A 6 may mean failure in school, but a letter will get you high marks in your diet. The two biggest 6s in nutrition—fiber and fermented foods—are top priorities for maintaining healthy digestion, and they may offer a lot more. How can you incorporate these nutrients into your meals? Can doing so help your overall health as well as your gut health?
Fiber, fermented foods, and the gut microbiome
The gut microbiome is made up of bacteria, viruses, fungi, and other microorganisms that live in the large intestine. What you eat, the air you breathe, where you live, and many other factors affect the composition of the gut microbiome. Some experts consider it a hidden organ because it plays a role in many important bodily functions—for example, it helps the immune system function optimally, reduces chronic inflammation, keeps gut cells healthy, and provides some important micronutrients that may not be found in a regular diet.
Your gut communicates with your brain through pathways in the gut-brain axis. Changes in the gut microbiome have been linked to mood and mental health disorders like depression and anxiety. But it’s not yet clear whether these changes directly cause these types of problems.
We know that a healthy diet low in processed foods is key to a healthy gut microbiome. And a growing body of evidence suggests that fiber and fermented foods may play an important role here.
Fiber 101
The main job of fiber is to ease digestion by softening and adding bulk to stool so it moves through the gut faster.
But fiber has other benefits for your microbiome and overall health. A high-fiber diet helps keep body weight under control and lowers LDL (bad) cholesterol levels. Research has found that eating enough fiber reduces the risk of heart disease, type 2 diabetes and some types of cancer.
What you should know about fiber
There are two types of fiber: insoluble (which makes you feel full and promotes regular bowel movements) and soluble (which helps lower cholesterol and blood sugar). However, recent research suggests that one should focus on the total amount of fiber in their diet, rather than the type of fiber.
If you’re trying to incorporate more fiber-containing foods into your diet, be sure to slowly ease into new high-fiber habits and drink plenty of water. Your digestive system needs to adjust slowly to avoid bloating, diarrhea and stomach cramps caused by eating too much in too short a time. Your body will gradually adjust to increased fiber intake after about a week.
How much fiber do you need?
The fiber formula is 14 grams per 1,000 calories consumed. Your specific calorie intake may vary depending on your activity level.
“But instead of tracking daily fiber intake, focus on getting more servings of high-fiber foods in your diet,” says Eric Rimm, a professor of epidemiology and nutrition at Harvard’s T.H. Chan School of Public Health.
What foods are high in fiber?
Fruits, vegetables, legumes, nuts, seeds and whole grains are all high in fiber. The Dietary Guidelines for Americans provides a comprehensive list of high-fiber foods and their calorie content.
What about over-the-counter fiber supplements in capsule form, as a powder to mix with water or as chewable tablets? “If you’re having trouble getting enough high-fiber foods, you can take these occasionally, and there’s no evidence that they’re harmful,” says Rimm. “But they shouldn’t be your primary source of fiber.”
Fermented Foods 101
Fermented foods contain both prebiotics — ingredients that cause healthy changes in the microbiome — and beneficial live bacteria called probiotics. Both prebiotics and probiotics help maintain a healthy gut microbiome.
What You Should Know About Fermented Foods
A healthy gut not only supports digestion and the absorption of vital nutrients from food, but it also helps your immune system fight infections and protectfrom inflammation. Some research suggests that certain probiotics may help reduce symptoms of gut conditions like inflammatory bowel disease and irritable bowel syndrome, although not all experts agree.
Many fermented foods undergo lactic acid fermentation, in which natural bacteria feed on the sugars and starches in the food and create lactic acid. This process not only removes simple sugars, but also creates various types of good bacteria, such as Lactobacillus or Bifidobacterium. (Keep in mind that some foods go through steps that remove probiotics and other healthy microbes, as in beer or wine, or render them inactive, as in baking and canning.)
The exact amounts and specific strains of bacteria in fermented foods vary depending on how they are made. In addition to probiotics, fermented foods may contain other valuable nutrients, such as enzymes, B vitamins, and omega-3 fatty acids.
How often should you eat fermented foods?
There is no recommended daily amount for prebiotics or probiotics, so it’s impossible to know exactly which fermented foods or amounts are best. The general guideline is to add more to your daily diet.
Which fermented foods should you choose?
Fermented foods have a range of flavors and textures due to the special bacteria they produce during fermentation or that are added to the foods. Yogurt is one of the most popular fermented foods (look for the words “live and active cultures” on the label). Still, there are plenty of options available if you’re not a yogurt fan or want to expand your fermented food choices. Kimchi, sauerkraut, kombucha and pickles are a few examples.
Like fiber, probiotics are marketed as over-the-counter supplements. However, like all supplements, they don’t require FDA approval, so there’s no guarantee that the types of bacteria listed on a label can provide the promised benefits—or are even in the bottle. “Therefore, it’s best to get probiotics from fermented foods,” says Rimm.
To learn more about the value of fiber, fermented foods, and a healthy gut microbiome, listen to this episode of the Food, We Need to Talk podcast: “Understanding the Microbiome.”