Coenzyme Q10 (CoQ10) is a nutrient that occurs naturally in the body. CoQ10 is also in many foods we eat. CoQ10 acts as an antioxidant, which protects cells from damage and plays an important part in the metabolism.

Although CoQ10 plays a key role in the body, most healthy people have enough CoQ10 naturally. There is some evidence that adding more — in the form of CoQ10 supplements — may be beneficial. Increasing age and some medical conditions are associated with dropping levels of CoQ10. But in these cases, it’s uncertain that adding CoQ10 will have an effect.

CoQ10 has been used to treat many different conditions. There’s evidence that CoQ10 supplements can lower blood pressure slightly. CoQ10 is also used to treat heart failure and other heart conditions, possibly helping to improve some symptoms and lessen future cardiac risks when combined with regular medications, but the evidence is conflicting.

Though still controversial, some preliminary evidence suggests that CoQ10 may help to prevent or treat the adverse effects, such as muscle pains and liver problems, of taking statin-type cholesterol drugs.

Preliminary studies have shown that CoQ10 may slow, but not stop, the progression of Alzheimer’s disease. Additional research is needed to confirm this effect.

CoQ10 has also been studied as a preventive treatment for migraine headaches, though it may take several months to work. It was also been studied for low sperm count, cancer, HIV, muscular dystrophy, Parkinson’s disease, gum disease, and many other conditions. However, the research has not found any conclusive benefits. Although CoQ10 is sometimes sold as an energy supplement, there is no evidence that it will boost energy in a typical person.

There is no established ideal dose of CoQ10. Studies have used doses of CoQ10 ranging from 50 milligrams to 1,200 milligrams in adults, sometimes split into several doses over the course of a day. Follow the instructions on the bottle or get advice from your doctor or a dietitian. Keep in mind that different supplement brands might have different ingredients and strengths.

• Good food sources of CoQ10 include:
• Cold water fish, like tuna, salmon, mackerel, and sardines
• Vegetable oils
• Meats

Side effects from CoQ10 seem to be rare and mild. They include diarrhea, nausea, and heartburn.

Risks. People with chronic diseases such as heart failure, kidney or liver problems, or diabetes should be wary of using this supplement. CoQ10 may lower blood sugar levels and blood pressure. Doses of more than 300 milligrams may affect liver enzyme levels.

Interactions. People taking blood thinners and thyroid medications should check with their doctors before using CoQ10 supplements.

Given the lack of evidence about its safety, CoQ10 supplements are not recommended for children or for women who are pregnant or breastfeeding.