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How do you comfort yourself when everything in life seems like it’s going wrong? For millions of Americans, that answer lies in food. Not just any food, either. Junk food. We are a nation obsessed with our burgers, pizzas, and fries. One needs only to look at the stats to understand that stark reality.

According to the American Psychological Association, around 33% of American adults use junk food to combat stress. Americans eat to ignore stress, to outrun stress, and numb the emotional turmoil in their lives. But at what cost…?

New research has highlighted a surprising link between junk food and higher levels of anxiety and depression. Could our addiction to junk food be fueling the increasing levels of anxiety and depression so many are experiencing? The evidence is compelling.

A new study shows a compelling link between junk food and anxiety.

Humans are quickly becoming an anxious and unhappy bunch. A recent federal survey in the U.S. showed that nearly 4 in 10 adults in the country had experienced clinical symptoms of anxiety and depression. Understandably, this has sent researchers on a wild goose chase of exploration. What is making us so unhappy? What can we do to fix it?

For researchers at the University of Colorado, an interesting hypothesis took place. Rather than looking in all the obvious places, their 2024 study focused on the relationship between gut health, behavior, and the brain.

Essentially, what their study found was this:

• In animals, high-fat diets can disrupt natural gut bacteria.
• The disruption of a healthy gut biome can alter behavior and influence brain chemicals in a way that increases anxiety.

The study was conducted by dividing adolescent rats into two groups. One group got a standard diet of 11% fat for nine weeks. The other group of adolescent rats was given a high-fat diet of 45% fat. These fats were primarily saturated fats derived from animal products.

Over the course of the study, researchers collected fecal samples from the two groups. Each was analyzed for the diversity and health of their gut biomes. The two groups were subjected to behavioral tests at the end of the nine-week study.

The researchers found that the group of rats fed on a high-fat diet gained weight and also had a significantly lower diversity in their gut biome. They also had a higher level of serotonin in their systems, which, when overly activated, can create an anxiety-like response.

When compared to the control group, the rats on the high-fat diet also had abnormalities in the expression of their genes. Specifically, the heightened expression of tph2 (tryptophan hydroxylase) which has been associated with mood disorders in humans.

The researchers theorized that it came down to the gut lining. The more diverse the bacteria in the human gut, the healthier the gut was. However, unhealthy diets - like the high-fat diet fed to the group of adolescent rats - compromise the gut lining, which enables bacteria to slip into the bloodstream.

It paints a compelling picture and points to the absolute importance of considering gut health in those with anxiety issues.

The power of the microbiome-gut-brain axis.

The link between gut health and physical health has been a long-established one. For example, doctors know that gut health contributes to disorders such as irritable bowel syndrome (IBS) and ulcerative colitis (UC). What we put into our guts can take a toll over time.

What we are all just beginning to understand, however, is just how complex the relationship is between the microbiomes of our digestive systems and the rest of our internal systems.

This system is known as the microbiome-gut-brain axis.

Gut bacteria cooperate within our stomachs to regulate the development and function of the immune, metabolic, and nervous systems. In recent years, researchers have established definitive links that prove that what you put into your body (via nutrition) can contribute to nervous system disorders such as Alzheimer’s and Parkinson’s disease.

The relationship is centered around the nervous system.

The vagus nerve, one of the largest nerves in the body, connects the gut and the brain. This nerve sends signals back and forth via the millions of neurons that connect all the other nerves in your body to the brain. The decreased function of this vagus nerve has been connected to both IBS and Crohn’s disease, and the same decrease in vagal function has been linked to anxiety disorders and higher levels of stress in humans.

Neurons and nerves aren’t the only elements in play. Neurotransmitters, which are the chemicals that pass information along the nerves, are produced in the human gut. Specifically, the neurotransmitters serotonin and GABA (gamma-aminobutyric acid), which help control feelings of fear and anxiety.

What’s the importance there?

Survivors of trauma and neglect can find function within their vagus nerve already impaired. Because of the long-term effects of trauma and stress on the brain, survivors can find themselves with tightly wound, hypersensitive nervous systems that struggle with an imbalance in function and neurotransmitters.

This research into the microbiome-gut-brain axis highlights the importance of gut health for trauma survivors. Especially those who struggle with anxiety and low tolerance to stress.

How do we build better gut health?

