Scientific Name(s): Centranthus ruber L., Valeriana officinalis L., Valeriana sambucifolia Mik., Valeriana wallichi DC.
Common Name(s): Baldrian, Cat's love, Cat's valerian, Garden heliotrope, Garden valerian, Kesso root, Radix valerianae, St. George's herb, Valerian, Valerian fragrant, Vandal root
Members of the genus Valeriana are herbaceous perennials widely distributed in the temperate regions of North America, Europe, and Asia. The hollow stemmed plant can grow up to 2 m and is branched at the terminal end with opposite leaves and small white or pink flowers. Fruits are oblong, 4-ridged, and single seeded. Of approximately 200 known species, the Eurasian Vakeruaba officinalis is most often cultivated for medicinal use. The dried rhizome used in valerian extracts has numerous rootlets and one or more stolons and contains a volatile oil with a distinctive, unpleasant odor.1, 2, 3, 4
Valerian has been used in Unani, Ayurvedic, and traditional Chinese health systems and for homeopathic uses for cardiotonic and sedative properties, as well as in epilepsy, hysteria, and other conditions.5 Despite its odor, valerian was considered a perfume in 16th-century Europe. The tincture has been used for its sedative properties for centuries; it is still widely used in France, Germany, and Switzerland as a sleep aid.6 Other uses attributed to valerian include a digestive aid, emmenagogue, and antiperspirant.2
Three distinct classes of compounds have been associated with the sedative properties of valerian. These compounds consist of mono- and sesquiterpenes and iridoid triesters (valepotriates). Other compounds identified include flavonoids, triterpenes, lignans, and alkaloids. The composition of the volatile oil varies markedly between cultivars and species, as does the amount and relative proportion of cytotoxic valepotriates, making chemical standardization difficult but highly desirable.
The most important sesquiterpenes include valerenic acid and its congeners, although in Japan, V. officinalis var. latifolia, kessyl alcohols, and esters predominate. Valtrate, acevaltrate, and didrovaltrate are the most important iridoids; European valerian extracts were formerly standardized on these unstable compounds, which have a short shelf life in the tincture.
The alkaloid concentration in roots and rhizomes is low, usually less than 0.2%. The aqueous extract of valerian contains substantial quantities of gamma-aminobutyric acid (GABA); however, it is doubtful whether GABA penetrates the blood-brain barrier.
Many analytical high performance liquid chromatographic methods have been developed for the sesquiterpenes and valepotriates. The seasonal variation in valerenic acids and valepotriates has been studied. Tissue culture of valerian species has focused on the production of valepotriates.2, 7, 8, 9, 10, 11, 12
Uses and Pharmacology
Several in vitro and animal experiments have attempted to elucidate the mechanism of action for various valerian compounds. Many of these experiments provide contradictory evidence, but most attribute the observed actions of valerian extracts to central actions on GABA, serotonin, and adenosine receptors. The sesquiterpene valerenic acid and its derivatives and the valepotriates are generally thought to be the active constituents; however, wide variations in the composition of commercial preparations make interpretation of clinical data difficult.9, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22
Both a meta-analysis and systematic review comment on the lack of trials meeting inclusion criteria because of poor methodology, the use of healthy volunteers, and combination therapies.14, 23 One small, pilot clinical trial meeting inclusion criteria evaluated the effect of valepotriates 150 mg per day in 3 divided doses over 4 weeks in generalized anxiety disorder.24 No difference was demonstrated for the standardized valerian extract versus placebo or diazepam 20 mg.24 Until studies with a larger sample size are conducted, the efficacy of valerian remains unclear.14, 23
Another review of clinical trials and in vitro experiments suggests the effect of valerian may be because of anxiolytic action, rather than sedation.13 This was demonstrated by a laboratory experiment with rodents that found no decrease in spontaneous locomotor activity and no increase in ether-induced anesthesia, but did find a reduction in anxiety using the elevated plus maize test.25 Older experiments in rodents found conflicting results for spontaneous motor activity.22, 26
