N=1 After 40

Not run · August 2026

Meldonium

I considered it for endurance, recovery, and body recomposition, then decided that its defining fuel shift solves the wrong problem for my goals. A personal research decision, not medical advice, prescribing, sourcing guidance, or an instruction to copy.

Decision: I did not run meldonium. It reduces long-chain fatty-acid oxidation and increases carbohydrate dependence without demonstrated benefits for fat loss, muscle growth, strength, recovery, or healthy athletic performance.

The Decision

Why I considered it

Meldonium has an unusually strong reputation relative to its healthy-athlete evidence. It was widely used in elite sport, is prohibited by WADA, and has a plausible oxygen-efficiency mechanism. The appealing claims are greater endurance, less fatigue, faster recovery, and cardiovascular protection during hard training.

Why I passed

The mechanism is real, but it is not a general energy upgrade. Meldonium lowers carnitine availability, reduces mitochondrial use of long-chain fatty acids, and shifts fuel selection toward glucose and glycogen. That can be useful when cardiac oxygen supply is the constraint. It is poorly matched to a healthy recomposition goal built around retaining muscle, losing stored fat, and developing fat-oxidation capacity during lower-intensity work.

What the mechanism does not prove

Reduced fat oxidation during a given period does not mean meldonium completely stops fat burning or makes calorie-deficit fat loss impossible. Acute fuel selection and long-term body-fat change are different outcomes. The problem is simpler: meldonium offers no demonstrated recomp benefit that would justify deliberately pushing fuel use away from long-chain fatty acids.

The bodybuilding mismatch

Resistance training already relies heavily on carbohydrate, and sufficient dietary carbohydrate can support that work directly. Pharmacologically lowering carnitine availability does not add a demonstrated hypertrophy, strength, muscle-retention, or recovery advantage. During Zone 2 work, greater carbohydrate dependence may also work against the fat-oxidation and glycogen-sparing capacity I am trying to develop.

What could reopen the decision

I would reconsider if well-controlled studies in healthy trained people showed a meaningful improvement in performance, recovery, or body composition that outweighed the substrate-use tradeoff. Evidence from ischemic cardiac patients, athlete popularity, and prohibited-substance status do not establish that result.

Evidence Review

What it is

Meldonium, often sold under the Mildronate brand, is a prescription cardiovascular metabolic modulator in several European countries. It is a structural analogue of gamma-butyrobetaine, the immediate precursor involved in carnitine synthesis. It is not an anabolic compound, fat burner, or conventional stimulant.

The carnitine mechanism

Meldonium inhibits gamma-butyrobetaine hydroxylase and interacts with the OCTN2 carnitine transporter. Lower carnitine availability limits transport of long-chain fatty acids into mitochondria for beta-oxidation. Energy production consequently shifts toward greater glucose use. The effect is a change in fuel selection, not the creation of additional energy or oxygen.

Why it can help an oxygen-limited heart

Carbohydrate oxidation produces more ATP per unit of oxygen than fatty-acid oxidation. In stable angina or heart failure, where oxygen delivery can limit cardiac work, that trade can be useful. In the 512-person MILSS I trial, 1,000 mg per day added to standard therapy improved bicycle exercise time in patients whose exercise was limited by ischemia. That is disease-specific evidence, not proof of an ergogenic effect in a healthy athlete.

The healthy-athlete evidence

A 2026 sports-performance review found only one controlled meldonium study in healthy trained athletes. It enrolled 20 skiers and biathletes for 15 days, used performance-based rather than random allocation, and began with materially unequal VO2 max values. Its tabulated results did not show a clear benefit and instead included negative trends in aerobic-performance and mood measures. No rigorous human study has demonstrated better recovery, lactate clearance, anaerobic capacity, or training adaptation in healthy athletes.

Safety and practical cost

The authorized product information lists headache, gastrointestinal symptoms, and allergic reactions as common effects, with tachycardia and hypotension reported very rarely. It warns that meldonium can intensify several cardiovascular medicines, including hypotensive agents and peripheral vasodilators, and calls for caution with chronic kidney or liver disease. Long-term safety in healthy athletes remains poorly characterized.

Anti-doping status

Meldonium is prohibited at all times under WADA's metabolic-modulator category. That status does not prove efficacy. Its urinary excretion is also unusually prolonged: small volunteer studies detected it for up to 65 days after one 500 mg dose and up to 117 days after six days of 500 mg twice daily. Detection does not mean pharmacological action lasts that long, but it creates a substantial anti-doping liability.

Sources