In past articles, we have discussed fiber and how it has become the most deficient macronutrient in our diets. Our Paleolithic ancestors used to get around 50-100 grams per day, but that number has dwindled to around 17 grams per day for the average American male. As manufacturing and globalization have grown, the food industry has taken to removing the fiber and pumping our “food” full of additives and chemicals to increase profits and preserve shelf life. While this has led to a more abundant supply of food, it has also resulted in an increase in many deficiencies and diseases as our bodies have gotten less of this beneficial nutrient.
In this short series, we will take a closer glimpse at fiber and why you should get more. Here in Part One, we will discuss the different types of fiber, how they work, and examine the “whole grain” movement as fiber has come back into the spotlight.
Fiber is the indigestible part of plant-based foods that our bodies cannot break down. You have probably heard of the two main types of fiber: soluble and insoluble. Soluble fiber is dissolved in water and forms a gel, boosting the feeling of satiety. Insoluble fiber can’t be dissolved in water, but instead absorbs water and fills up like a sponge, increasing the bulk of digested foods in our intestines. Aside from these two main groups of fiber, there are smaller components of fiber that serve different functions as well.
1. Polysaccharides are the biggest component and can be found in every type of fibrous food. This includes the bran and beta glucans from grains, the pectins found in fruits and vegetables, and the gums from the sap of plants such as Guar and Acacia.
2. Lignin comes from the stalks and skins of fruits and vegetables and comprises the second largest components of fiber. This is basically the indigestible part of the plant cell walls that our bodies can’t break down.
3. Oligosaccharides and resistant starches are known as the “prebiotic fiber” that helps to feed the good bacteria in your gut. This group includes the psyllium and inulin and other components of fiber that are commonly extracted and added to foods to boost fiber content (comes from legumes, fruits, veggies, seeds and grains).
How It Works
In case you had forgotten or never heard this before, the human body’s digestive tract is around 30 feet long--stretching from the stomach to the colon at the end of the large intestine. Food starts to be digested in the stomach, being broken down into smaller pieces to increase the surface area and allow your intestines to pull more nutrients out of the food. It takes somewhere between 1.5 to 3 days for food to travel all the way through your gastrointestinal tract. Fiber begins its work at the start of the small intestine, where it provides bulk to the mass of food that is deposited from your stomach 1 to 3 hours after you finish eating. The bulkier that mass is, the easier it is for the muscles in your intestines to force the contents along the pipeline and keep you from getting backed up (constipated). Without sufficient bulk, your muscles can’t move the food along quickly and food lingers in the intestines, which can cause bloating and discomfort, and also poses a risk that any toxic substances can stay in contact with the intestinal walls, increasing your chance of contracting colon cancer and leading to problems such as leaky gut syndrome and food sensitivities/allergies.
On top of increasing the transit time of the food mass in your intestines, those oligosaccharide/starch prebiotic fibers act as a food source for the 2+ lbs of gut bacteria found in your digestive tract. These good probiotic bacteria ferment the undigested fibers—while in the process. crowding out any bad bacteria, boosting immune functioning, and producing short chain fatty acids to fuel your colonic cells (which is thought to reduce the risk of colon cancer).
Obviously fiber will have an impact on the makeup of your bowel movements as well, but you should use that more as an indicator of how healthy your gut is than how much fiber you are eating. The ideal poop should be a “foot-long floater with no odor,” and anything else could indicate that you have a problem somewhere along the chain of digestion or that your diet sucks and needs to be changed.
As fiber has become more of a key word--similar to protein, carbohydrates, and trans fats in past years--the food industry has responded by unleashing the “whole grain” movement. This is the latest sham in a long series of politically fishy marketing campaigns meant to fool the public into thinking that they are making the effort to make better foods. Every once in a while, you will find foods that indeed contain more fiber due to the use of better products. More often than not, it simply means that at some point along the line of manufacturing there were whole grains used before the product was broken down into the partial food components that you find in your brightly colored box. It’s likely that there is some brown food coloring or tricky food ingredient labeling used.
Don’t pay attention to the words “whole grain” and make sure you read the label. Check the fiber content and the ingredients list, and if the words “bleached enriched wheat flour” are the first ingredient (or even worse listed after some type of sugar ingredient like high fructose corn syrup) on a bread that has less than one gram of fiber per serving, know that the food manufacturer is trying to play you for a fool. Studies have shown that 75 percent of people who read the words “whole grain” on a label believe that that food product contains more fiber, and that nearly 70 percent of people eat whole grain products in order to get more fiber. Don’t be one of the sheep that are fooled by this new ploy. Make sure you know how to find the real amounts of fiber.
As you can see, fiber is essential for a healthy digestive system and you need to get as much as you possibly can. In Part Two, we will browse through some of the research on fiber and provide some easy tips for you to boost your fiber intake on a daily basis.
Bonci, L, MPH, RD, CSSD, LDN, Fiber-pe-dia. Kellog. 2010
Institute of Medicine Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein and Amino Acids (macronutrients). Washington, DC. National Academies Press, 2005.
2009 Kellogg Company Whole Grains and Fiber Survey.
Jefferson A (2005) Diet and Digestive Health Primary Healthcare 15: 27-31.
Guamer et al (2003) Gut fl ora in health and disease. The Lancet 360: 512-519.
Gibson et al (1995) Dietary modulation of the human colonic microbiota: introducing the concept of prebiotics. J Nutr 125, 1401-1412.
International Food Information Council Fiber Fact Sheet 2008. See www.IFIC.org.
Peter Bauman – Peter is a chef first and personal trainer second, with a background in the biological sciences and degree in psychology from UC Berkeley. He takes the tactics that work with elite athletes at California Strength—one of the leading athletic training facilities in the country—and helps to apply them to the lives of the Average Joe to get results.