First example: Your blood test shows adequate levels of calcium. Does this mean your calcium metabolism is good? Not necessarily. It could be that your body is robbing calcium from your bones and teeth to support a major organ. A hair test would show the actual mineral status of your tissues. A blood test could miss it.

Second example: After a person ingests lead, a poisonous metal, the lead levels in the blood stay high for about 30 days. Then the lead disappears. Is it gone? Is the person out of danger? No. The answer is that the lead has now been removed from the blood. It is being stored in the tissues and would show up in a hair test - not a blood test.

The quantities of minerals being measured from the blood are 1,000 times smaller than those found in hair tests. The standard of mineral measurement from blood tests is a nanogram. This is one-millionth of a gram. In a hair test, we use measurements of a thousandth of a gram which is 1000 times larger.

For this reason, I recommend the use of hair tests. It is easier to get experimental error when you are working with the smaller quantities of minerals found in the blood. Another factor is the cost of the blood test for minerals would be prohibitive.