Need to Know
  1. Studies are finding links between gut bacteria and mood
  2. A healthy gut could mean a healthier overall body and brain
  3. Diet changes may not be the whole answer—but they can help

The next frontier in health research is probably so small we can’t see it. A growing amount of studies are beginning to reveal what our gut bacteria  — the tiny organisms that live in our gastrointestinal tract — may say about our health, from digestive diseases to autoimmune conditions to metabolic issues to weight disorders. And now, scientists are beginning to discover what those same bacteria might do to our minds.

In a new New York Times Magazine article this week, writer Peter Andrey Smith speaks with researchers seeking to answer the headline’s question: “Can the bacteria in your gut explain your mood?” The article focuses on two researchers — Mark Lyte and Sarkis Mazmanian — who are at the forefront of studying how bacteria in the gut could affect mental health and brain function. It’s a long and fascinating read, but if you don’t have time for that, here are some of the most intriguing points, along with thoughts from our nutrition team on what this means for you.

First of all, just how important are gut bacteria? Pretty darn important. Smith writes, “Bacteria in the gut produce vitamins and break down our food; their presence or absence has been linked to obesity, inflammatory bowel disease and the toxic side effects of prescription drugs. Biologists now believe that much of what makes us human depends on microbial activity.” The gastrointestinal tract also accounts for around 75 percent of the body’s immune system!

So what happens when your gut is healthy — and when it’s not? Well:

  • A healthy gut leads to proper nutrient digestion and absorption, no bloating or cramping, a healthy immune system, a happy brain. All good things!
  • Poor gut health can express itself through a number of symptoms, ranging from bloating, cramping, excess gas, constipation, nausea and/or fatigue to an increased risk of chronic conditions such as arthritis, infections, candida, allergies, metabolic syndrome, and mood swings.

According to research presented in the NYT article, scientists are beginning to find links — though they are not yet entirely understood — between bacteria in the gut and disorders of the brain.  As Smith writes, gut microorganisms secrete a large number of chemicals, including “the same substances used by our neurons to communicate and regulate mood, like dopamine, serotonin, and gamma-aminobutyric acid (GABA).” Now, the question is how the health of gut microbes may affect the creation or the function of those chemicals. For example, Lyte has studied how animals behave differently when exposed to (or removed from) various types of bacteria — discovering, for example, that mice exposed to certain types of bacteria act more anxious than others. Recently, the National Institute of Mental Health has awarded grants to scientists looking to study links between the gut microbiome and mental disorders.

So, how do you get a healthy gut? Well, there are a lot of factors that influence the health of our gut bacteria, including medications, stress, environment, and of course food — plus, perhaps, things scientists are yet to discover. But if the symptoms above sound a little too familiar, diet is definitely one thing to consider.

  • Foods that promote gut health: fermented foods (and drinks) such as yogurt, kefir, kombucha, kimchi, sauerkraut, high-fiber foods such as legumes, fruits, and whole grains, and garlic. Greens, almonds, and onions may also help.
  • What to eat less of/avoid: processed foods, high-sugar foods, alcohol, and in some cases (depending on individual sensitivities) dairy, gluten, and soy products.
  • There are also probiotic supplements available, but that doesn’t always fix the problem. There are trillions of bacteria strains in our guts, and not all are represented in supplements. It could be a little like taking a dose of vitamin C every day instead of a full multivitamin.

Could probiotics the answer to our mood disorders? Not so fast. While improving gut health is certainly valuable, any individual dietary or environmental change may not necessarily cure the kinds of diseases and disorders that scientists are currently studying. Researcher Lyte’s big fear is that “the hype is running ahead of the science.” As he told Smith, “It’s the Wild West out there…You can go online and buy any amount of probiotics for any number of conditions now, and my paper is one of those cited. I never said go out and take probiotics.’’

Many of the implications of this story ring true in our dietitian‘s experience. There are clearly emotional side effects to health issues such as obesity and irritable bowel syndrome, and stomach issues — which typically stem from the gut/small intestine — can cause extreme amounts of distress and frustration, affecting day-to-day mood and well-being.

Generally, if we feel good physically, we feel good mentally and emotionally as well. Research like this suggests that it may be more than just a feeling — it turns out those could be processes deeply linked on a cellular level.

Photo via the New York Times