Vitamins are organic compounds required by the body in small doses to perform essential functions. Recent times have seen a surge in the hype for excessive intake of Vitamins. Here we breakdown the yays and nays of Vitamin consumption, and why excess of these tiny compounds can be more injurious than beneficial.


The human body produces a very limited amount of its own vitamins. They mainly need to be acquired and/or activated through diet, and, in some cases, through environmental factors such as sunlight.

The main vitamins needed for essential functions can be broadly classified into fat soluble and water soluble. As is obvious, fat soluble vitamins are stored in the fatty tissues and the liver after being absorbed by the intestines. Because of their storage, they need to be replaced less often than water soluble vitamins, which are excreted in the urine. The following is a list of the major vitamins and their main functions, along with RDA (recommended daily allowance).

Some vitamins have hormone like functions, such as regulating mineral metabolism (vitamin D), while others regulate cell and tissue growth and differentiation (vitamin A).

The reason that vitamins skip directly from E to K, is that the vitamins corresponding to the letters F to J were later on discovered to either be false leads, or were renamed due to their relationship with Vitamin B, which then became a complex, instead of a single Vitamin.


  • Chemical names – retinol, retinal, and four carotenoids (including beta carotene)
  • Fat soluble
  • Deficiency may cause night-blindness and keratomalacia (an eye disorder that results in a dry cornea)
  • Good sources include: liver, cod liver oil, carrots, broccoli, sweet potato, butter, kale, spinach, pumpkin, collard greens
  • RDA: 3000 IU/900 microg
  • Chemical name – thiamine
  • Water soluble
  • Deficiency may cause beriberi and Wernicke-Korsakoff syndrome.
  • Good sources include: yeast, pork, cereal grains, sunflower seeds, brown rice, whole-grain rye, asparagus, kale, cauliflower, potatoes, oranges, liver, and eggs
  • Chemical names – ascorbic acid.
  • Water soluble.
  • Deficiency may cause megaloblastic anemia.
  • Good sources include: fruit and vegetables, especially citrus fruits. The Kakadu plum and the camu camu fruit have the highest vitamin C contents of all foods. Liver also has high levels. Cooking destroys vitamin C.
  • RDA: 90 mg
  • Chemical names – ergocalciferol, cholecalciferol.
  • Fat soluble.
  • Deficiency may cause rickets and osteomalacia (softening of the bones).
  • Good sources: produced in the skin after exposure to UV (ultraviolet) B light from the sun or artificial sources. Also found in fatty fish, eggs, beef liver, and mushrooms.
  • RDA: 600 IU/ 10 microg
  • Chemical names – tocopherols, tocotrienols.
  • Fat soluble.
  • Deficiency is uncommon. Deficiency may cause hemolytic anemia in newborns (a condition where blood cells are destroyed and removed from the blood too early).
  • Good sources include: kiwi fruit, almonds, avocado, eggs, milk, nuts, leafy green vegetables, unheated vegetable oils, wheat germ, and whole-grains.
  • RDA: 15 mg
  • Chemical names – phylloquinone, menaquinones.
  • Fat soluble.
  • Deficiency may cause bleeding diathesis (an unusual susceptibility to bleeding).
  • Good sources include: leafy green vegetables, avocado, kiwi fruit. Parsley contains a lot of vitamin K.
  • RDA: 120 microg

High doses of supplements are associated with risks, so it is advisable to  be warned of the upper limit (UL) of any nutritional supplement that you take. The UL is usually many times higher than the RDA. It is almost impossible to intake too much of any vitamin through food, but overdosing from vitamin supplement ingestion does occur.

Dr. Annie

Physician, mom and wife

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