Clinical Studies

 Clinical Studies,  References,  and Resources lab tech image

Studies on the immunomodulatory effects of Ashwagandha.
Ziauddin M, Phansalkar N, Patki P, Diwanay S, Patwardhan B.
Medinova Diagnostics Center, Indian Drugs Research Association, Pune, India.
AJ Ethnopharmacol. 1996 Feb;50(2):69-76. PMID: 8866726[Read the Abstract]

Anxiolytic-antidepressant activity of Withania somnifera glycowithanolides: an experimental study.

Bhattacharya SK, Bhattacharya A, Sairam K, Ghosal S.
Department of Pharmacology, Institute of Medical Sciences, Banaras Hindu University
Phytomedicine. 2000 Dec;7(6):463-9. PMID: 11194174 [Read the Abstract]

Search for natural products related to regeneration of the neuronal network.

Tohda C, Kuboyama T, Komatsu K.
Research Center for Ethnomedicines, Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, Japan.
Neurosignals. 2005;14(1-2):34-45 PMID: 15956813 [Read the Abstract]

Withania somnifera (ashwagandha) – monograph.
Altern Med Rev. 2004 Jun;9(2):211-214.
Withania somnifera, also known as ashwagandha, Indian ginseng, or winter cherry, has been an important herb in the Ayurvedic and indigenous medical systems for over 3000 years. Historically, the plant has been used as an aphrodisiac, liver tonic, anti-inflammatory agent,  and more recently to treat asthma, ulcers, insomnia, and senile dementia. Clinical trials and animal research support the use of ashwagandha for anxiety, cognitive and neurological disorders, inflammation, and Parkinson’s disease. Ashwagandha’s chemopreventive properties make it a potentially useful adjunct for patients undergoing radiation and chemotherapy. Ashwaganda is also used therapeutically as an adaptogen for patients with nervous exhaustion, and debility due to stress, and as an immune stimulant in patients with low white blood cell counts.

Relaxation and immunity enhancement effects of gamma-aminobutyric acid ( GABA ) administration in humans.
Biofactors. 2006;26(3):201-8. Department of Research and Development, Pharma Foods International Co. Ltd., Kyoto, Japan.
The effect of orally administrated gamma-aminobutyric acid ( GABA ) on relaxation and immunity during stress has been investigated in humans. Two studies were conducted. The first evaluated the effect of GABA intake by 13 subjects on their brain waves. Electroencephalograms (EEG) were obtained after 3 tests on each volunteer as follows: intake only water, GABA, or L-theanine. After 60 minutes of administration, GABA significantly increases alpha waves and decreases beta waves compared to water or L-theanine. These findings denote that GABA not only induces relaxation but also reduces anxiety. The second study was conducted to see the role of relaxant and anxiolytic effects of GABA intake on immunity in stressed volunteers. Eight acrophobic subjects were divided into 2 groups (placebo and GABA). All subjects were crossing a suspended bridge as a stressful stimulus. Immunoglobulin A (IgA) levels in their saliva were monitored during bridge crossing. Placebo group showed marked decrease of their IgA levels, while GABA group showed significantly higher levels. In conclusion, GABA could work effectively as a natural relaxant and its effects could be seen within 1 hour of its administration to induce relaxation and diminish anxiety. Moreover, GABA administration could enhance immunity under stress conditions.

l-Theanine reduces psychological and physiological stress responses.
Biol Psychol. 2006 Aug 21; Nagoya University Department of Psychology, Chikusa-ku, Nagoya, 464-8601, Japan.
Because the characteristics of l-Theanine suggest that it may influence psychological and physiological states under stress, the present study examined these possible effects in a laboratory setting using a mental arithmetic task as an acute stressor. Twelve participants underwent four separate trials: one in which they took l-Theanine at the start of an experimental procedure, one in which they took l-Theanine midway, and two control trials in which they either took a placebo or nothing. The experimental sessions were performed by double-blind, and the order of them was counterbalanced. The results showed that l-Theanine intake resulted in a reduction in the heart rate (HR) and salivary immunoglobulin A (s-IgA) responses to an acute stress task relative to the placebo control condition. Moreover, analyses of heart rate variability indicated that the reductions in HR and s-IgA were likely attributable to an attenuation of sympathetic nervous activation. Thus, it was suggested that the oral intake of l-Theanine could cause anti-stress effects via the inhibition of cortical neuron excitation.  l-Theanine reduces psychological and physiological stress responses.

