MCT oil

Medium-chain triglycerides carry fatty acids eight to twelve carbons long, mostly caprylic and capric acid. They bypass the usual fat absorption route, entering the portal circulation and reaching the liver directly, where they are oxidised quickly and raise blood ketones within hours. That is the basis for both the weight-management claim and the brain-fuel claim.

The Interventions Testing Program tested MCT oil from 4 months of age in the same cohort as resveratrol, green tea extract, curcumin and oxaloacetic acid. None of the five had a statistically significant effect on lifespan in either sex.

The human weight literature is real but modest. Pooling 13 randomised trials in 749 adults, substituting MCTs for long-chain triglycerides reduced body weight by 0.51 kg, waist circumference by 1.46 cm and hip circumference by 0.79 cm, with consistent reductions in total, subcutaneous and visceral fat and no change in blood lipids. The meta-analysis authors flagged that many trials lacked information for full quality assessment and that commercial bias was detected.

The cognitive claim rests largely on one trial of a proprietary MCT formulation, AC-1202, in 152 people with mild to moderate Alzheimer's disease. It raised beta-hydroxybutyrate and produced a significant difference in ADAS-Cog score at day 45, with the effect concentrated in participants who did not carry the APOE4 allele and largely absent in those who did. Gastrointestinal adverse events were more common on treatment.

So: a fat that changes body composition slightly, raises ketones reliably, and did not change how long a mouse lived.

A lifespan null from this programme is a real, expensive, well-powered finding, and it is narrower than it sounds. What was tested was one concentration in the diet, started at one age, in one mouse strain, with death as the endpoint. A null tells you that this dose, in these animals, did not move that endpoint. It does not tell you the compound is inert, that a different dose would also fail, that the mechanism is wrong, or that the reason people actually take it has been refuted. Those are separate questions and most of them were never asked. The failure mode this site is trying to avoid runs in both directions: treating a mouse lifespan positive as proof that a supplement works, and treating a mouse lifespan null as proof that it does nothing.

MCT oil is a good place to say what the ITP test did and did not cover. It fed the oil to mice from 4 months of age and measured when they died. It did not measure body composition trajectories, cognition, or anything about ketosis, and it certainly did not test the ketogenic diet, which is a different intervention involving carbohydrate restriction rather than an added fat.

So the sentence that survives is narrow: adding MCT oil to mouse chow from young adulthood did not extend life. Everything people actually buy MCT oil for, which is ketone elevation, appetite and body composition, was tested elsewhere, in people, with modest positive results.

The Alzheimer's evidence deserves its own caution. A 1.9 point ADAS-Cog difference at day 45 that concentrates in APOE4 non-carriers is a subgroup finding from a single trial by the product's developer. It was enough to support marketing as a medical food, which is a lower regulatory bar than drug approval, and it has not been replicated at the same scale.

The Interventions Testing Program is funded by the National Institute on Aging and run in parallel at three independent laboratories, in Bar Harbor, Ann Arbor and San Antonio. It uses UM-HET3 mice, a four-way genetic cross, so no result can be an artefact of a single inbred background. Both sexes are studied, cohorts are sized to detect roughly a 10 percent shift in lifespan, compounds are fed in the diet from a stated starting age, and the programme commits in advance to publishing negative results alongside positive ones. That last commitment is why this batch can exist at all: almost no other part of ageing research reliably tells you what did not work.