The biggest dose tried, 3,000 mg a day, was tolerated for four weeks
Twenty people with Parkinson's disease took it daily for four weeks. Nothing moderate or severe happened, blood NAD rose up to fivefold, and homocysteine ticked up.
What the study found
Three grams a day for four weeks passed, with one shadow
Twenty people with Parkinson's disease took 3,000 mg of nicotinamide riboside a day for four weeks, a record dose. Nothing moderate or severe happened, and blood nicotinamide adenine dinucleotide rose up to fivefold. Homocysteine ticked up early, a sign of methyl groups spent clearing it.
The caveat · Four weeks, not long-term use
Twenty people over four weeks, in a phase one safety trial. Its apparent improvement in Parkinson's symptom scores is not an efficacy finding: the authors traced it to participants on the compound having taken their levodopa more recently before assessment. Four weeks establishes the highest dose tested, not a dose anyone has certified for long-term use.