic effects on your body. Some are more energy efficient than others, providing your body with more power for the amount you consume. Some are pro-inflammatory and come with greater risks of the kinds of metabolic health factors we discussed in chapter 6. Others bring along increased levels of important nutritional components like dietary fiber.
I won’t get too deep into the nutritional chemistry that determines carb quality, but I do want to highlight an important concept that helps determine which carbs to eat and which to avoid. The glycemic index (GI) is a 100-point scale that measures how quickly different carbohydrates raise your blood sugar—in other words, how long it takes for the food you eat to turn into energy in your bloodstream. In most cases, a lower score is better for you, because it means less of a spike in blood sugar, which can stress your metabolism and lead to metabolic conditions that are risk factors for anxiety.
Pure glucose sets the top of the range with a glycemic index of 100, while more complex carbs that take longer to digest have lower scores. High glycemic index foods (GI scores of 70 and above) include white bread, white rice, peeled potatoes, and many processed breakfast cereals. Medium glycemic index foods (GI scores of 56–69) include whole wheat bread, basmati rice, unpeeled potatoes, and certain fruits like bananas and grapes. Low glycemic index foods (GI scores of 55 or less) include intact grains like oats and brown rice, mushrooms, and fruits like peaches and berries.
Diets heavy in high-GI carbs have been correlated with higher rates of anxiety in both animal and observational human studies25 as well as in case studies of specific patients.26 High-GI diets have also been found to be risk factors for depression,27 lead to a higher concentration of inflammatory markers,28 and contribute to poor metabolic health29—a familiar lineup of anxiety comorbidities. So even if you don’t have any interest in seriously limiting carbs, I encourage replacing processed foods and other high-GI carbs with low-GI carbs. Instead of a processed breakfast cereal, have a bowl of steel-cut oats with berries. Instead of potatoes, choose sweet potatoes or, even better, carrots or a more adventurous root vegetable like taro. Instead of a sugary dessert, go for an apple, orange, or banana.
In recent years, some of my patients who struggle with blood sugar have used continuous glucose monitors, devices that track blood glucose levels at all times, allowing you to see exactly how different foods affect your blood sugar. Though their results generally track with conventional wisdom on glycemic index, I’ve also come across some surprising results, where blood sugar spikes more or less dramatically than I would expect in relation to different foods. My takeaway from this clinical data is that we are each unique, and each person’s response to a certain food may differ. This is another sign that we need personalized medicine moving forward.
Another major plus for foods rich in low-GI carbohydrates is that they tend to be higher in dietary fiber, which is a crucial part of an anxiety-lowering diet. Dietary fiber is not actually a carb itself, but its main sources are carb-rich foods like fruits, vegetables, legumes, and whole grains. Fiber plays a unique role in nutrition because it’s a nutrient that we can’t actually digest and absorb into our bodies. Even though our bodies can’t turn fiber into energy, it still helps to control appetite, slow digestion, ease the passage of waste, and promote a healthy gut microbiome.
In recent research, dietary fiber has emerged as one of the most important factors in fighting anxiety with food. For instance, in a 2021 study from Iran, high-fiber diets were significantly correlated with lower levels of anxiety.30 Furthermore, fiber has been shown to be a bulwark against inflammation and depression as well.31 And fiber has long been known to lead to better metabolic health indicators like cholesterol levels.32
These positive effects of fiber are partially attributable to its importance to gut health. Remember from chapter 2 that different gut microbiota thrive on different types of substances in your gut. Foods that provide nourishment for bacteria are called prebiotics, and fiber is one of the most advantageous types of prebiotic, promoting helpful strains of bacteria, discouraging toxic strains, increasing absorption of minerals, and improving gut permeability and immune response.33 Furthermore, recent evidence suggests that the bacteria that produce important metabolism-regulating substances like SCFAs thrive on the dietary fiber passing through your gut.34 In other words, ample fiber in your diet means a greater concentration of good bacteria, which leads to good gut health, which in turn results in good metabolic health and less anxiety.
Given the prevalence of processed carbs in the modern US diet, it’s quite common to fall short of the proper amount of fiber in your diet—most adults need at least 25–35 grams of fiber per day, but the typical American diet includes only about 15 grams per day.35 Getting enough fiber can be particularly difficult on a low-carb diet, which focuses on fats and proteins from animal and seafood sources that have little to no fiber content. Fiber comes from plants, especially whole grains, fruits, nuts, beans, lentils, and leafy greens. While you can supplement your diet with fiber from natural sources like psyllium husk (the key ingredient in fiber mixes sold under brands like Metamucil), foods rich in fiber are healthy in so many ways that I heartily encourage you to try to get as much fiber as you can from whole foods first.
