Simply put, fiber is a type of carbohydrate.  And what exactly is a carb?  A carbohydrate is a group of organic compounds which contain a 2:1 ratio of hydrogen:oxygen, just like water (H20).   The two main types of carbohydrates are complex (starches and fiber) and simple (sugars).  


Fiber is a key nutrient that keeps our blood sugar stable and our appetite in control by regulating the way our body processes sugar.   It is unique as it cannot be broken down into sugar molecules like other carbohydrates can.  Instead, fiber remains undigested as it passes through our digestive tract.  Even though we do not metabolize fiber, it still offers us many benefits.   For instance, fiber takes up space in our stomach which makes us feel fuller for longer.  This helps us maintain a healthy weight, because it prevents us from overeating.  Which by the way is one of the secrets to longevity!  Take it from the Okinawans who have some of the highest life expectancy in the world.  When it comes to eating, they embrace the “Hara hachi bu” style – which means “Eat until you’re 80% full.”    



  • cannot dissolve in water, instead it absorbs water
  • moves food through your digestive system 
  • often referred to as “bulky” fiber
  • promotes regularity
  • gives you a sense of satiety 
  • cleanses your GI tract 
  • lowers the risk of colon cancer 
  • Slowly (if at all) fermented by our gut microbiota


  • dissolves in water
  • once dissolved becomes gel-like and absorbs sugar and fat from other foods
  • slowly releases these sugars and fats throughout the day to give us energy 
  • helps stabilize blood sugar 
  • aids in lowering blood cholesterol
  • easily fermented by our gut microbiota, in essence it feeds our good bacteria
  • makes short-chain fatty acids which provide nourishment to our colon wall.   

Clearly,  both soluble and insoluble fiber are vital to our health. Within these two broad categories of fiber, there are actually seven types of fiber that are worthy of mention which I will delve into at the end of this post.  First I want to be sure to provide you with a list of high fiber foods. 

Like any shifts in your diet, when increasing the amount of dietary fiber be sure to start slow and gradually increase.

How much fiber should we eat daily? 

In the past century, the amount of fiber we eat has decreased by about 90%!   In fact, most Americans are only getting about 15g of fiber per day when really we should be aiming for closer to 38g (males) and 25g (females)each day.  Although these numbers vary slightly depending on your age and gender.  See these tables below for the current fiber RDI.   I would be remiss in my health coaching duties if I didn’t remind you that too much of a good thing is not always good.   Aim to stick close to the RDI, too much fiber can create bloating and stomach upset.   Not to mention diarrhea which would leave you deplete of minerals and nutrients.   


ADULTS (<50yo)ADULTS (50yo +)


1-3 yo19g
4-8 yo25g
9-13 yo26g (f), 31g (m)
14-18 yo26g (f), 38g (m)


Ideally we are getting both our soluble and insoluble fiber from our foods rather than supplements because whole, natural food is best for our body and our gut bacteria.  High fiber foods contain key health promoting nutrients that supplements do not.  While fiber supplements such as psyllium and wheat dextrin can contribute to your daily intake, it is important to first discuss the idea with your primary care physician.  There is no evidence that usage of fiber supplements is harmful, however they can in some cases cause intestinal upset and interact with certain prescription medications.  Because fiber slows down digestion, it may decrease the rate at which some drugs are absorbed. So again, have a conversation with your doctor if you are considering supplements

Personally, I aim to get my fiber through food but on the rare occasion my digestion feels like it needs a little oomph I resort to psyllium. Like any supplement, it is crucial to find a  quality, vetted brand. Organic India is my favorite.    You can take psyllium in the morning or night, I prefer to take it before bedtime.  PLEASE NOTE YOU MUST TAKE  PSYLLIUM WITH WATER.  Because it absorbs water so quickly, it needs to be taken with a full glass of water to reduce the choking hazard.   I find a little goes a long way and only take ½ a TB in 1 cup of water, which is ½ the recommended serving size. Some of my clients feel the same way, but others use a full TB.  I’m an advocate of always starting with the lower dose to see if you can achieve your results.   You can always go up from there if need be.  

OK.. last but not least… here are the 7 forms of fiber mentioned earlier!   

