Black ginger

Black ginger also known as Kaempferia parviflora (Zingiberaceae family), “Thai ginseng”, Thai black ginger or in Thai as “Krachaidum”, is a Thai ginger species with deep purple-colored rhizomes (roots) that has traditionally been used as food and a folk medicine for more than 1000 years in Thailand . Kaempferia parviflora is found in tropical areas such as Malaysia, Sumatra, Borneo Island, and Thailand. Among the Hmong hill tribe, Kaempferia parviflora is widely believed to reduce perceived effort, improve physical work capacity, and prolong hill trekking . The dried Kaempferia parviflora root is generally pulverized and used as tea bags, while the fresh Kaempferia parviflora root is utilized to brew wine. The wine preparation is increasingly used in Thailand as a tonic and as an aphrodisiac . Black ginger supplement has been made into various preparations such as medicinal liquor or liquor plus honey, pills (powdered Kaempferia parviflora root with honey), capsules and tablets. Black ginger or Kaempferia parviflora has been long term used in Thai traditional medicine for treating various ailments including to cure allergy , anti-depressant, asthma, fatigue, weakness, impotence, gout, colic disorder, diarrhea, dysentery , peptic ulcer  and lower blood sugar in diabetes . In addition, it is also used as longevity promoting substance and as nerve tonic. A large number of recent studies have demonstrated the biological activities of black ginger extract (Kaempferia parviflora extract) contained numerous flavonoids , methoxyflavones , phenolic glycosides and terpenoids , which was previously reported to possess antioxidant activity , cardioprotective , aphrodisiac , anticholinesterase , anti-inflammatory , anti-obesity and antimutagenic , neuroprotective, and cognitive-enhancing properties . Kaempferia parviflora extract has been shown to improve physical fitness performance in clinical studies . The anti-oxidative activity of Kaempferia parviflora extract has been reported to exhibit antimalarial, antiviral, antimycobacterial and antibacterial anti-gastric ulcer activities . Kaempferia parviflora extract has also exhibited antitumor activity against Hela human cervical and SKOV3 ovarian cancer cells .

According to the previous reports by Wongsrikaew et al.  and Mekjaruskul et al. , typical high-performance liquid chromatography of Kaempferia parviflora root ethanol extract were found to have 5,7-dimethoxyflavone (DMF), 3,5,7,3′,4′-pentamethoxyflavone (PMF), and 5,7,4′-trimethoxyflavone (TMF) as major phytochemicals. These three molecules have a common structure, which comprises two methoxy groups at C-5 and C-7 of the A ring in polymethoxyflavones (Figure 2). In an in vitro study, methoxyflavone was examined for its inhibitory activities against nitric oxide production. Compound 5 (5-hydroxy-3,7,30,40-tetramethoxyflavone) exhibited the highest activity, followed by compounds 4 (5-hydroxy-7,40-dimethoxyflavone) and 3 (5-hydroxy-3,7,40-trimethoxyflavone), whereas other compounds possessed moderate or weak activity . In addition, more than 20 chemically identifiable constituents have been reported to have potent pharmacological effects . For example, flavonoids contained in Kaempferia parviflora root extract was reported to possess antioxidant activity, neuroprotective effects, and cognition-enhancing effects.21 Methoxyflavone substances in Kaempferia parviflora showed an inhibitory effect of phosphodiesterase types 5 and 6, which enhanced sexual performance . For antimicrobial activity, 5,7,4′-trimethoxyflavone (TMF) and 5,7,3′,4′-tetramethoxyflavone exhibited antiplasmodial activity against Plasmodium falciparum, and 3,5,7,4′-tetramethoxyflavone showed antifungal activity against Candida albicans  . For cholinesterase inhibitory effect, Kaempferia parviflora showed the potential inhibitors toward acetylcholinesterase and butyrylcholinesterase, which may be of great interest to be considered as a treatment agent for Alzheimer’s disease  .

Figure 1. Kaempferia parviflora bioactive compounds

Footnote: The main structure of methoxyflavone includes benzene A ring with 2 substituent groups at positions 5 and 7, an aromatic B ring with 2 substituent groups at positions 3′ and 4′, and C ring with a substituent group linking on position 3. The substituent groups might be -H, -OH, or -OCH3.

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Figure 2. Chemical structures of methoxyflavones

Footnote: Chemical structures of polymethoxyflavones. Structures of (A) 5,7-methoxyflavone (DMF), (B) 5,7,4′-trimetholxyflavone (TMF), and (C) 3,5,7,3′,4′-pentamethoxyflavone (PMF).

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Kaempferia parviflora benefits

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A systematic review on clinical effects of Kaempferia parviflora has shown positive benefits, but it is inconclusive due to small studies included . Modern research technologies have demonstrated that Kaempferia parviflora can suppress body weight gain, inhibit lipid accumulation, and prevent from pathological changes resulted by insulin resistance, fatty liver, and hypertension . The weight gain may be obtained by the imbalance between energy expenditure and energy intake. brown adipose tissue plays a crucial role in controlling the whole-body energy expenditure and body fatness. The ethanol extract of Kaempferia parviflora at the dose of 100 mg causes a significant increase in whole-body energy expenditure by recruiting brown adipose tissue in male volunteers aged 21-29 in Japan .

In Mong hill tribe in Thailand, Kaempferia parviflora is believed to enhance physical work capacity and reduce perceived efforts. Kaempferia parviflora extract at the doses of 25 mg or 90 mg for 8 weeks has been demonstrated to increase physical fitness performance in 30-second chair stand test and 6 minute walk test, increase the scavenger enzymes superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px)) expression, and decrease malondialdehyde production . In the double-blind, placebo-controlled clinical trial, oral administration of sports nutritional supplement (Fitnox) at the single dose of 250 mg can significantly increase the levels of nitrate (NO3–) and nitrite (NO2–) in serum and saliva, leading to enhancement of overall performance and physical endurance . Consistently, Kaempferia parviflora extract has been found to improve physical fitness, as indicated by enhancement of grip and leg strength, balance, endurance, and locomotor activity. In addition, the daily visual analog scale (VAS) figure score, postphysical fitness test VAS fatigue score, and chronic fatigue syndrome score are found to be enhanced greatly than those in the placebo group . However, a randomized, double-blind, and crossover study has been demonstrated that acute administration of Kaempferia parviflora (1.35g) does not enhance exercise performance, compared with the placebo, as confirmed by repeated sprint exercise and submaximal exercise to exhaustion in college males in Thailand . In contrast, supplement with Kaempferia parviflora extract at 180 mg per day for 12 weeks, the soccer players are found to increase the right-hand trip strength and left-hand grip strength, compared with those in the placebo group. On the other hand, the back and leg strength, the 40-yard technical test, the sit-and reach test, the 50-metre sprint test, and the cardiorespiratory fitness test do not show any significant difference from those in the placebo group .

Blood circulation is closely associated with blood fluidity. It has been demonstrated that 70% methanol extract of Kaempferia parviflora significantly improves blood fluidity through activation of fibrinolysis, as indicated by elongation of euglobulin lysis time in disseminated intravascular coagulation (DIC) rat models and the fibrinolysis assays in vitro. Kaempferia parviflora methoxyflavones been involved in activation of fibrinolysis . In the ventricular fibrillation (VF) of swine heart model, the saline extract of Kaempferia parviflora at high doses of 100 mg/kg and 50 mg/kg is found to increase the defibrillation threshold and the upper limit of vulnerability. But it does not change ventricular fibrillation threshold. In addition, Kaempferia parviflora administration attenuates diastolic and systolic blood pressures . On the other hand, the extract of Kaempferia parviflora (100mg/kg) has been demonstrated to decrease cardiac functions in normal rat hearts through upregulation of cyclic guanosine monophosphate (cGMP) level and nitric oxide (NO) signaling and downregulation of Ca2+ transient . This is consistent with 5,7-dimethoxyflavone induced vasorelaxation through increased K+ efflux and attenuated Ca2+ influx .

Kaempferia parviflora is believed to benefit men’s sexual activity. However, the ethanol extract of Kaempferia parviflora at dose of 70 mg/kg does not have any effects on weights of reproductive organs but decreases mount latency, ejaculation latency, and postejaculation latency . On the other hand, the ethanol extract of Kaempferia parviflora has been found to increase blood flow to the testis dose-dependently . Phosphodiesterase type 5 (PDE-5) inhibition has become the strategy for management of erectile dysfunction. However, PDE-5 inhibitors require sexual stimulation to activate cGMP-NO and trigger erection. Thus, targeting for relaxation directly to corpus cavernosum might be a new effective approach for erectile dysfunction management. It has been demonstrated that 3,5,7,3′,4′-pentamethoxyflavone exhibits a relaxant activity on isolated human cavernosum precontrated by phenylephrine. The possible mechanism might be that 3,5,7,3′,4′-pentamethoxyflavone inhibits L-type Ca2+ channel and induces immobilization of Ca2+ from sarcoplasmic reticulum. On the other hand, 3,5,7,3′,4′-pentamethoxyflavone does not act as a calcium-activated potassium channels (KCa channels) opener, a PDE inhibitor, and a Rho-kinase inhibitor but a rather weak stimulator of NO release . Kaempferia parviflora extract has been demonstrated to potentially manage age-related erectile dysfunction. At the dose of 90 mg/day, Kaempferia parviflora extract significantly increases all parameters. However, it does not alter the concentration of testosterone, follicle stimulating hormone (FSH), and luteinizing hormone (LH) .