We’ve seen several patients in the book whose anxiety was worsened by excess sugar in their diet. That checks out with what we know about high-GI carbs promoting anxiety, since sugars are among the highest GI foods, providing quick raw energy without delivering much else in the way of nutrition. We all know the feeling of the “sugar rush,” where you get a burst of energy after eating something sweet, followed quickly by the “sugar crash,” where your energy collapses. That can lead to eating more sugar to regain the high, which turns into a cycle of bad diet choices and leads to anxiety.
A large cross-sectional study from France found that nondiabetic individuals under forty-five with anxiety ate more sugar than those without anxiety.36 Sugar consumption has also been correlated with depression37 and is one of the primary drivers of bad metabolic health.38 Eating a lot of sugar can mean disruptions in gut health as well, leading to a welcoming environment for pro-inflammatory bacteria while discouraging the anti-inflammatory bacteria that help maintain the integrity of your gut mucosa.39 If you haven’t noticed, these effects are the polar opposite of what we just saw with dietary fiber. In all the ways dietary fiber helps your physical health and fights anxiety, sugar harms your physical health and feeds anxiety.
Unfortunately, we just don’t crave dietary fiber the same way we crave sugar. I’m sure you’ve heard people say they have a “sugar addiction” in a joking manner, but the similarities between compulsive sugar consumption and drug addiction are quite real. The brain pathways that sugar activates are similar to those activated by drugs like opioids.40 The sweet tooth is a powerful thing, and I believe that’s a big reason why anxiety is so rampant.
Of course, while sugar’s role in causing anxiety is only recently becoming understood, it hasn’t been a secret that sugar is bad for your health. That has driven people to try to satisfy their sweet tooth while avoiding the ill effects of sugar, turning to artificial sweeteners like sucralose (Splenda) and aspartame (sold under the brands NutraSweet and Equal, and used in many diet sodas such as Diet Coke). In July 2023, aspartame was listed as a possible carcinogen to humans by the WHO, the International Agency for Research on Cancer (IARC), and the Joint Expert Committee on Food Additives (JECFA). While the IARC cited limited evidence, this is still worth noting.41 Unfortunately, studies have found that artificial sweeteners are not quite as magical as they might appear, since they promote gut dysbiosis by providing bad gut bacteria with a feast—remember Tilo, whom we met in chapter 2? Aspartame in particular has been linked with anxiety symptoms in both animal studies42 and human studies,43 but I discourage artificial sweeteners across the board. If you absolutely cannot live without them, erythritol is a natural sweetener that cannot be digested by you or your gut bacteria, so it is less likely to cause anxiety and metabolic dysfunction.44 Another new option is allulose, a compound that naturally occurs in certain fruits. While there hasn’t yet been any research on its role in anxiety, research into its effects on metabolic health has looked promising, so it may be worth trying in moderation.
A particularly contentious subset of the carb wars is the potentially harmful effects of gluten, a protein found in several grains, most importantly wheat. As evidenced by the explosion of gluten-free diets, gluten-free bakeries, and aggressive food labeling to announce products as gluten-free (whether they could reasonably contain gluten or not—for example, I’ve even seen “gluten-free” water!), there has been a growing movement toward discouraging gluten. It’s important to note that gluten is not harmful to everyone. Unlike sugar and trans fats, it is not inherently bad for you. However, a small percentage of people react poorly to gluten in a very real way, and the prevalence of these negative reactions has increased dramatically over the past few decades. Scientists attribute this increase in gluten intolerance to changes in the wheat supply. Today’s wheat has been hybridized and modified until it is quite different from the original ancient grain. Industrial farming, designed to be as cheap and efficient as possible while yielding the largest harvests possible, has truly harmed the quality of our grains, which has changed the ways our body reacts to them.45
Gluten intolerance is most clearly seen in sufferers of celiac disease. Celiac is a chronic autoimmune disease that causes gluten to trigger an immune response in your gut, damaging parts of your gut mucosa. The result is a host of symptoms, including fatigue, diarrhea, and decreased absorption of crucial nutrients. Remembering what we know about the role of the immune system in the gut mucosa from chapter 3, it’s unsurprising that celiac has also been linked to anxiety. Among many individual studies showing this association, a 2020 review of thirty-seven studies found that celiac comes with an increased chance of anxiety, as well as other mental health conditions like depression and ADHD.46 Since celiac is treated by avoiding gluten, going gluten-free may very well help alleviate anxiety, too. Still, celiac presents in only about 1 percent of the population—fairly high for a chronic condition, but still not super common.
