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What Your Gut Says About Your Health

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Your Stomach's Role in Your Health

Going with your gut feelings is a good practice. Too bad I don't always like what mine are saying. When I'm stressed, nervous, or feeling down, my stomach pings and my insides churn. It's as if there's an E-ZPass lane connecting my brain and bowels, its sign flashing "Go, go, go." And I suddenly have to. Badly.

See, when it comes to mood, it's not all in your head — it's in your gut, too. "The brain influences the digestive tract and vice versa," says Rebekah Gross, MD, a clinical gastroenterologist at NYU Langone Medical Center. In fact, new research has found that our esophagus, stomach, small intestine, and colon have a big say in how our minds and bodies function and how happy we feel. "The gut is a critical group of organs that we need to start paying more attention to," says Steven Lamm, MD, the author of No Guts, No Glory. "Doing so may be the secret to improving our overall wellness."

Inside Your Other Brain

If it seems as if your stomach sometimes has a mind of its own, that's because it does. The gut's lining houses an independent network of hundreds of millions of neurons — more than the spinal cord has — called the enteric nervous system. It's so complex and influential that scientists refer to it as "the second brain." In addition to being in charge of the digestive process, your gut lining is the core of your body's immune system (who knew?) and defends you against such foreign invaders as viruses and bacteria. "It's a very important barrier, as important as the skin," says Michael Gershon, MD, the author of The Second Brain and the pioneering gastroenterologist who coined the term.

Cells in the gut lining also produce 95 percent of the serotonin in our bodies. (The rest occurs in the brain, where the hormone regulates happiness and mood.) In the gut, serotonin has a range of functions, including stimulating nerve-cell growth and alerting the immune system to germs.

Thanks to serotonin, the gut and the brain are in constant contact with each other. Chemical messages race back and forth between the brain's central nervous system and the gut's enteric nervous system. When we're stressed, scared, or nervous, our brain notifies our gut, and our stomach starts to churn in response. When our digestive system is upset, our gut alerts our brain that there's a problem even before we begin to feel the symptoms. Scientists suspect that our moods are negatively affected as a result. "The gut is sending messages that can make the brain anxious," Dr. Gershon explains. "You're in good mental shape only if your gut lets you be."

Our Buggy Systems

Other key — and minuscule­ — players in all this brain-and-bowels communication are the microbes that line the walls of the gut, says gastroenterologist Gianrico Farrugia, MD, the director of the Mayo Clinic Center for Individualized Medicine. There are hundreds of types of bacteria in the gut; some of them do helpful things like break down carbohydrates in the intestine and produce infection-fighting antibodies and vitamins, while other, destructive bacteria secrete toxins and promote disease.

In a healthy gut, the good bacteria far outnumber the bad. But what's going on in your head can affect the balance. "Emotional issues can help influence what lives in your GI tract," says William Chey, MD, a professor of internal medicine at the University of Michigan Medical School. Being under a great deal of stress or feeling depressed or anxious could change the way your bowels contract and how your immune system functions, which in turn can change the type of bacteria in the small intestine and colon, he explains. Symptoms can include cramping, bloating, diarrhea, or constipation.

For instance, irritable bowel syndrome (IBS), a disorder that causes abdominal pain, diarrhea, and constipation, often accompanied by gas and bloating and sometimes by anxiety and depression, can be related to an overabundance of bad bacteria in the small intestine. Women are particularly susceptible to this, especially if they experienced sexual abuse or psychological trauma as a child. It's not known if the stress causes the symptoms or vice versa. "But the two definitely feed off each other, and IBS flares in stressful circumstances," Dr. Gross says.

The Probiotic Prescription

Our stressed-out lifestyle may be our stomach's biggest enemy. According to María Gloria Domínguez Bello, PhD, a professor of microbiology at the University of Puerto Rico, society's hectic pace, which leads to our reliance on junk food and overuse of anti­biotics, is throwing our internal ecosystem out of whack; she believes that there's a link between our gut bacteria and the rise of food allergies and autoimmune diseases — Crohn's and rheumatoid arthritis among many others — in the industrialized world. "When there is a loss of balance in the different types of intestinal bacteria, they send signals to our immune system to overreact and become inflamed, leading to disease," Domínguez Bello says.

