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No matter how fit you are, and no matter how beautiful, tan, perfectly coiffed, or finely muscled, it all comes down to one thing: you’re basically a skin sack filled with bacteria. Of the estimated 100 trillion cells in the body, only about 10 percent are human. The rest are bacteria—up to 5 pounds worth, and most of them in the gut. And according to emerging research, they can have a profound impact on mood, behavior, and well-being.
Researchers have long known the bacterial makeup in the gut exerts a powerful influence on health. Studies show that a dysfunction in the internal ecosystem can increase the risk of a range of chronic diseases and conditions, including obesity, diabetes, asthma, sinusitis, colorectal cancer, and immune disorders. New research is also pointing to an intimate connection between the microbial makeup of the gut—called the microbiome—and anxiety, depression, autism, and brain chemistry.
Sometimes called the “second brain” or the “gut brain,” the digestive tract is the body’s only organ to house its own nervous system. Called the enteric nervous system, this neural network consists of 500 million neurons, five times the amount in the spinal column. It operates independently from the central nervous system, and continues to function even when the vagus nerve—the main channel of communication between the gut and the brain—is severed.
Related: How to Eat Healthy for Your Gut
Because of many similarities in the immune system and nervous system, researchers initially believed gut microbes influenced mood and behavior through the immune system, more or less by using immune cells to send signals to the brain. But new studies suggest gut microbes impact mood and behavior by directly interacting with the nervous system, without involving the immune system. There may be a complex neurochemical delivery system in which microbes like probiotics can send messages directly to the brain. And it’s also known that gut bacteria produce neurochemicals that impact learning, memory, and mood; for example, the gut is responsible for making about 95 percent of the body’s serotonin, which influences mood, appetite, and sleep.
Dozens of new and compelling studies have found that the makeup of bacteria in the gut has a profound impact on brain chemistry, behavior, learning, and mood.
How Your Microbiome Affects Your Health:
- The microbiome in patients with major depressive disorder is significantly different from that of people who don’t suffer depression.
- A lower amount of certain bacteria (for example, Faecalibacterium) is associated with more severe depression.
- Taking probiotics can lessen anxiety and improve feelings of well-being.
- MRI (magnetic resonance imaging) findings show changes in regions of the brain crucial in emotional processing after taking probiotics.
- Specific probiotics can significantly decrease anxiety-like behavior in rats and reduce psychological distress in humans.
- Altering gut flora has been shown to decrease stress response and improve overall feelings of well-being.
- Higher levels of Lactobacillus rhamnosus bacteria in the gut can increase the number of GABA (gamma-aminobutyric acid) receptors. GABA is a neurotransmitter that curbs anxiety.
- Bifidobacterium longum helps ease anxiety and depression in people who suffer from GI disorders like Crohn’s disease, ulcerative colitis, and irritable bowel syndrome (IBS).
In light of these findings, researchers are experimenting with fecal microbiota transplantation (FMT), in which microbiota from a healthy person are inserted into a sick person’s gut. This process has been shown to effectively treat C. difficile, an antibiotic-resistant pathogen that can be fatal. And it may be effective as a treatment for diabetes and obesity. In animal studies, obese mice that received transplants from lean mice lost weight; in human studies, when microbiota from lean donors were transferred to the guts of patients with metabolic syndrome, the researchers found striking improvements in the recipients’ sensitivity to insulin. The next frontier of research: FMT for treating depression, anxiety, and mood disorders.
But the practical use of fecal transplants for mental health is many years away. In the meantime, you can heal your gut, ease anxiety, and lessen depression with simple, effective cures.
8 Ways to Improve Your Gut Health and Mood
1. Reduce or eliminate foods that harm gut bacteria
The first step in improving your microbiome: reduce or eliminate foods that harm beneficial gut bacteria and consequently impact mood and behavior. These include sugar, corn syrup, and processed foods. Certain medications, especially antibiotics, NSAIDs, steroids, and proton-pump inhibitors, also upset the microbiome.
