Carbs were once eeeeeeevil, but now they're chill. Ditto with fat (lookin' at you, avocados and peanut butter). People are still fighting over whether meat is good or horrible, and whether dairy is the best or the worst.
One thing that's never been the victim of food shaming? Fiber—that stuff has always been on the good-guy list. But it is possible to have too much of a good thing: Too much sunshine on vacation, too many glasses of wine, and too much exercise (yes, really). And fiber is no exception.
How much fiber do you need?
The general recommendation for daily fiber intake is 25 to 35 grams, says Sarah Mattison Berndt, R.D., nutrition advisor for Complete Nutrition. That may vary depending on your age and gender, though. (Men need more, women need less.) Preferably, those grams are coming from naturally fibrous foods such as fruits, vegetables, whole grains, nuts, beans, and legumes, rather than supplements.
Chances are you're not getting that much. The average fiber intake in the U.S. is about 15 grams per day, according to Sharon Palmer, R.D.N., The Plant-Powered Dietitian and author of Plant-Powered for Life. The FDA even considers dietary fiber to be a "nutrient of public health concern" because low intakes are associated with potential health risks. (Need help hitting that number? Here are six sneaky ways to get more fiber in your diet.)
What happens if you get too much fiber?
While most Americans are getting too little fiber, it's definitely possible to overdo it, resulting in "a range of gastrointestinal distress that would make the best of us blush," says Berndt. Translation: gas, bloating, and abdominal pain. This usually occurs at around 45 grams for most people, according to Palmer, although if you've always had a high-fiber diet, you might be totally fine.
"This GI distress occurs especially when people make drastic changes in their diet—ramping up the fiber too quickly," she says. "However, many people (e.g., vegans) who eat a lifelong diet high in fiber have no problems tolerating high amounts."
PSA: People with certain medical conditions (like irritable bowel syndrome, or IBS) may also find it extremely difficult to comfortably adopt a high-fiber diet, says Palmer—and that's where the types of fiber come into play. ICYMI, dietary fiber can be classified as either soluble or insoluble. Soluble fiber is found in foods like vegetables, fruits, and oat cereals. It dissolves in water, becomes a soft gel, and is readily fermented. Insoluble fiber—found in legumes, seeds, root vegetables, cabbage-family vegetables, wheat bran, and corn bran—does not dissolve or gel in water and is poorly fermented. People with digestive issues or IBS often find that insoluble fiber is to blame, though either type of fiber can cause GI distress, according to the International Foundation for Functional Gastrointestinal Disorders. (The best way to know, unfortunately, is by trial and error.)
Consuming too much fiber can also potentially reduce your body's ability to absorb certain valuable vitamins and minerals, Berndt says. Calcium, magnesium, and zinc are at the biggest risk of reduced absorption.
Don't get us wrong, we're not saying fiber is bad for you in the slightest: "It has a laundry list of health benefits including aiding digestion, lowering cholesterol, steadying blood sugar, and reducing your risk of diabetes, heart disease, and certain cancers," says Berndt. It also helps feed important bacteria in your gut, says Palmer, and can be a key nutrient for supporting weight loss. (It helps you feel full!)
There are two important tricks for effective fiber consumption. One is to increase the amount of fiber in your diet slowly over time, and to spread your intake throughout the day, says Berndt. (That means don't save all your veggies for dinnertime.) Second is to chug some H2O. "If you eat a high-fiber diet without adequate hydration, it can increase symptoms," says Palmer.
So, yes, your beloved kale is safe, as long as you don't eat 10 cups in one sitting. Because fiber is great—but a fiber food baby? Not so much.