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Medical Fiber and nutrients

  1. Mar 21, 2017 #1
    What is fiber in food? It is said that fiber is a non-digestible starch kind of food, ie it does not contribute energy, such as carbohydrates or proteins from the food.

    Am I right in this understanding? If fiber is non-digestible, what good it will do to our health and why it is insisted for our consumption by nutritionists?
  2. jcsd
  3. Mar 21, 2017 #2

    Fervent Freyja

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    Gold Member

    Insoluble fiber provides the bulk material that aides movement through the digestive track and prevents toxic byproducts from being reabsorbed on the way out. A person could live without it for a while, but they won't be very healthy. Soluble fibers can ferment in the colon to deliver multiple benefits. We evolved to utilize both types of fibers. Even though they don't contribute calories they are involved in many important processes that keep us healthy.
  4. Mar 22, 2017 #3

    jim mcnamara

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    Staff: Mentor

    @Fervent Freyja is right on the money.

    Fiber is interesting and a little complicated, to say the least.

    You may know that wood is ~75% a polymer of sugar. It is called cellulose. Humans cannot digest it. Cellulose is one of many compounds in foods that contribute to fiber. For example, cellulose exists in plant leaves - the "veins" you see in a spinach leaf. As you would guess, cellulose is insoluble fiber.

    Dextrin is another sugar polymer, that is soluble. Humans digest dextrin poorly, but gut bacteria can break it down, ferment it by anaerobic respiration. Whole wheat promotes dextrin. Let me be clear - small amounts of dextrin results from acid hydrolysis of other carbohydrates, in your stomach. It is not "in" foods as they sit on the table. Commercial dextrins from hydrolysis are also commercial food additives. So processed foods may have man made dextrin.

    Phytates are another fiber-like indigestible component of plant based foods, particularly legume (bean) seeds. Phytates break down with long cooking times. Which is helpful. They do provide fiber, but they are anti-nutrients. They grab and hold onto mineral micronutrients, preventing your body from absorbing those micronutrients. This is why uncooked (particularly raw fresh) beans are completely edible, but not a great idea for long term nutrition. Also why beans "lose" some fiber during cooking. Cause: Phytate breakdown by hydrolysis. Tannins in foods, like sorghum, are somewhat like phytates, except that they render protein less digestible. The flip side of tannins is that some related polyphenols found in herbs and spices are extremely valuable as antioxidants. Sage (Salvia spp. ), thyme (Thymus spp.) and cloves (Syzygium aromaticum) are very high in polyphenols.

    List of polyphenol contents in herbs and spices - this is a quick, really interesting read:
    Last edited: Mar 22, 2017
  5. Mar 22, 2017 #4
    Ooh. That was great many info about fiber. It will take long to 'digest' for me. But sure will do. Thanks a lot.
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