How much fiber should we eat each day?

You may not think about it, but there are some foods that your body can’t digest. Sure, if you swallow a stone or a ring, it’ll pass out the other side of your body without you getting any nutrients, but the same goes for some of the components of your diet.

Cellulose and lignin, two molecules that make up the structure of plants, are present in lettuce leaves or in the hulls of whole grains for example, and our body is not able to digest them. Insoluble fibers add bulk to stools and are supposed to make them pass more easily through the digestive tract, acting as a kind of broom that sweeps away the rest of the matter.

But also, in our diet, there is another type of fiber that we cannot digest either: soluble fiber. This type of fiber is found, for example, in legumes, vegetables and oats. It is called soluble because it absorbs water and forms a gelatinous substance. This gel also acts as a “lubricant” to facilitate the passage of stool through the intestine.

Insoluble fiber has another function. We can’t benefit from it, but the bacteria in our gut microbiota can. So-called prebiotic fibers help maintain a healthy gut by increasing the number of beneficial bacteria. This helps reduce the risk of type 2 diabetes, heart disease, and obesity. Most fiber-rich foods contain a mixture of insoluble and soluble fiber in varying proportions.

How much fiber do you need?

The Hadza are a hunter-gatherer tribe from Tanzania who consume a multitude of plants and animals daily. Researchers estimate that each consumes up to 150 grams of fiber per day and that they are in excellent health. The European Food Safety Authority (EFSA) recommends that adults consume at least 25 grams of dietary fiber per day. The equivalent of the United States Department of Agriculture (USDA) recommends even more.

Unfortunately, few people in modern societies even reach these minimums. According to the latest ANIBES nutrition report, in Spain the average fiber intake is 13.5 grams per day and drops to 12 grams in obese people. Studies indicate that increasing fiber intake with two servings of whole grain products per day could reduce the risk of type 2 diabetes by up to 21%.

Fiber has another very important role in health: controlling appetite and, therefore, weight. Foods rich in fiber tend to be more voluminous and therefore more satiating. This can help us feel satisfied sooner and for longer. In particular, soluble fiber, present in foods such as oats, nuts and various types of fruits, when dissolved to form a gel, slows digestion, gives the feeling of being still full and prevents us from eating prematurely.

Additionally, soluble fiber helps regulate blood sugar levels. By slowing down the digestion of sugars in the gut, it prevents blood sugar spikes, which is very important for people with prediabetes or type 2 diabetes.

Some soluble fibers, such as those found in oats and legumes, bind to bile salts in the intestine, making it easier to remove cholesterol from the body and may improve blood levels. For this reason, eating more fiber is associated with a significantly reduced risk of heart disease and stroke.

Cardiovascular health, in general, greatly benefits from a diet rich in fiber. Fiber not only helps lower cholesterol, but also improves blood pressure and endothelial function, helping to reduce the risk of heart disease. Data from a study published in the prestigious journal The Lancet showed that for 200 grams of fiber-rich fruits and vegetables per day, the risk of developing coronary heart disease and mortality is reduced by 10%.

Another important benefit of fiber is its role in preventing colon cancer. Although the exact mechanisms are not completely clear, fiber is thought to contribute to colon health by promoting bowel regularity and reducing the transit time of waste through the colon, which reduces the risk of toxin production through protein fermentation. This reduces the contact of potentially carcinogenic substances with the intestinal lining.

How to Add More Fiber to Your Diet

Sources of fiber are diverse and range from whole grains and legumes to fruits and vegetables, so it is advisable that all of these foods are present in our diet. It is also important to combine soluble and insoluble fiber and try to reach that minimum of 25 grams per day. One way to increase the fiber content of our diet is to add these foods that contain it in greater quantities:

Additionally, we can supplement insoluble fiber by eating wheat or oat bran, green leafy vegetables like spinach or kale, almonds, lentils, zucchini, green vegetables and many other vegetables.