If the microbiome-gut-brain axis is so important, how do we get on track for better gut health? The answer, thankfully, is not an entirely complex one. By making small, incremental changes to the way we eat (and the way we think about eating), we can put ourselves on a path to better gut health and mental and emotional health. How? Through diet and the use of probiotics.

Probiotics

Probiotics are the first step for anyone who is looking to build better gut health. These live bacteria are eaten and ingested into the digestive tract. There, they promote better health, and have even been shown to improve symptoms of stress, anxiety, and depression.

What probiotics should you focus on?

Every individual is different, but studies have shown that probiotics such as Bifidobacterium longum significantly improve the symptoms of IBS and mild-to-moderate depression in just six weeks. Likewise, prebiotics (which are fermented in your own gut), such as galactooligosaccharides, have been shown to significantly lessen the presence of stress hormones like cortisol in the body.

Better food choices

As great as probiotics are, they don’t provide the full picture of regaining our gut health. To do that, we have to look at the foods that we are ingesting and how they directly affect our quality of life. What we eat affects how we behave and how we feel. Getting our mental and emotional health on track, then, requires that we fuel ourselves more intelligently in the food choices we make.

The first focus should be foods high in Omega-3 fats. Omega-3 encourages brain health and can increase learning, memory, and cognitive well-being. These are the types of fats found in fish like mackerel, cod, lake trout, salmon, sardines, and light tuna. Adding these healthy fats to your normal diet can increase the good bacteria in your gut and reduce the risk of brain disorders like dementia.

Fermented foods are also great for promoting a healthy microbiome-gut-brain axis. Yogurt, kefir, sauerkraut, and cheese are all great examples of healthy fermented microbes that can help your gut and your mind. Time and time again, fermented foods have been shown to alter brain activity in ways that can be beneficial in regulating mental and emotional health.

One can’t just stop at fish oils and fermented foods, though. High-fiber diets have also been shown to improve gut health and promote microbial diversity in the human gut. Whole grains, seeds, nuts, fruits, vegetables - they are all good for your brain and your stomach and may improve anxiety and depression.

Polyphenol-rich foods are the best bet for improving cognition (that is, the efficiency with which you think). By adding cocoa, green tea, coffee, and olive oil into your daily diet, you may be able to increase your healthy gut bacteria and improve your memory and reasoning skills.

Last but not least, tryptophan-rich foods round out the healthy gut gambit. Foods like turkey, eggs, and cheese are high in the amino acid tryptophan, which is the amino acid that is turned into serotonin. It’s thought that these foods can help us better regulate the serotonin that is produced in the gut and, therefore, our moods as it passes along into the nervous system.

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As we strive toward healthier, more peaceful lives, we cannot ignore the very real physical realties of our bodies. Humans are complex, inside and out, and we are only just scratching the surface of understanding when it comes to our various systems. That’s why it’s so important to keep and open mind and an open heart when striving for a better life.

It’s not only a matter of thinking happy thoughts or taking positive actions. Our emotional bodies are very much tied to our physical bodies. For us to achieve that state of emotional peace we crave, an inside-out approach is necessary. One must set the groundwork for physical health so that your emotional health can take its place within that system of peace.

Are you on a healing and wholeness journey? Then, check in with your physical body and take a holistic approach to your mental and emotional wellness. What you feed your gut fuels your mind. Take care of your body to the best of your ability; it will nurture you throughout this life.

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de Noronha, S.I.S.R., de Moraes, L.A.G., Hassell, J.E. et al. High-fat diet, microbiome-gut-brain axis signaling, and anxiety-like behavior in male rats. Biol Res 57, 23 (2024). https://doi.org/10.1186/s40659-024-00505-1

Dinan TG, Cryan JF. The Microbiome-Gut-Brain Axis in Health and Disease. Gastroenterol Clin North Am. 2017 Mar;46(1):77-89. doi: 10.1016/j.gtc.2016.09.007. Epub 2017 Jan 4. PMID: 28164854.

Shivani Ghaisas, Joshua Maher, Anumantha Kanthasamy. Gut microbiome in health and disease: Linking the microbiome–gut-brain axis and environmental factors in the pathogenesis of systemic and neurodegenerative diseases. Pharmacology & Therapeutics. Volume 158. 2016. Pages 52-62. ISSN 0163-7258. https://doi.org/10.1016/j.pharmthera.2015.11.012.