What is soluble fiber?
Soluble fiber is plant material your body can't digest. It is a carbohydrate component. Vegetables and grains have both soluble and insoluble fiber. Soluble fiber dissolves in water. It forms a gel-like material. It is prebiotic since it enhances the growth of beneficial bacteria.
Types of soluble fibers in this article include both dietary fiber and functional fiber. Dietary fiber is a fiber that is found intact in plants; it has carbohydrates and lignins. Functional fibers are isolated or synthesized from the plants; these are only carbohydrates. This type of fiber is used in the different studies of the benefits of fiber and is eaten as supplements. (Source)
Tap here to get a list of high soluble fiber foods.
| Non-Starch Polysaccharides | Isolated fibers |
|---|---|
| HEMICELLULOSES | Xylans Mannans Galactans Glucans |
| GUMS | Agar Carrageenan Psyllium Guar Gum |
| FRUCTANS | Inulin |
| PECTINS | |
| B-GLUCANS |
Lignan
Lignan should not be mixed with lignin. Lignin is insoluble fiber. Some do not classify Lignans as soluble fiber, but some do since they are fiber-associated compounds. Lignans are building blocks to lignins, but they are converted to enterodiol and enterolactone when the lignans ferment. These are phytoestrogens.
Phytoestrogens are plant compounds that can somewhat mimic our body's own estrogen. But they bind to different estrogen receptors than our own hormones. Another type of phytoestrogen is isoflavones(in legumes). Phytoestrogens have been shown to have many health benefits, like reducing breast cancer risk, increasing bone density, and reducing prostate and colorectal cancers.
Lignan is found in the highest amounts in flax seeds, sesame seeds, and cashews. Also, outer layers of cereal have lignan. Triticale(a hybrid of wheat and rye) wheat, rye, oats, corn, rice, buckwheat, and barley are highest in lignans in whole grains.
Of beans and legumes, lentil, soybean, kidney, and navy bean have the most lignan. In vegetables, broccoli, kale, Brussel sprouts, cabbages, cauliflower, peppers, and carrots win the game. Fruits and berries high in lignan content are pears, grapefruit, apricot, peaches, kiwi, melon, strawberries, grapes, and cloudberries. (Source)
Lignans are maybe most known for the link of reduced breast cancer risk. Lignans are a class of phytoestrogens that contain enterolactone and enterodiol. Since breast cancer patients have lower levers of enterolactone, the consumption of this has been believed to have an anticarcinogenic effect. Flaxseed meal is very high in enterolactone.
Inulin
Inulin is a type of fructan. A source of inulin is chicory root fiber. This might be more familiar to you. Chicory root contains a large amount of inulin. Chicory root is widely sold as a fiber supplement in powder format. Chicory root was also used as a coffee alternative in history.
Inulin is low in calories, so it is a common food additive. Inulin comes in different forms, as a short-chain and long chain. Fructooligosaccharides, a type of short-chain inulin, are used as a flavor enhancer and to give texture. They have a slightly sweet taste. Long-chain inulin is used to improve fatty foods' taste since this type of inulin has a creamy mouthfeel.
Inulin sources are jerusalem artichokes, garlic, leeks, onions, hickory, soy, barley, flax, oat, and wheat.
- Lowers triglyceride levels. Dosage is 10-14 grams.
- Helps with constipation. Dosage of 20-40 grams a day is used for a limited period of time.
- Can help with weight loss
- It can help to lower cholesterol somewhat
- Blood sugar stabilizer
- Stimulates the growth of beneficial bacteria like bifidobacteria.
Inulin has also been studied in connection with a gluten-free diet and calcium absorption. It can help the calcium to absorb better from fortified products.
Some people get discomfort, gas and cramps from inulin, especially those with IBS.
Glucomannan
Glucomannan is hemicellulose. Glucomannan is a highly viscous fiber. It is more known as Konjac. It is derived from the konjac plant, also known as elephant yam. This plant is grown in many Asian countries.
