Wednesday, March 28, 2012

The thing about Dietary Fibre

Every once in a while there comes along some nutritional 'fad'. Someone tried a diet and it worked, writes a book, gets international attention and everyone tries it. Every once in a while there comes along come marketing 'fad' whether it may be 'no cholesterol' , 'low fat' or 'organic' there is some 'study' that was done to conveniently support this marketing strategy and everyone is happy.

Fibre may be seen as one of these fads but it actually is not. Having fibre in your diet is very important, however, as with all other strategies employed by health professionals it is indirectly endorsed in every diet.
For example, when you are being encouraged to consume more whole grain, peas and beans, fruits and vegetables, you are actually being encouraged to consume high fibre foods. You may not be told directly to consume fibre but if your diet is rich in these foods chances are you a well on your way to having a high fibre diet.

What is dietary fiber?

Dietary fibers promote beneficial physiological effects including laxation and/or blood cholesterol attenuation and/or blood glucose attenuation. According to this definition, dietary fiber consists of nondigestible carbohydrates and lignin that are intrinsic and intact in plants.

Added fiber, which refers to fiber that is added to foods during food processing, consists of isolated nondigestible carbohydrates that have proven beneficial physiological effects in humans. For food labeling purposes, the Institute of Medicine defines Total Fiber as the sum of Dietary Fiber and Added Fiber.
Despite the controversy surrounding the exact definition of dietary fiber, experts agree on one important thing is dietary fiber is an important weapon in the fight against heart disease, colon cancer, diabetes, and obesity.

Categories of Dietary Fiber
  • Cellulose, found in bran, legumes, peas, root vegetables, cabbage family, outer covering of seeds, and apples
  • Hemicellulose, found in bran and whole grains
  • Polyfructoses (Inulin and Oligofructans)
  • Galactooligosaccharides
  • Gums, found oatmeal, barley, and legumes.
  • Mucilages
  • Pectins, found in apples, strawberries, and citrus fruits
  • Lignin, found in root vegetables, wheat, fruits with edible seeds (such as strawberries)
  • Resistant Starches, found in ripe bananas, potatoes
What can high-fiber foods do for you?
  • Support bowel regularity
  • Help maintain normal cholesterol levels
  • Help maintain normal blood sugar levels
  • Help keep unwanted pounds off
What events can indicate a need for more high fiber foods?
  • Constipation
  • Hemorrhoids if related to straining from constipation
  • High blood sugar levels
  • High cholesterol levels 
What is the function of dietary fiber?
Until very recently, the functions of a specific type of fiber were determined by whether or not the fiber was classified as soluble or insoluble. Soluble fibers, such as the type found in oat bran, are known to reduce blood cholesterol levels and normalize blood sugar levels.
On the other hand, insoluble fiber, such as the type found in wheat bran, are known to promote bowel regularity. Many commonly used plant sources of fiber contain both soluble and insoluble fibers. Psyllium husks, for example, contain a mixture of 70% soluble and 30% insoluble fibers. Despite the widespread use of the terms "soluble" and "insoluble" to describe the health benefits of dietary fiber, many medical and nutrition experts contend that these terms do not adequately describe the physiological effects of all the different types of fiber. These experts are now proposing the use of the terms "viscous" and "fermentability" in place of soluble and insoluble to describe the functions and health benefits of dietary fiber.

What factors might contribute to a deficiency of dietary fiber?
Even though fiber is often defined as the "undigestable" part of food, a certain amount of healthy digestive function is important for realizing the health benefits of this nutrient.
Inadequate chewing can prevent the health benefits of fiber from being realized, since fibers that cannot be solubilized (like lignins, celluloses, and some hemicelluloses) require extra chewing in order to participate in biochemical processes.

How do other nutrients interact with dietary fiber?
Foods high in nonfermentable fiber, or the fiber that passes all the way through the intestines unchanged, may reduce the absorption and/or increase the excretion of several minerals, including calcium and iron.

A diet high in fiber may play a role in the prevention and/or treatment of the following health conditions:
  • Breast cancer
  • Cardiovascular disease
  • Colon cancer
  • Constipation
  • Diabetes
  • Diverticulitis
  • Gallstones
  • High cholesterol
  • Irritable bowel syndrome
  • Obesity
  • Syndrome X
What foods provide dietary fiber?
Excellent food sources of fiber include turnip greens, mustard greens, collard greens, , navy beans, eggplant, raspberries, and cinnamon.
Very good sources of dietary fiber include romaine lettuce, celery, Swiss chard, spinach, fennel, asparagus, cabbage, Brussels sprouts, green beans, cauliflower, carrots, tomatoes, green peas, beets, bell peppers, broccoli, shiitake mushrooms, kale, pinto beans, black beans, kidney beans, dried peas, lentils, strawberries, pear, cranberries, strawberries, oranges, whole wheat, barley, flax seeds, coriander seeds, cloves, and oregano.
Good sources of dietary fiber include apricots, grapefruit, banana, figs, pineapple, cantaloupe, avocado, plums, papaya, kiwifruit, blueberries, apple, sweet potato, summer squash, onions, shiitake mushrooms, yam, leeks, olives, crimini mushrooms, potatoes, corn, beets, rye, quinoa, buckwheat, oats, spelt, garbonzo beans, soybean, miso, sesame seeds, rosemary, black pepper, cayenne pepper, dill, and turmeric.