I’m sure you’ve heard the nutrition recommendation to “eat more fiber.” I’ve always obliged under the assumption that fiber “makes you regular.” After all, who wants to live a constipated life?
As I mentioned in my post about my family’s no-sugar experiment, I’m reading a wonderful book called Fat Chance by Robert Lustig, M.D., about the nation’s obesity pandemic. He believes that dietary sugars, causing increased blood glucose levels and subsequent insulin release, are the root of the problem. However, he also suggests that fiber helps mitigate some of these deleterious effects in certain situations.
What foods have fiber? Why is fiber important to consume? How much do you need? Why aren’t we eating as much as we did in the past? How does it work in your body? Keep reading to find out more.
Where To Find Fiber
Dietary fiber is found in fruits, vegetables, nuts, whole grain products and peas, beans and other legumes. Fiber is the part of a plant that the human gut cannot digest. There are two types: soluble (dissolves in water) and insoluble (doesn’t dissolve in water). Soluble fiber slows down digestion and absorption while insoluble fiber is not digested at all, thus providing a laxative effect.
Sources of soluble fiber include: oatmeal, oat cereal, lentils, apples, oranges, pears, oat bran, strawberries, dried peas, blueberries, phyllium, cucumbers and carrots.
Sources of insoluble fiber include: whole wheat, whole grains, wheat bran, corn bran, seeds, nuts, barley, couscous, brown rice, bulgur, zucchini, celery, broccoli, cabbage, onions, tomatoes, celery, carrots, cucumbers, green beans, dark leafy vegetables, fruit and root vegetable skins.
Where Not To Find Fiber
Fiber is stripped from foods in processes like milling (e.g., breads) and juicing. What foods have been enriched, or stripped of fiber? Ones like white rice, white bread, naan, pizza, corn dogs, “whole grain” Lucky Charms cereal and 100% juices.
Also, many fast foods with lots of fat, salt and sugar are devoid of fiber that has been processed right out of them.
How Much Fiber Do You Need?
According to Harvard School of Public Health, the Institute of Medicine recommends that children and adults consume 14 grams of fiber for every 1,000 calories of food they eat each day. That means a person who eats 2,500 calories each day should get at least 35 grams of fiber daily, while a person who eats 1,700 calories each day needs somewhat less fiber—about 24 grams. A toddler who eats only 1,300 calories each day needs about 18 grams of fiber.
Guess what? Due to all the processing of foods, our median consumption of fiber is a mere 12 grams/day.*
How Fiber Works in Your Body
Fiber binds to foods as it progresses through the small and large intestine, slowing down the rate at which foods cross the lining into the bloodstream. Dr. Lustig provides a great analogy: Fiber is like the hair that clogs your bath or shower drain. Though not always ideal in the bathroom, fiber that “clogs” up your intestinal lining is a good thing! This is so because the liver isn’t forced to metabolize foods so quickly. This means less work for your liver (liver is happy!), less of a spike in your blood glucose level (pancreas is happy!) and less of a subsequent insulin peak (your body is happy because less energy is stored as fat!).
And The Other Benefits Are….
According to Dr. Lustig, there are five primary benefits to eating fiber as it pertains to food digestion:
1. After fiber is eaten, it delays the rate at which glucose is absorbed by the intestine. What this means is that your blood glucose doesn’t rise as high, and less insulin is released by the pancreas. If fiber is eaten along with fructose, in a piece of fruit for example, it helps alleviate the burden on the liver to process the sugars.
2. Insoluble fiber can help lower LDL (“bad”) cholesterol by binding with the bile acids it produces.
3. Fiber helps food move through the intestine faster so that you feel “full” faster. This helps you cut down on seconds and thirds.
4. Fiber helps delay dietary fats from being absorbed in the small intestine, thus keeping insulin levels lower. The downside is that the fiber produces an array of gases in the process. Translation: You may fart a lot.
5. Fiber delivers nutrients further down the digestive tract into the large intestine, where bacteria can use them for energy. The net result is that “good” bacteria proliferate in your gut.
There are also studies which link dietary fiber to cancer prevention, including colon, breast and prostate. You can read more about this on WebMD.com.
What Are You Waiting For?
Start eating more fiber NOW. You’ve got nothing to lose and a lot to gain. Except weight.
Illustration Tufts Open Courseware