Table 1. Clinical effects of Kaempferia parviflora classified by outcomes

Outcomes, StudySample SubgroupInterventionsTime or Methods of MeasurementKaempferia parviflora ControlSummaryMeanSDMeanSDPhysical or exercise performance Maximum power output (watt) Deema, 2007Endurance training groupsKaempferia parviflora 1.35 g/day vs placeboBaseline203.53.3214.22.4Significantly increased at weeks 4 and 8 in the Kaempferia parviflora group and week 8 in the placebo group (difference from baseline)4 weeks233.72.9232.11.68 weeks2453.22472.9No endurance training groupsBaseline184.12.8200.84.9No significant effects4 weeks190.52.1197.45.38 weeks1922198.25.3Wasuntarawat, 2010Anaerobic exercise (exhaustive sprint)Kaempferia parviflora 1.35 g/day vs placeboWingate 154595554114Maximum power output declined (P < .05) across Wingate tests 1, 2, and 3 but there were no differences (P > .05) between Kaempferia parviflora and placeboWingate 249999495109Wingate 345411647396Mean power output (watt) Wasuntarawat, 2010Anaerobic exercise (exhaustive sprint)Kaempferia parviflora 1.35 g/day vs placeboWingate 14176541665Mean power output declined (P < .05) across Wingate tests 1, 2, and 3 but there were no differences (P > .05) between Kaempferia parviflora and placeboWingate 23695936958Wingate 33236133457Time to finish work max test (minutes) Deema, 2007Endurance training groupsKaempferia parviflora 1.35 g/day vs placeboBaseline8.20.18.50.1Significantly increased at weeks 4 and 8 in the Kaempferia parviflora group and week 8 in the placebo group (difference from baseline)4 weeks9.20.19.40.18 weeks9.70.19.90.1 0No endurance training groupsBaseline7.20.17.90.2No significant effects4 weeks7.50.17.80.28 weeks7.50.17.80.1Time to exhaustion (minutes) Wasuntarawat, 2010Anaerobic exercise (exhaustive sprint)Kaempferia parviflora 1.35 g/day vs placebo28.312.527.611.5Acute ingestion of Kaempferia parviflora did not improve time to exhaustionRating of perceived exertion Wasuntarawat, 2010Anaerobic exercise (exhaustive sprint)Kaempferia parviflora 1.35 g/day vs placebo10 min142142Ratings of perceived exertion at 10 and 20 minutes and immediately after exhaustion were also not different between placebo and Kaempferia parviflora. Time to exhaustion was rated between 17 (“very hard”) and 19 (“extremely hard”)20 min172172Post a191181Percentage fatigue (%) Wasuntarawat, 2010Anaerobic exercise (exhaustive sprint)Kaempferia parviflora 1.35 g/day vs placeboWingate 143134015No differences in percent fatigue during each 30-second sprint were observed between placebo and Kaempferia parviflora. Percent fatigue during the third Wingate test was significantly (P < .05) greater than during the first Wingate test in both placebo and Kaempferia parviflora trialsWingate 248124415Wingate 351135310Heart rate (BPM) Deema, 2007Maximum heart rateEndurance training groupsKaempferia parviflora 1.35 g/day vs placeboBaseline1810.8179.60.5Significantly increased at week 8 in the placebo group (difference from baseline)4 weeks184.70.7181.30.68 weeks184.60.8186.60.8No endurance training groupsBaseline18521802.4No significant effects4 weeks199.60.6176.22.68 weeks186.41.6181.21.8Wasuntarawat, 2010Aerobic exercise (endurance)Kaempferia parviflora 1.35 g/day vs placebo10 min1651316411Heart rate at 10 and 20 minutes and immediately after exhaustion were also not different between placebo and Kaempferia parviflora20 min174101729Posta177817410Lactate threshold (watt) Deema, 2007Endurance training groupsKaempferia parviflora 1.35 g/day vs placeboBaseline129.61.7142.51.7Significantly increased lactate threshold at weeks 4 and 8 in the Kaempferia parviflora group (difference from baseline)4 weeks156.82.71552.38 weeks165.93.3 01601.8No endurance training groupsBaseline1204.21204.2No significant effects from baseline4 weeks118.805.4118.8068 weeks118.802.8106.33.1Hand grip strength test Wattanathorn, 2012Right hand (kg)Kaempferia parviflora 25 mg/day vs placeboBaseline25.063.0124.532.55No significant effects4 weeks252.9724.332.288 weeks24.863.1824.332.46Kaempferia parviflora 90 mg/day vs placeboBaseline23.933.3——No significant effects4 weeks24.63.13——8 weeks24.83.14——Left hand (kg)Kaempferia parviflora 25 mg/day vs placeboBaseline22.061.8621.061.83No significant effects4 weeks21.661.521.331.588 weeks21.261.4821.21.56Kaempferia parviflora 90 mg/day vs placeboBaseline20.862.72——No significant effects4 weeks21.62.02——8 weeks21.61.84——Promthep, 2015Right hand (kg/wt)Kaempferia parviflora 180 mg/day vs placeboBaseline0.650.090.630.07Significantly enhanced at weeks 4, 8, and 12 (difference from the placebo group in the same week) and significant difference compared with the baseline score at week 44 weeks0.70.090.660.078 weeks0.680.10.630.0712 weeks0.650.080.620.07Left hand (kg/wt)Kaempferia parviflora 180 mg/day vs placeboBaseline0.620.080.60.08Significantly enhanced at week 8 (difference from the placebo group in the same week)4 weeks0.650.10.620.078 weeks0.640.080.590.0812 weeks0.610.080.570.0730-Second chair stand test (seconds) Wattanathorn, 2012Kaempferia parviflora 25 mg/day vs placeboBaseline18.332.5819.132.79No significant effects4 weeks192.7719.261.438 weeks203.1118.931.7Kaempferia parviflora 90 mg/day vs placeboBaseline18.62.52——Significantly increased at week 8 compared with baseline4 weeks19.62.13——8 weeks20.662.28——6-Minute Walk Test (m) Wattanathorn, 2012Kaempferia parviflora 25 mg/day vs placeboBaseline571.2633.68567.3333.52No significant effects4 weeks570.3338.32598.7331.578 weeks575.5336.04571.2632.05Kaempferia parviflora 90 mg/day vs placeboBaseline572.832.65——Significantly increased at week 8 compared with either baseline or placebo4 weeks575.4634.29——8 weeks601.2633.7——Tandem stance test (seconds) Wattanathorn, 2012Opened eyeRight leg is in frontKaempferia parviflora 25 mg/day vs PlaceboBaseline161.811.16164.812.34No significant effects4 weeks164.069.63163.0610.358 weeks162.268.93165.069.8Kaempferia parviflora 90 mg/day vs placeboBaseline16410.5——No significant effects4 weeks166.66.81——8 weeks168.466.9——Left leg is in frontKaempferia parviflora 25 mg/day vs placeboBaseline111.937.77112.3311No significant effects4 weeks112.3311.39110.6610.018 weeks111.810.1610910.2Kaempferia parviflora 90 mg/day vs placeboBaseline108.211.32——No significant effects4 weeks109.3313.62——8 weeks111.813.31——Closed eyeRight leg is in frontKaempferia parviflora 25 mg/day vs placeboBaseline31.8610.1233.89.22No significant effects4 weeks32.67.4430.810.748 weeks32.737.6731.6610.41Kaempferia parviflora 90 mg/day vs placeboBaseline31.2611.09——No significant effects4 weeks31.869.33——8 weeks33.48.94——Left leg is in frontKaempferia parviflora 25 mg/day vs placeboBaseline20.933.4118.83.6No significant effects4 weeks21.333.7919.865.018 weeks21.263.1921.24.57Kaempferia parviflora 90 mg/day vs placeboBaseline20.464.24——No significant effects4 weeks21.264.58——8 weeks22.063.93——A sit-and-reach test (cm) Promthep, 2015Kaempferia parviflora 180 mg/day vs placeboBaseline17.984.616.144.93Significant difference compared with the baseline score at week 4 (both the treatment and placebo groups)4 weeks16.435.1514.644.928 weeks16.885.1914.615.2412 weeks18.285.117.014.55A back-and-leg strength test (kg/wt) Promthep, 2015Kaempferia parviflora 180 mg/day vs placeboBaseline2.770.542.450.39No significant effects4 weeks2.680.552.450.518 weeks2.770.552.440.412 weeks2.790.592.530.52A 40-yard technical test (seconds) Promthep, 2015Kaempferia parviflora 180 mg/day vs placeboBaseline11.610.0711.990.86Significantly decreased at week 12 compared with the baseline4 weeks12.061.1612.341.338 weeks11.50.7411.460.7512 weeks10.080.4710.470.9A 50-metre sprint test (seconds) Promthep, 2015Kaempferia parviflora 180 mg/day vs placeboBaseline6.240.316.290.37No significant effects in both groups. No significant differences between the groups4 weeks6.260.316.330.498 weeks6.370.266.50.512 weeks6.330.246.470.52A cardiorespiratory fitness test VO2 max (mL/kg/min) Promthep, 2015Kaempferia parviflora 180 mg/day vs placeboBaseline45.099.8845.099.96Significantly increased cardiorespiratory fitness, as indicated by VO2 max values at week 12. No significant difference between the groups4 weeks46.957.6147.8510.088 weeks49.48.448.347.1712 weeks51.058.447.18.45Pain indicators Chalee, 2010Pain severityKaempferia parviflora 7% w/w vs analgesic creamBaseline8.110.998.151.09Significantly decreased at week 4 compared with the baseline (both the treatment and placebo groups). No significant difference between the groups4 weeks6.80.766.870.65Circumference of knee joint (cm)Baseline37.912.7537.1534 