Hordenine (or N,N-dimethyltyramine) is an a phenethylamine alkaloid occurring naturally in grains, barley (Hordeum vulgare L.), and certain grasses. As a supplement hordenine is classified as thermogenic compound and is quickly gaining a reputation as an effective supplement that helps people lose weight.
Is Hordenine Effective as Weight Loss Supplement?
Hordenine is investigated as fat burning supplement, however, research is minimal. It is believed that hordenine helps people lose fat and is also claimed that it is a stimulant of the central nervous system. Hordenine was shown to indirectly act as adrenergic agent that produces its pharmacological effects by liberating norepinephrine from stores . Norepinephrine is stress hormone and neurotransmitter which directly increases heart rate, triggers the release of glucose from energy stores, and increases blood flow to skeletal muscle .
When hordenine (2.0 mg/kg of bodyweight) was intravenously administered to horses a substantial respiratory distress was observed. Hordenine increased respiratory rate by 250%, heart rates were approximately double that of resting values, and caused sweating without changes in basal body temperature or behavior. After 30 minutes of dosing all effects disappeared and animals appeared normal. When horses were dosed orally with 2.0 mg/kg of hordenine no changes in heart rate, respiratory rate, basal body temperature or behaviour. Because of low plasma levels of hordenine after oral administration it appears that it is very difficult to obtain any pharmacological effect. It is highly unlikely that oral hordenine would cause a measurable increase in performance.
Hapke and Strathmann  have shown that hordenine has a positive inotropic effect on the heart, it increases blood pressure and can inhibit gut movements but has no effect upon the psychomotorical behaviour of mice. Same as Frank et al., Hapke and Strathmannalso reported that all effects are short and only possible after high doses which are not to be expected after oral ingestion.
Some people who supplement with hordenine also report reduced appetite. This is not scientifically proven, however, there is one study that reported reduced feeding time in caterpillars .
Most of effects of reported when hordenine was administered by injection were usually not reproduced by oral administration. Furthermore, there are no scientific reports of the effects of hordenine in humans.
Hordenine Side Effects
When supplementing with hordenine side effects such as increased systolic and/or diastolic blood pressure may occur. In most studies, side effects occur only after very large doses and are usually short-lived.
Hapke, H. J., and W. Strathmann. “Pharmacological effects of hordenine.” DTW. Deutsche tierärztliche Wochenschrift 102.6 (1995): 228.
Frank, M., et al. “Hordenine: pharmacology, pharmacokinetics and behavioural effects in the horse.” Equine veterinary journal 22.6 (1990): 437-441.
Bernays, E. A., et al. “Taste sensitivity of insect herbivores to deterrents is greater in specialists than in generalists: a behavioral test of the hypothesis with two closely related caterpillars.” Journal of Chemical Ecology 26.2 (2000): 547-563.