Cofactor vs Coenzyme

Many enzymes have to link to their respective helpers to promote optimal arrangement of their atoms and proper functioning. Cofactors and coenzymes are two sorts of such helper molecules.

Cofactors are inorganic ions. Examples include magnesium (Mg++), selenium (Se++) and iron (Fe++).

Coenzymes are organic helper molecules. The main atoms in their structure are carbon and hydrogen.

The most common sources of coenzymes are vitamins derived from food. Some vitamins act as coenzymes and don’t require any modifications. Others are precursors to coenzymes.


Vitamins are organic compounds. They are very important nutrients that organism needs in limited amounts.

Many enzymes do not work partially or completely if they are not associated with certain non-protein helper molecules. Vitamins can connect to their enzymes in two ways - either through ionic or hydrogen bonds (for a short time) or through stable covalent bonds (permanently).

Co-factors, co-enzymes, and vitamins

Water soluble and fat soluble vitamins

Vitamins can be either water soluble or lipid soluble.

Water soluble vitamins can be directly absorbed from the intestine into the bloodstream. Vitamin C (ascorbic acid) and vitamin B group are water soluble. Because excess amounts of these vitamins are excreted in the urine, it is unlikely to overdose them and to reach toxic levels in the body.

Fat soluble vitamins enter the body in the same manner as lipids and therefore a small amount of fat intake along with them is essential for their better absorption. Fat soluble vitamins are A (retinol), D (calciferol), E (α-tocopherol), and K (phylloquinone). They readily pass through the plasma membranes of the gastrointestinal tract and other tissues.

Excessive consumption of lipid soluble vitamins can lead to the fact that they accumulate in the fatty tissues of the body and reach toxic levels. It is especially important to take them properly in supplements to prevent vitamin overdose.

Types of vitamins
 Water soluble vitamins Fat soluble vitamins

C (ascorbic acid)

B1 (Thiamine)

B2 (Riboflavin)

B3 (Niacin, Niacinamide, Nicotinic Acid)

B5 (Pantothenic acid)

B6 (Pyridoxine, Pyridoxal 5'-phosphate)

B7 (Biotin)

B9 (Folic acid)

B12 (Cobalamin)

A (retinol)

D (calciferol)

E (α-tocopherol)

K (phylloquinone) 

Cofactors and Coenzymes (one more good video to watch)

Recommended daily intake of vitamins

The Food and Nutrition Board of the US Institute of Medicine established several different types of reference values for healthy nutrition guidelines:

Recommended dietary allowance (RDA). The RDA is the average day-to-day dietary intake level of a nutrient sufficient to meet the needs of almost any healthy person based on age and gender.

Adequate intake (AI). The AI is a recommended intake value based on observed or experimentally determined estimates of nutrient intake by a group of healthy people that are assumed to be sufficient. An AI is established when an RDA cannot be determined.

Tolerable upper intake level (UL). The UL is the highest level of daily intake of a specific nutrient which probably does not pose a risk of adverse health effects in almost all individuals of a specified age and gender. Exceeding this level may lead to vitamin overdose.


Related Articles: