A Fibromyalgia Diet Trial Where the Cholesterol Result Is Stronger Than the Pain Result
Fibromyalgia comes with a great deal of dietary advice and very little dietary evidence. Anyone who has searched for what to eat with this condition has met the elimination protocols and the confident claims that a particular way of eating will ease the pain. A trial published in May in Nutrition tested one of those ideas properly, and it produced two findings that deserve to be treated differently.
What the FIBROVEG trial found
The FIBROVEG study randomly assigned 22 women with fibromyalgia to one of two diets for six weeks [1]. Eleven followed a vegan Mediterranean diet, and eleven followed a traditional Mediterranean diet. The two diets were isocaloric and matched for macronutrient distribution, which means the calories and the broad protein, fat, and carbohydrate proportions were held the same in both arms. The variable being tested was whether the food was plant-only or included animal products.
The primary outcome, decided in advance, was change in LDL cholesterol. The vegan Mediterranean group achieved a greater reduction than the traditional Mediterranean group, with an estimated mean difference of -21.2 mg/dL (95% CI -38.3 to -4.08). Triglycerides also fell further, by an estimated 27.4 mg/dL (95% CI -52.1 to -2.73).
The finding most likely to be shared is the one on pain. The vegan Mediterranean group improved more on the pain item of the Fibromyalgia Impact Questionnaire, by an estimated 1.88 points (95% CI -2.99 to -0.77, p = 0.002).
One distinction determines how much you can conclude from each result. LDL cholesterol was the primary outcome, and the trial was designed around it. Everything else, including the pain item, was a secondary outcome that the authors themselves designate as exploratory. An exploratory outcome is a lead to follow rather than a conclusion to act on, seeing as the more outcomes a study measures, the more likely it becomes that one of them separates the groups by chance alone.
Size is the other constraint. Twenty-two people, eleven per arm, over six weeks, all women, at a single center in Spain. Look at the confidence interval on the LDL result: the true difference is somewhere between about 4 and 38 mg/dL. That range is compatible with a small effect and with a large one.
How this compares with larger studies
On the cholesterol side, this result is consistent with a much larger body of evidence. A meta-analysis of 30 randomized trials comparing vegetarian or vegan diets against omnivorous diets found LDL cholesterol lower by 0.30 mmol/L, which is roughly 12 mg/dL, along with reductions in total cholesterol and apolipoprotein B [2]. Those effects were similar across age, study duration, health status, and study design.
Two details in that comparison change how to interpret FIBROVEG's numbers. Its LDL difference is about double the pooled estimate, which is the pattern you expect from a very small trial, where chance produces wider swings in both directions. And the meta-analysis found no significant difference in triglycerides, whereas FIBROVEG did. The comparators were not the same, given that FIBROVEG set two Mediterranean diets against each other rather than a plant-based diet against an omnivorous one. Even allowing for that, a triglyceride finding which 30 trials did not produce should be treated as unconfirmed until someone repeats it.
The pain research is where I would apply the most caution. A network meta-analysis of 23 randomized trials covering 1,409 people with fibromyalgia compared acupuncture, intravenous lidocaine, and diet against physiotherapy and sham or placebo controls [3]. Acupuncture significantly reduced pain and depression and improved quality of life. Diet showed no significant difference from sham or placebo.
A single exploratory pain finding in 22 people has to be weighed against that existing evidence.
The placebo problem in fibromyalgia research
Fibromyalgia trials have a placebo problem, and it is not a small one.
The clearest demonstration is a double-blind, sham-controlled trial of low energy neurofeedback in 34 people with fibromyalgia [4]. Both the active and the sham groups improved on the Fibromyalgia Impact Questionnaire and on most secondary outcomes, with no statistically significant difference between them at the end of treatment, at three months, or at six months. People improved in both arms.
The mirror image of that is what happens with no control group at all. An open-label pilot of D-ribose in 41 people with fibromyalgia or chronic fatigue syndrome reported improvement across energy, sleep, mental clarity, pain, and wellbeing, with a mean global improvement of roughly 61 percent [5]. It was uncontrolled, so there is nothing to compare that number against.
