Your body is a machine, and a shockingly versatile and adaptable one at that. As such, keeping your body performing at tip-top shape is (of course) a priority on a daily basis, but it also means paying close attention to how your nutritional needs change over time.

While maintaining a healthy diet is important at all stages of life, there are some nutrients that play a greater role as we get older. Protein is a prime example. Another such nutrient is fiber. Sure, you’ll want to make sure that you’re getting enough fiber whether you’re 17 or 71, but you may be surprised to learn how your body—and in particular, your digestive system—evolves in ways that make getting an adequate fiber intake ever more critical.

Here, we talked to an expert to better understand how your gastrointestinal (GI) system changes as you age and the importance of eating fiber for healthy aging.

How does age impact your digestive system?

Aging affects both the external and internal organs of the body. “As you age, the muscles in your GI tract can weaken, and this causes a slow down that can produce constipation,” explains Samantha Cassetty, MS, RDN. “Also, it becomes more common to take medication as you get older, and several prescription and non-prescription meds can impact your digestive system,” she adds. These prescription medications may result in digestive issues, such as (more) constipation as well as acid reflux.

How can fiber help your digestive system?

A 2016 benchmark population-based study examined a cohort of more than 1,600 adults over the age of 49, and found that those who consumed the most fiber had a nearly 80 percent greater chance of living a long and healthy life. Folks who followed fiber-rich diets were less likely than their counterparts to suffer from hypertension, type 2 diabetes, dementia, depression, and functional disability. Why is that the case?

“Fiber is a type of carbohydrate in plant foods that resists digestion,” says Cassetty. It’s found in fruits, veggies, whole grains, nuts, and seeds, and can help to form the soft, bulky type of stool that moves through your digestive system smoothly and passes easily. “Fiber has plenty of other science-backed benefits, like helping to feed your gut microbes, so you maintain a diverse and healthy microbiome,” Cassetty adds. Your body’s microbiome is closely linked to your immune system and mood-regulating functions, which means that the health of your microbiome plays a substantial role in your overall wellbeing. The average adult needs between 21 and 38 grams of fiber each day, but most folks consume less than 15 grams of fiber per day. As such, Americans of all ages could stand to significantly increase their uptake of fiber.

Excellent foods filled with fiber for healthy aging

Given the many nutritional benefits of fiber—and our apparent chronic underconsumption of the nutrient—it’s worth highlighting the many fiber-rich ingredients that you likely have sitting in your kitchen already.

“The goal is to eat a variety of whole, plant foods every day,” says Cassetty. “An ideal eating pattern is to include half a plate of veggies or fruits—or a mix of the two—at meals, and then a quarter of the plate as a starchy veggie or whole grain.” The remaining quarter should be protein, plus fat used to cook or accent meals. That said, Cassetty notes, this is a “north star goal,” and meant more as a directional suggestion than a hard-and-fast rule.

“While some foods have more fiber than others, don’t discount lower-fiber plant foods,” Cassetty adds. “They’re also among the best foods to eat because plant foods offer digestive benefits beyond their fiber counts. For instance, walnuts contain polyphenols and ellagic acid, substances that influence our gut microbes.”

Beans are famously high in fiber, and some of our favorite varieties come from Fillo’s and A Dozen Cousins, whose lineups of well-seasoned beans come in easy-to-serve pouches that make for an excellent side dish or snack.

Some of our other favorites include:

• 1 cup raspberries: 10 grams of fiber
• ½ cup cooked lentils: 6.5 grams of fiber
• ½ cup cooked quinoa: 5 grams of fiber
• 1 medium apple: 5 grams of fiber
• ½ cup dry oats: 4 grams of fiber
• 1 cup Brussels sprouts: 3.5 grams of fiber
• 1 cup broccoli: 2 grams of fiber

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