What is Fiber?
Fiber, sugar and starch make up total carbohydrates. Fiber is a type of carbohydrate that does not get fully digested in the digestive tract and therefore it is generally not absorbed by our bodies.
Turns out explaining fiber is not a simple thing. It’s not cut and dry and there is overlap between the types of fiber. Your take away should be
- You need to eat fiber
- Vary the kinds of fiber you consume.
- The best source of fiber is whole foods (dietary fiber).
Types of Fiber
Dietary Fiber– Fiber from intact plant sources.
Functional fiber– These are found in foods, but they are isolated / extracted from foods or synthesized and used as supplements or to fortify various processed foods.
Types of Dietary Fiber
-Soluble fiber dissolves easily in liquid.
-Supports blood sugar balance, cardiovascular health, and appetite control.
-Increases the production of the hormone glucogon-like peptide 1, which reduces blood sugar levels.
-Soluble dietary fiber, due to its higher rate of digestibility by the bacteria in the large intestine, has higher calorie content compared to insoluble fiber.
-Examples of soluble fiber are pectin, beta-glucans, fructans, oligosaccharides, some hemicelluloses, mucilage and gums.
-Food sources rich in soluble fiber components include legumes (beans, lentils), vegetables (such as Brussels sprouts and cabbage), fruits (such as apple and berries) and oat bran.
Viscous vs. Nonviscous Soluble Fiber
-Viscous fiber is a gel forming fiber that helps in regulating cardiovascular health and blood sugar, controls the thickness of food being digested. slows gastric emptying, binds with cholesterol in the intestines and prevents its absorption.
-Choosing fiber-rich fruits and vegetables is usually going to be helpful in getting the cholesterol-lowering effects of soluble fiber.
-The most viscous fibers—including the beta-glucans are found in barley, oats, sea vegetables, shiitake mushrooms, and other foods, as well as the pectins found in the skins of cherries, grapes, berries, citrus fruits, and other foods—have all been shown to have blood cholesterol-lowering effects.
-It stabilizes blood sugar by slowing it’s absorption into the blood stream, making it function as a sugar blocker.
-Viscous fiber includes glucomannan, beta-glucans, pectins, guar gum and psyllium.
-Good whole-food sources include legumes, asparagus, Brussels sprouts, oats and flax seeds.
-Insoluble fiber is just as important as soluble fiber, but in different ways. You need to be getting both.
-Insoluble fiber doesn’t dissolve, but it increases stool bulk, moves food through the digestive tract and helps you stay regular. It works like a broom cleaning out your colon. Removes waste from colon in less time.
-Hemicellulose, cellulose, resistant starch, chitin and lignin are types of insoluble fiber.
-Sources of insoluble fiber include flaxseed, whole grains, breakfast cereals, and vegetables such as celery and carrots.
Fermentable vs. Non-Fermentable Fiber
-Both soluble and insoluble fiber can be fermented. Only some insoluble fiber is slightly fermentable.
-Fermentable fiber reaches the gut and the bacteria are able use them as fuel. It is food for your gut bacteria. Think prebiotic fiber.
-These fibers are prebiotics for your bacteria. For more on prebiotics, see here.
-The probiotic bacteria can then produce short chain fatty acids which are beneficial to your health. Among the SCFA produced is butyrate. Butyrate helps control the growth of the cells lining the gut, to make sure there’s good balance between old cells dying and new cells being formed. It’s also the most important source of energy for those cells. It is suggested that a lack of butyrate contributes to colon disease.
-Improving your gut bacteria has all sorts of other health benefits, including benefits to your brain.
-Fermentable fibers include pectins, beta-glucans, guar gum, inulin, oligofructose, beans and legumes.
-Some common foods that contain fermentable (prebiotic) fiber are yams, artichoke, chicory root, dandelion greens, bananas, onion, garlic, leek, cauliflower, jicama, mushrooms, asparagus, wheat and other grains, raw nuts and seeds like almonds and flaxseed and legumes.
