What is a Cofactor?

H.R. Childress

A cofactor is a chemical compound that is required for certain enzymes — called conjugated enzymes — to become active. Vitamins and minerals serve as the cofactors required by the human body to function properly. These nutrients may either be cofactors themselves or may be chemically modified to become cofactors once they are in the body.

Trace amounts of iodine are necessary cofactors for hormones produced by the thyroid.
Trace amounts of iodine are necessary cofactors for hormones produced by the thyroid.

Vitamins are organic substances that are not produced by the body, but are required in order for it to function. Many, but not all, vitamins become cofactors in the body. Coenzyme is another term often used to describe vitamins that function as cofactors. Most vitamins are converted into cofactors once they are in the body; only vitamin C is used directly as a cofactor.

Red meat is the main source of dietary iron for many people.
Red meat is the main source of dietary iron for many people.

Both fat-soluble and water-soluble vitamins function as cofactors. Vitamins A, D, E, and K are fat-soluble; however, only K is used as a cofactor. The remaining vitamins — all the B vitamins, vitamin C, niacin, biotin, folic acid, panthothenic acid, and lipoic acid — are water-soluble, and all are converted into cofactors once in the body — with the exception of vitamin C, which is utilized directly.

Most minerals required by the human body also function as cofactors. Potassium, chloride, sodium, calcium, phosphorous, and magnesium are the major minerals required by the body. Iron, zinc, manganese, iodine, copper, selenium, and molybdenum are also required in trace amounts.

Deficiency in any one vitamin or mineral cofactor can lead to a number of medical conditions. In fact, enzyme cofactors were first discovered because of one such disease: beriberi. This condition — a deficiency in vitamin B1, or thiamine — was due to diets composed mainly of white rice. It is less common in modern times than when it was first diagnosed in the early 1900s.

Anemia, which is a deficiency in iron, is one of the more commonly found deficiencies. It may be caused either by not getting enough iron in one's diet or by an inability of the body to properly absorb iron. While red meat is commonly thought to be the main source of iron in a diet, leafy vegetables and beans are also good sources.

Vitamin B12 is another common deficiency and is of particular concern for vegetarians and vegans. Vegetarians who consume enough eggs and dairy products generally receive enough B12, unless their bodies have difficulty absorbing vitamin B12. Vegans may find it necessary, however, to take a vitamin B12 supplement or eat fortified foods, as B12 is mainly found in animal products.

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Discussion Comments


@cloudel – My friend had both low iron and low B12 after she became a vegetarian. She had such a low energy level that she could hardly get out of bed! She had to take supplements and vitamins in order to function, because she refused to go back to eating meat and dairy products.


Vitamin C is so useful for so many things in the body. It's probably best that it doesn't have to be converted to a cofactor once inside the body.

I've read that it can break down and lose its potency if left in the cupboard for too long. I've also heard that it's best to consume it in raw fruits and vegetables to get the most out of it.

I love oranges and spinach, and I eat one or the other every day. This seems to have kept me from getting sick as much as I used to, because I haven't had a cold in over a year.


Iron is the only cofactor I've ever lacked. I was anemic for awhile as a child, and I felt very weak and tired.

I looked pale, and I stayed cold all the time. My mother was afraid that something awful was wrong with me, so she took me to a pediatrician. He said that I simply needed more iron in my diet.

To get me started, he gave me this liquid iron supplement that tasted so bad I nearly vomited every time I took it. I wonder if this wasn't a sneaky way to get me to eat food containing iron, because my mother told me that if I ate what she told me to, then I wouldn't have to take the supplement anymore.


Babies can get beriberi if their mothers don't have sufficient thiamine. Thiamine gets transferred through breast milk.

When my sister was pregnant, we read up on what sort of nutrients she would need in order to supply the baby properly with minerals and vitamins. We discovered that beriberi can kill a baby if it isn't caught and treated.

The treatment is simple. You just receive thiamine injections, and you start getting more of it in your diet.

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