Fiber has always been viewed as a boring but essential part of good nutrition. For decades it was thought to be useful in keeping the digestive tract healthy, curbing food cravings, lowering cholesterol, and preventing diet-related cancer. Now, scientists are taking a hard look at human gut microbes, and all of a sudden, fiber is being viewed very differently.

Fiber comes from eating plants. As the structural backbone of plants, fibers are carbohydrates that resist digestion and therefore, don’t provide calories. Every plant is a combo of fibers tightly interwoven with other nutrients. This slows down how quickly food gets turned into blood sugar and gets other nutrients to specific destinations in your bowels. 

The beneficial bacteria in your lower gastrointestinal (GI) tract transform indigestible carbohydrates into fuel. The nutrition discovery of the past few years has come from observing what happens when gut bacteria eat your fiber. By-products made from digesting microbial fiber positively impact health issues like anxiety, depression, insomnia, attention, dementia, type 2 diabetes, and much more. 

Getting fiber from food is critical because the heartier your gut microbe population, the better your overall health. Using an over-the-counter fiber supplement doesn’t work the same as eating a wide variety of plant food to coax your bacteria into working hard. A study published last year evaluated over 10,000 human participants and found that eating more than 30 unique types of plants a week produced the most abundant and diverse gut microbes. Participants who ate less than 10 had the least. 

Over-the-counter prebiotic fiber may offer an additional advantage to what you get from food. New supplements called synbiotics pair probiotic microbes with their preferred prebiotic fuel. Not all prebiotic fibers are the same. Use these supplements with a diverse plant-based diet.

Other fiber supplements have been used for weight loss or constipation. This can provide short-term success, but long-term improvements result from better food and lifestyle choices. With Irritable Bowel Syndrome (IBS) or other digestive diseases, use caution with probiotics and supplemental fibers because they can trigger increased irritation and pain in some people.

A review of more than 240 international clinical studies published this year found that eating 25–29 grams per day was protective but eating more than 30 grams offered the greatest benefit. This is ten 1/2 cup servings a day of vegetables, fruit, whole grains, and/or legumes.

To improve fiber diversity, eat 30 unique types of plants per week. Begin by organizing your grocery list by category. Try for ten varieties of vegetables, five fruits, three grains, two legumes, two nuts, two seeds, and two herbs. Focus on progress, not perfection.