-Non-fermentable fiber tends to be insoluble as well, although some insoluble fiber is slightly fermentable. Nonfermentable fiber includes lignin, chitin, hemicellulose and mucilage .
*Most foods contain a combination of types of fiber
Why is Fiber Important?
- Fiber is food for the bacteria in our digestive tract
- Improves cholesterol levels
- Stabilization of blood sugar- regular fiber rich meals can result in better blood sugar control
- Reduces the risk of type 2 diabetes
- Increase insulin sensitivity
- Blood pressure reduction
- Reduces risk of cardiovascular disease
- Anti-inflammatory benefits
- Improve your gut bacteria
- Keeps colon clean
- Reduces risk of colon cancer
- Keeps healthy bacteria functioning which keeps your colon healthy
- May help with weight control because it helps you feel full longer
- reduce symptoms of constipation, hemorrhoids and diverticulosis
- promote appetite control by filling you up
- Help move toxins out of your intestines quicker
How Much Fiber Should We Consume?
-Based on a 2010 survey most Americans get average 16 grams per day. Teenage girls get only 12 grams. No age group consumed the minimum recommended amount.
-A minimum amount should be 25 grams of fiber per day. Optimal levels though are closer to 50 grams of fiber.
-Low carb diets tend to be low fiber. Find ways to get more fiber into your diet daily.
-You should also drink plenty fluids when increasing your fiber to keep it moving and prevent constipation or blockages.
-Get most of your fiber from foods because they have many other nutritional benefits. Use supplements to fill in any gaps.
Side Effects of Fiber
If you are eating very little fiber, increase slowly to reduce gas and bloating, which will go away after your body adjusts to the increase. This is also reduced by getting your fiber from whole food rather than processed supplements.
Various medical conditions require the reduction of fiber such as those under going chemotherapy and those that have IBS, IBD or diverticulitis.
Some report that regular excessive soluble fiber (over 50 grams) could pull certain nutrients out of your body like it pulls out cholesterol. These nutrients could include iron, zinc, magnesium, calcium and phosphorus. The National Institute of Health believes this happens only when a large amount of fiber is eaten in a short period of time, and is rarely an issue, especially if you are getting fiber from nutritious foods rather than supplements.
A side effect of fermentation is gas. Increase fiber gradually and make sure you drink plenty water to reduce this side effect. It should improve after a while.
Ways to Increase Fiber
- Go for fruit instead of fruit juice. Have an orange instead of orange juice.
- Eat the skins of fruits and vegetables.
- Eat whole fruits and vegetables instead of processed ones. Eat apples instead of applesauce.
- Go for whole grain instead of processed products.
- Eat beans a few times a week.
- Increase your vegetable intake.
- Add seeds and nuts to dishes, like flaxseeds or chia seeds.
- Add fiber to baked goods
High Fiber Foods
In order for a food to be considered high-fiber, it must have 5 grams of fiber per serving. Products with over 2.5- 4.9 grams of fiber per serving are considered good sources of fiber.
There is no fiber in animal products, only plants.
Vegetables- Beans and legumes group are tops in providing fiber. One cup provides 10-20 grams of fiber. They also include both soluble and insoluble fiber. They are however, high in calories.
Navy beans are the highest fiber provider per serving.
Greens such as beet, turnip and collard greens provide 5 gms of fiber per serving with much fewer calories.
Other high fiber standouts are raspberries, lentils, pinto beans, black beans, barley, kidney beans, broccoli, pears, peas, winter squash, chickpeas, avocado, sweet potato, quinoa, rye, wheat and tempeh.
Grains- Whole grains provide a large amount of fiber, especially rye. Other whole grain sources are wheat, corn, brown rice, bran, barley and oats.
Adding enough fiber may seem difficult at first, but if you are eating a healthy diet it’s not as difficult as it seems.
“If my people, who are called by My name, will humble themselves and pray and seek My face and turn from their wicked ways, then I will hear from heaven, and will forgive their sin and heal their land.” 2 Chronicles 7:14
Fiber and Prebiotics: Mechanisms and Health Benefits