One randomized, controlled clinical trial evaluated the use of valerian compared with identical placebo in college-age women for management of dysmenorrhea symptoms. Both valerian and placebo produced significant reductions in pain compared with baseline scores, but the pain reduction seen with valerian was significantly larger compared with placebo. Severity of systemic symptoms was reduced with both valerian and placebo, with valerian’s scores nonsignificantly lower than placebo scores for all symptoms except syncope. Valerian’s reduction of syncope was significantly lower compared with placebo.57 A Cochrane systematic review and meta-analysis of dietary supplements for dysmenorrhea identified only low or very low quality studies with very small sample sizes. Very limited evidence of effectiveness was found for the treatment of primary dysmenorrhea with valerian 255 mg root powder 3 times daily compared to placebo or no treatment (1 randomized clinical trial, n = 100); however, no difference was identified between valerian 250 mg compared to mefenamic acid 250 mg (1 randomized clinical trial, n = 99).61
A meta-analysis of studies published through September, 2008 evaluated data from eighteen randomized controlled trials (>1300 patients). The authors did not find significant benefits for sleep latency time or sleep quality as rated by visual analogue scale. Patients’ subjective rating of sleep quality did significantly favor valerian.30 Reviews of older trials not included in the meta-analysis found valerian to exert an effect similar to the benzodiazepines, but a number of negative trials are also described.5, 13
Two additional studies, one in oncology patients, and the other in postmenopausal females, were published after the meta-analysis mentioned above. The study in cancer patients was a phase III trial that found no significant benefit for insomnia, but valerian did provide statistically significant improvements for the patient-rated, secondary outcomes of fatigue and mood.31 The study in postmenopausal women found a significant improvement in patient-rated sleep quality with valerian compared with placebo.32 Valerian 160 mg combined with lemon balm 80 mg taken for 1 month also significantly improved sleep quality compared with baseline (P = 0.001) and placebo (P = 0.0001) in women experiencing sleep disruption/disorders subsequent to natural menopause. The placebo group in this randomized trial (n = 100) also experienced a significant improvement in sleep scores compared with baseline (P = 0.0001). No adverse events were reported.59
The American Academy of Sleep Medicine clinical practice guideline for the pharmacologic treatment for chronic insomnia (2017) suggests that valerian not be used as a treatment for sleep onset or sleep maintenance insomnia (versus no treatment) in adults. Benefits are considered to be approximately equal to risks (Weak; Low).54
A randomized, double-blind, placebo-controlled pilot study evaluated valerian in a small group of patients who qualified for inclusion according to DSM-IV-TR criteria for obsessive-compulsive disorder, and Yale-Brown Obsessive Compulsive Scale (Y-BOCS) scores 21 or higher. The valerian group had significantly lower Y-BOCS scores beginning 4 weeks after study initiation, and this significant difference continued through the end of study at week 8. Somnolence was reported more frequently in the valerian group.58
Postoperative cognitive dysfunction
Cognitive dysfunction has become a common complication after cardiac surgery since the introduction of cardiopulmonary bypass (CPB) in the 1950s and leads to increased length of hospital stay, costs, risk of dementia, and mortality. Mechanisms involved include acute inflammation and decreased serotonin levels. A double-blind, randomized, placebo-controlled trial enrolled 61 adult Iranians who were candidates for coronary artery bypass surgery using CPB to evaluate the effect of V. officinalis (530 mg root extract every 12 hours × 8 weeks) on the prevention of postoperative cognitive dysfunction. Cognitive function was assessed using the Mini-Mental State Examination at baseline, 10 days postoperation, and 60 days postoperation. Patients receiving valerian had reduced odds of cognitive dysfunction compared to placebo based on a generalized estimation equation (estimate, −2.2; odds ratio, 0.108; 95% confidence interval, 0.022 to 0.545).60
Restless legs syndrome
Guidelines have been published regarding the use of valerian in restless legs syndrome (RLS). A joint European task force developed evidence-based guidelines on the management of RLS (2012) and stated that a low quality study with valerian failed to demonstrate efficacy in the treatment of RLS symptoms or sleep.55 Likewise, an American Academy of Sleep Medicine evidence-based guideline (2012) determined there is insufficient evidence at present to evaluate the use of valerian for RLS based on one small controlled trial.56
The valepotriates, isovaltrate, and valtrate, along with valerenone, had antispasmodic effects in isolated guinea pig ileum and other smooth muscle preparations.33
