The headline number
In a randomized trial of 54 people with rheumatoid arthritis (RA), a 100 mg daily dose of coenzyme Q10 (CoQ10) was followed by a drop in average disease activity score (DAS-28) from 5.01 to 2.34, a fall of about 53%. That is a large move on a scale where scores above 3.2 indicate active disease and scores below roughly 2.6 are generally treated as remission.
The catch is that the placebo group improved too. Here is what the trial shows and what it doesn't.
The study at a glance
The paper, published in Clinical Rheumatology (2019), came from Iranian researchers at Kermanshah, Tabriz and Urmia universities.
- Design: randomized, double-blind, placebo-controlled
- Participants: 54 adults with RA, aged 18-56, diagnosed at least 6 months earlier, with active disease (DAS-28 > 3.2)
- Groups: 27 received 100 mg/day CoQ10 and 27 received placebo
- Duration: 8 weeks (2 months)
- Context: participants were on standard RA therapy, so CoQ10 was an add-on, not a substitute
- Outcomes: serum MMP-1 and MMP-3, DAS-28, pain score, and tender and swollen joint counts
The numbers, side by side
| Measure | CoQ10 | Placebo |
|---|---|---|
| DAS-28 (mean) | 5.01 → 2.34 | 4.88 → 4.04 |
| Swollen joint count (median) | 2 → 0 | 2 → 0 |
| MMP-1 (median) | 0.20 → 0.16 | 0.18 → 0.15 |
| MMP-3 (median) | no significant rise | 2.26 → 2.57 (P = 0.020) |
After the intervention, the groups differed significantly on DAS-28 (P < 0.001), pain score (P < 0.001), tender joint count (P < 0.001) and swollen joint count (P = 0.012). Within the CoQ10 group, ESR (an inflammation marker), pain and tender joint count also improved significantly from baseline (P = 0.001, P < 0.001 and P < 0.001). The paper reports no such within-group changes for the placebo group.
The placebo improved too
The placebo group's DAS-28 fell from 4.88 to 4.04, a meaningful drop (P = 0.009). Swollen joint counts and MMP-1 also fell in both arms. This is common in RA trials. Disease fluctuates, participants are closely monitored, and expectations matter. The fair comparison is therefore the gap between groups, not CoQ10's before-and-after number alone. That gap was still statistically significant, but the "cut in half" framing describes the CoQ10 arm only.
What is MMP-3, and why does it matter?
Matrix metalloproteinases (MMPs) are enzymes that break down the structural proteins of connective tissue. In RA, inflamed joint tissue overproduces them. MMP-3 (stromelysin-1) degrades cartilage components and activates other MMPs, so it is often used as a marker of joint destruction. Higher levels are generally associated with more active, more damaging disease.
In this trial, MMP-3 rose significantly in the placebo group (2.26 to 2.57) but did not in the CoQ10 group. The between-group difference was significant (P = 0.027). The authors read this as CoQ10 "attenuating" MMP-3. In plain terms, the supplement was associated with a lack of the worsening seen on placebo, not with a reduction below baseline.
MMP-1, a collagenase, fell in both groups, so it doesn't separate CoQ10 from placebo.
Why would CoQ10 help?
CoQ10 is a fat-soluble compound that sits in the mitochondrial membrane, where it shuttles electrons for energy production. It is also an antioxidant. Chronic inflammation is tied to oxidative stress and mitochondrial dysfunction, and CoQ10 has been studied for dampening inflammatory signaling, including pathways that drive MMP expression. The trial did not test these mechanisms directly, so they remain plausible explanations, not demonstrated ones.
Limits to keep in mind
- Small and single-trial: 54 people, 8 weeks, one research effort. Replication is needed.
- Short duration: no data on long-term joint damage, X-ray progression or remission.
- Add-on only: participants stayed on their usual RA medication. Nothing here suggests CoQ10 can replace DMARDs or biologics.
- Surrogate markers: MMP-3 is a biomarker, not proof of protected joints.
- Narrow population: adults aged 18-56 with moderate-to-high disease activity.
The authors' own conclusion is cautious: CoQ10 "may provide a new complementary approach."
What this means for you
Dose tested: 100 mg per day for 8 weeks. The abstract does not specify the product form or timing.
Timing: CoQ10 is fat-soluble, so the usual practice is to take it with a meal that contains some fat. This is general guidance, not something the trial tested.
Ubiquinone vs. ubiquinol: ubiquinone is the oxidized form and is the cheaper, more common one. Ubiquinol is the reduced form and costs more. The abstract doesn't say which was used, so there is no trial-based reason to pay extra for ubiquinol. Whichever you choose, pick a third-party-tested brand.
Statin users: statins reduce the body's own CoQ10 production, which is why the combination often comes up. Ask your prescriber before adding it.
Who it may suit: adults with active RA who are already on prescribed treatment, are curious about an adjunct, and will discuss it with their rheumatologist first.
- Anyone planning to stop or reduce RA medication in favor of CoQ10. Don't.
- People on warfarin. CoQ10 may weaken its effect, so INR monitoring is essential.
- People on blood pressure or diabetes medication, or who are pregnant or breastfeeding. Check with a clinician first.
- Anyone under 18 or over 56, since the trial didn't enroll them.
The bottom line
A low-cost, widely available supplement was associated with a large improvement in RA disease scores and a more favorable MMP-3 trend than placebo. That is interesting, but the evidence is one small, short trial in which the placebo group also improved. Treat CoQ10 as a promising add-on worth discussing with your rheumatologist, not a replacement for proven therapy, until larger and longer trials confirm it.
