Valerian (herb)

Valerian (plant)
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Asterids
Order:	Dipsacales
Family:	Valerianaceae
Genus:	Valeriana
Species:	V. officinalis
Binomial name
Valeriana officinalis L. & Maillefer

Valerian (Valeriana officinalis, Valerianaceae) is a hardy perennial flowering plant, with heads of sweetly scented pink or white flowers. The flowers are in bloom in the northern hemisphere from June to September. Valerian was used as a perfume in the sixteenth century.

Native to Europe and parts of Asia, Valerian has been introduced into North America. It is consumed as food by the larvae of some Lepidoptera (butterfly and moth) species including Grey Pug.

Other names used for this plant include garden valerian (to distinguish it from other Valeriana species), garden heliotrope (although not related to Heliotropium) and all-heal. The garden flower red valerian is also sometimes referred to as "valerian" but is a different species, from the same family but not particularly closely related.

Valerian, in pharmacology and phytotherapic medicine, is the name of a herb or dietary supplement prepared from roots of the plant, which, after maceration, trituration, dehydration processes, are conveniently packaged, usually into capsules, that may be used for certain effects including sedation and anxiolytic effect.

The amino acid valine is named after this plant.

History

Valerian has been used as a medicinal herb since at least the time of ancient Greece and Rome. Hippocrates described its properties, and Galen later prescribed it as a remedy for insomnia. In medieval Sweden, it was sometimes placed in the wedding clothes of the groom to ward off the "envy" of the elves^[1]. Valerian can be consumed as a tea.

Etymology

According to the Oxford English Dictionary (second edition 1989), valerian is derived from a Latin adjectival form of the personal name Valerius.

Valerian extract

Biochemical composition

Known pharmacologically active compounds detected in valerian extract are:

• Alkaloids: actinidine, catinine, valerianine, and valerine
• Isovaleramide
• Gamma-aminobutyric acid (GABA)
• Valeric acid
• Valepotriates, acevaltrate, isovaltrate and valtrate
• Volatile oil containing active sesquiterpenes (acetoxyvalerenic acid, valerenic acid)
• Flavanones such as hesperidin, 6-methylapigenin and linarin

Mechanism of action

Because of valerian's historical use as a sedative, anti-convulsant, migraine treatment and pain reliever, most basic science research has been directed at the interaction of valerian constituents with the GABA neurotransmitter receptor system. These studies remain inconclusive and all require independent replication. The mechanism of action of valerian in general, as a mild sedative in particular, remains unknown. Valerian extracts appear to have some affinity for the GABA_A receptor, a class of receptors on which benzodiazepines are known to act.^[2][3]

Valerian also contains isovaltrate, which has been shown to be an inverse agonist for adenosine A₁ receptor sites.^[4] This action likely does not contribute to the herb's sedative effects, which would be expected from an agonist, rather than an inverse agonist, at this particular binding site. Hydrophilic extractions of the herb commonly sold over-the-counter, however, probably do not contain significant amounts of isovaltrate (according to the paper cited previously).

Preparation

Valeriana officinalis

The chief constituent of Valerian is a yellowish-green to brownish-yellow oil which is present in the dried root varying from 0.5 to 2 percent though an average yield rarely exceeds 0.8 percent. This variation in quantity is partly explained by location: a dry, stony soil, yielding a root richer in oil than one that is moist and fertile.^[5] The volatile oils that form the active ingredient are extremely pungent, somewhat reminiscent of well-matured cheese. Valerian tea should not be prepared with boiling water, as this may drive off the lighter oils.

Medicinal use

Valerian is used for insomnia and other disorders as an alternative to benzodiazepine drugs. A sedative for nervous tension, hysteria, excitability, stress and intestinal colic or cramps.^[6][7][8][9] However some of these research studies have shown it to be ineffective in this use. A recent article states, "Most studies found no significant differences between valerian and placebo either in healthy individuals or in persons with general sleep disturbance or insomnia." ^[10]

In the United States Valerian is sold as a nutritional supplement. Therapeutic use has increased as dietary supplements have gained in popularity, especially after the Dietary Supplement Health and Education Act was passed in 1994. This law allowed the distribution of many agents as over-the-counter supplements, and therefore allowed them to bypass the regulatory requirements of the Food and Drug Administration (FDA).

