The Best Soluble Fiber Supplement – According to a Dietitian 

In this article we will be telling you what the best soluble fiber supplement is for you and why.

You may be looking for a soluble fiber supplement to boost your overall intake or to improve a specific digestive symptom.

It can be particularly challenging to meet the recommended target of 30g of fiber per day if you have IBS. This is because foods which contain high amounts of fiber may also contain IBS triggers. 

There are many soluble fiber supplements which are suitable and they can help relieve symptoms, including constipation and diarrhoea.

The Best Soluble Fiber Supplements

This section will discuss the best soluble fiber supplements available to help you meet your daily fiber target.

We will discuss the properties of these soluble fiber supplements and how to take them.

Psyllium Husk

Psyllium husk, in our opinion, is the best soluble fiber supplement. 

It is derived from the seed husks of the Plantago ovata plant and is an excellent source of soluble fiber. 

Psyllium husk can draw in and hold large amounts of water, adding mass to your stool which is soft. This can modify the speed of your gut motility, by making it slow down if too fast, or speed up if too slow.

Due to the actions described, psyllium husk can help manage both constipation and diarrhoea. Psyllium has also been found to improve general IBS symptoms (1).

Psyllium husk is also ‘non-fermentable’, meaning that our gut bacteria do not break it down to produce gas and cause bloating. Being non-fermetnablemakes psyllium a well-tolerated soluble fiber supplement in IBS.

Research suggests that 10g of psyllium husk per day over at least four weeks may be optimal for managing constipation (2). The amount you need as an individual may vary. 

You start by initially trying approximately one tablespoon per day in week one. You can gradually increase to 3 tablespoons per day over the course of 3 weeks.  

Psyllium husk is commonly available in powder or capsule form. But we recommend the powder form as the capsules only contain 0.5g each so you would need to take a lot to reach your target.

You can also buy products such as Fybogel and Metamucil, which contain psyllium husk. 

You can read more about this in our post “What is Metamucil (Psyllium Husk) and Can it Help With IBS-Diarrhoea?”.

Partially Hydrolyzed Guar Gum (PHGG)

PHGG which is the active ingredient in Sunfiber is made from guar beans. The guar gum is hydrolyzed, breaking down into smaller units. 

Hydrolysing the beans reduces the viscosity and increases the solubility of the fiber. This means it dissolves easily without thickening (3), making it a texture that is much easier to tolerate when taking.

PHGG has shown positive results in improving symptoms, stool consistency and frequency and reducing laxative use in constipation dominant IBS (4).

PHGG is also a prebiotic fiber that has been shown to increase levels of Bifidobacteria, the type of gut bacteria that are low in individuals with IBS (4).

We discuss prebiotics further  in our post What Are Prebiotics and How Do They Work?.

You can buy low FODMAP-certified PHGG products from Regular Girl and Sunfiber.

Acacia Fiber

Acacia fiber, also known as ‘gum Arabic’, is sourced from the sap of the Acacia Senegal tree. It is another soluble fiber supplement that is low in viscosity and is a prebiotic. 

One study found that bowel habit satisfaction and IBS symptoms were improved in participants who took a daily yoghurt containing Bifidobacterium lactis and acacia fiber (5).

However, we do not know if the improvements were due to the probiotic or the acacia fiber.

Acacia fiber is often available in powder form and can be easily mixed into beverages or used as a food ingredient.

Azacen acacia gum powder sachets are certified low FODMAP.

Dietary Soluble Fiber supplements

This section discusses some popular dietary soluble fiber supplements that can be easy to add into your snacks or meals, such as yogurts, soups and salads.

It is important to remember that these also require adequate fluid intake to work well.

Linseeds or Flaxseeds

Linseeds, also known as flaxseeds, are another great soluble fiber supplement.

Positive research shows the benefits of flaxseeds in IBS-C by relieving constipation, abdominal pain and bloating (6).

You can buy either ground or whole linseeds. You can start with half a tablespoon per day for week one and increase this gradually to 1.5 tablespoons per day over three weeks if symptoms do not improve. 

Linseeds are high FODMAP in quantities above 1.5 tablespoons. 

You can sprinkle linseeds onto yogurts, cereals/porridge, or soups and salads.

Chia seeds

One tablespoon of chia seeds contains about 5g of fiber, which is mostly soluble fiber. They are also low FODMAP at a serving size of two tablespoons (7).

Chia seeds are a great source of soluble fiber that can be added to porridge, yogurts and smoothies. 

Alternatively, try a daily chia pudding.

However, if you are constipated, then this is not an ideal soluble fiber supplement. This is because chia seeds are high viscosity, which can worsen constipation.

Is Inulin a Good Soluble Fiber Supplement?

Inulin is a soluble, prebiotic fiber. It is found naturally in many vegetables, such as asparagus, garlic and leeks. Inulin supplements usually contain inulin extracted from chicory.

One study found that 10g of inulin daily improved stool frequency and increased stool softness (8).

However, inulin is high FODMAP and can be poorly tolerated in some people with IBS, resulting in bloating, flatulence and abdominal pain. This is due to its high fructan content.

So it is not recommended that people with IBS use inulin as a fiber supplement.

Top Tip when starting a fiber supplement:

It is important to remember that a soluble fiber supplement can take 2-3 days to work, so you will not see an instant improvement.

We recommend trying a supplement for at least four weeks if you tolerate it well, as the positive effects do not happen overnight. 

You may find some digestive discomfort initially, so we also recommend starting at a low dose and gradually increasing this dose over three weeks. 

It is also important to remember to drink enough water when you increase your fiber intake or start a soluble fiber supplement. If you don’t, this can cause digestive discomfort, including constipation.

Other Dietary Sources of Soluble Fiber

Soluble fiber is naturally found in many foods, including:

• Oats
• Chia seeds
• Kiwi fruit 
• Peas
• Beans

Health Benefits of Soluble Fiber Supplements

As we have discussed, soluble fiber supplements can help improve gut function. They do this by improving stool size and consistency, which improves gut transit time. 

If the fiber you choose is a prebiotic, this will also help modify the gut microbiome and increase the population of positive gut bacteria.

Soluble fiber supplements can also help lower LDL cholesterol (9). Soluble fiber binds to bile acids in the large bowel, preventing their reabsorption into the bloodstream to make cholesterol.

Summary

This post lists some of the best soluble fiber supplements, such as psyllium husk and PHGG.

However, selecting the best soluble fiber supplement for you will depend on your needs and preferences. 

By considering factors such as high soluble fiber content, low caloric value, and ease of use, such as viscosity, you can make an informed decision. 

There are also plenty of foods which also have a high soluble content, such as linseeds and chia seeds. 

Article written by Bethany Willson, Specialist Gastroenterology Dietitian, reviewed by Kirsten Jackson, Consultant Dietitian BSc Hons, RD, PG Cert