Proof of the mysterious efficacy of ginseng: basic and clinical trials: suppression of adrenal medullary function in vitro by ginseng.
J Pharmacol Sci. 2004 Jun;95(2):140-4.
The root of Panax ginseng C.A. MEYER has been reported to have an anti-stress action. Therefore, the effects of ginseng components on functions of adrenal medulla, which is one of the most important organs responsive to stress, were investigated in vitro. First, the components of ginseng were mainly divided into two fractions, that is, the saponin-rich and non-saponin fractions. The saponin-rich fraction greatly reduced the secretion of catecholamines from bovine adrenal chromaffin cells stimulated by acetylcholine (ACh), whereas the non-saponin fraction did not affect it at all. The protopanaxatriol-type saponins inhibited the ACh-evoked secretion much more strongly than the protopanaxadiol-type. On the other hand, the oleanane-type saponin, ginsenoside-Ro, had no such effect. Recent reports have demonstrated that the saponins in ginseng are metabolized and absorbed in digestive tracts following oral administration of ginseng. All of the saponin metabolites greatly reduced the ACh-evoked secretion. M4 was the most effective inhibitor among the metabolites. M4 blocked ACh-induced Na(+) influx and ion inward current into the chromaffin cells and into the Xenopus oocytes expressing human alpha3beta4 nicotinic ACh receptors, respectively, suggesting that the saponin metabolites modulate nicotinic ACh receptors followed by the reduction of catecholamine secretion. It is highly possible that these effects of ginsenosides and their metabolites are associated with the anti-stress action of ginseng.

Lack of behavioural effects after acute tyrosine depletion in healthy volunteers.

J Psychopharmacol. 2005 Jan;19(1):5-11.
Acute dietary l tyrosine depletion has previously been shown to reduce dopamine neurotransmission in both animals and humans. In this study, we investigated the effects of brain dopamine depletion, through acute l-tyrosine and phenylalanine depletion, on plasma prolactin, mood and neuropsychological function in 12 normal subjects. In a randomized, double-blind, cross-over design, subjects received two amino-acid drinks separated by a week, a nutritionally balanced mixture (Bal) and on the other occasion a tyrosine and phenylalanine deficient mixture. The plasma ratio of tyrosine and phenylalanine to the other large neutral amino acids decreased significantly on the tyrosine and phenylalanine deficient mixture and there was an increase in plasma prolactin concentration relative to the balanced drink in the seven subjects for whom results were available for both occasions. Acute tyrosine depletion did not alter mood as measured by visual analogue scale ratings, and measures of memory, attention and behavioural inhibition were also unaffected. Our results are consistent with acute dietary tyrosine depletion causing a reduction in brain dopamine neurotransmission but raise questions about how robust or consistent the effects are on psychological function.

5HTP induced increase in salivary cortisol in panic disorderPanic Disorders. Read more ... » patients and healthy volunteers.

Psychopharmacology (Berl). 2002 Jun;161(4):365-9.
Department of Psychiatry, Institute of Brain and Behaviour, Maastricht University, Maastricht The Netherlands
Hypersensitivity of brain serotonin receptors has been proposed as a causal mechanism in the pathophysiology of panic disorder. This theory can be tested, using serotonergic stimulation of the HPA axis. Up to now, plasma cortisol has generally been used as the outcome measure in such studies. Assessment of salivary cortisol is a non-invasive alternative to measure HPA axis activity. METHOD: Salivary cortisol levels were measured in 24 panic disorder patients and 24 healthy volunteers, following ingestion of 200 mg 5htp or placebo. RESULTS: A significant rise in cortisol was observed in both patients and controls following ingestion of 5htp. No such effects were seen in the placebo condition. CONCLUSION: The results show that 5htp stimulated salivary cortisol is a useful probe of serotonin function in healthy volunteers as well as panic disorder patients, and provide some evidence against a serotonin receptor hypersensitivity in panic disorder.

Acute Rhodiola rosea intake can improve endurance exercise performance.

Int J Sport Nutr Exerc Metab. 2004 Jun;14(3):298-307.
The purpose of this study was to investigate the effect of acute and 4-week Rhodiola rosea intake on physical capacity, muscle strength, speed of limb movement, reaction time, and attention. PHASE I: A double blind placebo-controlled randomized study (n= 24) was performed, consisting of 2 sessions (2 days per session). Day 1: One hour after acute Rhodiola rosea intake (R, 200-mg Rhodiola rosea extract containing 3% rosavin + 1% salidroside plus 500 mg starch) or placebo. Speed of limb movement (plate tapping test), aural and visual reaction time, and the ability to sustain attention were assessed. Day 2: Following the same intake procedure as on day 1, maximal isometric knee-extension torque and endurance exercise capacity were tested. Following a 5-day washout period, the experimental procedure was repeated, with the treatment regimens being switched between groups (session 2). PHASE II: A double blind placebo-controlled study was performed. Subjects underwent sessions 3 and 4, identical to Phase I, separated by a 4-week rhodiola intake, during which subjects ingested 200 mg rhodiola or placebo per day. RESULTS: PHASE I: Compared with placebo, acute rhodiola intake in Phase I increased time to exhaustion from 16 min to 17 min. Accordingly, VO2peak and VCO2peak increased during rhodiola compared to Placebo. Pulmonary ventilation tended to increase more during rhodiola rosea than during P. All other parameters remained unchanged. PHASE II: Four-week rhodiola intake did not alter any of the variables measured. CONCLUSION: Acute Rhodiola rosea intake can improve endurance exercise capacity in young healthy volunteers. This response was not altered by prior daily 4-week Rhodiola intake.

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