Coenzyme Q10 (CoQ10), also known as ubiquinone, coenzyme Q, and CoQ10, is a natural substance that cells use to convert food into energy. While CoQ10 has shown beneficial results for Alzheimer's disease in preclinical studies, it has failed in human clinical trials. There is no evidence that CoQ10 supplementation can slow aging biology in humans either. Very few adverse effects have been reported with CoQ10 supplementation, and it is generally considered safe for most people.
Clinical studies are limited and do not support CoQ10’s potential to promote cognitive function or prevent dementia. Our search found:
• 1 small randomized clinical trial in Alzheimer’s disease patients
• 1 longitudinal study examining the relationship between blood CoQ10 levels and incidence of dementia
• 1 observational study examining the link between blood CoQ10 levels and mild cognitive impairment
• Numerous preclinical studies on possible mechanisms of action
Based on limited clinical research, CoQ10 is not likely to prevent dementia or protect the aging brain. Blood levels of CoQ10 were reportedly similar in people with and without mild cognitive impairment, suggesting that there is no association between lowered CoQ10 concentrations and cognitive decline [1]. Although preclinical studies on Alzheimer’s and dementia suggest that CoQ10 supplements could improve memory skills and cognitive abilities [2-4], a clinical trial in Alzheimer’s patients found no effect on oxidative stress in the brain or on biological markers of Alzheimer’s disease [5].
In a 16-week double-blind randomized clinical trial with 78 Alzheimer's patients, CoQ10 supplementation failed to improve cognitive ability [5]. In small clinical trials, CoQ10 supplementation has also failed to help patients with other neurodegenerative conditions such as Huntington's disease [6], Parkinson's disease [7], and ALS (Lou Gehrig's disease) [8].
CoQ10 is likely safe when used by healthy adults at moderate doses. The few adverse effects reported in trials include nausea, lowered blood sugar, and gastrointestinal problems [9]. CoQ10 supplementation may increase the tolerability of some chemotherapeutic treatments [9]. If CoQ10 supplements are taken simultaneously with blood pressure medication, blood pressure may become too low. CoQ10 may also decrease the effectiveness of warfarin, which would increase the risk of blood clotting. As with most supplements, safety has not been studied with chronic use and different brands may have differences in manufacturing that influence safety and quality. More information on doses, side effects, and drug interactions with CoQ10 can be found on Drugs.com.
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
CoQ10 is naturally found in foods such as oily fish, organ meats, whole grains, vegetable oil, and fruit [10]. CoQ10 supplements are widely available over-the-counter as oral pills and sprays in the United States. (It is also found in many fat emulsion medications used by patients whose diets do not contain enough fat.) Most studies have used supplements in doses ranging from 50 to 1200 mg/day. For healthy people, the observed safe level for ingestion is reported to be 1600 mg/day [11], although some studies report that doses of up to 2600 mg/day are well-tolerated [12].
Quality Control of Sources: United States Pharmacopeial Convention (USP), ConsumerLab, and FDA Information on Dietary Supplements offer information on the quality of specific supplements and assist in finding a trusted brand.
NCAAM (National Center for Complementary and Alternative Medicine), Mayo Clinic, and University of Maryland offer additional information on CoQ10 as a dietary supplement, including further information on dosing and safety.
Check for drug-drug and drug-supplement interactions on Drugs.com.