Increasing the number of good bacteria in our GI tract, by taking probiotic supplements and eating foods that contain probiotics, may help combat such health problems, a growing number of scientists say. New research indicates that specialized strains of these good bacteria could also alleviate mood and anxiety disorders. When University of Toronto researchers gave chronic fatigue syndrome sufferers three daily doses of a Lactobacillus strain for two months, it boosted their levels of good bacteria. "At the same time, we reduced their anxiety," says lead researcher A. Venket Rao, PhD. When the patients stopped taking the probiotic, their symptoms reverted as well, he says.

Digestive Aids

Someday we may all pop designer probiotics tailored to our particular stomachs to fix any ailments. In the meantime, take these actions to keep your gut — and your entire body — happy and healthy.

Clean up your diet.

Consume more fiber from fruit and veggies and cut back on processed foods, animal protein, and simple sugars, all of which feed harmful bacteria and contribute to obesity and disease, says Carolyn Snyder, RD, a dietitian at the Cleveland Clinic. Choose foods that have the fewest ingredients listed on their labels, and chow down on those that contain probiotics (including milk, sauerkraut, and yogurt) and prebiotics, which are certain nondigestible ingredients (found in high-fiber fruit like bananas; whole grains, such as barley and rye; and vegetables like onions and tomatoes) that act as fertilizer for the probiotics in our guts.

Consider a probiotic supplement.

If your GI system is a well-oiled machine and you feel great, you probably don't need a probiotic, Dr. Gross says. But if you have symptoms of a condition, like IBS, have your doctor help you pick the right strain for your problem. "If there's an indication for which a probiotic could be useful, I typically suggest looking for formulations containing Bifidobacterium or strains of Lactobacillus," Dr. Gross says. A dose of one billion to 10 billion colony-forming units is usually recommended for diarrhea.

Avoid unnecessary meds.

These include laxatives and NSAIDs (such as aspirin, ibuprofen, and naproxen) as well as broad-spectrum antibiotics (like amoxicillin or tetracycline), which wipe out the good bacteria with the bad. Anyone on an antibiotic should take a probiotic for twice as long as the antibiotic prescription to prevent the nausea, diarrhea, and stomach cramping that the medicine can cause, studies suggest.

Go easy on alcohol.

New research from Dartmouth-Hitchcock Medical Center found that as little as one drink a day can increase your risk of an overgrowth of bad bacteria in the small intestine and cause GI distress. If you have diarrhea, bloating, gas, or cramping and drink regularly, cut back on cocktails and see if your symptoms ease up, says study author Scott Gabbard, MD.

Exercise stress management.

Get in a 30-minute daily sweat session, especially when you're feeling frazzled. "To function optimally, the gut needs exercise," Dr. Gross says. "It likes to be jiggled to help move food through your system." When you don't have time to squeeze in a walk, jog, or yoga class, take at least a few minutes a day for some deep breathing or anything else that helps you relax.

Happy (Gut) Meals

Eat your way to a healthier GI tract with this probiotic- and prebiotic-packed menu created by Carolyn Snyder, RD, a dietitian at the Cleveland Clinic.


An egg-white omelet with onions, asparagus, and tomato, and a slice of rye or whole wheat toast

Midmorning snack

Lowfat Greek yogurt and a banana. (Look for brands with the probiotic strains Streptococcus thermophilus and Lactobacillus, such as Chobani, Fage, and Stonyfield Oikos.


Mixed greens topped with 4 ounces grilled chicken, artichokes, onions, asparagus, and tomatoes and dressed with a mixture of olive oil, red wine vinegar, and garlic, and a whole-grain roll

Afternoon snack

Hummus and baby carrots or green bell pepper strips


3 ounces grilled salmon with lemon-yogurt sauce, brown rice, and a green salad with onions and tomatoes (To make the lemon-yogurt sauce, stir together 3/4 cup plain whole-milk yogurt, 2 tablespoons olive oil, 1 teaspoon fresh lemon juice, 1 tablespoon chopped chives, 3/4 teaspoon grated lemon zest, and 1/4 teaspoon salt.)

Nighttime snack

A slice of whole-grain bread with peanut butter and banana, or another Greek yogurt

Originally published in FITNESS magazine, January 2013.