Fiber is a marketing buzzword, loved by advertising teams. However, did you ever ask yourself whether there is any truth to this matter? I mean, if a new version of a product has 10% more fiber – then it has to be good for you, right?
No, this isn’t necessarily the case. Admittedly, many people would benefit from an increased intake of fiber, at least if they’re in the majority who are consuming a diet high in refined carbohydrates and trans and saturated fats, also known as the Standard American diet (SAD).
However, there’s a lot more to be said about this matter.
- First, there are more types of fiber.
- Second, the notoriously claimed health benefits of fiber are more type specific. Foods with different types of fiber also have different effects on our bodies. With that said, it’s important to realize that the amount of health benefits we receive by consuming fiber will depend on its chemical composition and how it looks.
Fiber is a indigestible carbohydrate and complex polymer which can be found in plants, and foods derived from plants. It’s also being used as one of the key arguments for the paleo community. They often state the reduced amount of fiber consumed in modern times, when compared to our pre-agricultural ancestors. This is true, the average consumption of fiber has drastically lowered over the course of the last few thousand years. However, we now know it’s more important to be consuming the right type of fiber, and not just consuming fiber, if we’re doing it for the proposed health benefits.
There are two main components of fiber.
As the name already suggests, this type of fiber gets dissolved in water. Moreover, when we consume soluble fiber it is being continuously fermented and produces certain important byproducts (acetate, propionate, butyrate). These can increase the growth of microorganisms which contribute to the well-being of your gut. It also slows down the speed with which food goes through your intestinal system.
Soluble fiber can be further broken down into viscous or non-viscous fiber. Again, the name is very straightforward; soluble fiber which gets introduced to liquid can form a gel around it. This happens when the outer parts of fiber become physically intertwined with liquids, forming an outter layer of gelatinous/viscous substance. This type of soluble fiber is called viscous soluble fiber, and the other is known as non-viscous soluble fiber.
As you might imagine, this type of fiber doesn’t get dissolved in water. It has two partially separate effects. It can ferment in your large intestine and promote how fast food goes through your intestinal system, or it can start bulking while it travels through your digestive system, absorbing water along the way (in a different way than viscous soluble fiber).
It’s also very important to realize that most types of fiber aren’t exclusively soluble or insoluble, it’s much more common to find fibers which are a mixture of both types of fibers.
Sources of fiber include vegetables, fruits, whole grains, and nuts and seeds, with the recommended daily intake being around 30g per day for either men or women; men are advised a few grams more. The best sources for viscous soluble fiber in particular are asparagus, Brussels sprouts, sweet potatoes, flaxseeds, and turnips.
What gives fiber its desired effects?
Whether fiber will give you the often-touted health benefits depends on its physical attributes, particularly how viscous and how soluble it is. As you will see further down the article, most health benefits will be reaped by people consuming soluble viscous fibers.
There are multiple health benefits associated with fiber which actually have, found in studies, effects.
I’ve said before that cholesterol is not the bad guy per-se and that we should be more worried about oxidized LDL particles found in our blood stream, and not just the umbrella word cholesterol. Soluble viscous fiber has an interesting effect on our bodies, it binds bile acid to itself (because it has viscous properties and bile acid is a liquid), and enables its secretion. This is important because cholesterol particles can be found in bile acid. Therefore, higher amounts of secreted bile acids result in lower LDL particle levels.
As stated above, raising the amount of soluble viscous fiber which is being eaten will cut cholesterol levels. 
Psyllium, one of the most extensively studied fiber types, has been reported to cut LDL particle levels from 6% to 20%, when the average daily intake is from 7 to 15g per day. However, it doesn’t affect HDL or triglyceride concentrations. 
Soluble viscous fiber has an amazing effect on our glycemic control, and there’s more than one possible way how adding more fiber to our diet will help us. The GI of foods which we eat becomes lower, glucose gets absorbed slower, and our bodily hormones respond better to nutrients from food. Another particularly interesting fact is that fiber consumption stimulates GLP-1, a peptide which has important implications in decreased food intake and improved insulin sensitivity and production. 
There is a warning, however, greater benefits will be reaped by those who start increasing their fiber intake from a worse diet. What I mean by that is, if you’re already eating very healthy and are consuming almost the daily recommended amount of fiber, you can expect less benefits when compared to someone whose diet can be characterized by large amounts of trans fats and lower fiber intake.
Fiber is also best taken before a meal, 5-10 grams a few times a day. Studies, where this principle was used, reported the best results.
People who start eating more soluble viscous fiber report reduced feelings of hunger. Furthermore, this type of fiber has an important effect on the glucose and insulin response following a meal, affecting it positively. 
However, healthy people aren’t the only ones who can benefit from this. People with type 2 diabetes benefit from soluble viscous fiber through an improved glycemic control as well. 
The effect, which will probably be of most interest to people, is its ability to regulate weight. A growing body of evidence shows that regular viscous soluble fiber consumption creates a sense of fullness for longer and faster, and it can delay gastric emptying. With that said, it’s not particularly surprising that high-fiber diets are associated with an increased weight loss, compared to a diet where a high-fiber intake was actually a placebo treatment. 
That was it. Adding more fiber in your diet, especially the viscous soluble type, is a smart move. It will improve key aspects of your health without a doubt. However, it’s important to stay aware that there are different types of fiber and not all are created equal. Furthermore, choosing dietary sources of fiber from foods is always better than supplements with only an isolated nutrient. Healthy nutrition is the culmination of a vast array of balanced nutrients, acting synergistically.