“For hundreds of thousands of years,” writes Max Lugavere in his New York Times bestselling book Genius Foods, “humans ate diets that were rich in fiber, with scientists estimating an intake of roughly 150 grams of fiber per day.”
Today, he continues, we consume an average of about 15 grams per day – quite a paltry intake, by comparison.
Ramping up your fiber consumption from 15 grams to 150 might seem like a daunting task, but never fear – it’s not one that most modern professionals would recommend. That said, experts are divided on how much fiber one should actually consume.
The Institute of Medicine, a research review4 in the American Journal of Lifestyle Medicine contends, suggests a daily dietary fiber intake of 25 to 38 grams per day, depending on age and sex, while the Dietary Guidelines for Americans5 suggests 14 grams of fiber per 1,000 calories consumed. For Dr. Robert Zembroski, a specialist in functional medicine, clinical nutritionist and author of REBUILD, however, both are still “far too low” for most people.
That said, data from Duke University6 shows that any more than 70 grams per day can have adverse effects on digestion, causing pain, cramping, or diarrhea.
The best way to figure out your own fiber threshold is to proceed slowly.
“The sudden addition of a ton of fibrous veggies can make a Western-adapted gut feel quite unpleasant,” says Lugavere. “If you’re eating the typically low fiber standard American diet, increase slowly by adding more salads and foods like garlic, onions, and leeks. You’re going to want your microbiome to adapt — indeed, you breed what you feed. So as your microbial ecosystem ramps up, flourishing under your new gut-healthy diet, you’ll be able to tolerate more fiber.”
The University of Michigan7 recommends adding about 5 grams of fiber to your diet per day at two-week intervals to keep your digestive system from becoming overwhelmed by the sudden influx (which can have some, uh, uncomfortable results if you’re not careful!)
To start things off, try adding some of the following fiber sources to your diet: