Introduction



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Chapter 1 : Introduction

Topics covered in this snack-sized chapter:



Introduction arrow_upward


  • Vitamins are essential organic nutrients required in small amounts.
  • Vitamins are organic compounds which the body needs to function normally.
  • Vitamins cannot be synthesized or manufactured by the body.
  • Vitamins must be obtained from outside sources like:
    • Diet
    • Rumen bacteria
    • Sun
  • Vitamins have diverse biochemical functions and are required for growth, maintenance, reproduction and lactation.

    • Discovery of Vitamins arrow_upward


  • The first vitamin was discovered in 1897 by a Dutch biologist named Eijkman.
  • He found that when bran was removed from rice, people consuming the refined rice developed Beriberi, a serious disease.
  • Eijkman also observed that when people ate the rice with the bran intact, no beriberi resulted.
  • This finding directed Eijkman and other scientists to chemically analyze rice for the substance which, when not present in adequate amounts, resulted in the development of beriberi.
  • Thiamine, named vitamin B1, was discovered to be this mystery substance.

    • Characteristics of Vitamins arrow_upward


  • Vitamins must have the following five characteristics in order to be classified as a vitamin:
    • Required in relatively small quantities.
    • Essential because certain chemical reactions cannot occur without them.
    • For example, at least thirteen are known to be required as co-factors or helpers in order for enzymes to function properly in the metabolism.
    • Must be obtained from the diet because the body cannot manufacture them or cannot make adequate amounts.
    • Must be eaten regularly because they are stored in limited quantities and are gradually lost.
    • A deficiency results in at least one specific disorder.

    Classification of Vitamins arrow_upward


  • Vitamins are classified in two forms:
    • Fat-soluble vitamins
    • Water-soluble vitamins

    Fat-Soluble Vitamins arrow_upward


  • Fat-soluble vitamins are found in the fats and oils of food.
  • Absorbed into the lymph and carried in blood with protein transporters.
  • Stored in body fat tissues and liver
  • Can become toxic if large amounts are consumed.
  • They include:
    • Vitamin A: Retinol
    • Vitamin D: Calciferol
    • Vitamin E: Tocopherol
    • Vitamin K

    Water Soluble Vitamins arrow_upward


  • Found in vegetables, fruits, grains, and meat.
  • Absorbed directly into the blood stream.
  • Not stored in the body and toxicity is rare.
  • Alcohol can increase elimination; smoking causes decreased absorption.
  • It includes:
    • Vitamin C
    • Vitamin B:
    • Vitamin B1: Thiamin
    • Biotin
    • Vitamin B2: Riboflavin
    • Vitamin B5: Pantothenic acid
    • Vitamin B3: Niacin
    • Vitamin B6: Pyridoxine
    • Folate (folic acid)
    • Vitamin B12: Cobalamin

    Difference between Water Soluble Vitamins and Fat Soluble Vitamins arrow_upward



    Water Soluble Vitamins

    Fat Soluble Vitamins

    Absorption

    Directly into the blood.

    First into the lymph, then into the blood.

    Transport

    Travel freely.

    Many require protein carriers.

    Storage

    Circulate freely in water-filled parts of the body.

    Stored in the cells associated with fat.

    Excretion

    Kidneys detect and remove excess in urine.

    Less readily excreted; tend to remain in fat-storage sites.

    Toxicity

    Possible to reach toxic levels when consumed from supplements

    Likely to reach toxic levels when consumed from supplements

    Requirements

    Needed in frequent doses.

    Needed in periodic doses.




    Thank You from Kimavi arrow_upward


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