Just In: Eating Enough Fiber Makes You…Happier?

Fiber is famous for filling you up, smoothing your digestion, and even improving heart health. And now, new research shows that getting your daily dose of roughage could have yet another benefit: reducing the severity of depression symptoms. That’s right, an October 2024 study published in Behavioral Neurology identified a negative association between fiber intake and moderate-to-severe depression. Here’s more about the study, as well as some simple ways to incorporate more fiber into your own diet. 

• ABOUT OUR EXPERTS: Alyssa Simpson, R.D.N., C.G.N., C.L.T., is a digestive health-focused dietitian. Amanda Sauceda, M.S., R.D., creator of The Mindful Gut, is a registered dietitian and a nutrition and dietetics lecturer at California State University, Long Beach.

What the Study Revealed About Fiber and Depression

To examine the relationship between fiber and depression, a Chinese research team examined data from the National Health and Nutrition Examination Survey (NHANES), a long-running program designed to assess Americans’ health and nutrition status. It tracked over 29,000 adults over 11 years. 

The subjects provided two 24-hour diet recalls (basically food journals), which were analyzed for fiber content. They also completed a nine-item questionnaire to assess depressive symptoms in the prior 14 days. They were categorized into groups based on this: no symptoms of depression, mild depression, moderate depression, moderately severe depression, and severe depression.

The researchers used these data points to investigate whether any links existed between fiber and feeling blue. The results were profound: The lower people’s fiber intake, the more likely they were to experience more severe symptoms of depression. 

Why Fiber Might Reduce Severe Depression Risk 

Considering that fiber passes through the gut, not the brain, its potential impact on depression might seem like a head-scratcher. But gut health experts say there’s a logical connection at play. 

“Fiber is essential for feeding gut bacteria, which, in turn, produce short-chain fatty acids, compounds that help reduce inflammation in the brain,” explains digestive health-focused dietitian Alyssa Simpson, R.D.N., C.G.N., C.L.T. This connection between gut bacteria and the metabolites they produce is known as the gut-brain axis—a link that’s as powerful as it sounds. “These metabolites enhance neurotransmitter function and may help work against depression symptoms,” she adds. 

Read More: 8 Small Ways To Support Your Mental Health Today

There’s another reason high-fiber foods might have mental health potential. “Fiber-rich foods are some of the healthiest foods around; where you find fiber, you’ll also find micronutrients the brain needs,” Sauceda says. “For example, beans are rich in B vitamins like folate, which can play a role in neurotransmitter production.” In fact, one 2023 study found that micronutrients like protein, B vitamins, vitamin D, magnesium, zinc, selenium, iron, calcium, and omega-3 fatty acids all significantly impacted the function of the brain and nervous system, and could thus affect depressive symptoms.  

Lastly, a balanced, high-fiber diet indicates that you’re probably taking good care of yourself in general, making an elevated mood more likely. “Eating more fiber can be a sign that someone is eating a healthier diet and may also be partaking in general healthy behaviors like getting good sleep and managing stress,” suggests Amanda Sauceda, M.S., R.D., creator of The Mindful Gut and nutrition and dietetics lecturer at California State University, Long Beach.

“Fiber plays many roles in our body, so I don’t find it surprising that it could affect depression risk,” Sauceda says. Of course, though the study’s results are intriguing, they don’t guarantee that eating bran muffins and broccoli will brighten your mood. The research used self-reported diet data, which might not reflect accurate everyday habits, Sauceda points out. She adds that people experiencing depression might also have altered diet patterns, creating a chicken-or-the-egg conundrum of whether a lack of fiber is a result of a depressed mood or its cause.

That said, you can hardly go wrong including more fiber in your diet—especially when we know it does a few different things in the body that may bring a little sunshine to your spirits. 

How to Get More Fiber in Your Diet

Bumping up your fiber intake doesn’t have to involve eating like your grandmother. Here are five ways to do it that are plenty appealing.

1. Swap Refined Grains for Whole Grains

No matter the meal, if it involves grains, you can usually make at least some of them whole. Since whole grains retain their bran, germ, and endosperm, they’re higher in fiber than their refined counterparts. “Make breakfast count by swapping out refined cereals with a high-fiber alternative like overnight oats with oats, berries, and chia seeds,” Simpson suggests. “Or, instead of white pasta or white rice as a side dish or bowl base, opt for brown rice, quinoa, or a mix of whole grains such as farro.” These simple swaps will easily earn you at least a few extra grams of fiber.

2. Sneak More Fiber Into Smoothies

Smoothies are simple to make—and these blended, sippable snacks are a great way to squeeze in high-fiber foods, Sauceda says. “I love using frozen fruit and blueberries because they pack in fiber and can have brain-boosting nutrients,” she suggests. “Make sure to add some protein if you’re having a smoothie for a meal so it has staying power.” Other fibrous foods to add to your blend include avocado, leafy greens like spinach, chia, or hemp seeds. You can also sprinkle a powdered fiber supplement in there!

3. Benefit From Beans

Beans and lentils are some of the highest-fiber foods around—and when you purchase them in cans, they’re some of the most convenient, too. “Add black beans or lentils to soups, salads, or wraps for an added nutrition and fiber boost,” recommends Simpson.

Read More: The Best Foods And Supplements For Longevity

Stumped on how to make a bean-based snack? Sauceda suggests making a dip with mashed or pureed beans. (A basic hummus is an excellent starting point for beginners.) “Eat it with other fiber-filled foods like carrots or celery,” she says. “You can even use the dip as a spread for sandwiches; every bit counts.”

4. Hang On to Leftover Veggies

Speaking of making every bit count, don’t toss that little pile of vegetables left over from dinner. They’re loaded with fiber and other nutrients and are more versatile than they might appear. “Those veggies are perfect for breakfast the next morning. Add them to eggs, to oats for savory oatmeal, or to a breakfast burrito,” Sauceda suggests. 

5. Slip Extra Fiber Into Soups

Soups welcome all sorts of high-fiber ingredients into their tasty fold. Veggies like carrots, zucchini, and potatoes, prebiotic foods like onions and garlic, beans like chickpeas, and grains like quinoa and barley can all ratchet up a soup’s fiber content (not to mention flavor). “If you’re someone who isn’t used to a lot of fiber, soups can work well because the long simmering time will soften the fibers, making them easier to digest,” says Sauceda. “You can also cook your veggies and blend them into your broth.” It’s also another instance in which you can mix a little fiber powder into your bowl, should you need an extra boost.