Complicating matters is a more prevalent but less well understood condition called gluten sensitivity, which is estimated to affect six times more people than celiac. Gluten sensitivity is not necessarily a precursor or a mild case of celiac but is rooted in a different kind of immune response. While there is much more to understand about gluten sensitivity, some studies have tied it to anxiety.47
If you are suffering from anxiety and feel you are sensitive to gluten—for instance, if you notice bloating, gas, or other gastrointestinal distress after eating food made from wheat—going gluten-free could help improve your anxiety even if you test negative for celiac. But unless you have a strong reason to believe gluten could be the culprit, I always recommend focusing on carb quality before you worry too much about gluten specifically. And since issues with gluten are tied to industrial farming, the source of gluten is also key: a slice of processed store-bought bread is different from an artisanal loaf of sourdough made from heritage grains and a fermented starter.
Compared to the other two macronutrients, protein is less controversial. There are arguments over which protein sources are best, but it’s widely agreed that protein is important. Low-protein diets do exist, but they are used only in rare cases, for instance, when treating kidney and liver disease. In other words, I’m not concerned about a low-protein diet catching on as the next major shift in macronutrient thought.
Perhaps because of its universal acceptance as an important dietary component, there’s not a wide body of research on how protein affects anxiety. There is evidence that protein malnourishment can promote anxiety—for example, a 2020 study of Indian schoolchildren found that those who consumed less protein-rich foods like milk and legumes had higher levels of anxiety.48 But since a true protein deficit isn’t a huge concern for those who live in the developed world, it’s more important to focus on the sources of protein and the amino acids that are their building blocks.
Another of the most contentious macronutrient debates is whether you should eat animal products or follow a strictly plant-based diet. The idea of eating a plant-based diet stretches back to ancient times. Greek philosophers like Pythagoras and Plato encouraged vegetarianism for moral and health reasons. Religions like Hinduism and Buddhism rejected the eating of animals. Thinkers from the Renaissance and the Enlightenment, including da Vinci, Rousseau, and Voltaire, also turned to vegetarianism. Centuries later, Albert Einstein would say that “nothing will increase the chances of survival for life on earth as much as the evolution to a vegetarian diet.”49 And since Einstein’s time, we have come to understand far more fully how the mass-farming of livestock can promote animal cruelty and threaten the environment through unsustainable practices. Vegan diets, which totally eschew animal products, are a newer trend that has exploded in recent years. Veganism increased an estimated 600 percent from 2014 to 2018,50 and the number of food and drink products that were labeled “plant-based” increased 287 percent from 2012 to 2018.51 Based on what I see in my clinic—particularly among younger patients—I believe the movement toward plant-based diets will continue to grow.
Though I personally am a vegetarian, I respect everyone’s individual food choices and acknowledge that meat and seafood bring their own nutritional strengths for those who choose to eat them. I simply don’t see the wisdom in leaning into divisiveness. As a chef and a clinician, I choose to respect all foods, trying to account for environmental and social issues the best I can.
Recently, I have been aware of a steady march of recent headlines proclaiming that either meat eaters or vegetarians benefit from stronger mental health. These articles aren’t always total bunk; they are often based on medical studies. For example, one meta-analysis found that meat eaters had lower anxiety and depression than vegans.52 Another review claimed that vegans suffer from less stress and anxiety than omnivores.53 And studies in France54 and Australia55 found no associations between vegetarian diets and altered anxiety levels.
As that broad range of study outcomes suggests, there is no definitive evidence for either a vegetarian or an omnivorous diet with respect to anxiety. That aligns with what I’ve seen in my more than twenty years of clinical experience. It’s clear to me that for some, the psychological burden of eating animals—whether that concern stems from compassionate or environmental reasons—is simply too heavy to outweigh any possible benefit that could be gained from eating meat. I would never suggest that a committed vegetarian compromise their principles, because there are so many good ways to ensure that you are getting appropriate nutrition on a vegetarian diet.
If you choose to follow a vegetarian diet, it’s important to account for any nutritional gaps your diet may have. For instance, we’ve already discussed that it can be difficult to get sufficient omega-3s without eating any fish, though a combination of plant-based foods rich in ALA like flaxseeds, walnuts, and soybeans, as well as a vegetarian algal supplement, can do the trick. In chapter 8, we will also see some ways in which eating a plant-based diet can risk shortages of some micronutrients.
If you choose to include animal protein in your diet, it’s important to focus on moderate amounts of full-fat dairy, omega-3-rich fish, and high-quality sources of poultry, pork, and beef rather than greasy cheeseburgers and deep-fried chicken tenders. And meat should be accompanied by a range of whole grains, beans, lentils, colorful vegetables, and other plant-based foods that provide dietary fiber and anxiety-fighting compounds.
