Mitochondria are the structures inside your cells that convert food and oxygen into usable energy. In people with chronic fatigue syndrome, researchers have repeatedly measured lower mitochondrial metabolism, reduced ATP synthesis and elevated oxidative stress. That much is real and reproducible. But the most honest summary of the field, from a 2025 review, is this: whether mitochondrial dysfunction is a cause of the illness or a consequence of it is currently unclear. That distinction matters enormously, and almost nobody selling you a mitochondrial supplement will mention it.
Studies of people with ME/CFS have found lower mitochondrial metabolism and a reduced ATP synthesis rate in skeletal muscle, along with increased intracellular acidosis consistent with a shift toward glycolysis, the less efficient backup pathway cells use when oxidative energy production falters (Syed et al., 2025).
The same review documents increased oxidative stress, measured through elevated lipid peroxidation products, protein carbonyls and oxidised DNA bases. Oxidative stress is essentially cellular wear from an imbalance between damaging reactive molecules and the antioxidant systems meant to contain them.
A separate study measured cellular bioenergetics against illness severity and found something counterintuitive: mitochondrial function did not correlate with how severe the illness was, and even moderately affected patients showed impaired bioenergetic function. What separated the severely affected was an additional problem with glycolysis on top of the mitochondrial impairment (Tomas et al., 2020).
That is a genuinely useful finding. It means impairment is present early, and it means something other than mitochondrial capacity alone determines how sick a person becomes.
Search “mitochondrial dysfunction” and you will find confident claims that damaged mitochondria are the root cause of chronic fatigue, followed by a supplement recommendation.
The literature does not support that confidence.
The 2025 review notes that experimental studies have used different tissue types and different techniques, with sometimes contrasting or negative findings, though a detectable pattern of dysfunction generally emerges. The authors explicitly decline to classify this as mitochondrial disease, because no specific genetic mutations explaining the dysfunction have been identified (Syed et al., 2025).
A broader review across multiple fatiguing conditions reached a similar conclusion, finding potential relationships but noting the results were confounded by the use of multiple definitions of fatigue and drawn largely from cross-sectional studies (Filler et al., 2014).
So the accurate statement is narrower than the marketing: mitochondrial abnormalities are consistently detectable in this population, their causal role is unresolved, and treating them is not the same as treating the disease.
If causation is unclear, why care at all?
Because the functional consequence is measurable and severe. In a controlled two-day exercise test, people with ME/CFS took an average of 12.7 days to recover while sedentary healthy controls took 2.1 days (Moore et al., 2023). Whatever is happening at the cellular level, the body’s capacity to produce and restore energy after exertion is genuinely different.
That delayed, disproportionate crash after ordinary activity is its own clinical phenomenon with its own diagnostic significance. It is covered in full on post-exertional malaise.
The practical implication is about sequencing. If a patient’s cells are struggling to produce energy, adding an aggressive antimicrobial protocol on top of that is asking a depleted system to absorb more stress. That is a common reason people crash during treatment, and it is the reasoning behind building the body before going after the pathogen.
Several things plausibly contribute, and most patients have more than one.
Chronic infection. Persistent immune activation and inflammation impose ongoing oxidative stress. Patients with chronic Lyme disease symptoms frequently show the fatigue pattern associated with impaired energy production.
Mold and mycotoxin exposure. A recognized driver of inflammatory and oxidative burden, and one of the most commonly missed. See mold exposure and fatigue.
Nutrient depletion. The electron transport chain depends on specific cofactors. Coenzyme Q10 is the clearest example: it shuttles electrons within the chain, and low levels were the most consistent finding associated with fatigue across the conditions reviewed (Filler et al., 2014).
Prolonged medication exposure. Some drug classes affect mitochondrial function directly.
Sustained physiological stress. Long illness, poor sleep and nervous system dysregulation all impose metabolic cost.
There is no single clean test for mitochondrial function in routine clinical practice, and any clinic promising one is overstating what is available.
What can reasonably be evaluated:
This is the diagnostic groundwork of a full chronic fatigue and pain evaluation.
Some peptides are being studied for mitochondrial support. SS-31, also called elamipretide, targets cardiolipin in the inner mitochondrial membrane, and it received FDA accelerated approval in 2025 for Barth syndrome, a rare genetic mitochondrial disorder. That approval is specific to Barth syndrome and does not extend to chronic fatigue, Lyme disease or mold illness, where its use would be off-label and investigational. The detail is covered on the SS-31 peptide page.
Anyone presenting peptides as a proven mitochondrial fix for chronic illness is going beyond the evidence.
Unknown. Abnormalities are consistently measurable, but a 2025 review states plainly that whether the dysfunction is a cause or an effect of the underlying disease is currently unclear.
No. Classic mitochondrial disease is genetic. In ME/CFS no specific mutations explaining the dysfunction have been identified, and researchers deliberately avoid that classification.
Low coenzyme Q10 is consistently associated with fatigue, so correcting a genuine deficiency is reasonable. But correcting a nutrient level is not the same as curing the illness, and results vary considerably between people. Any supplement plan should be guided by testing and by a clinician who knows your full picture.
Apparently not. One study found mitochondrial function did not correlate with disease severity, and even moderately affected patients showed impairment.
Some people improve substantially when underlying drivers such as infection, mold exposure or nutrient depletion are addressed. Others improve less. Nobody can honestly promise reversal.
Be careful. In people who experience delayed crashes after exertion, pushing past that threshold reliably makes things worse rather than building capacity.
Every source below was checked against the specific claim it supports.
Written and medically reviewed by Dr. Diane Mueller, ND, LAc, DAOM. Dr. Mueller is a naturopathic doctor and licensed acupuncturist who has worked with more than 1,000 patients across the six states where she is licensed. Read more about Dr. Mueller.
Last reviewed: August 21, 2026
If exhaustion has not responded to the explanations you have been given, a full evaluation can look at what is actually driving it. You can book an initial visit.
This page is for general educational purposes and is not medical advice. It does not create a doctor and patient relationship, and it is not a substitute for diagnosis or treatment from your own clinician. Always talk with a qualified healthcare provider before starting, stopping, or changing any treatment or supplement. If you are experiencing a medical emergency, call 911 or go to the nearest emergency room.
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