Active constituents
Rhodiola species contain a range of antioxidant compounds, including p-tyrosol, organic acids (gallic acid, caffeic acid, and chlorogenic acid), and flavonoids (catechins and roanthocyanidins).
The stimulating and adaptogenic properties of Rhodiola rosea are attributed to p-tyrosol, salidroside (synonym: rhodioloside and rhodosin), rhodioniside, rhodiolin, rosin, rosavin, rosarin, and rosiridin.1,4 Rosavin is the constituent currently selected for standardization of extracts.
p-Tyrosol has been shown to be readily and dose-dependently absorbed after an oral dose;6,7 however, pharmacokinetic data on the other adaptogenic compounds found in Rhodiola rosea is unavailable.
Mechanisms of Action
The adaptogenic properties, cardiopulmonary protective effects, and central nervous system activities of Rhodiola rosea have been attributed primarily to its ability to influence levels and activity of biogenic monoamines such as serotonin, dopamine, and norepinephrine in the cerebral cortex, brain stem, and hypothalamus. It is believed the changes in monoamine levels are due to inhibition of the activity of enzymes responsible for monoamine degradation and facilitation of neurotransmitter transport within the brain.
In addition to these central effects, Rhodiola has been reported to prevent both catecholamine release and subsequent cyclic AMP elevation in the myocardium, and the depletion of adrenal catecholamines induced by acute stress.
Rhodiola’s adaptogenic activity might also be secondary to induction of opioid peptide biosynthesis and through the activation of both central and peripheral opioid receptors.
Dosage
Dosage varies depending upon standardization. For chronic administration, a daily dose of 360-600 mg Rhodiola extract standardized for 1% rosavin, 180-300 mg of an extract standardized for 2% rosavin, or 100-170 mg of an extract standardized for 3.6% rosavin is suggested. Administration is normally begun several weeks prior to a period of expected increased physiological, chemical, or biological stress, and continued throughout the duration of the challenging event or activity. When using Rhodiola rosea as a single dose for acute purposes (e.g., for an exam or athletic competition), the suggested dose is three times the dose used for chronic supplementation. Rhodiola rosea has been administered for periods ranging from as little as one day (acute administration) up to four months. Until more specific information is available, a dosing regimen following the established patterns used with other plant adaptogens - with periodic intervals of abstinence - seems warranted when Rhodiola rosea is being used chronically.