2. Heal your gut
Poor diet and lifestyle can lead to a condition called “leaky gut,” or intestinal permeability, which has been implicated in many diseases, including depression. Many natural herbs and supplements promote healing of the intestine’s mucosal lining. Some of the best are: L-glutamine, an amino acid that can heal soft tissue like the lining of the intestine; quercetin, which helps reduce permeability; N-acetylglucosamine (NAG), a monosaccharide that can improve intestinal permeability, especially in conjunction with MSM; zinc, which can tighten the junctures characteristic of leaky gut; and deglycyrrhizinated licorice (DGL) root, a form of licorice that’s free of glycyrrhiza—the compound that can raise blood pressure—that helps maintain the mucosal lining of the stomach and duodenum.
3. Take a good probiotic supplement
New research suggests probiotics can ease anxiety, and may even be a powerful treatment for autism. In one study, mice with features of autism had lower levels of certain probiotics than did normal mice; when they were given the strains of probiotics they were lacking, symptoms were reversed. In another study, volunteers who took probiotic supplements for a four-week period had improved mood and had fewer ruminating thoughts. Choose a broad-spectrum supplement, and be sure it includes Lactobacillus plantarum, Lactobacillus acidophilus, Lactobacillus brevis, Bifidobacterium lactis (B. animalis), and Bifidobacterium longum.
4. Include fermented food in your diet
In addition to taking a probiotic, include fermented food in your diet. Naturally fermented or cultured foods have been used for thousands of years, and contain a wide range of bacteria so you’ll cover all your bases. Yogurt, sauerkraut, kefir, kimchi, miso, and kombucha are some of the most common and easily accessible fermented foods. You’ll also find fermented cod-liver oil, green foods, and protein powders—great ways to add probiotics to your morning smoothies.
Related: Kimchi Stew
5. Feed your gut.
Prebiotics, indigestible foods that provide “food” for beneficial microorganisms in the intestines, can improve the microbiome and enhance mood. In one study, people who took a daily prebiotic supplement for three weeks were better able to deal with anxiety and depression than a placebo group. The best prebiotic foods include Jerusalem artichokes, asparagus, onions, garlic, jicama, and radishes. For supplements, choose inulin, chicory root, arabinogalactan polysaccharides, and cal-mag butyrate. Or look for a prebiotic supplement that contains FOS (fructooligosaccharides).
6. Reduce inflammation
Some evidence suggests depression may be an allergic reaction to irritation and inflammation in the gut. Omega-3 fatty acids have been shown in many studies to reduce inflammation, and are also beneficial for mood. White willow bark contains salicin, similar to salicylic acid, the active compound in aspirin; it works by blocking inflammatory chemicals in the body. Curcumin, the active ingredient in turmeric, is a powerful anti-inflammatory, suppressing compounds in the body that trigger inflammation. Other good inflammation reducers: green tea, boswellian, resveratrol, and pycnogenol.
7. Avoid sugar
New research shows that a high-sugar diet causes changes in the gut bacteria of mice, impairing their “cognitive flexibility,” or the ability to adjust to changing situations. Microbiota alterations also negatively affected their short- and long-term memories, and impacted their performance on mental and physical function tests. Natural sweeteners like honey, maple syrup, and agave (though better options to white table sugar) have the same impact. Xylitol, erythritol, and other sugar alcohols are indigestible and can cause digestive distress. Your best bet: look for stevia, a natural sweetener derived from a South American herb, available in powders, droppers, and packets.
8. Use natural cleaning products
Historically, our gut adapted to interaction with the outside world by ingesting a little dirt here and there; we develop immunity to potential pathogens through low-grade, routine exposure. But modern cleaning products and antibacterial agents wipe out everything, including some beneficial bacteria the body needs. Be choosy about household cleaners; look for nontoxic, natural alternatives, and steer clear of antibacterial ingredients and hand sanitizers (other than natural versions made with essential oils). Or consider a probiotic made from SBO (soil-based organism). SBOs are extremely hardy and can survive stomach acid and heat. They’re still a little controversial, but at least one study showed significant improvement in irritable bowel patients.