  1. Lectin is a natural fiber found in the cell walls of plants.  It falls under the soluble category and is a key player in the game of blood sugar control.  By stalling glucose absorption, it dampens the glycemic response of the foods we ingest.  Say see ya to blood sugar spikes!  Our gut bacteria can easily ferment pectin and it has been shown to lower LDL (the “bad” cholesterol).    FOOD SOURCES WITH THE HIGHEST AMOUNT: Citrus fruits: Pears, apples, guavas, quince, plums, gooseberries, and oranges 
  2. Like pectin, lignin is abundant in the cell wall of plants however it is not a soluble, but rather an insoluble, fiber.  As mentioned earlier this means that instead of dissolving in water, lignin will actually absorb water.   No wonder it helps keep us regular!   While insoluble fiber speeds things along in the GI tract, it decreases the amount of time cancer causing agents can spend interacting with our tissue.  Researchers believe this to be the reason it is considered protective against colon cancer.   FOODS HIGH IN LIGNINS: Root veggies, Fruits with edible seeds (tomatoes, strawberries, avocados), Green beans, Flaxseed 
  3. Cellulose is another insoluble fiber that helps comprise the cell walls of plants.  Since your body cannot digest it, cellulose will latch on to other food pieces you have ingested and help move them along your digestive tract.  Again, promoting regularity and keep your GI tract clean.  FOOD SOURCES HIGHEST IN CELLULOSE: Legumes (peas, beans, lentils); cruciferous veggies (broccoli, cauliflower, cabbage, kale, bok choy, arugula, Brussels sprouts, collards, watercress and radishes); bran and nuts 
  4. Inulin is a soluble fiber, so we know it helps control blood sugar spikes. What’s neat is that it is also a prebiotic that can be used as food for the beneficial microflora that live in our large intestine. Better yet, inulin has been shown to create an environment in the colon that prevents the growth of harmful bacteria such as e. Coli.  One thing to keep in mind is that because this fiber is so easily fermented by our gut bacteria, if it is consumed too quickly or in very large amounts it might cause GI discomfort.  Our ancestors ate tons of roots and tubers where inulin concentration is quite high, in fact they consumed up to 15-20g!  Today, the average american consumes closer to 2g of inulin per day.    One of my favorite ways to ensure a safe amount of inulin in my diet is to drink teecino, a delicious coffee substitute made from chicory root.   Having experienced a lot of anxiety in my life, teecino has also been a saving grace while cutting down my caffeine intake.  Other foods high in inulin are: burdock root, dandelion root, asparagus, garlic and leeks
  5. Another soluble fiber that is considered a prebiotic for our gut bacteria is beta glucan.  Like most soluble fibers it helps control spikes in our blood sugar and increases satiety.  It is also closely linked to heart health and improving serum cholesterol levels.  Because of its powerful effect on our immune system, beta glucan is becoming a hot item in many research studies.  While many people promote beta glucan supplements, there are many yummy foods that will give you plenty of this soluble fiber.   FOODS HIGHEST IN BETA GLUCAN:  nutritional yeast, oats, barley, shiitake mushrooms, reishi mushrooms, seaweed and algae. 
  6. Depending on where it is along its journey through our digestive tract, resistant starch is similar to both soluble and insoluble fibers.  Most starches are rapidly broken down into glucose in our small intestine.  “Resistant” starch, however, resists digestion until it reaches the colon, just like insoluble fiber.  Then, like soluble fiber, it is fermented by the good microbiota that live in the colon. Needless to say, resistant starch helps to protect the GI tract from harmful bacteria, control blood sugar, maintain a healthy weight and regulate digestion.  Not to mention, it is one of the best sources of short chain fatty acids which, again, help to maintain the health of colonic cells.  FOODS HIGHEST IN RESISTANT STARCH: oats, brown rice, green bananas, legumes (esp fava beans!) 
  7. Psyllium is a soluble fiber and is what is found in most fiber supplements, such as metamucil.  In fact because psyllium comes from the husks of the Plantago ovata plant’s seeds it is only available in supplement form.  Like all soluble fibers, psyllium binds with water in the gut to create a gel-like substance which grabs on to sugars and inhibits reabsorption of cholesterol in the GI tract.  Because it absorbs so much water from the intestines, psyllium is referred to as a ‘bulk forming laxative’ as it adds bulk to the stool, making it easier to pass.  With its lubricating and absorptive properties, you can think of this fiber as a gentle internal scrub brush for the colon.   Lastly, psyllium is a prebiotic, once again meaning it acts as food for that ‘good’ gut bacteria.  Again, here is my favorite brand: 

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