• High amounts of CoQ 10 are found in the heart, kidneys, liver and pancreas.heart attack image by JASON WINTER from Fotolia.com
  
  Coenzyme Q10, or ubiquinone, supports other complex enzymes in the body's production of energy. Plentiful in youth, CoQ 10 is a cofactor in three or more complex mitochondrial enzymes. Originally marketed as a heart drug in Japan, CoQ 10 was reclassified as a food in 2001 and is considered safe according to most medical research around the world. According to the National Cancer Institute, CoQ 10 is a safe supplement under a doctor's care.
  
  

Japanese Research

• CoQ 10 was formerly dispensed as a heart drug in Japan prior to 2001.prescription image by robert lerich from Fotolia.com
  
  Producing almost 90 percent of the world's supply, Japanese researchers have studied potential risks associated with supplementing CoQ 10. The Japanese Health & Nutrition Food Association, JHNFA, and Japan's Coenzyme Q Association believe that up to 300 mg per day is safe for most people. The conclusion of Japanese researchers is that more than 300 mg per day may cause symptoms such as stomach upset and insomnia.
  
  Maximum dosage of CoQ 10 as a Japanese prescription drug is 30 mg per day. Doctors believe that young, healthy people do not need supplementation of ubiquinone, because it is naturally present in their bodies.
  
  

U.S. Research

• U.S. Researchers believe that CoQ 10 supplementation about 1200 mg/day should be avoided.pills and pill bottle image by Effie White from Fotolia.com
  
  According to research performed by the Council for Responsible Nutrition, daily dosages above 1200 mg cause no toxicity. However, symptoms of nausea, dizziness and insomnia may occur with higher consumption levels of ubiquinone and should therefore be avoided. Why these symptoms occur in some people is unclear, but compounding of gel capsules or minute non-active filler ingredients may affect some people.
  
  Researchers also conclude that ubiquinone works in concert with other cofactors, enzymes and antioxidants. Supplementation should occur only on the direction of a physician.
  
  

Possible Risks Associated with High CoQ 10 Levels

• CoQ 10 should be supplemented only under a doctor's care.pills image by Maria Brzostowska from Fotolia.com
  
  Surprising research from the Cancer Research Center of Hawaii in 2010 demonstrates a positive correlation between high-plasma CoQ 10 levels and breast cancer risk in postmenopausal women. The reasons for high-circulating levels in the study are unknown in these patients. The researchers' conclusion: "Plasma CoQ10 levels were positively associated with breast cancer risk, overall (P = 0.04)".
  
  

Israeli Research

• Coenzyme Q 10 is naturally present in sufficient amounts in healthy people.pills image by Karol Grzegorek from Fotolia.com
  
  Researchers at Brunner Institute for Cardiovascular Research, Wolfson Medical Center in Israel studied the long-term effects of antioxidants on arterial elasticity and protection from bad cholesterol. The researchers' conclusion: use of any supplement in their study works best in concert with others. CoQ 10, while not considered dangerous, requires the presence of other enzymes and nutrients to perform its job. Use of CoQ 10 when it is not required by the body does not provide known benefits.
  
  

Risks Associated with CoQ 10 Supplementation

• pills image by Karol Grzegorek from Fotolia.com
  
  Compounding differences between laboratories and use of non-active fillers and capsule ingredients may cause stomach upset in some patients. Overall, researchers around the world conclude that CoQ 10 is safe. Since CoQ 10 is not approved by the FDA, use as a supplement should occur only under a doctor's care.