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 ¹. 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 ². 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 ¹. 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 ³, anti-depressant, asthma, fatigue, weakness, impotence, gout, colic disorder, diarrhea, dysentery ⁴, peptic ulcer ⁵ and lower blood sugar in diabetes ⁶. 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 ⁷, methoxyflavones ⁸, phenolic glycosides ⁹ and terpenoids ¹⁰, which was previously reported to possess antioxidant activity ¹¹, cardioprotective ¹², aphrodisiac ¹³, anticholinesterase ¹⁴, anti-inflammatory ¹⁵, anti-obesity ¹⁶ and antimutagenic ¹⁷, neuroprotective, and cognitive-enhancing properties ¹⁸. Kaempferia parviflora extract has been shown to improve physical fitness performance in clinical studies ¹⁹. The anti-oxidative activity of Kaempferia parviflora extract has been reported to exhibit antimalarial, antiviral, antimycobacterial and antibacterial ⁴ anti-gastric ulcer activities ²⁰. Kaempferia parviflora extract has also exhibited antitumor activity against Hela human cervical and SKOV3 ovarian cancer cells ²¹.

According to the previous reports by Wongsrikaew et al. ²² and Mekjaruskul et al. ²³, 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 ²⁴. In addition, more than 20 chemically identifiable constituents have been reported to have potent pharmacological effects ²⁵. 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 ²⁶. 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 ²⁷. 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 ²⁸.

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.

[Source ²⁹ ]

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).

[Source ³⁰ ]

Kaempferia parviflora benefits

A systematic review on clinical effects of Kaempferia parviflora has shown positive benefits, but it is inconclusive due to small studies included ³¹. 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 ³². 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 ³³.

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 ³⁴. 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 ³⁵. 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 ³⁶. 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 ³⁷. 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 ³⁸.

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 ³⁹. 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 ⁴⁰. 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 ⁴¹. This is consistent with 5,7-dimethoxyflavone induced vasorelaxation through increased K+ efflux and attenuated Ca2+ influx ⁴².

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 ⁴³. On the other hand, the ethanol extract of Kaempferia parviflora has been found to increase blood flow to the testis dose-dependently ⁴⁴. 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 ²². 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) ⁴⁵.

