Food and Mood: How Your Gut Affects the Way You Feel

The last time you thought about microbiology was probably in that lecture-hall science class you took to fulfill your college curriculum requirements. For the most part, the topic isn't exactly known for inciting thrills. But microbes may be a whole lot more interesting than you think -- and much more relevant to your everyday life, too.

The connection between nutrition and mental health isn't a new concept, but interest in the relationship between food and mood has exploded in the past decade. Researchers have focused on how the microbiome, the vast ecosystem of microorganisms in the human gut, affects our psychological well-being.

It turns out that what you eat and the kinds of microbes that those foods foster have a considerable impact on how you feel. But how does it all work?

The Gut-Brain Axis

Research suggests that certain gut bacteria can help alleviate symptoms in patients suffering from mental health conditions such as depression and anxiety. Scientists hypothesize that these bacteria, which they term psychobiotics, produce and deliver neurotransmitters such as dopamine, serotonin, norepinephrine, acetylcholine, and gamma-aminobutyric acid.

When gut bacteria secrete these neurotransmitters, they may cause cells in our bodies to release molecules that can change signaling within the collection of neurons that governs our gastrointestinal system. Through a line of communication known as the gut-brain axis, this change in neural signaling can impact brain function and a person's behavior.

Understanding Leaky Gut

However, due to certain lifestyle factors and medical conditions, the cell wall surrounding the digestive system can become compromised, enabling toxins and bacteria to leak into the bloodstream. This condition is known as leaky gut, and it's been closely correlated with mental health issues. One study found that more than 1 in 3 patients with clinical depression showed signs of leaky gut in their blood work.

Researchers haven't yet identified the exact causal relationship between leaky gut and mental ailments, but it may have to do with inflammation and autoimmune responses to bacteria, which are beneficial in the gut but may turn on the body's immune-system response when they're released into the bloodstream. Both autoimmunity and inflammation are linked to depression, poor mood, and lagging energy.

Which Foods Are Best for Improving Gut and Mental Health?

Leaky gut can result from poor dietary habits, but by extension, improving gut health through changes in diet and lifestyle could have a positive impact on mood disorders such as depression and anxiety. What foods should you eat to foster a healthy gut and improve your mood?

• Fermented foods. Fermentation allows beneficial bacteria to break down some of the nutrients in a food. Traditional cultures use the practice as part of their culinary heritage, but research suggests that fermented foods have a positive influence on the microbiome through both the live bacterial cultures and the nutrients they contain. Great choices include fermented dairy products such as kefir and yogurt, as well as fermented vegetables such as kimchi and sauerkraut, both of which are made by fermenting cabbage.
• Whole plant foods. The fiber content in vegetables, particularly prebiotic fiber, has a number of benefits. Prebiotics can selectively feed healthy gut microbes and encourage microbes to produce mild acids while breaking down the fiber, which can reduce the growth of bad gut bacteria. Foods high in prebiotic fiber include leeks, asparagus, artichokes, garlic, and onions.
• Resistant starches. Resistant starch is another type of fiber that has gut health benefits, which can lead to improved blood sugar regulation and decreased hunger. Foods containing resistant starch include seeds, legumes, bananas, and starchy foods such as potatoes after they've been cooked and cooled.

Our growing understanding of the link between gut microbes and mental health is poised to revolutionize the way people view the relationship between food and mood. If you or a loved one suffer from mental conditions such as depression and anxiety, talk to your doctor about how dietary changes could provide relief.