Konjac is widely used in Japan, especially in dessert jellies. Nowadays, glucomannan is popularly used as a pill to aid weight loss. 1-2 tablets are taken with water 30 minutes before a meal. The fiber reduces appetite and promotes feelings of fullness. The fiber expands a lot in water. Often 2-4 grams a day are recommended dosage for weight loss.
Konjac is also made into pasta and noodles, mostly used by people who want to lose weight since they barely have any calories. Noodles are often called shirataki noodles. The noodles are used in soups, woks, and all common recipes where you would use normal pasta or noodles. The consistency is a little different, some describe it as just a bit slimy and very tasteless, so good condiments and spices are needed.
Konjac can also be added to a smoothie and used as a gelatin replacement for vegans. Also, the konjac sponge used in facial care is made of the konjac plant.
Konjac should not be consumed in too large quantities since it can cause bloating, gas, and other problems. Glucomannan pills also have a choking hazard and should be taken with a large glass of water. If you want to use glucomannan for weight loss, start with a small amount and let your digestive tract become used to it first; otherwise, you might get tummy cramps the first days.
Glucomannan is not only good for weight loss. It is a prebiotic that ferments and produces probiotics like other soluble fibers also. Especially lactobacilli and bifidobacteria can increase eating glucomannan.
Glucomannan is beneficial for:
- For people who have type 2 diabetes, it can balance glucose levels.
- High cholesterol levels. It has also been shown to decrease LDL cholesterol.
- Constipation.
Arabinoxylan
Arabinoxylan is also a hemicellulose. Arabinoxylan is a major component of fiber in cereal grains. It is found in the outer shell of grains. The highest content is in rye. Arabinoxylan is not widely used in the food industry as an additive. It is best to consume in natural form but it is also sold as supplements.
Some supplements are derived from wheat, although quite rare, most made from rice bran, but if you choose to use this as supplement and are gluten intolerant, make sure to read the package list carefully.
Arabinoxylan supplements are used for:
- To improve glucose and insulin responses.
- Constipation
- To treat dysbiosis, a "bad" gut microbiome.
- Improve treatment outcomes and as complementary immune therapy in cancer treatment.
Beta-Glucan
Beta Glucan is one of the most known fiber types since it has many health benefits.
Beta-glucan is found in wholegrain like oats and barley, mushrooms, seaweed, and algae. Beta-glucans are used in the food industry as a food additive.
To get health benefits, it is good to consume 3-10 grams of beta-glucan a day. Beta-glucan effectively lowers cholesterol. When it is used for this purpose, at least 3 grams is recommended. This amount can reduce LDL cholesterol levels by 5-10%.
Did you know that beta-glucan can also be given by IV as an intravenous treatment? IV treatment can be used before or after surgery to help prevent infections. The IV treatment can also be used to boost the immune system.
Beta glucans are also used in the treatment or prevention of:
- Diabetes
- Weight loss
- High blood pressure
- IBS, irritable bowel syndrome.
- Cancer, as IV treatment to prolong lice expectancy.
- HIV/AIDS. IV treatment.
- Immune system booster
- Colds
- Allergies, especially to ragweed. Treated with yeast beta-glucans.
- Asthma
- Ulcerative colitis
- Crohn´s disease
- Rheumatoid athritis
- Multiple schlerosis
- Dermatitis and eczema
- Burns and wounds
There are no conclusive data to show if beta-glucans are an effective treatment in these conditions.
Side effects of beta-glucan, when eaten as a supplement, can be digestive issues. If applied as a skin treatment, some can get skin rashes. As IV or injection to the muscle, more side effects appear. Beta-glucans can also have interactions with medicines, especially with immunosuppressants and antihypertensive drugs.
Pectin
Pectin is a sugar acid and is mainly found in fruits and berries. Also, vegetables, legumes, and beets have some amounts of pectin. Apples, pears, plums, peaches, apricots, and citrus fruits have much pectin and soft berries, a bit less.
Pectin is most known because it is used in making jellies and marmalades. Pectin gives the right consistency to those and forms a gel-like substance, like gelatine. You can make pectin yourself by cooking apples or citrus fruits and then straining them through a cheesecloth. Pectin content is high in the skins, so you only need to cook the skins if you make your own.
