The level of coenzyme Q10 in human blood between 0.30 and 3.84 µg/mL is considered to be the normal range [3-5]. About 1/4 of coenzyme Q10 in a person's blood comes from diet: meat, poultry and fish are the main food sources. The remaining 3/4 are produced by the body itself.
For most of the general population, the amount of coenzyme Q10 synthesized by itself is large enough, and there is no problem of coenzyme Q10 deficiency. However, the level of coenzyme Q10 naturally produced in the body will decrease with age, because of increased demand, decreased synthesis, or insufficient intake of chemical precursors required for synthesis.
Some diseases (such as heart failure, high blood pressure, gum disease, Parkinson's disease, blood infections, certain muscle diseases and HIV infection) may have lower than normal levels of coenzyme Q10 in patients, but there is currently no evidence that coenzyme Q10 It is the cause of the disease—that is, it is not yet certain that the reduction in CoQ10 levels directly causes these diseases—but it is just an observed and related phenomenon.