On 2015 Mar 19, David Keller commented:

High-dose Coenzyme Q10 was safe in the Parkinson Study Group trial

In their reply to my letter [1] pointing out that the doses of Coenzyme Q10 tested may have been too small to treat statin-induced myopathy, Banach and Mikhailidis state: "Another question is whether higher dosages of CoQ10 have adverse effects. Contemporary data concerning the administration of CoQ10 at dosages higher than 1200 mg/d are limited" [2].

To address these safety concerns, consider the Parkinson Study Group's trial of high-dose CoQ10; 600 subjects with early Parkinson disease were randomized to placebo or to high-dose CoQ10. 94 subjects received placebo, 87 received 1200 mg/d of CoQ10, and 86 received 2400 mg/d of CoQ10 [3]. Only 65 participants withdrew prematurely: 29 who received placebo, 19 who received 1200 mg/d of CoQ10, and 17 who received 2400 mg/d of CoQ10, and it was reported that "treatments were well tolerated with no safety concerns".

While it was disappointing that high-dose Coenzyme Q10 did not slow the progression of Parkinson's disease, at least we learned that doses of up to 2400 mg per day seem to be safe and well-tolerated.

References

1: Keller DL. Coenzyme Q10 and statin-induced myopathy--I. Mayo Clin Proc. 2015 Mar;90(3):419-20. doi: 10.1016/j.mayocp.2015.01.006. PubMed PMID: 25744125.

2: Banach M, Mikhailidis DP; Lipid and Blood Pressure Meta-analysis Collaboration (LBPMC) Group. In reply-Coenzyme Q10 and Statin-Induced Myopathy. Mayo Clin Proc. 2015 Mar;90(3):420-1. doi: 10.1016/j.mayocp.2015.01.003. PubMed PMID: 25744127.

3: Parkinson Study Group QE3 Investigators, A randomized clinical trial of high-dosage coenzyme Q10 in early Parkinson disease: no evidence of benefit. JAMA Neurol. 2014 May;71(5):543-52. doi: 10.1001/jamaneurol.2014.131. PubMed PMID: 24664227.

On 2015 Mar 19, David Keller commented:

High-dose Coenzyme Q10 was safe in the Parkinson Study Group trial

In their reply to my letter [1] pointing out that the doses of Coenzyme Q10 tested may have been too small to treat statin-induced myopathy, Banach and Mikhailidis state: "Another question is whether higher dosages of CoQ10 have adverse effects. Contemporary data concerning the administration of CoQ10 at dosages higher than 1200 mg/d are limited" [2].

To address these safety concerns, consider the Parkinson Study Group's trial of high-dose CoQ10; 600 subjects with early Parkinson disease were randomized to placebo or to high-dose CoQ10. 94 subjects received placebo, 87 received 1200 mg/d of CoQ10, and 86 received 2400 mg/d of CoQ10 [3]. Only 65 participants withdrew prematurely: 29 who received placebo, 19 who received 1200 mg/d of CoQ10, and 17 who received 2400 mg/d of CoQ10, and it was reported that "treatments were well tolerated with no safety concerns".

While it was disappointing that high-dose Coenzyme Q10 did not slow the progression of Parkinson's disease, at least we learned that doses of up to 2400 mg per day seem to be safe and well-tolerated.

References

1: Keller DL. Coenzyme Q10 and statin-induced myopathy--I. Mayo Clin Proc. 2015 Mar;90(3):419-20. doi: 10.1016/j.mayocp.2015.01.006. PubMed PMID: 25744125.

2: Banach M, Mikhailidis DP; Lipid and Blood Pressure Meta-analysis Collaboration (LBPMC) Group. In reply-Coenzyme Q10 and Statin-Induced Myopathy. Mayo Clin Proc. 2015 Mar;90(3):420-1. doi: 10.1016/j.mayocp.2015.01.003. PubMed PMID: 25744127.

3: Parkinson Study Group QE3 Investigators, A randomized clinical trial of high-dosage coenzyme Q10 in early Parkinson disease: no evidence of benefit. JAMA Neurol. 2014 May;71(5):543-52. doi: 10.1001/jamaneurol.2014.131. PubMed PMID: 24664227.