weeks37.032.5636.32.64Range of motion of knee joint (range of motion)Baseline110.579.45109.3910.664 weeks117.435.86116.216.62Modified WOMAC scoreBaseline40.316.6339.976.024 weeks39.295.84395.5Energy expenditure Matsushita, 2015Energy expenditure change (kJ/day)AllKaempferia parviflora 100 mg/day vs placeboBaseline62131436196150No significant in the placebo group but significant difference between the groups at 30 and 60 minutes, difference from baseline and maximal rise at 60 minutes60 minutes6442212NRNRHigh-brown adipose tissueKaempferia parviflora 180 mg/day vs placeboBaseline60761846103184No significant in the placebo group but significant difference between the groups at 30 and 60 minutes, difference from baseline at 30, 60, 90 minutes and maximal rise at 60 minutes60 minutes6427234NRNRLow-brown adipose tissueKaempferia parviflora 180 mg/day vs placeboBaseline64182236334261No significant effects60 minutesNRNRNRNRErectile response Wannanon, 2012Penile circumference (cm)Resting stateKaempferia parviflora 25 mg/day vs placeboBaseline9.40.7990.73No significant effects1 month90.798.70.592 months9.40.798.80.59Delayb9.153.19.153.1Kaempferia parviflora 90 mg/day vs placeboBaseline9.20.6990.73After 1 and 2 months of treatment, significant increase in the length and width of penis when compared with the placebo treated group1 month10.20.798.70.592 months10.150.798.80.59Delay b9.652.719.153.1Erection stateKaempferia parviflora 25 mg/day vs placeboBaseline10.93.8711.53.87No significant effects1 month10.53.6810.63.12 months11.54.2611.82.71Delay b11.73.111.72.71Kaempferia parviflora 90 mg/day vs placeboBaseline10.84.2611.53.87After 1 and 2 months of treatment, significant increase in the width when compared with the placebo treated group1 month12.14.2610.63.12 months11.94.2611.82.71Delay b11.70.3911.72.71Penile length (cm)Resting stateKaempferia parviflora 25 mg/day vs placeboBaseline9.74.269.957.55No significant effects1 month9.653.879.93.492 months10.93.87103.1Delay b10.63.4910.250.07Kaempferia parviflora 90 mg/day vs placeboBaseline9.44.079.957.55After 1 and 2 months of treatment, significant increase in the length when compared with the placebo treated group1 month11.253.499.93.492 months11.12.71103.1Delay b10.653.4910.250.07Erection stateKaempferia parviflora 25 mg/day vs placeboBaseline12.55.2713.14.96No significant effects1 month12.954.0312.23.872 months13.14.3412.44.18Delay b13.553.8713.22.79Kaempferia parviflora 90 mg/day vs placeboBaseline12.94.3413.14.96After 1 and 2 months of treatment, significant increase in the length when compared with the placebo treated group1 month13.754.3412.23.872 months13.94.0312.44.18Delay b13.54.6513.22.79Latency time (mins)Erection stateKaempferia parviflora 25 mg/day vs placeboBaseline10.913.9411.612.39No significant effects1 month8.612.3911.711.812 months812.391010.65Delay b7.80.5910.912.78Kaempferia parviflora 90 mg/day vs placeboBaseline10.49.311.612.39Significantly decreased the response latency to sexual erotic stimuli and still showed the significant changes during the delay period1 month5.57.1711.711.812 months5.56.581010.65Delay b7.46.210.912.78Serum hormones concentrationsTestosterone (ng/mL)Kaempferia parviflora 25 mg/day vs placeboBaseline4.111.564.140.92No significant effectsSingle dose4.794.635.282.761 month5.113.135.925.492 months4.641.225.651.23Delay b5.712.385.140.92Kaempferia parviflora 90 mg/day vs placeboBaseline4.111.34.140.92No significant effectsSingle dose4.892.635.282.761 month4.260.835.925.492 months5.742.65.651.23Delay b6.063.195.140.92FSH (IU/L)Kaempferia parviflora 25 mg/day vs placeboBaseline8.84.297.884.34No significant effectsSingle dose7.354.236.732.541 month7.235.376.525.512 months7.963.325.952.34Delay b8.815.125.883.34Kaempferia parviflora 90 mg/day vs placeboBaseline7.532.927.884.34No significant effectsSingle dose6.142.266.732.541 month6.292.256.525.512 months6.012.795.952.34Delay b7.032.355.883.34LH (IU/L)Kaempferia parviflora 25 mg/day vs placeboBaseline7.255.97.145.62No significant effectsSingle dose8.122.727.593.211 month7.045.347.34.242 months8.484.647.822.34Delay b8.724.678.143.23Kaempferia parviflora 90 mg/day vs placeboBaseline6.994.377.145.62No significant effectsSingle dose7.651.887.593.211 month8.553.647.34.242 months7.414.677.822.34Delay b8.824.448.143.23

Footnote: a Post: immediately after exercise; b Delay: 1 month after the cessation of Kaempferia parviflora administration.

Abbreviations: VO2 = oxygen consumption; ROM = range of motion; high-BAT = high brown adipose tissue; low-BAT = low brown adipose tissue; FSH = follicle-stimulating hormone; LH = luteinizing hormone.

Kaempferia parviflora on physical or exercise performance

To determine the effects of Kaempferia parviflora on physical or exercise performance, many tests were used, including maximum power output, mean power output, time to exhaustion, rating of perceived exertion, percentage fatigue, heart rate, lactate threshold, hand grip strength, 6-minute walk test, and so on (see Table 1). The main findings from 2 studies  , indicated that Kaempferia parviflora showed no acute improvement in either repeated sprint performance or endurance exercise. However, other 2 studies , provided data of hand grip strength test, which determined the upper-body muscle strength by using a digital dynamometer. It was found that the Kaempferia parviflora 90 to 180 mg/day group significantly increased hand grip strengths of both right-hand and left-hand sides at 2 months compared with the placebo group . This might be explained by the increased blood flow effect of Kaempferia parviflora . A previous study demonstrated that Kaempferia parviflora supplementation could increase blood flow to the organs due to vasorelaxation induction . This partly was mediated through cyclooxygenase and nitric oxide–dependent pathways and Kaempferia parviflora also showed anti-inflammatory effects . Therefore, the combination effect of increased blood flow and anti-inflammatory effects may facilitate muscle strength .

Kaempferia parviflora effect on erectile dysfunction

Only one randomized controlled trial compared Kaempferia parviflora with placebo in human subjects on erectile response . Subjects receiving Kaempferia parviflora 25 mg/day (n = 15), or 90 mg/day (n = 15), were compared with those receiving placebo (n = 15) for 8 weeks of study period. The study found that Kaempferia parviflora at a dose of 90 mg/day exhibited a significant enhancement in all parameters (ie, response latency time to visual erotic stimuli, size and length of penis both in flaccid and erectile states) after 1 and 2 months of treatment compared with placebo  . In addition, after 1 month and 2 months, the Kaempferia parviflora group at a dose of 90 mg/day experienced a statistically significant increase in length and width of penis both in resting state and erection state compared with the placebo group. Kaempferia parviflora showed no effects on serum hormones (ie, follicle-stimulating hormone, luteinizing hormone) see Table 1. The authors explained that the effects involved nitric oxide (NO). The experimental studies reported that Kaempferia parviflora extract could induce an increase of endothelial nitric oxide synthase and protein expression in human umbilical vein endothelial cell . Thus, abundance of endothelial nitric oxide synthase in endothelium of penile vasculature and sinusoidal endothelium within the corpora carvernosa might increase penile erection .

Kaempferia parviflora effects on pain

A study by Chalee compared Kaempferia parviflora cream with analgesic cream on pain reduction in knee osteoarthritis. Pain severity, circumference of knee joint, range of motion of knee joint, and modified Western Ontario and McMaster Universities Arthritis Index score were assessed and compared within the group from baseline, or between the groups with analgesic cream. Comparing with baseline, the results in both groups showed significantly reduce pain in all indicators at 4 weeks. On the contrary, comparing with analgesic cream, Kaempferia parviflora cream showed no significant difference (Table 1). Since anti-inflammatory effect was studied only using oral administration of Kaempferia parviflora , the mechanism of Kaempferia parviflora cream on pain reduction was still unclear.

