[Last updated 23rd March, 2017]
A high fiber diet is thought to be very beneficial for health.
Increasing your intake is thought to protect against a wide variety of diseases and conditions, particularly for heart and digestive health (1).
Unfortunately, the average Western diet is seriously low in fiber.
This article summarises the best fiber supplement available to you, based on current research.
We Don’t Consume Enough Fiber
Fiber is a type of indigestible carbohydrate in plant food.
The Institute of Medicine recommends men and women consume 38 grams and 25 grams of fiber each day, respectively.
But in reality the average adult is only having 15-18 grams per day (2).
This is largely due to the amount of processed and packaged foods in the Western diet, which contain little to no fiber in the end product.
Summary:The average adult only consumes about half of the recommended fiber intake.
Conditions Influenced By Fiber Intake
Fiber intake is not just crucial for digestion, but for health overall.
Increasing our intake can prevent and improve a wide variety of medical conditions, as well as improve general health.
These conditions include, but are not limited to:
- Type 2 diabetes (3)
- Weight gain and obesity (4)
- Diverticulitis (5)
- Food intolerance and/or Irritable Bowel Syndrome (IBS) (6)
- Coronary Heart Disease (7)
- Colorectal Cancer (8)
- Bloating and constipation (6, 9)
- Chronic diarrhea.
Summary: Fiber intake appears to influence numerous aspects of health, from digestive to metabolic.
The Different Types of Fiber Supplements
There is a wide variety of fiber supplement types.
The main difference between them is soluble vs insoluble, as well as if they hold water, gel within the gut, and absorb bile.
Insoluble fibers are though to assist with digestive issues. They may also help you feel full for longer, but they don’t have any metabolic health effects.
Here is a summary of the main types you need to know:
Psyllium is produced from the seeds and husks of the plant.
The husk is approximately 70% soluble fiber while the seeds are almost entirely insoluble fiber.
Most psyllium supplements only contain the husks, so psyllium typically does mean psyllium husk. If you want more insoluble fiber then choose psyllium that includes the seeds.
Psyllium has been shown in clinical trials to reduce abdominal pain associated with IBS, as well as reduce risk factors for several metabolic diseases including heart disease and type 2 diabetes (10, 11, 12, 13).
It’s also thought to help bulk up stool for bowel regularity, and appears to help keep you feeling full for longer.
Just be aware that many psyllium products contain additives such as sugar.
Inulin is a fiber common in a wide variety of fruits and vegetables.
Supplement forms are often sourced from chicory root, and are usually 100% soluble fiber.
It may also be beneficial for those with diabetes, improving blood sugar and liver function (16).
Wheat dextrin is produced as a by-product of the processing of wheat.
It has trace amounts of gluten, however those with celiac disease do not typically experience a reaction.
Wheat dextrin is 100% soluble fiber , which makes it a great choice for those who need to improve metabolic health.
It’s often used in cooking as it has a desirable consistency and dissolves well in water.
Methylcellulose is the most popular non-fermentable fiber; this means that it’s unlikely to cause digestive distress.
Methylcellulose supplements are usually 100% soluble fiber and don’t cause digestive distress. However, it’s unlikely to solve existing digestive issues like constipation or diarrhea.
Like psyllium, methylcellulose forms a gel within the digestive tract which helps bulk up stool and help you feel satiated.
It only dissolves in cool water; hot water will result in little to no absorption.
Calcium polycarbophil is a prescription synthetic laxative drug and fecal stabiliser.
It’s 100% insoluble fiber and designed for those suffering from constipation, or diarrhea, or those intolerant to other fiber supplements.
Unlike most insoluble fibers it does hold water quite well, gels in the gut, and is an effective way to bulk up your bowel movements.
Calcium polycarbophil was shown to be very effective at improving abdominal symptoms in IBS patients, at least in one study (19).
Summary: The main difference between different fiber supplements is the ratio of soluble to insoluble fibers, as well as how they interact with the gut.
What Is The Best Fiber Supplement?
The best fiber supplement overall is psyllium fiber, ideally containing a mix of husks and seeds.
This is based on weight of scientific evidence, longest history of use, and ability to help the widest variety of symptoms.
Psyllium contains a unique blend of both soluble and insoluble fiber, whereas most other fiber supplements usually contain either one or the other.
Interestingly psyllium may improve both diarrhea and constipation associated with IBS.
Researchers believe that soluble fiber helps to make stools a soft yet thick consistency. This helps stools firm up considerably during diarrhea, yet move along during constipation. So the consistency is kept at a happy-medium, so to speak.
In a clinical trial of IBS patients, 10 grams (about 2 teaspoons) of psyllium daily reduced perceived abdominal pain by 90 points, compared to just 58 points in the bran group and 49 points for placebo (fake pill) (15).
Proportion of patients with strong relief of symptoms each week. You can see the psyllium group (blue line) did far better than bran or placebo. Click to enlarge.
Anecdotal feedback from IBS patients are mixed for psyllium, and I suspect it depends on an individual’s FODMAP intolerance. But otherwise it’s the only fiber supplement recommended for it at this stage.
I recommend this psyllium supplement, which is available on Amazon (aff link).
If you are hyper-sensitive to psyllium, then a non- fermentable fiber supplement is a better option, such as Methylcellulose.
Summary: Psyllium (a mix of husks and seeds) is the best fiber supplement type due to its unique blend of soluble and insoluble fiber. It is the best choice for IBS sufferers at this stage.
Recommended Dosage & Important Tips
Metamucil (a branded psyllium supplement) recommends adults with digestive stress take 1 heaped teaspoon up to 3 times daily.
That can be high for those who with sensitive guts, so I recommend starting with taking just 5 grams (1 teaspoon) once per day .
This can be increased based on your response, with single doses up to 30 grams (6 teaspoons) usually tolerated.
Always consume psyllium with at least 200ml of water; higher doses require up to 500ml. Do not ingest the dry powder or you could choke.
Mineral supplements should not be taken alongside psyllium as it can interfere with their absorption. Always speak with your doctor before starting any new supplement.
Summary: The standard dose is 5 grams, three times per day. The dose can be bumped up considerably depending on your tolerance and response.
Are Supplements or Whole-Food Sources Better?
Very rarely is a supplement better than its whole-food counterpart.
Fiber is no exception to this rule.
This is because high fiber foods also contain other important nutrients, rather than just fiber in isolation. So where possible you should always choose whole, real foods first.
Great food sources of fiber include but are not limited to:
- Split Peas
- Leafy greens
- Brussel sprouts
Aside from increasing your vegetable intake, switching out certain carbohydrate foods for their whole grain counterparts is also a good place to start.
Brown rice vs white rice, steel-cut oats vs fast cook oats, and whole grain rye vs white bread are all direct switches that increase fiber intake.