Commercially sold pectin is made from citrus fruits. Pectin is used in the food industry quite widely. It is found in medicines, laxatives, sweets, juices, and even milk drinks. One popular brand that produces vegan yogurts is Alpro; the Alpro go on greek style yogurt has pectin; this gives a very firm consistency.
Pectin is not only good for cooking. It can be bought as a fiber supplement as capsules or powder. Pectin is used for constipation and diarrhea. For diarrhea, the dose is usually 10-20 grams a day.
Pectin also improves glucose tolerance. Studies on rats lowered their cholesterol levels when they consumed pectin. Pectin probably lowers cholesterol in humans, but more studies would be needed since the type of pectin can affect this. Grapefruit pectin supplement decreased plasma cholesterol by 7,6% even without lifestyle changes. Also, pectin, like glucomannan, can act as an appetite reducer.
Guar gum
There are different types of gums, but guar gum is a quite known soluble fiber type. Other hums are, for example, tara gum and locust bean gum.
Guar gum is made from guar beans; it is in the endosperm of the bean. Guar gum is also known as guaran. The Guar plant has been grown in India and Pakistan as a vegetable. Nowadays, it is also grown in the US since it began to used widely by industries in the second world war.
It is used as a food additive in processed foods. Guar gum is also used in other industries and is found in cosmetics, textiles, and paper products.
As a health product it is used to:
Psyllium
Psyllium is also known as Ispaghula husk or Isbaghol. Psyllium is used for constipation and is sold with brand names; Metamucil, Fiberall, Perdiem fiber, Fybogel.
Other conditions psyllium can be used for:
- High cholesterol
- can be used to replace half of the cholesterol medicine and still get the same cholesterol-lowering results.
- To decrease cardiovascular risk factors.
- To decrease glucose absorption.
- In weight management
- some other soluble fibers are though a bit more efficient.
Often psyllium husk is taken as a powder mixed in a drink or sprinkled on porridge or smoothie bowl. Psyllium can also be bought as capsules and should be taken with plenty of water.
Psyllium is often used in baking. Psyllium can be used as an egg replacement. Psyllium is especially used in gluten-free baking. It works a bit like gluten and makes the dough formable. It also retains moisture and makes breads more moist and not crumbly. Psyllium is also commonly used in Keto baking.
Carrageenan
Carrageenan is obtained from red seaweeds around the coasts of North Atlantic, South America, and the Far East. There are different species and different carrageenan extracts.
Carrageenan is widely used as a thickener, stabilizer, and texturizer in foods. I find carrageenan in almost all milk products and vegan milk products, especially in heavy cream and plant-based creams, yogurts, and puddings.
There is much debate around if carrageenan is safe to consume or healthy. Some say it causes inflammation in the body and is toxic to the digestive tract. It might be the culprit for IBS, colitis, and even colon cancer. (Source)
So why is it used? It acts as a good substitute for fat since it has a somewhat fatty mouthfeel and is an excellent stabilizer. Especially many vegan processed foods have carrageenan; vegan cheeses, puddings, plant-based milk and creams, ice creams, and even some baby formulas(some countries have banned the use in baby formulas)
Carrageenan causes stomach problems to many people, so check the labels in your food and try not to eat processed foods.
Health benefits of soluble fiber
Soluble fibers form a gel-like substance; this delays sugar absorption after meals leading to regulated blood glucose levels. These soluble fibers also ferment, and short-chain fatty acids are produced. Short-chain fatty acids have anti-inflammatory, antitumorigenic, and antimicrobial effects. They have a significant role in protecting us from different diseases, especially inflammatory ones.
Since we want to have a "big production" of short-chain fatty acids, it is important to eat a high fiber diet. Fiber is best consumed in its natural form from whole foods; this way, you also get other phytonutrients and minerals with health benefits. A plant-based diet is perfect for optimal health since it is naturally high in fiber.
Other recommended articles about fiber in fiberfoodfactory:
- What foods are highest in fiber?
- Different types of fiber in foods. This list includes both soluble and insoluble fiber types.
- 45 high soluble fiber foods
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