Kaempferia parviflora effects on energy expenditure

The effect of Kaempferia parviflora on energy expenditure has been linked to the activity of brown adipose tissue, a site of nonshivering thermogenesis  . A previous study found that the components of Kaempferia parviflora extract activate hormone-sensitive lipase in adipocyte . Furthermore, 5,7-dimenthoxyflavone, the major flavonoid in Kaempferia parviflora extract, was demonstrated to have a the potent inhibitory effect on phosphodiesterase 5 (PDE5) enzyme . Since cGMP is a signal of hormone-sensitive lipase in adipocyte, it activates brown adipose tissue thermogenesis. Thus, it is possible that the brown adipose tissue–mediated thermogenic effect of Kaempferia parviflora extract exist via the inhibition of phosphodiesterase in brown adipose tissue. A study showed that Kaempferia parviflora extract could potentially increase whole-body energy expenditure probably through the activation of brown adipose tissue, which might benefit as an antiobesity treatment . A study by Matsushita et al  evaluated the effect of 2 doses of Kaempferia parviflora 100 mg/day or 180 mg/day on energy expenditure change compared with placebo. They found that when comparing with baseline, Kaempferia parviflora showed significant increase in energy expenditure at 30 minutes and 60 minutes in both groups. However, compared with placebo, no significant additional benefit of Kaempferia parviflora on energy expenditure was found (Table 1).

Kaempferia parviflora dosage

Till now, there is not enough scientific evidence to elucidate the optimal Kaempferia parviflora dose. Recommendation from Thai traditional medicine institute suggests the daily dose of Kaempferia parviflora is 1.2g. In addition, the powder of Kaempferia parviflora extract has been developed as a food ingredient on the market, which is standardized for containing not less than 2.5% of 5,7-dimethoxyflavone (Compound-6) and 10% of total methoxyflavones .

Fitnox, a sports nutritional supplement, is a unique blend of Kaempferia parviflora methoxyflavones, pomegranate peel polyphenols, and Moringa oleifera leaf saponins . Subchronic toxicological study shows that administration of Fitnox (at the dose of 1000 mg/kg/day for 90 days) to rats exhibits no any drug-related toxicity or mortality in either sex and no significant changes between the control and Fitnox treated groups in all parameters at the hematological, biochemistry, and histological levels . Another study for evaluating the toxicology of the ethanol Kaempferia parviflora extract (5, 50, and 500 mg/kg/day for 6 months) demonstrates no notable histological changes in all groups. The hematological parameters are also within the normal range in both sexes. But the body weight and the triglyceride levels at the 500 mg/kg dose rats group are lower, and the glucose and cholesterol levels are higher .

Kaempferia parviflora side effects

Administration with 1.35g of Kaempferia parviflora daily does not produce any adverse effects . Acute and chronic toxicity study has been proven that oral administration of Kaempferia parviflora does not induce any abnormal changes in body weight and histology in various visceral organs , . Toxicological study exhibits that the ethanol Kaempferia parviflora extract (at the doses of 60, 120, and 240 mg/kg for 60 days) does not induce significant changes in hemoglobin, white blood cells, or differential cell count. No any negative effects on renal and hepatic functions have been found at the tested doses .

An animal study of Kaempferia parviflora extract on chronic toxicity was conducted  . They randomly divided 120 Wistar rats into 5 groups, 24 rats each (12 males and 12 females). Then, 3 treatment groups were orally administered with Kaempferia parviflora extract at doses of 5, 50, and 500 mg/kg/day for 6 months, respectively, which were equivalent to 1, 10, and 100 times that of human use, while 2 control groups were orally given distilled water and 1.0% tragacanth, respectively . The results showed that the histopathological study of visceral organs revealed no remarkable lesions related to the toxicity of Kaempferia parviflora extract . There has only been one reported case of anaphylaxis caused by black ginger in a dietary supplement .