Can Diet Affect Mental Health?

anxiety blood glucose carbohydrates cortisol depression elimination diet glycemic index gut microbiome hormones inflammation insulin insulin resistance leaky gut linoleic acid mental disorders mental health mental illnesses probiotics stress supplements vegetable oils Aug 18, 2023

A chalk drawing of a brain with half of it filled with healthy food

Almost 1 billion people worldwide had mental disorders in 2019. On top of that, cases of depression and anxiety rose by over 25 percent in the first year of the COVID-19 pandemic.¹ More people are only expected to get treated for mental problems in the next decades. But at times, drugs and therapy fail to provide the desired results. This is why other forms of treatment have been getting more attention in recent years. There has been much research especially on the effects of nutrition on mental well-being.² In this article, we'll give an overview of the topic as we cover the following:

Diet and Inflammation
The Effect of Carbohydrates
The Role of the Microbiome
Foods and Supplements for Better Mental Health

Let's start exploring the influence of certain foods and diet patterns on mental health.

Diet and Inflammation

Inflammation is part of the immune system's response to toxins, microbes, injury, or any other stimuli harmful to the body. The stimuli trigger sequences of events, including the production of molecules called inflammatory markers. Inflammation can be acute (quick, severe, and short-term) or chronic (slow, low-level, and long-term).^3,4 Chronic inflammation is a major contributor to many chronic diseases, such as diabetes, heart disease, and cancer.⁴ It is also linked to mental disorders.⁵

Food affects inflammatory activity and marker levels. So, as a lifestyle factor that we are exposed to daily, diet plays a big role in chronic inflammation. Pro-inflammatory diets are high in refined starches, sugars, and grains; trans fats; and processed foods.⁶ Vegetable oils — i.e., those derived from the seeds of plants like soybean — are another major culprit. These widely used oils contain linoleic acid, the main omega-6 polyunsaturated fatty acid (PUFA) linked to chronic inflammation.⁷ Regular consumption of the above food items therefore raises the risk of mental health problems.

The Effect of Carbohydrates

The glycemic index is a number that measures how fast certain foods affect glucose levels in the blood. High-glycemic foods are rich in refined starches and sugars (simple carbs), which get broken down and absorbed into the blood fast. So, eating these foods leads to a rapid increase in blood glucose and release of insulin (the hormone that helps glucose enter cells for energy use or storage).⁸ People on high-glycemic diets are at a greater risk of depression and anxiety.⁹

Besides being a risk factor for inflammation, high-glycemic diets can cause insulin resistance. Insulin resistance has been linked to brain abnormalities and deficits similar to those found in people with depression.⁹

What's more, eating high-glycemic foods results in repeated sharp rises and falls in blood glucose. The body makes up for after-meal spikes in blood glucose by releasing large amounts of insulin. This event can then decrease blood glucose to levels that compromise brain glucose. In response, the brain triggers the release of hormones like cortisol and adrenaline that oppose insulin action. High levels of both hormones are associated with anxiety. Plus, high cortisol causes irritability.⁹

The Role of the Microbiome

The gut microbiome consists of the trillions of microbes living in our gastrointestinal (GI) tract. These microbes include bacteria, viruses, and fungi that perform various functions. They help break down food and drugs. Also, they protect against disease-causing organisms and adjust the body's immune response. They maintain the structure and function of the GI tract as well.^10,11 Research shows that through different signals, the brain communicates with the microbes in the gut. At the same time, the microbes communicate with the brain. This means that the gut microbiome can influence mental processes and behavior. Indeed, altered microbiomes have been found in patients with major depressive disorder and other brain conditions.^12,13

The foods we eat determine the nutrients available to the body, and, in turn, the types of microbes that dominate the gut. Too many or too few of a certain type leads to an imbalance in microbe species and lower diversity. This condition is known as dysbiosis. It is linked to many illnesses, including those of the mind.^13,14

Some bacteria thrive on a diet low in fiber and high in refined sugars and processed foods. Such microbes can degrade the mucus layer that protects the GI tract against toxins. Thus, with a "leaky gut", harmful substances can easily leave the GI tract and enter the bloodstream. This makes the body launch an inflammatory response.^15,16 In short, an unhealthy gut microbiome composition can promote inflammation — a key contributor to mental disorders.

Foods and Supplements for Better Mental Health

Anti-inflammatory foods and micronutrients help reduce chronic inflammation, thus benefiting mental health. Anti-inflammatory micronutrients include folic acid, methylcobalamin, and magnesium L-threonate. They help with conditions like stress, depression, anxiety, and bipolar disorder.¹⁷ It should be noted that micronutrients exist in several forms. These forms vary in bioavailability (the portion of a drug that gets absorbed into the blood and has an active effect). So, different forms of vitamins and minerals best serve different functions. For instance, magnesium L-threonate and magnesium citrate are two forms of magnesium. The former is usually taken for brain health. In contrast, the latter is typically used to treat constipation.^18,19

Low-glycemic foods fight inflammation by causing a smaller and slower increase in blood glucose levels. Examples are whole-grain bread, sweet potatoes, and yams. Vegetables such as broccoli, cauliflower, zucchini, and celery have a low glycemic index as well. Also on the list are fish, seafood, meat, and eggs. Nuts (almonds, cashews, walnuts, and pistachios) and some fats and oils (avocado oil, olive oil, coconut oil, and palm oil) make the cut too.²⁰

Probiotics are live microbes that restore the gut microbiota. By doing so, they improve GI tract function and immune balance. Studies show that probiotics can help decrease symptoms of anxiety, depression, and autism. In addition, they appear to aid memory and other mental functions in Alzheimer's disease patients. They have even been found to improve the brain's response to emotion-focused tasks in healthy people.^9,14

As for herbal supplements, ashwagandha, passionflower, and kava reduce stress hormones. On the other hand, St. John's Wort increases serotonin (a hormone that boosts mood). In these ways, the said supplements can help lower anxiety.^22,23,24

Conclusion

Diet affects mental health and function through its effects on inflammation, carbohydrate metabolism, and the gut-brain network. Low-glycemic foods, probiotics, and certain supplements promote mental well-being mainly by fighting inflammation.

Did you know that your mental and physical health are interconnected? By adjusting your diet to optimize your mind, you can optimize your body too. But you're a unique individual, so what works for others may not work for you. Click here to discover how an elimination diet designed especially for you can work wonders for your performance.

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