Let's talk fiber. Do we really need as much as doctors claim? If so, how much? Can we get too much? Will it prevent cancer? Are grass-fed steak and whole eggs good sources of fiber? How the heck do I get rid of this constipation?

This is just a sampling of the many questions I get regarding dietary fiber.

What is Dietary Fiber?

Fiber is a complex carbohydrate made up of non-starch polysaccharides, resistant starches, and/or cellulose. In simple terms, when you hear fiber, think plants, namely veggies, fruits, and whole grains. Just as we have cells that give our body structure, so do plants. (Don't eat humans, though. They don't provide fiber.) These plant cells can hold nutrients, water, and other things. There are essentially two kinds of fiber. Each is unique, and possesses specific beneficial qualities.

This type is very resistant to breakdown by the digestive enzymes in your mouth, stomach, and small intestine. Gums, pectins, and inulin are in this category.

  • Gums stabilize food, giving it more of a shelf life. They also add texture to food. Probably most importantly, they slow down the absorption of glucose.
  • Pectins are a little different in structure than gums. They're more acidic, aiding in the absorption of certain minerals like zinc. Similar to gums, they also lower blood sugar levels. Probably the most well known source of pectin is apples. They're the source for many commercial pectin formulations.
  • Inulin is a FOS, or fructooligosaccharide. If you read my article on digestion you'd know that inulin is a pre-biotic that feeds the good bacteria in your stomach. When I noticed this was in Metabolic Drive® Protein, I did cartwheels (figuratively, of course). When you see foods containing FOS in the chart below, take note.

You'll generally find soluble fiber in fruits, beans, barley, oats, and some other sources. It does get digested – sort of – but not until it hits the large intestine, where good bacteria ferment it, producing butyric acid (found in butter) and acetic acid (found in vinegar). This helps the digestive system maintain its acidity.

Some soluble fibers provide a bit of energy, about two calories per gram; likely not enough to get you through a particularly harsh drop-set on the leg press. Others such as gums are non-caloric.

So what are the key benefits to soluble fiber? There are three that warrant attention.

1 Stabilizes blood sugar.

Soluble fiber slows down transit time (the time it takes for food to enter and leave the body) and encourages a more gradual breakdown of food. Specifically, it slows down the emptying of the stomach and the digestion of starches (and subsequent entry of glucose into the blood stream). Since glucose absorption will be slower, you can avoid the blood sugar ups and downs. I've even heard of people mixing guar gum with water before meals to accomplish this. If you're a diabetic, you should consider this before you opt to skip the veggies. Eating your veggies could mean you'll need less insulin.

2 Lower LDL levels.

When short chain fatty acids are made as a result of the fermentation of soluble fiber, it appears to result in a decrease in LDL levels. Good news for those concerned about cardiovascular disease.

3 Increased defense against cancer.

Fiber can bind with cancer-producing compounds and remove them from the body, rather than letting them hang around to wreak havoc. Also, as fiber is fermented into short chain fats like acetic acid in your intestine, it helps the colon maintain its pathogen-killing acidity.

Flax Seeds

This type of fiber doesn't get digested anywhere. It's essentially lignin, cellulose, or hemicellulose, and you'll typically find it in wheat or veggies. Its job is to simply carry food and water through the digestive system.

Unlike soluble fiber, insoluble fiber doesn't dissolve in water. This means that it swells up like a sponge, and adds bulk to the stool. This makes your feces move faster through your intestines (called intestinal hurry). There are several key benefits to insoluble fiber.

1 Less constipation.

Since insoluble fiber adds bulk to your stool, it aids in elimination, resulting in less constipation. One of the most common complaints I hear from dieters is that they're constipated. If you've ever competed in bodybuilding, you know what I mean. It happens to almost everyone, and can be very problematic. I go so far as to consider it a sort of "silent killer," like high blood pressure. There are many studies that demonstrate adding raw bran decreases intestinal transit time. Constipation and the non-evacuation of waste tie directly into the next point.

