The body needs a combination of vitamins, minerals and nutrients to sustain its overall function, improve and support organs and systems, and prevent infections and diseases. Fiber is one of the most recommended nutrients, which is not at all surprising, since research has linked it with positive impacts towards different body parts, such as the gut, digestive system, brain and heart.
Unfortunately, many people around the world are consuming inadequate amounts of fiber, unaware of the potential health consequences if their body's levels are too low.
Dietary fiber is a plant-based nutrient that provides crucial health benefits. Sometimes called roughage or bulk, fiber is a carbohydrate that cannot be broken down into digestible sugar molecules. It usually passes through the body's intestinal tract relatively intact, and can be categorized into:1,2
• Soluble fiber — This dissolves in water and then becomes a gel-like substance. Examples include gum, pectins, beta-glucans and mucilage.
• Insoluble fiber — When it enters the body, this type of fiber retains its shape and doesn't dissolve. Known insoluble fibers include hemicellulose, cellulose and lignin.
Both soluble and insoluble fiber are linked to valuable health benefits:3
• Helps optimize cholesterol levels by preventing some dietary cholesterol from being broken down and digested
• Slows down the rate at which nutrients are digested
• Aids in stabilizing blood sugar levels and preventing spikes in blood sugar levels
• Helps diabetes patients by altering hormonal signals, slowing down nutrient absorption and altering fermentation that occurs in the large intestine4
• Helps feed good bacteria in your gut
• Lessens the amount of time food spends in your colon and assists with eliminating it
• Boosts skin health by moving yeast and fungi out of the body, preventing them from being excreted through the skin where they can cause acne or rashes5
• Promotes satiety and weight loss, since once microbes in your gut digest fiber, a short-chain fatty acid called acetate is released and travels from the gut to the hypothalamus in the brain to signal you to stop eating6
• Improves your sleep-wake cycles,7 as dietary prebiotics in fiber-rich foods have provided a significant effect on rapid-eye-movement (REM) and non-rapid-eye-movement sleep cycles8
A high-fiber diet can also play a role in:9
• Helping prevent leaky gut and constipation by absorbing fluid once it reaches the intestinal tract, allowing byproducts to stick to it
• Providing relief from irritable bowel syndrome
A 2015 American Journal of Epidemiology study also revealed that a 10 percent reduced risk for all-cause mortality was recorded for every 10 grams of fiber you add to your overall fiber intake.13
Some fiber-rich foods can further improve gut health by providing digestive-resistant starch. What makes this type of fiber special is its potential for fermentation in the large intestine.14 Resistant starches are able to feed healthy bacteria, act as prebiotics and bulk up bowel movements for easier elimination without making you feel bloated or gassy.
On the other hand, there are consequences linked to a low-fiber diet. Animal studies discovered that low-fiber diets trigger "waves of extinction" in the gut of mice, with the unhealthy gut potentially being passed on to the offspring. Each successive generation of offspring from the low-fiber group ended up with less bacterial diversity compared to their parents.15,16,17
Plus, even after the mice were given high-fiber meals, the amount of good bacteria still remained low. This suggests a difficulty in repopulating certain good gut bacteria strains once they have been negatively impacted. Aside from depletion of healthy bacteria, consuming little to no fiber-rich foods can lead to:18,19
• Higher risk for constipation, hemorrhoids, and chronic and cardiovascular diseases
• Weight gain
• Increased cholesterol levels
National fiber recommendations call for a daily fiber intake of 30 to 38 grams a day for men, 25 grams a day for women between 18 to 50 years old, and 21 grams a day for women 51 years old and above.20 However, my recommendation for an ideal fiber intake stands at 25 to 50 grams per 1,000 calories consumed, usually from fiber-rich foods. This amount may help boost your overall health and well-being.
To significantly raise your fiber intake, incorporate these high-fiber fruits and high-fiber vegetables into your meals. These can also double as high-fiber snacks you and your loved ones can munch on. Ten of the most notable fiber-rich foods to try include:21,22
1. Split peas and green peas — Despite their small size, peas are a very good fiber source. Cooked split peas roughly contain 16.3 grams of fiber per cup, while cooked green peas have 8.8 grams of fiber per cup.
2. Artichokes — Fiber is one of the main nutrients in artichokes. A medium-sized cooked artichoke may deliver 10.3 grams of fiber.
3. Raspberries — A cup of these sweet antioxidant-rich berries has 8 grams of fiber.
4. Collard greens: Eating these low-calorie leafy greens can help raise your fiber intake, since a cup contains around 7.6 grams of fiber.
5. Blackberries — Another type of berries that contain both soluble and insoluble fiber, a cup of blackberries has 7.6 grams of this nutrient.
6. Avocados: Avocados aren't just a source of healthy fats that are vital for overall health. Half an avocado typically contains 6.7 grams of fiber.
