Once you've polished off a meal, you probably don't give it much thought. But when you push away from the table, your gut's work is only beginning — it will take between 9 hours and a day or two for the food you just ate to be fully digested. During that time, your stomach and small intestine break your food down into molecules that the small intestine's thin lining can absorb, allowing essential nutrients — the energy stream that fuels every cell in your body — to enter your bloodstream. The lower part of your small intestine then wrings out the water remaining in your meal and ushers it into your colon, which funnels it into your bloodstream to help keep you hydrated.
As straightforward as this process sounds, the seemingly simple chore of digestion depends on a finely orchestrated series of muscular contractions, chemical secretions and electrical signals all along the 30-foot-long gastrointestinal tract. But there's also plenty you can do to keep this operation running smoothly.
Follow its pace
A rushed meal is out of sync with the creeping pace of the gut. Savor your meal. In a neat bit of mind/body magic, the thought, sight and aroma of good food jump-start the digestive process, signaling the stomach and salivary glands to secrete chemicals that will help break down food. Chew your food well so your gut doesn't have to work as hard to break it down. Eat slowly to avoid gulping air, which will make you gassy, bloated and — thanks to the mind's payback to the body — irritable.
Nurture its residents
Gut-friendly bacteria use fiber, an indigestible carbohydrate, as their main food source, so eat plenty of fruits, vegetables and whole grains, such as oats, barley, whole wheat and popcorn. Fiber also aids the passage of food and waste through the gut. Most adult women should aim for over 20 g of fiber a day; men should get at least 30 g. But again, go slowly: Increasing your fiber intake too quickly can cause gas and bloating.
Respect its opinions
Even the most finely tuned machine has its quirks — if certain foods trigger GI problems for you, avoid them. Common heartburn culprits: acidic, spicy and fatty foods; caffeinated and carbonated drinks; chocolate; and onions.
Notorious gas producers include beans, onions and cruciferous vegetables like cauliflower, cabbage and radishes. (These veggies are loaded with vital nutrients, so don't shun them altogether, but enjoy them in small doses.) The same goes for packaged low-carb treats and other foods containing artificial sweeteners — especially the sweetener sorbitol.
Lighten its load
People who are overweight are more likely to suffer from GI problems. Whatever your weight, though, regular exercise can help alleviate digestive distress. In a study involving 983 people participating in a weight loss program, the more physical activity people got each week, the fewer GI symptoms they had. Aim for at least 20 minutes of moderate activity each day.
It's your second brain
Your gut is also intimately involved in some intensely emotional business: We rely upon our gut instinct to tell us the right thing to do. We have a gut reaction to people who offend or delight us. We do a gut check when facing a challenge and congratulate ourselves when we display the intestinal fortitude, or guts, to take it on.
When you think about it, you won't be surprised to learn that your gut, or "second brain," is synced up with your real brain. Just think about how a bout of intense fear or panic can liquefy your innards — or, more commonly, when a cramp or brief wave of nausea alerts you to a nagging anxiety your mind had been working so hard to suppress. There's a good reason your gut and your "first brain" communicate so seamlessly: Every class of neurochemical produced in the first brain is also produced in the second.
Another kind of chemical is the primary go-between for these two brains: stress hormones. When the brain detects any kind of threat — whether an impending layoff or a dustup with your spouse — it shoots stress hormones to your gut. Sensory nerves there respond by adjusting acid secretion and shutting down both appetite and digestion — a throwback to more dangerous times in our past, when we needed to summon all our resources to stand and fight, or flee. The result may be a nagging stomachache or a full-blown bout of GI distress.
Tummy trouble is the body's way of saying, "Pay attention to what's bugging you!" says clinical nutritionist Elizabeth Lipski, PhD, CCN, author of Digestive Wellness and Digestive Wellness for Children. "If my gut doesn't feel right, my job is to figure out what's out of balance." Although resolving work or personal problems requires long-term strategizing, you can tamp down the symptoms of a troubled gut with these tried-and-true anxiety-reducing techniques:
Breathe into your belly
Meditation, yoga, deep breathing, and other practices that encourage mindful relaxation make the body less sensitive to stress, research suggests. Deep breathing, using the muscles of your diaphragm (you should feel your belly expand and deflate with each inhale and exhale), can also help calm your mind and release tension in your abdominal muscles, easing indigestion. Another way to calm the body's autonomic nervous system — which regulates digestion, among other things—is through progressive muscle relaxation, tightening and then relaxing small groups of muscles beginning in your toes and working your way up to your face.
Go for easy workouts
Moderate exercise is a known enemy of stress. (Whenever you can, exercise outdoors — natural settings help calm frayed nerves.) Start slowly and increase activity gradually — even a 20-minute stroll will help soothe nerves, improve digestion and reduce bloating, gas, and constipation by optimizing the passage of waste through your bowels.
Remember: Your ultimate goal in soothing a troubled tummy is to get clearer intuitive signals. When something really bugs you, your second brain will let you know loud and clear.
It's your shield against germs
If you've ever had food poisoning, you know your gut is an uncompromising vigilante. When a nasty microbe hitchhikes a ride into the body on the back of real food, the gut quickly recognizes the interloper and strong-arms it to the nearest exit. To make the ID in the first place, it calls upon a reliable army of sentries, millions of immune system cells residing in its walls.
If the fact that the gut plays a major role in immunity sounds surprising, consider that the whole purpose of the immune system is to differentiate what's you from what's not you. Then consider that every day, you introduce pounds of foreign material — your daily bread — into your gut. The immune system has to decide what's okay to let through and what's not, so it makes sense to headquarter that process right where the food comes in.
This powerful system gears up from day 1. A newborn's gastrointestinal tract is entirely germ free, but immediately after birth, pioneering bacteria begin to colonize it. The first few years of life, everyone's gut develops a unique extended family of bacterial species, determined in part by genetics and in part by diet, hygiene, medication use and the bacteria colonizing those around us. Perhaps bacteria's most important job: stimulating and training the body's immune system and, by its overwhelming presence, crowding out more harmful critters.
The specific microbial mix (your gut contains thousands of species of bacteria) you wind up with has a big impact on your health. Besides making you more resistant to disease, the balance (or lack thereof) of microbes in your gut may lower your risk of obesity or influence your risk of autoimmune disorders such as rheumatoid arthritis, multiple sclerosis, psoriasis and inflammatory bowel disease. Clearly, this extended family deserves coddling. Just in time for cold and flu season, here are immune-boosting ways to protect it:
Steer clear of detoxes
Colonic "cleansers" rid the colon of good bacteria and can cause overgrowth of bad bacteria.
Avoid overusing antibiotics
They kill not only pathogens causing your ailment but also good bacteria.
Consume foods with probiotics
Look for yogurts and soy milks that contain strains of Lactobacillus and Bifidobacteria. In addition to protecting against colds and flu and promoting healthful bacteria, probiotics can help relieve diarrhea caused by infection or antibiotics, irritable bowel syndrome, or Crohn's disease.