I’m not a big believer in supplements.  If I do use them in patients I use them in specific situations like for nutrient deficiencies, and once we are able to correct the deficiency through natural foods, my preference is to cut back or stop the supplement.

However, I can’t ignore the multiple studies that show potential benefits of taking soluble fiber supplements and I’ve seen improvements in parameters like body composition, cholesterol, and digestive health.  So let’s talk a bit about soluble fiber and then summarize 2 of my favorites.

Soluble Fiber Defined

Soluble fiber is the form of fiber that absorbs water (aka water “soluble”) transforming it into a gel-like substance inside your digestive tract that softens stools and helps it move smoothly through your intestines.  That’s why it’s a popular supplement taken for constipation.

Food sources include beans, peas, oats, fruits like berries and apples, and avocados. Soluble fiber also binds cholesterol and sugar, which gives it cholesterol and glucose lowering properties which we’ll discuss in a moment.

Finally, soluble fiber also appears to boost levels of healthy bacteria in the gut which can improve immunity, lower inflammation and improve mood.  Overwhelming recent research shows our gut health is intimately tied to all aspects of our physical and mental health, so this is an added bonus of getting more soluble fiber in the diet.


Psyllium seed husks are a source of soluble dietary fiber found in the popular supplement, Metamucil.  Interestingly they come from the plant, Plantago ovata, which is most abundant in India and other parts of Southern and Western Asian.  Indians know psyllium by the popular name, Isabgol, which usually come in a bright green box or container found in many South Asian households.

Multiple studies show that psyllium supplementation has a number of benefits including improvements in digestive symptoms (diarrhea, constipation, IBS, etc.), lowering of cholesterol and improvements in blood glucose control.

The specific cholesterol lowering effects are on total cholesterol and LDL in particular, while in diabetics it can lower the glycemic (blood glucose-raising) impact of starchy foods.

Although I mentioned the beneficial effects of soluble fiber on healthy bacteria, it appears the results of psyllium supplementation are mixed.  This study suggests psyllium is not adequately fermented by gut bacteria, so it may not be the optimal fiber source for improving gut bacterial population, although it still can improve overall digestive function.

More consistently beneficial effects on gut population have been shown in the next source of fiber I’ll discuss.

Glucomannan (GM)

Let’s now travel from the psyllium capital of South Asia to tropical east Asian countries like Japan and China, where we find the root of the konjac plant (Amorphophallus konjac-aka “elephant yam”), the source of high soluble fiber glucomannan (GM) supplements.

GM acts as a potent soluble fiber sponge that absorbs up to 50 times its weight in water, keeping your stomach full, and making it effective as a weight loss supplement.

This study shows GM improving several biometric parameters such as total and LDL cholesterol, triglycerides, body weight and fasting blood glucose.  Like psyllium, GM can also reduce postprandial (after meal) glucose spikes.

GM also appears to have a more beneficial impact on healthy gut bacteria than psyllium since it is fermented by gut bacteria into healthy short chain fatty acids (SCFAs) as shown in this study.

Aside from the powder or capsule supplement form, shirataki noodles made from konjac plant, are a thin, translucent Japanese noodle that is extremely low in carbohydrates and is found in Asian and many standard grocery stores in the refrigerated section.  Shirataki noodles are now being rebranded as “low carb” noodles, rice and pasta.

To remove the unpleasant smell, be sure to rinse well and “dry fry” in a pan without oil until most of the moisture evaporates.

When and How to Use Soluble Fiber Supplements?

In my practice I still push natural, dietary sources of fiber first.  Having said this, often patients become constipated when they remove excess carbohydrates in the diet, even after increasing their intake of water which is absolutely necessary to allow the fiber to pass through smoothly.  Soluble fiber is a useful adjunct to help get constipated bowels moving again.

In patients with elevated cholesterol, especially high levels of LDL and poor glucose control despite following all my recommendations, soluble fiber can often move numbers in the right direction.  In most cases these improvements are not dramatic.  Dramatic numerical improvements come from making appropriate dietary changes in conjunction with increasing activity levels as I’ve discussed in this blog and extensively throughout my book.

For our patients who are struggling with weight loss and appetite control, soluble fiber supplements, especially GM, can be very effective in helping with weight loss.  Right now we are in the midst of holiday season and in addition to our holiday tips outlined in this post, pre-filling your stomach with a soluble fiber supplement like GM can be effective in curbing your appetite before hitting the holiday buffet at work.

For psyllium husk or GM, we recommend you start with a low dose and go up slowly as tolerated to avoid the abrupt onset of abdominal bloating, gas and cramping.  I also recommend taking the powdered form (over capsules) mixed well in water.  Soluble fiber, especially GM, can expand in your throat and cause choking.  Mixing it into liquidy foods like shakes and smoothies is another option that allows safer intake.

What About High Fiber Foods?

Food manufacturers have leveraged the power of a healthy nutrient like soluble fiber by adding it to processed foods and labeling these “high fiber.”  You may be eating a “high fiber” labeled cereal, bread or bar thinking you’re benefiting but this small amount of fiber does not counteract the sugar, fructose and abundant artificial chemicals in these foods.

Check out the Fiber One multigrain bread below.  Does the 6 grams of fiber make up for all of the other artificial ingredients on the list, many of which have been tied to diabetes, heart disease and cancer in human and/or animal studies?

Wouldn’t it be easier to just eat an apple where you get 4 grams of fiber or a cup of raspberries where you get 8 grams, along with disease-fighting, inflammation-lowering phytonutrients?  You make the choice.