(CNN) Constipation isn't the most glamorous of topics — but having it sure isn't fun. For one, it's extremely common, afflicting 42 million people in the United States. Each of us has different bathroom habits, but most experts say that three or fewer bowel movements per week could indicate a problem. And although constipation can be caused by medical conditions (hypothyroidism, inflammatory bowel disease), medications (painkillers, antidepressants), and other factors that may be out of your control, for most of us, it's caused by what we're eating — or, rather, not eating, says Elizabeth Blaney, MD, gastroenterologist and clinical assistant professor of medicine at the University of Pittsburgh. The average American gets just 15 grams of fiber a day, though experts recommend at least 25. Most of us don't drink enough water, either, which also contributes to constipation. Get things moving again with the 15 foods that follow.
Prunes—or if you prefer a tastier sounding name, dried plums—are the first food you thought of, right? There's a reason they're famous. For one, they're rich in fiber. The nutrient is what increases the bulk of your stool so it can move along on its merry way. One prune has about 1 gram of fiber. "That's a pretty concentrated amount," says Dr. Blaney. They also have fructans and sorbitol, fermentable sugars that can have a laxative effect, she adds.
Related: 13 surprising causes of constipation
One downside to some fruits is that they contain a lot of fructose—fruit sugar—that can cause gas. That's why Dr. Blaney suggests high-fiber, lower-sugar fruits that don't bring on the bloated tummy, like kiwi. One cup of kiwi offers 5 grams of fiber, plus you'll get other good-for-you nutrients, like more than double your daily vitamin C quota.
For a savory afternoon snack, skip potato chips and have plain popcorn instead, recommends Gina Sam, MD, director of the Gastrointestinal Motility Center at the Mount Sinai Hospital. It's an easy way to add more fiber into your day—3 cups of air-popped contains 3 grams for just 93 calories. Pop it yourself or buy the bags of yummy versions that are popping up all over store shelves, like Skinny Pop ($22 for 30 bags; amazon.com).
Along with fiber and getting regular exercise, drinking enough water is the most important factor in relieving constipation. H2O is critical to help stool move easily through the colon. "The colon's main job is to reabsorb water. If you're a bit dehydrated, your stool will be harder and more difficult to pass," says Dr. Blaney. Drink 8 to 10 glasses of water a day, recommends Dr. Sam, and fill up on foods with a high water content.
Just a tablespoon of ground flaxseeds packs in 2 grams of fiber. That may sound like a little, but the beauty of flaxseeds is that they're so easy to throw into everyday eats for a fiber punch. Add a scoop to smoothies, oatmeal, or atop a salad. Note: don't eat flaxseeds whole. Your body can't digest them, which means they'll pass through you without giving you any nutrients. Buy them pre-ground, or throw them in a coffee or spice grinder to get the benefit.
Related: 20 best foods for fiber
Skip the OJ in favor of a big juicy orange. Dr. Sam favors the fruit because one large orange offers 4 grams of fiber for just 86 calories. Bonus, citrus fruits contain a flavonol called naringenin, which Chinese researchers in an animal study found could work like a laxative to help treat constipation.
Oatmeal offers up the best of both fiber worlds: a half-cup of dry oats contains 2 grams of insoluble and 2 grams of soluble fiber. Insoluble fiber adds bulk to stool and helps food pass more quickly through the stomach and intestines, while soluble fiber dissolves in water and forms a gel-like material. Together, the two types of fiber work together to bulk up stool, soften it, and make it easier to pass.
Eating a bowl of rice may make your gut happy. In a Japanese study, people who ate the highest intake of rice had 41% lower odds of suffering from constipation. The researchers didn't examine exactly why, but rice's fiber may play a role, or it may be that people who ate rice naturally had healthier diets. Since it may be the fiber, go for brown rice—it offers four grams per cup compared to one in white.
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This bottled beverage is popping up in more stores, fueled by the healthy-drink trend (think coconut water). Made from the aloe vera plant, aloe can act as a laxative for some people. In fact, aloe was traditionally included in laxative products. Dr. Blaney suggests that if you want to try aloe juice, start with 2 ounces and work your way up to 8. One to try: ALO Exposed Aloe Vera ($20 for a 12-pack; amazon.com).
Not only does one cup of cooked spinach pack 4 grams of fiber, but it's also an excellent source of magnesium. The mineral helps the colon contract and also "helps draw water in to flush things through," says Dr. Blaney. In fact, in some cases, she'll give patients a laxative with magnesium in it. Before you go that route though, it couldn't hurt to add more magnesium-rich foods into your diet first.
Related: 13 foods that are high in magnesium
Beans contain resistant starch, a fiber-like starch that helps improve transit time in the colon, acts as a mild laxative, and helps balance the bacteria in your GI tract. Yes, upping your intake of beans may provoke gas and bloating. "Increase your intake of fiber-rich foods gradually. You may feel worse before you get better," says Dr. Blaney. Eating cooled beans, like in a salad, may increase the resistant starch.
If traditional beans are too tough on your stomach, you can try green beans, says Dr. Blaney. Though they're very different from traditional beans (they're much lower in protein and carbs), they still contain 4 grams of fiber per 1-cup serving, making them a good constipation fighter. Better yet, they contain fewer fermentable sugars, so they likely won't come with the gassy side effect of regular beans.
Many yogurts contains live active bacterial cultures, or probiotics, that replenish the good bacteria in your gut. That can help with the entire health of your GI system. In fact, in one meta-analysis in the American Journal of Clinical Nutrition in 2014, probiotics helped increase the number of bowel movements by 1.3 per week, and—sorry for the image—improved consistency, too, making things more comfortable when you go.
If you've ever had constipation, you've probably tried to get things moving again by having a cup of java. Experts believe that coffee stimulates muscle contractions in the colon, which then helps you go to the bathroom. (Coffee has many other health benefits, too: it improves circulation, your memory, makes your workouts more effective, and is full of antioxidants.) To stimulate movement in your colon, coffee may help, so when you get up in the morning, have a cup, recommends Dr. Sam.
Sure, breakfast technically isn't a food, but Dr. Sam suggests eating a morning meal to speed things up down there. "Your body's contractions of the colon work at its highest level in the morning. That's when your body is designed to poop!" she says. Eating a breakfast filled with higher fiber foods will prompt your natural urge to go.