PQQ for Antioxidant Protection

Caveats

Antioxidant capacity in a test tube does not predict health benefit, and this is one of the better-established lessons in nutrition research - large trials of beta-carotene, vitamin E and vitamin C at supplemental doses found no benefit and in some cases harm, with beta-carotene increasing lung cancer in smokers. Reactive oxygen species also have necessary signalling roles, including in exercise adaptation, so blanket suppression is not desirable. Safety of PQQ: human trials are short and small, so the long-term safety profile is genuinely unknown - this is a compound with a thin safety database rather than an established one. Reported side effects at 20-40 mg/day include headache, fatigue and sleep disturbance. A rodent study found kidney effects at very high doses, and there is no established upper limit for humans, so doses above the 20 mg/day studied should be avoided. Avoid in pregnancy and breastfeeding, as no safety data exist. No significant drug interactions are documented, but the absence of data is not the same as the absence of risk, and anyone on medication should discuss it. If oxidative stress is the concern, a diet rich in vegetables, fruit, legumes and whole grains has the evidence that isolated antioxidant supplements lack.