Just as fatty acids are the building blocks of fat, amino acids are the building blocks of protein. Your body takes in proteins through your food and breaks them down into amino acids that perform a huge number of tasks to keep your body running, including aiding in digestion, metabolism, growth, immunity, and mental health.
Tryptophan is an essential amino acid, meaning it’s not produced naturally inside our bodies; it’s available only through food. Tryptophan plays a variety of roles in our internal processes of protein synthesis and metabolism, but the most important for our purposes is that it is the precursor of serotonin. As we discussed in chapter 2, serotonin production relies on both a steady supply of dietary tryptophan and a healthy gut microbiome, and gut dysbiosis can affect how efficiently your body turns tryptophan into serotonin.56
While research into either restricting or supplementing tryptophan has proved its role in maintaining healthy serotonin levels, results have not always been straightforward when it comes to tryptophan’s direct effect on anxiety. There have been studies that show reduced anxiety in a high-tryptophan diet compared to a low-tryptophan diet.57 Older studies have found that taking a tryptophan supplement helps reduce anxiety but increasing dietary tryptophan does not,58 while more recent studies have challenged this idea.59 Yet another recent review found no correlation between low levels of tryptophan and anxiety.60
Despite the muddled evidence, I see enough of a clinical connection between anxiety, tryptophan, and the gut microbiome that I always recommend including tryptophan-rich proteins in your diet. Tryptophan is most abundant in poultry (I’m sure you have heard about the nap-inducing properties of Thanksgiving turkey), but it is also present in fish like tuna and salmon. Tryptophan can be found in plant sources, too, like soybeans and tofu, chickpeas, and pumpkin seeds.
In contrast to tryptophan, glutamic acid is a nonessential amino acid, meaning your body can synthesize it. Still, it is found in natural dietary sources like tomatoes and cheese, and in man-made seasonings in the form of monosodium glutamate, or MSG. You’re probably familiar with MSG as an additive used to impart the umami flavor, enhancing the savory taste of dishes in a variety of Asian cuisines, as well as in condiments and snacks across the world. MSG developed a bad rap in the twentieth century, associated with a spurious condition called “Chinese restaurant syndrome,” which supposedly caused headaches and other minor maladies; this never had much if any scientific grounding.61
Though MSG is now recognized as generally safe to eat, there is some possibility that it could increase anxiety. Like serotonin and GABA, glutamate is a neurotransmitter that’s active in your brain. But serotonin and GABA are inhibitory neurotransmitters, calming your neurons from getting too worked up. Glutamate is an excitatory neurotransmitter, riling your neurons into action, so there is reason to believe that a surplus of it could keep your brain from calming down. Ongoing research is exploring the possibility of pharmaceuticals that alter glutamate transmission as a way of fighting anxiety, providing an alternative to SSRIs.62 Moreover, there have been animal studies that link dietary glutamate to increased anxiety.63 However, other researchers have theorized that MSG’s possible ill effects are more connected to the fact that it’s often consumed as part of a diet full of processed foods.64
While I am following the research, I have not seen enough evidence to suggest totally avoiding glutamates. Still, in my clinic I discourage my patients from eating snack foods and takeout that are loaded with MSG; these foods are usually unhealthy choices that can worsen anxiety on their own. I also caution them about natural glutamates in tomatoes and mushrooms—despite being otherwise healthy whole foods, I’ve treated some individuals whose anxiety amps up after eating them. That’s rare—these foods are the last ones to be eliminated if we are trialing foods to limit—but it’s worth considering.
We’ll dive into specific eating plans and recipes in part 3, but you can already see the outlines of how the biggest components of your diet should come together. Though we are talking about the macronutrients as if they are totally separate, most foods contain more than one of them, and full meals should contain all three. You should always look for foods that cover as many healthy macronutrients as possible. For example, salmon is a great source of protein and of crucial omega-3 fats. Beans, lentils, and chickpeas are sources of both protein and carbohydrates that have healthy doses of dietary fiber. Avocado sourdough toast with a fried egg provides healthy MUFAs, medium-GI carbs rich in dietary fiber, and protein. Once you understand how the basics fit together, it’s a fun—and delicious—puzzle to put together a fresh, wholesome, antianxiety diet.
Just as those foods consist of a combination of macronutrients, they’re also full of other types of substances that are hugely important to your body—vitamins and minerals. Since these essential nutrients occur in much smaller quantities, we call them micronutrients, and they’re our next area of focus.