Keto and ketones for mitochondria: a new review says the evidence is thin

The ketogenic diet and ketone supplements get a lot of credit for “supporting mitochondria.” A new evidence review from researchers at Yonsei University, published October 2, 2026 in Nutrients, goes looking for the receipts — and finds fewer than the marketing suggests. Proposed mitochondrial mechanisms are “plausible but not established,” most human studies never measured mitochondrial outcomes at all, and the effects that do exist seem to depend on your genes: potential benefit for some mtDNA variant carriers, but possible harm in POLG-related disease and mtDNA-deletion myopathy.

What the review actually found

The authors surveyed human and preclinical evidence on how ketogenic diets and beta-hydroxybutyrate (BHB) — the main ketone body — affect mitochondrial function. Their verdict is notably restrained for a field full of confident claims. In epilepsy, where keto is an established therapy, mitochondrial mechanisms remain unproven as the explanation for benefit. Across the broader literature, they found proposed mechanisms (biogenesis signaling, redox shifts, alternative fueling) plausible but not established, and flagged that most human trials of keto or ketone supplements measured clinical or metabolic endpoints — not mitochondrial ones. In other words, the mitochondrial story is largely inferred, not measured.

The genotype warning

The most clinically important finding is the genotype dependence. For some carriers of mtDNA variants, the review sees potential benefit. But it flags possible harm in POLG-related disease and in mtDNA-deletion myopathy — conditions where forcing cells onto fat oxidation could backfire. The authors present this as a precaution from limited data, not a new trial result: the right framing is “may carry risk in certain genetic mitochondrial diseases,” and anyone with a diagnosed mitochondrial disorder should discuss dietary changes with their specialist. This is exactly the kind of nuance our evidence labels exist for.

What this means for the healthy longevity crowd

If you're healthy and considering keto or BHB supplements for “mitochondrial support,” this review says: the mitochondrial benefit is plausible but unproven in humans, and the evidence base is thinner than the claims. That's not a verdict that keto is useless — epilepsy alone shows it does something real — but it separates what keto is established for from what is marketing extrapolation.

Where the evidence stands

• Established: The ketogenic diet is an established therapy for drug-resistant epilepsy.
• Preliminary: Proposed mitochondrial mechanisms (biogenesis, redox, fuel switching) are plausible but not established; most human keto/BHB studies never measured mitochondrial outcomes.
• Contested: The flagged risk in POLG-related disease and mtDNA-deletion myopathy is a precaution drawn from limited data, not a trial finding.
• Absent: No large human trial has shown that keto or BHB supplements improve mitochondrial function in healthy people.