7. Pears — A medium-sized pear has 5.5 grams of fiber, alongside phytonutrients like beta-carotene, lutein and zeaxanthin.
8. Spinach (with the leaves intact) — Spinach is another fiber-rich leafy green – just one cup may provide you with 4.32 grams of the said nutrient.
9. Brussels sprouts — One cup of boiled Brussels sprouts can deliver around 4.1 grams of fiber.
10. Flaxseeds — These seeds have an impressive fiber content, with 2 tablespoons having roughly 3.82 grams of fiber.
You can also count on these high-fiber fruits and vegetables to deliver some amounts of this nutrient:
- Berries like strawberries, elderberries,cranberries and loganberries
- Stewed prunes
- Dried figs or dates
- Apples with the skin intact
- Sweet potatoes
- Green beans
- Chicory root
- Fennel bulb
- Savoy cabbage
- Turnip greens, beet greens and mustard greens
- Summer and winter squash
- Swiss chard
- Chili peppers
- Bell peppers
- Bok choy
Other fiber-rich foods include burdock root, tempeh, seaweed, couscous, cinnamon, cloves, hemp and chia seeds, and nuts like almonds, pistachios and walnuts.23 When buying fiber-rich fruits and vegetables, pick those that are fresh, organically grown and GMO-free, so you may be able to reap other nutrients and benefits these foods have to offer and avoid side effects linked to substances like pesticides and herbicides sprayed on conventionally grown crops.
Organic whole psyllium husk is also a good fiber source. When it interacts with water in your body, it swells and develops into a gelatin-like mass that helps move waste throughout the intestinal tract.24,25 However, since some psyllium crops are sprayed with the mentioned substances, it's best to purchase this fiber source organic, so you can avoid health risks.
Lastly, when eating fiber-rich fruits, do so in moderation because these may contain a type of sugar called fructose, which can negatively impact your health when consumed in excess.
Some foods have been promoted to be a notable fiber source, when in reality, they actually contain low amounts of this nutrient. As much as possible, limit or entirely avoid your consumption of these low-fiber foods:26
- White bread without nuts and seeds
- White rice, plain white pasta and crackers
- Refined hot cereals or cold cereals with less than a gram of fiber per serving
- Pancakes or waffles made from white refined flour
- Fruit and vegetable juice with little or no pulp
- Fruit-flavored drinks and flavored waters
Meanwhile, there are foods that are low in fiber, but provide other exceptional nutrients. These include grass fed meat, free range poultry, raw dairy, eggs and wild-caught seafood. Take note of these nutrient-rich but low-fiber fruits and vegetables too:27
|Low-Fiber Fruits||Low-Fiber Vegetables|
|Honeydew melon||String beans|
|Papaya (if ripe)||Acorn squash without seeds|
These low-fiber foods contain other vitamins, minerals and antioxidants that your body may benefit from, so make sure to still add them to your meals. Eating various fruits and vegetables greatly helps with balancing the amount of various nutrients (fiber included) in the body.
Believe it or not, there may be negative impacts linked to consuming too much fiber. Some side effects can occur if you increase your fiber intake very quickly, namely:
- Abdominal pain
- Loose stools or diarrhea
- Temporary weight gain
- Intestinal blockage in people with Crohn's disease
- Reduced blood sugar levels
If you or someone you know experiences nausea, vomiting, high-temperature fever or a complete inability to pass gas or stool after consuming fiber-rich foods or fiber supplements, contact a doctor immediately.28
Fiber supplements may sometimes be recommended to help you add more fiber to your system. However, if you're consuming a well-balanced, fiber-rich diet, then there may be little need for you to rely on these supplements. In fact, fiber supplements shouldn't be considered alternatives to high-fiber foods.
Ideally, before taking fiber supplements, talk to your doctor first. If you have been given the go signal, drink at least 8 ounces of high-quality filtered water alongside the supplements. Generally, you can take these on a full or empty stomach. Don't forget to drink more water during the day to prevent constipation, and avoid taking supplements before bedtime.
For people who were prescribed medicines because of certain conditions, it's recommended that you take these at least an hour before taking fiber supplements, or between two to four hours after taking a fiber supplement.29 Fiber pills like psyllium husk supplements should be avoided altogether by people taking these medicines because of possible side effects:30,31
• Tricyclic antidepressants
• Cholesterol-lowering medicines called bile acid sequestrants
• Diabetes medications
Unless you consume more fiber than what your body actually needs, a high-fiber diet can be a win-win situation because of its well-researched links towards health improvement and against certain diseases. Purchasing fruits and vegetables high in fiber is a simple but potent way to improve your health at a fraction of the cost, without burning a hole in your pocket. Take note of the strategies above and strive to meet your recommended daily intake of fiber, before it's too late.