2 Toxic waste dump clean up.

When your colon doesn't completely evacuate, or when bad bacteria begin to dominate the good bacteria, putrefaction occurs. This means that toxic substances can get reabsorbed back into the blood and other tissues. By binding with toxins and hormones, insoluble fiber is very good at keeping you "cleaned out." The payoff is that without so much of these toxins and hormones sitting around in your gut, you'll be better protected against bowel diseases, cancers, and other maladies.

Note: You may have heard of the "fiber hypothesis." It means that a low intake of fiber promotes certain diseases such as high blood pressure, obesity, colon disease, and 30-40 other diseases, while a high fiber intake protects you against them. If you're a research junkie, look up the work of Drs. Denis Burkitt and Hugh Trowell. Their work in Africa is what formed this hypothesis.

First, you shouldn't rely on fiber supplements. I believe it's best to get your fiber from a wide variety of whole food sources that contain different types of fiber. One of the major benefits of dietary fiber is that the phytonutrients, antioxidants, vitamins, minerals, etc., within the food choice often accompany it. This is also what makes fiber research problematic. Which of these factors is helping the most? Or is it all these things working in concert that prevent disease? It's a tough call.

For how much should we eat, the common recommendation is 25-35 grams a day, with some experts saying around 40 grams. It's recommended that diabetics get upwards of 50 grams a day.

When determining your needs remember that as a weight training athlete, you're probably eating way more protein, fat, etc., than the "normal" person these recommendations were designed for. In all likelihood, fiber is simply one of those things that you have to play around with until you get it right. When you're passing soft bowel movements a few times a day without reliving the dinner scene from Alien, you're probably there or well on your way.

Note: You may get gassy and bloated upon increasing fiber intake. You may also get diarrhea if you eat too much insoluble fiber (mainly from bran). For the sake of your social life, increase gradually!

So now that we've covered the fiber basics, where do we find it? Here's just a sampling to get you started.

Whole grains

  • Whole oats contain a type of soluble fiber called beta-glucan, a gummy soluble fiber. Studies demonstrated a lowering of cholesterol from this type of fiber, hence Quaker's label claims that oats reduce cholesterol. Oat bran is also very popular due to its insoluble fiber content.
  • Rice bran is an interesting fiber source. According to Dr. Ann Gerhardt, it's been shown to lower LDL levels.
  • Cocoa Bran sounds tasty. This is the outside layer of the cocoa bean. According to Dr. David Jenkins of the University of Toronto, it's been shown to protect against oxidized cholesterol and raise HDL.
  • Konjac mannan is another interesting fiber. It contains a high concentration of glucomannan. I'd never even heard of this until I recently bought some "Miracle Noodles." Turns out that researcher Dr. Hsaio-Ling Chen has also been using this type of soluble fiber to lower LDL levels.
  • Buckwheat. I had to add this whole grain as many don't understand that it's completely unrelated to wheat. The nice thing is that even with buckwheat flour, you still get the good parts of the seed.


Beans, lentils, peas, and peanuts are all part of the legume family. Beans in particular are a great source of both soluble and insoluble fiber. My favorite are black-eyed peas (not the band).

I toss them in rice, add a cayenne-based hot sauce, and it's pure awesomeness. If you're concerned about flatulence because you're in a new relationship or work around a lot of exposed flames, you have to give beans a few weeks to work. They contain loads of soluble fiber, which means it's going to get fermented in the large intestine. This is a good thing. Be patient and your flora will adjust.



Pectins are common in fruits, and being a soluble fiber get fermented in the large intestine, thus producing short chain fatty acids. Fruit also contains cellulose much of the time, an insoluble fiber that will keep things moving.


You may have heard about "phytates" in nuts, which are anti-nutrients that bind with certain minerals that cause a depletion of that mineral. Here's my take: in a well-balanced diet, it's not something worth losing sleep over. If you're concerned, I suggest soaking the nuts until they begin to sprout, and then dry them again. Sprouting breaks down the phytate into inositol and phosphate. You're good to go.


I should also mention a few seeds. Flax seeds are very high in fiber, 7 grams per tablespoon, and have a portion of lignan (insoluble fiber type), which have been reported to be cancer protective. Sesame seeds are popular too, but have the phytate issue to contend with. As stated, I wouldn't worry about this, as a strong case could be made that phytates are also cancer protective.