Valerian had no effect on haloperidol-induced orofacial dyskinesia in rats.34
Oral administration of valerian root extracts was protective against vasopressin-induced coronary spasms and pressor response in guinea pigs.7 In the same experiment, bronchial resistance was reduced in both histamine- and antigen-induced bronchospasm.7
In a triple-blind, randomized, placebo-controlled study that enrolled 60 postmenopausal Iranian women, administration of valerian 530 mg twice daily for 2 months significantly reduced severity (50% none, 40% mild; P=0.02) and frequency (mean diff, −3/day; P=0.03) of hot flushes compared to placebo (0% none, 30% mild and +0.26/day, respectively). Valerian was well tolerated an no side effects were reported.63
A dose of a commercial preparations of valerian extract 600 mg in healthy subjects peaked at 30 minutes to 2 hours, with an elimination half-life of 1.1 ± 0.6 hours, and the marker valerenic acid was in the serum for at least 5 hours after dosing.35
A clinical trial evaluating valerian as an anxiolytic used valeprotriates 150 mg in 3 divided doses for 4 weeks.24 Other trials have used valerian dried herb 0.5 to 2 g, extract 0.5 to 2 mL, and tincture 2 to 4 mL.14
Valerian extract 400 to 600 mg taken 1 hour before bedtime for 2 to 4 weeks has been used in clinical trials evaluating valerian in insomnia.13, 31, 32 A study conducted in children with insomnia (mean age, 11 years) used valerian extract 20 mg/kg body weight at night for 2 weeks. No adverse reactions were noted at this dosage; however, results were inconclusive.6, 36 Studies have consistently found no effect for a single dose of valerian in improving sleep latency or quality.27, 28, 29
Valerian extract up to 1,215 mg has been used as a sedative, but clinical trials have not established an optimal dose, and issues of standardization of content and preparation quality have been raised.6, 13 Many commercial preparations exist either as valerian alone or in combination with other compounds.
Pregnancy / Lactation
Despite common use without apparent harm during pregnancy, the use of valerian preparations in pregnancy and lactation cannot be supported without evidence of safety. Widespread differences in dosages, duration, and preparations exist, and the stage of pregnancy may be a factor.37 Valerian is reported in the Complete German Commission E Monographs to stimulate uterine contractions.38 Information regarding safety and efficacy in pregnancy and lactation is lacking.
Valerian has been classified as GRAS in the United States for food use; extracts and the root oil are used as flavorings in foods and beverages.13
Generally, clinical studies have found that valerian has a wide margin of safety, is devoid of adverse effects, and has fewer adverse reactions than positive control drugs, such as diazepam. Headache and diarrhea have been reported in clinical trials, but hangover is seldom reported.5, 6, 13, 24, 30, 31, 32
An intentional overdose has been reported, in which 20 times the recommended dose was ingested; the patient experienced mild symptoms that resolved within 24 hours.42 A case of withdrawal after chronic use of valerian has been reported; however, the complex nature of the patient's medical history provides weak evidence of valerian's role.43 Farmers growing valerian were evaluated for adverse reactions, with few notable effects observed.44
Hepatotoxicity associated with valerian use was first reported in 1989. Six cases have been reported in women, all of whom reported marked improvement or normalization of liver function tests over 1 to 19 months after valerian discontinuation. However, one case of severe acute hepatitis refractory to improvement subsequent to valerian discontinuation was reported in a 57-year-old man. He had taken 2 g/day of valerian for 3 days and developed worsening liver function over the following 4 weeks. He was successfully treated with oral prednisolone 50 mg daily.62
Concern was raised following the discovery that valepotriates are mutagenic in the Ames assay; however, their poor bioavailability and hepatic detoxification makes them a dubious source of toxicity for patients.2, 45 The cytotoxicity of baldrinal compounds (metabolites of the valepotriates) is higher in vivo than in vitro because they are more readily absorbed, and these metabolites have been detected in commercial preparations.2
No teratogenicity or overt toxicity of valepotriate compounds was found in rodents in 2 different studies.2, 13, 46 Mice receiving doses of valerian more than 1 g/kg by oral and intraperitoneal routes have experienced ataxia, muscle relaxation, and hypothermia.47
No evidence of hepatitis was observed following consumption of oral valerian at average dosages of 2.5 g/day for 4 years.46
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