A popular longevity supplement didn’t slow Parkinson’s in a large trial

A year-long Phase 3 trial of nicotinamide riboside (NR) found no clinical benefit in people with early Parkinson’s disease. NR is a compound that raises cellular levels of nicotinamide adenine dinucleotide (NAD).¹ The NOPARK trial results were published in JAMA.¹ NR raised blood NAD levels, but participants did not have milder symptoms or slower disease progression.²

Charalampos Tzoulis of Haukeland University Hospital and the University of Bergen led the trial. Participants were enrolled at 11 Norwegian centers.¹ In the university’s statement, he said:¹

We had a strong biological rationale for testing this treatment, and earlier, smaller clinical studies had produced encouraging findings. NR clearly increased NAD metabolism, but this did not translate into clinical improvement. Our results therefore do not support NR as a treatment to slow Parkinson’s disease.

How the trial worked

NOPARK enrolled 410 people with early Parkinson’s. All were 35 or older, had been diagnosed within the previous two years and were on stable doses of Parkinson’s medication.² They were randomly assigned to take NR or a placebo twice daily for 52 weeks.² Neither the participants nor the study teams knew who received which treatment.¹

The main outcome was the Movement Disorder Society Unified Parkinson Disease Rating Scale (MDS-UPDRS), a standard clinical score. The researchers used its first three parts, which cover movement, daily activities and nonmotor symptoms. Combined, these parts range from 0 to 236, and higher scores mean more severe problems.² According to the trial registry record, participants were assessed at baseline and at 13, 26, 39 and 52 weeks. Measurements included dopamine transporter imaging (DaTscan) and brain MRI.³

The rationale was mitochondria, the structures that produce energy for cells. Problems with mitochondria are thought to play a role in how Parkinson’s develops and progresses. NAD is essential for healthy mitochondrial function.² NAD is also involved in DNA repair and in regulating inflammation. Preclinical studies and small trials had suggested that raising NAD might protect the nerve cells affected by the disease.¹

The results

Of the 410 participants, 393 were included in the main analysis. Their average age was 65.6 years.² After one year, MDS-UPDRS scores had risen by 2.45 points in the NR group, meaning symptoms got worse. Scores in the placebo group fell by 0.27 points.² The adjusted difference was 2.72 points in favor of placebo. It was statistically significant but modest, and below the commonly used threshold for a clinically important difference.¹

• Nonmotor symptoms, including mood and sleep problems, worsened more in the NR group than in the placebo group.²
• Brain imaging showed no evidence that NR slowed or sped up changes in the brain’s dopamine system.¹
• Safety: overall rates of adverse events were similar in the two groups.¹ Problems reported in both groups included high blood pressure, low folate levels, falls, nausea and fainting. Most events were judged unrelated or unlikely to be related to treatment.²

The authors wrote that “these findings do not support nicotinamide riboside as a disease-modifying treatment for Parkinson disease.”² Based on the results, they said they do not recommend that people with Parkinson’s use NR or other NAD-boosting supplements outside controlled clinical studies.¹

What it does not show

The result applies to one compound, in one disease stage, over one year. Inside Precision Medicine noted that the negative result does not show NAD metabolism is irrelevant to Parkinson’s. It suggests that raising NAD with NR, at the dose and duration tested, was not enough to produce a meaningful clinical benefit.⁴ The researchers said the findings do not rule out benefits from NAD-boosting treatments in other diseases. Those would need to be tested separately in controlled trials.¹

The team is still analyzing the data. They want to understand the biology behind the findings and check whether different groups of patients responded differently.¹ Those subgroup analyses have not been reported yet.

Some trial details differ between sources. The trial registry record, accessed through the CDEK database, describes NOPARK as a phase II trial with 400 planned participants.³ A 2025 report on a licensing deal described it as a phase III trial of 400 people at 12 Norwegian sites.⁵ The 2026 reports on the published results give 410 participants at 11 centers.²¹ Biohack did not have access to the full JAMA paper. The figures above come from the University of Bergen’s release and independent coverage.

Who is behind it

The University of Bergen is listed as the trial’s lead sponsor.³ NR is sold under the brand name Niagen by Niagen Bioscience, formerly ChromaDex Corporation. ChromaDex Inc., a Niagen Bioscience subsidiary, supplied both the NR and the placebo for the study.²

The company also had a commercial stake in the outcome. In July 2025, before the results were public, Niagen Bioscience announced a worldwide exclusive license from Haukeland University Hospital to develop NR as a potential Parkinson’s therapy. The deal gave the company access to intellectual property and clinical data, including NOPARK data, that were expected to support future filings under European Medicines Agency guidelines.⁵ Coverage at the time said the trial had been completed in June 2025. It also said the company had set up a wholly owned subsidiary to move from supplements into regulated drug development, with possible EU routes including Conditional Marketing Authorization.⁵

The same report described a long-running collaboration between Tzoulis and the company’s external research program, CERP. It began with material transfer agreements in March 2018 and has covered four Parkinson’s trials of NR: NADPARK, NR-SAFE, N-DOSE and NOPARK.⁵ At the time of the license, Tzoulis called it “an important milestone in our efforts to bring a potentially disease-modifying treatment for PD closer to patients.”⁵ None of the sources Biohack reviewed include a company response to the published results.

How it fits the field

NOPARK followed the smaller NADPARK study from the same group.² That phase I trial was published in Cell Metabolism in 2022. It gave 30 people with early Parkinson’s NR or placebo for 30 days.⁶ Brain NAD rose in 10 of the 13 NR recipients with available data. Those with raised brain NAD showed altered brain metabolism and a mild clinical improvement.⁶ At the time, the authors said NR might be useful as a neuroprotective therapy, pending further trials.⁶

Inside Precision Medicine called the new result a setback for efforts to target cellular metabolism in Parkinson’s, a disease where available treatments mainly manage symptoms.⁴ The outlet said the trial shows why encouraging results from small mechanistic studies need confirmation in larger randomized trials.⁴

The finding also matters outside the clinic. Medical Daily noted that in the United States, NR is sold over the counter without a prescription. It also cited a Parkinson’s Foundation estimate that about 1.1 million people in the U.S. live with Parkinson’s.⁷

What to watch next

• Further NOPARK analyses on mechanisms and on whether particular subgroups responded differently.¹
• Whether Niagen Bioscience changes its plans to pursue EU regulatory pathways for NR in Parkinson’s. Before the results, the company had described pursuing them.⁵
• Controlled trials of NAD-boosting treatments in other conditions, which the researchers say need to be evaluated separately.¹