STORY AT-A-GLANCE

By Dr. Mercola

What constitutes soluble as opposed to insoluble fiber is something not everyone is clear on, especially in regard to their importance. In discussing fiber, there are two types: soluble and insoluble. Most consider fiber a tool to aid in healthy digestion, but it does so much more. Dietary fiber, the indigestible part of plant material, is considered an essential nutrient because only through eating it is fiber made available to your body, and you need both kinds. Some foods are made up of both soluble and insoluble fiber.

Any portion of a plant-based food that doesn't break down when you eat it or isn't readily absorbed into your body is referred to as indigestible. Fiber is also sometimes called roughage, a term that describes, to a degree, the function of fiber as it moves through your colon and, in the process, helps move along food particles that may tend to adhere to the sides. Food that remains stuck to your colon may cause bloating, pain and constipation, as well as other problems.

Vegetables, certain fruits, seeds and nuts are all important to include in your diet on a regular basis because, besides providing nutrients, they contain the fiber necessary topromote regular bowel movementsand keep your colon free of obstruction, while providing countless other health benefits.

Soluble fiber is easily dissolved in water and becomes gel-like when it reaches your large intestine so it's more easily broken down by liquids and gastrointestinal fluids and releases certain gases. Some of the benefits of this type of fiber are that:1

Insoluble fiber does not dissolve and stays basically intact as it moves through your colon. Because insoluble fiber isn't digested, it's not a source of calories. This type of fiber:

What fiber does for you overall is twofold: Soluble fiber helps you feel full for longer after you eat by slowing digestion, while insoluble fiber fills up the space in your stomach and intestines, both of which help you manage portion size. Both types of fiber also serve to decrease your risk of several health-compromising conditions, including heart disease, diabetes and obesity. In fact, one study showed a 10 percent decreased risk for all-cause mortality for every 10 grams of fiber you increase in your overall fiber intake.2

Many foods are good sources of fiber. Generally speaking, foods considered "good sources" contain at least 20 percent of the recommended daily value of dietary fiber per serving, but this doesn't tell the whole story of whether a food is healthy or not. Grains, for instance, are not recommended, even though they're high in fiber.3

Healthy foods with high amounts of fiber include green peas, artichoke, baked sweet potato with the peel intact, spinach, broccoli, Brussels sprouts, cauliflower and many other vegetables.

Additional foods that are also excellent in providing fiber include pears, raspberries, stewed prunes, dried figs or dates (eaten in moderation due to high sugar content), pumpkin, almonds, apples with the skin intact, bananas (also eaten in moderation) and oranges. Organic psyllium seed husk(nonorganic psyllium is typically loaded with pesticides) is another excellent way to optimize your fiber intake.

The Academy of Nutrition and Dietetics says 25 grams of fiber per day is enough for women, with a 38-gram target for men. However, my recommendation for daily fiber intake is 25 to 50 grams per 1,000 calories consumed. The Academy was right about one thing, though, for anyone wanting to increase their fiber intake:

The importance of and the differences between soluble and insoluble fibers began emerging when prebiotic soluble fibers were discovered about 15 years ago.5 Nutritionists and medical researchers found that certain soluble fibers such asinulin, FOS (fructooligosaccharide) and oligofructose, which turned out to be prebiotics, brought about remarkable changes in the bacterial makeup of the colon.

The benefits continue through the effect fiber has on preventingleaky gut, which may be reaching epidemic proportions. In fact, 80 percent of the American population is said to be wrestling with this often-misdiagnosed problem, known to cause anxiety, joint pain, chronic fatigue, brain fog, hives and depression, not to mention irritable bowel syndrome (IBS), food allergies and bloating. According to Food Integrity Now:

In addition, gut health and a clean colon are aspects of well-being that many don't connect with cardiovascular health, but fiber is one aspect of nutrition that fills this role in several ways. For instance, an inverse association has been found between fiber intake and heart attack, and research shows that those eating a high-fiber diet have a 40 percent lower risk of heart disease.7

Besides providing fiber, some foods go even further in terms of improving your gut health, one case in point being not-quite-ripe tropical fruits such as banana, papaya and mango. That's because they also containdigestive-resistant starch. While fiber is crucial for your diet, what makes it even healthier is its potential for fermentation. According to Today's Dietician:

In your large intestine, resistant starches feed healthy bacteria, essentially acting as prebiotics. They also bulk up your bowel movements for easier, timelier disposal without making you feel bloated or gassy. Best of all, they don't spike your blood sugar the way the completely ripened fruit would do, so they're also much more likely to improve insulin regulation.

Unripe papaya, banana and mango aren't the only foods with this ability; seeds and tapioca starch also have the same capability, but the tropical fruits also contain higher percentages in certain vitamins and minerals. In many ways, resistant starch could be considered a third type of fiber.9

Keeping your immune system healthyis crucial for preventing illness and disease. That said, the environment we live in makes optimal health a challenge at times, especially in choosing foods that will help, not harm, your gut health, which plays an integral role in your immune system health. In the same vein, while grains such as wheat and corn are typically placed on the "do" list as good for increasing your fiber, there are multiple reasons why they shouldn't be.

In addition to their tendency to promote insulin and leptin resistance, and the fact that they contain lectins, one of the most important is the way these and other grains are grown, both in regard to the soil and how they're chemically treated as they grow to discourage weeds and maximize yield. Processing makes such grains even worse for your health, and they're implicated in worsening disease rates in numerous ways.

How you prepare foods to maintain their fiber content includes eating the peelings of appropriate fruits and vegetables, but make sure they're organic to avoid potential pesticide overload. As for improving your microbiome, including fermented vegetables and other foods in your diet, such as cabbage, carrots, turnips, parsnips and beets, is important. Nearly any vegetable can be used, but root vegetables seem to be the hardiest with added herbs for flavor.

Take a look at these healthy, delicious fiber-rich recipesto obtain gut health, strengthen your immune system and maintain a clean colon. To work toward getting plenty of both soluble and insoluble fiber so you can stay regular and healthy, be sure to eat a wide variety of vegetables, seeds and nuts daily.

Sources and References

1, 3 Medical News Today August 31, 2017

2 American Journal of Epidemiology January 5, 2015

4 Academy of Nutrition and Dietetics August 5, 2017

5, 9 Prebiotin 2007-2017

6 Food Integrity Now May 27, 2015

7 JAMA. 1996 Feb 14;275(6):447-51.

8 Today’s Dietician September 2012 Vol. 14 No. 9 p. 22