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II. What we need to eat

What is an essential nutrient? What makes a nutrient essential? Different species have different requirements Nutrients essential for man Conditional requirements     Previous Page Next Page

Nutrients essential for man

Here are the known categories of essential nutrients for man.

  1. water
  2. calories (energy) from protein, carbohydrate or fat.
  3. 8-10 essential amino acids (all 20 are necessary for protein synthesis, but we can make some from other amino acids or from carbohydrate and ammonium ions).
  4. essential fatty acids
  5. 13 vitamins (organic compounds required in small amounts). These typically function as enzyme cofactors, e.g., niacin (precursor of NAD and NADP), riboflavin (precursor of FAD, FMN), pyridoxine or B6 (precursor of pyridoxal phosphate).
  6. 16-20 minerals (inorganic compounds required in "small" amounts).

The dramatic difference in the required amounts of certain nutrients gives rise to the following differentiation.

Macronutrient: Nutrient needed in large amounts (many grams daily).

Micronutrient: Nutrient needed in small amounts (typically milligrams daily).


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