MemoHoney Ingredients: All Six Names, and What Each One Was Tested At

The molecule an enzyme turns straight into nitric oxide, and the one the gut and liver take the biggest cut of.

Nitric oxide synthase converts arginine directly into nitric oxide, a gas that survives seconds and tells the muscle wrapped around a blood vessel to let go. Wider vessel, easier flow. The catch is the journey: swallow arginine and most of it is broken down in the gut wall and the liver before it reaches the circulation at all.

Where the published work sits: Vascular function, pressure and exercise capacity, in humans.

What a trial used: Whole grams a day in the supplement work. One isotope study followed a single labelled meal to see what fraction of it ever became the gas. See a stable-isotope study of dietary arginine.

Arginine bound to alpha-ketoglutarate, two parts to one. A pre-workout ingredient with a mixed record.

Two parts arginine to one part alpha-ketoglutarate, sold on the idea that the salt gets further than plain arginine does. The pharmacokinetic work found the plasma arginine rise it promises; the performance work mostly did not find the performance.

Where the published work sits: Trained young men, lifting and forearm blood flow.

What a trial used: Three servings of 4 g across a day, twelve grams in all, in the trial that tracked what reached the plasma. See the arginine AKG pharmacokinetic trial.

The precursor that slips past the first pass, then becomes arginine at the kidney.

Citrulline avoids the enzymes that strip out most oral arginine, and the kidney converts it to arginine afterwards. Gram for gram it raises blood arginine more reliably than arginine itself, which is the reason a formula aiming at nitric oxide reaches for citrulline at all.

Where the published work sits: Blood flow inside the skull, measured during sprint intervals.

What a trial used: Just under nine grams every day for five consecutive days, in athletes. See the citrulline cerebrovascular trial.

The same citrulline carried on malic acid, and the form most of the sports trials actually used.

Identical citrulline, bound to malic acid rather than hydrochloride. Malate is an intermediate in the cycle cells use to make energy, which is where the second half of the marketing story comes from. Nearly every repeated-sprint and resistance trial in this literature used this form.

Where the published work sits: Repeat sprinting, lifting, and one pilot in older women.

What a trial used: Eight grams daily over three days, and a pilot that set eight against twelve in a single session. See a three-day citrulline malate trial.

The raw material for NAD and NADP, the two electron shuttles every cell runs its energy on.

The body converts niacin into NAD and NADP, which carry electrons through energy metabolism in a neuron exactly as they do everywhere else. Run short of it badly enough and the result is pellagra, whose third classical symptom is dementia. That is a deficiency disease, not an argument for taking more than you need.

Where the published work sits: Observed in a Chicago ageing cohort, which is not a trial.

What a trial used: Ordinary food intakes, tens of milligrams daily. The supplemental ceiling set in the United States is 35 mg. See the Chicago Health and Aging Project analysis.

The slow half of carnosine, an acid buffer that is also present in brain tissue.

Carnosine is two amino acids joined together, and beta-alanine is the one that runs out first. Supplying it is what raises carnosine; the other half is never short. Carnosine buffers acid inside working muscle, and a small imaging trial measured changes in two brain regions in people aged 60 to 80.

Where the published work sits: Work capacity, and a single small scanning study in the over-sixties.

What a trial used: Two point four grams daily in the scanning study, and a band of 3.2 to 6.4 grams across the pooled exercise work. See the beta-alanine brain-imaging trial.