Despite the above mentioned studies finding valerian ineffective as an alternative for benzodiazepines, valerian is used against sleeping disorders, restlessness and anxiety, and as a muscle relaxant. Valerian often seems only to work when taken over longer periods (several weeks), though many users find that it takes effect immediately. Some studies have demonstrated that valerian extracts interact with the GABA receptors. Valerian is also used traditionally to treat gastrointestinal pain and irritable bowel syndrome. However, long term safety studies are missing. Valerian is sometimes recommended as a first-line treatment when benefit-risk analysis dictates. Valerian is often indicated as transition medication when discontinuing benzodiazepines.

Valerian has uses in herbal medicine as a sedative. The main current use of valerian is as a remedy for insomnia, with a recent meta-analysis providing some evidence of effectiveness.^[11] It has been recommended for epilepsy but that is not supported by research (although valproic acid—an analogue of one of Valerian's constituents, valeric acid—is used as an anticonvulsant and mood-stabilizing drug). Valerian root generally does not lose effectiveness over time.

While shown to be an effective remedy for the reduction of anxiety, it has also been reported to cause agitation, headaches and night terrors in some individuals. This may be due to the fact that some people lack a digestive conversion property necessary to effectively break down Valerian. One study found that valerian tends to sedate the agitated person and stimulate the fatigued person, bringing about a balancing effect on the system.^[12]

Oral forms, usage and adverse effects

Oral forms

Oral forms are available in both standardized and unstandardized forms. Standardized products may be preferable considering the wide variation of the chemicals in the dried root, as noted above. When standardized it is done so as a percentage of valerenic acid or valeric acid.

Dosage

Dosage is difficult to determine due to the lack of standardization and variability in available forms. Typical dosages of the crude herb vary from 2-10 grams per day. Valerian root is non-toxic but may cause side effects in large excessive doses such as giddiness and disorientation.

Adverse effects

Few adverse events attributable to valerian have been reported.^[6] Large doses or chronic use may result in stomach ache, apathy, and a feeling of mental dullness or mild depression. Because of the herb's tranquilizer properties, it may cause dizziness or drowsiness, effects that should be considered before driving or operating heavy or hazardous equipment.^[13] In some individuals, valerian can cause stomach ache, anxiety, and night terrors (see above). Though some people like the earthy scent, many others find it unpleasant. In rare cases, Valerian may cause an allergic reaction, typically as a skin rash, hives, or difficulty breathing.^[13]

Because the compounds in valerian produce central nervous system depression, they should not be used with other depressants, such as alcohol, benzodiazepines, barbiturates, or opiates.^[14][15][16] Moreover, nonpregnant adult human hepatotoxicity has been associated with short-term use (i.e., a few days to several months) of herbal preparations containing valerian ^[17]. Long-term use in a male has also been associated with benzodiazepine-like withdrawal symptoms resulting in cardiac complications and delirium ^[18].

The very limited animal and human data do not allow a conclusion as to the safety of valerian during pregnancy. Moreover, as a natural, unregulated product, the concentration, contents, and presence of contaminants in valerian preparations cannot be easily determined. Because of this uncertainty and the potential for cytotoxicity in the fetus and hepatotoxicity in the mother, the product should be avoided during pregnancy. Other authors have arrived at the same conclusion ^[14][15]. The risk to a fetus from short-term or inadvertent use during any part of gestation, however, is probably low, if it exists at all.

Effect on cats and rats

An unusual feature of valerian is that the essential oil of valerian root is a cat attractant similar to catnip. The active compound in valerian for this is actinidine. Cat attractants might mimic the odor of cat urine which is caused by 3-mercapto-3-methylbutan-1-ol (MMB). Anecdotes state that valerian is also attractive to rats, so much so that it had been used to bait traps. Some versions of the legend of the Pied Piper of Hamelin have him using valerian, as well as his pipes, to attract the rats.^[5] This might be related to the change of aversion into attraction to cat urine in rats infected with the parasite Toxoplasma gondii.^[19]

Notes

See also

• Nepeta
• Valine
• Sedative
• Valeric acid
• Valeriana
• Sweet Valerian
• Tisane
• Valerianaceae
• Insomnia
• Red Valerian
• Spikenard
• ATC code N05
• Valeriana
• Köhler's Medicinal Plants
• Anxiety
• Herbalism
• Special Herbs, Vols. 4, 5 & 6
• Special Herbs, Vols. 5 & 6
• Orvietan

External links

• Valerian at AAFP