The first thing people usually associate with fiber are veggies, and for good reason. My favorites are spinach, kale, asparagus, and broccoli.

Every good nutrition article needs a chart to help make sense of all the information. Ask and you shall receive!

Source Portion Fiber Miscellaneous Notes
Apple 1 whole 4 Good source of pectin.
Avocado Hass 1 whole 8  
Banana 1 whole 3 Contain FOS and inulin, food for good bacteria.
Blueberries 1 cup 4 Very high ORAC fruit, and good for the brain.
Dried Figs 5 figs 9 Have some laxative and diuretic properties. My first contest carb load was with figs! No, I didn't keep those posing trunks....
Kiwi 1 whole 3 Great source of Vitamin C.
Papaya 1 whole 5 Great source of digestive enzyme papain.
Pineapple 1 cup 2 Source of bromelain, but much is in the stem.
Prunes 10 prune 1.6  
Raspberries 1 cup 8 High in fiber! Great choice.
Strawberries 1 cup 3 Good source of anticancer nutrient ellagaic acid.
Whole Grains (cooked)
Brown rice 1 cup 4  
Buckwheat 1 cup 17 Whole-grain pancakes are awesome.
Quinoa 1/4 cup 3  
Oat bran 1/3 cup dry 2 High amount of insoluble fiber.
Oatmeal 1/2 cup 2  
Veggies (cooked)
Artichokes J 1 cup 2 Good source on inulin.
Asparagus 4 spears 1 Mild diuretic. Good source of inulin.
Green beans 1 cup 4  
Broccoli 1 cup 4 Don't forget the stems, a good source of cellulose.
Kale 1 cup 3  
Onion - raw 1 cup 2 Good source of inulin.
Mushrooms 1 cup 4  
Potato - baked 1 whole 5 Half the vitamin C is in the skin. Just saying.
Spinach 1 cup 4 Good source of cellulose and pectin.
Legumes (cooked)
Kidney beans 1/2 cup 6.5 Red kidney beans.
Pinto beans 1/2 cup 7  
Lentils 1/2 cup 8 Green ones have the most fiber. High in folate.
Black-eyed peas 1/2 cup 7 My favorite! I mix it in rice and put hot sauce on it.
Nuts (dry)
Almonds 1 ounce 4 Great source of monounsaturated fat.
Cashews 1 ounce 1 This measure is for dry roasted.
Brazil 1 ounce 1.5 Great source of selenium.
Pistachios 1 ounce 3  
Walnuts 1 ounce 2 Good source of omega-3 essential fatty acids.
  • If you're thinking that simply adding fruit to your diet will relieve constipation, think again. Most of the fiber in fruit is soluble and thus broken down in the colon and doesn't really have the bulking effect of cereal fibers like wheat bran.
  • Be very careful with fiber if you have an intestinal disease like Crohn's disease. High amounts of fiber can aggravate it.
  • It's possible that even a perfect diet will not relieve constipation problems.
  • Drink a lot of water!
  • Move around, exercise. When I was in the hospital, my digestive system was essentially asleep after my digestive surgeries. The doctors were on me 24-7 about walking to wake my system up. I must've clocked 50 miles walking the halls of the Mount Carmel Medical Center.

These things aid in a faster transit time, which means it can help solve constipation problems.

When you're new to the iron game, all you want to learn about is the training side of the equation like sets, reps, and exercises. You know, the fun stuff. But as you progress and graduate from white belt to yellow or blue belt, you soon learn that the nutrition side is just as important to bodybuilding success, if not more.

Moving beyond good nutrition is the pursuit of long-term health and vitality. While not sexy or exciting – what, fiber isn't exciting? – topics that prioritize health may be the most important of all. Because the strongest, most jacked physique on the stage or at the beach can still be a ticking time bomb if care isn't taken to keep key health markers in check.

That's the next level of enlightenment, when you marry a love for the iron with sound bodybuilding nutrition and lifestyle practices that promote lasting health and vitality. That's when you graduate to black belt. That's the level I hope all T NATION readers aspire to.

I'll see you there!