This is why the FIBROVEG design deserves credit rather than dismissal. Both arms received a structured diet and the same amount of attention and study contact. Whatever separated them is unlikely to be attention alone. That makes the pain signal more interesting than an uncontrolled result, and it remains exploratory.
In practice, the useful part does not depend on this trial at all. A Mediterranean pattern is well supported for cardiovascular risk, and people with fibromyalgia carry adverse cardiometabolic profiles, which is the rationale the authors give for running the study [1]. Improving someone's lipids has its own value, whether or not it affects their pain. When one change addresses two problems, and the evidence is strong for one and preliminary for the other, the strong one is the reason to make the change.
There are also things this trial does not support. These were not elimination diets, and they did not remove any food group thought to trigger symptoms. This trial is not evidence for cutting nightshades, gluten, or anything else. Restriction carries its own costs in a population already managing fatigue and the ordinary labor of a day.
If you have fibromyalgia and food is on your mind
Shifting a Mediterranean pattern in a more plant-forward direction is a reasonable thing to try, and the stronger reason to try it is your cardiovascular risk rather than your pain.
Six weeks is what was actually tested. If you do try something and want to know whether or not it helped, decide in advance what you are measuring and give it a defined window before judging it.
Nothing here supports eliminating food groups. Restriction is where dietary change tends to cost the most and deliver the least, and it warrants a clinician's involvement rather than a solo experiment.
If your pain does improve on a plant-forward pattern, that improvement is yours regardless of what the mechanism turns out to be. A study of 22 people cannot show whether the food caused it or something else did, and your own experience over a defined trial period is better information about you than this study is.
References
Primary research located and verified via PubMed.
Marrero-Fernández P, Fresán U, Nicaudie S, Rodrigo Huecas N, Abusaada M, Bertotti G, Roldán-Ruiz A, López-Moreno M. Vegan versus traditional Mediterranean diet effects on cardiometabolic outcomes in women with fibromyalgia: FIBROVEG study. Nutrition. 2026;150:113303. PMID 42320093. https://doi.org/10.1016/j.nut.2026.113303 (digest source article; publisher page blocks automated readers, so the PubMed record was used as the source of record)
Koch CA, Kjeldsen EW, Frikke-Schmidt R. Vegetarian or vegan diets and blood lipids: a meta-analysis of randomized trials. Eur Heart J. 2023;44(28):2609-2622. PMID 37226630. https://doi.org/10.1093/eurheartj/ehad211
Almutairi NM, Hilal FM, Bashawyah A, et al. Efficacy of Acupuncture, Intravenous Lidocaine, and Diet in the Management of Patients with Fibromyalgia: A Systematic Review and Network Meta-Analysis. Healthcare (Basel). 2022;10(7):1176. PMID 35885703. https://doi.org/10.3390/healthcare10071176
Neurotherapy of fibromyalgia? A double-blind, sham-controlled randomized trial of low energy neurofeedback. Pain Med. 2010. PMID 20624243. (held in the Yggdrasil Abstract Library; the LENS developer is a co-author, which the record notes)
Teitelbaum JE, Johnson C, St Cyr J. The use of D-ribose in chronic fatigue syndrome and fibromyalgia: a pilot study. J Altern Complement Med. 2006;12(9):857-862. PMID 17109576. https://doi.org/10.1089/acm.2006.12.857 (held in the Yggdrasil Abstract Library; cited here as an example of an uncontrolled design, not as support for the supplement)
A note before you go
This article is educational and is not medical advice. Fibromyalgia is individual, and what a six-week trial in 22 women found cannot tell you what belongs on your plate. If you are considering a significant change to how you eat, particularly one that removes foods, please work it through with a provider who knows your history and your labs. And if your cholesterol is part of why you are reading this, bring the numbers to that conversation rather than deciding from an article.
If this resonates with what you're experiencing and you'd like to explore a naturopathic approach, book a consultation with our clinic.
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