Many of us have heard that fiber is beneficial to our health, yet few know exactly how and why fiber is helpful. One of the better changes you can make in your diet is to increase fiber intake both through increased vegetables and grains and with supplemental fiber.
Dietary fiber is important to human health and nutrition because of its role in regulating glucose and cholesterol absorption, detoxification/elimination, and promoting healthy bowel function by serving as a pre-biotic. Vegetables, nuts, whole grains and legumes are the best dietary sources of fiber – and are nutrient dense foods high in micronutrients, protein and antioxidants.
The bottom line: Fiber really is good for you. Eat a lot of it and often.
Unfortunately, a relatively simple concept is mystified by advertisements announcing the miracle benefits of one fiber versus another. Even more unfortunately, very inexpensive fiber gets packaged, encapsulated and bottled for sale – making it very expensive to us. This marketing of expensive fiber distracts us from focusing on the most important – and least expensive – sources of fiber: vegetables!
Food Sources of Fiber:
Dietary fiber is generally considered indigestible to humans, and is broadly classified as water-soluble and water-insoluble fibers.
Water-insoluble fibers bind or attract water, becoming very viscous and add bulk to the stool. This bulking helps maintain normal bowel function by acting as a scouring agent in the bowel.
Water-soluble fibers actually dissolve in water and are further altered by the bacteria in our intestines.
All fibers can slow the absorption of sugar and fat from food, and therefore help prevent spikes in blood sugar and blood fat after eating, possibly reducing the inflammatory response to food. Fiber can also prevent the absorption of some fat and cholesterol all together, lowering blood triglyceride and cholesterol levels.
Although dietary fiber is called 'indigestible', that is not entirely accurate. Although we do not produce the needed enzymes to digest many of the fibers we eat in our diets, many of the beneficial bacteria that live in our intestines are able to break down (ferment) fibers to the benefit of both the bacteria and to ourselves.
The bacteria that live in our intestines have important health functions, including helping to maintain normal nutrient absorption, immune function, and bowel function. Fibers provide important nutrition for these bacteria and are thus called prebiotics. An example of a pre-biotic fiber is fructooligosaccharides (FOS), also known as inulin. A few examples of inulin-containing foods are: legumes, jicama, onions, and Jerusalem artichokes.
Fiber is further important in normal detoxification functions in the body. Our bodies are constantly breaking down (metabolizing) excess hormones, medications, synthetic food ingredients and environmental toxins. Much of this detoxification occurs in the liver. When the liver detoxifies these substances, the end products are frequently eliminated in the bile, a liquid substance made in our liver and secreted via the gall bladder into out intestinal tract.
When we eat a high fiber diet, the fiber from our meals binds these toxins and allows us to eliminate these waste products. Without a lot of fiber in the diet, these toxins can be reabsorbed, go back to our liver and need to be processed again. Requiring the liver to reprocess these toxins requires more energy and may result in higher levels of these toxins in the bloodstream.
One reason to use supplemental fiber, in addition to dietary fiber, is to create an acute bolus that will bind as much bile, conjugated hormones (excreted excess hormones), cholesterol and other unwanted substances as possible.
In physiological terms a bolus is "a rounded mass of food passing through the gastrointestinal tract". As a mass it picks up excess waste products and rids them from the body better. Fiber in food often is released more slowly into the small intestine, and while beneficial, works less effectively in removing large amounts of bile and its constituents.
Fiber, on the other hand, has few side effects and many benefits. Not only does eating fiber help lower your blood cholesterol levels, it also aids in blood sugar regulation, lowering of your hormone-dependent tumor and cancer growth, body weight regulation, and more.
An added side benefit of increased fiber will be improved satiety (feeling of 'fullness') after eating. Vegetarians and others who eat high fiber diets tend to eat less processed food and to eat overall healthier diets. Increasing fiber in your diet goes hand in hand with reducing total fat, saturated fats, and cholesterol. All of these in turn benefit your health and appearance.
While the typical American intake of fiber is between 5 and 10gm per day, the recommended intake is 25-30gm per day. And even more is needed when using fiber for pharmacological purposes. Somewhere in the order of 40-70gm of combined dietary and supplemental fiber works well in reducing health risks while minimizing any negative consequences of excessive intake.
Making the change to a high fiber diet should occur slowly, over weeks and months, in order to minimize gastrointestinal discomfort. For many switching from a diet consisting of processed foods to one full of vegetables, fruits, and whole grains will be a great start. Later, adding supplemental fiber can bring your daily intake above 40gm.
Many people need to increase their water intake when they increase their fiber intake to avoid constipation because of the water-binding/bulking effects of water-insoluble fibers.
Note: Similar to bile acid sequestrants, supplemental fiber should be ingested alone and separated from medications and nutritional supplements by two or more hours to limit any mal-absorption of essential nutrients.
Having regular blood panels taken, including a lipid profile, will allow you and your physician to monitor the positive changes taking place.
Psyllium is a popular fiber supplement which cleanses the intestines and promotes softer stools. It is a good source of both soluble and insoluble fiber.
Higher fiber diets may have additional benefits for those people with diabetes, including reducing blood sugar, lowering insulin and lowering cholesterol. Researchers studied 13 diabetes patients whose daily dietary fiber intake was 50gm and recorded reduction in total cholesterol, triglycerides, pre- and post-meal glucose levels, and measures of insulin sensitivity compared to those on a 24gm per day diet. [Chandalia, M., et al., Beneficial effects of high dietary fiber intake in patients with type 2 diabetes mellitus. N Engl J Med, 2000. 342(19): pp.1392-8.]
Vegetables, whole grains, nuts and legumes (beans and peas) remain the single best sources of fiber in the diet and – not coincidentally – these same foods are recommended as the foundation for a healthy diet for people with diabetes.
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