Table 1. Clinical effects of Kaempferia parviflora classified by outcomes

Outcomes, Study	Sample Subgroup			Interventions	Time or Methods of Measurement	Kaempferia parviflora		Control		Summary
						Mean	SD	Mean	SD
Physical or exercise performance
Maximum power output (watt)
Deema, 2007	Endurance training groups			Kaempferia parviflora 1.35 g/day vs placebo	Baseline	203.5	3.3	214.2	2.4	Significantly increased at weeks 4 and 8 in the Kaempferia parviflora group and week 8 in the placebo group (difference from baseline)
					4 weeks	233.7	2.9	232.1	1.6
					8 weeks	245	3.2	247	2.9
	No endurance training groups				Baseline	184.1	2.8	200.8	4.9	No significant effects
					4 weeks	190.5	2.1	197.4	5.3
					8 weeks	192	2	198.2	5.3
Wasuntarawat, 2010	Anaerobic exercise (exhaustive sprint)			Kaempferia parviflora 1.35 g/day vs placebo	Wingate 1	545	95	554	114	Maximum power output declined (P < .05) across Wingate tests 1, 2, and 3 but there were no differences (P > .05) between Kaempferia parviflora and placebo
					Wingate 2	499	99	495	109
					Wingate 3	454	116	473	96
Mean power output (watt)
Wasuntarawat, 2010	Anaerobic exercise (exhaustive sprint)			Kaempferia parviflora 1.35 g/day vs placebo	Wingate 1	417	65	416	65	Mean power output declined (P < .05) across Wingate tests 1, 2, and 3 but there were no differences (P > .05) between Kaempferia parviflora and placebo
					Wingate 2	369	59	369	58
					Wingate 3	323	61	334	57
Time to finish work max test (minutes)
Deema, 2007	Endurance training groups			Kaempferia parviflora 1.35 g/day vs placebo	Baseline	8.2	0.1	8.5	0.1	Significantly increased at weeks 4 and 8 in the Kaempferia parviflora group and week 8 in the placebo group (difference from baseline)
					4 weeks	9.2	0.1	9.4	0.1
					8 weeks	9.7	0.1	9.9	0.1 0
	No endurance training groups				Baseline	7.2	0.1	7.9	0.2	No significant effects
					4 weeks	7.5	0.1	7.8	0.2
					8 weeks	7.5	0.1	7.8	0.1
Time to exhaustion (minutes)
Wasuntarawat, 2010	Anaerobic exercise (exhaustive sprint)			Kaempferia parviflora 1.35 g/day vs placebo		28.3	12.5	27.6	11.5	Acute ingestion of Kaempferia parviflora did not improve time to exhaustion
Rating of perceived exertion
Wasuntarawat, 2010	Anaerobic exercise (exhaustive sprint)			Kaempferia parviflora 1.35 g/day vs placebo	10 min	14	2	14	2	Ratings 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 min	17	2	17	2
					Post a	19	1	18	1
Percentage fatigue (%)
Wasuntarawat, 2010	Anaerobic exercise (exhaustive sprint)			Kaempferia parviflora 1.35 g/day vs placebo	Wingate 1	43	13	40	15	No 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 trials
					Wingate 2	48	12	44	15
					Wingate 3	51	13	53	10
Heart rate (BPM)
Deema, 2007	Maximum heart rate
		Endurance training groups		Kaempferia parviflora 1.35 g/day vs placebo	Baseline	181	0.8	179.6	0.5	Significantly increased at week 8 in the placebo group (difference from baseline)
					4 weeks	184.7	0.7	181.3	0.6
					8 weeks	184.6	0.8	186.6	0.8
		No endurance training groups			Baseline	185	2	180	2.4	No significant effects
					4 weeks	199.6	0.6	176.2	2.6
					8 weeks	186.4	1.6	181.2	1.8
Wasuntarawat, 2010	Aerobic exercise (endurance)			Kaempferia parviflora 1.35 g/day vs placebo	10 min	165	13	164	11	Heart rate at 10 and 20 minutes and immediately after exhaustion were also not different between placebo and Kaempferia parviflora
					20 min	174	10	172	9
					Posta	177	8	174	10
Lactate threshold (watt)
Deema, 2007	Endurance training groups			Kaempferia parviflora 1.35 g/day vs placebo	Baseline	129.6	1.7	142.5	1.7	Significantly increased lactate threshold at weeks 4 and 8 in the Kaempferia parviflora group (difference from baseline)
					4 weeks	156.8	2.7	155	2.3
					8 weeks	165.9	3.3 0	160	1.8
	No endurance training groups				Baseline	120	4.2	120	4.2	No significant effects from baseline
					4 weeks	118.80	5.4	118.80	6
					8 weeks	118.80	2.8	106.3	3.1
Hand grip strength test
Wattanathorn, 2012	Right hand (kg)			Kaempferia parviflora 25 mg/day vs placebo	Baseline	25.06	3.01	24.53	2.55	No significant effects
					4 weeks	25	2.97	24.33	2.28
					8 weeks	24.86	3.18	24.33	2.46
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	23.93	3.3	—	—	No significant effects
					4 weeks	24.6	3.13	—	—
					8 weeks	24.8	3.14	—	—
	Left hand (kg)			Kaempferia parviflora 25 mg/day vs placebo	Baseline	22.06	1.86	21.06	1.83	No significant effects
					4 weeks	21.66	1.5	21.33	1.58
					8 weeks	21.26	1.48	21.2	1.56
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	20.86	2.72	—	—	No significant effects
					4 weeks	21.6	2.02	—	—
					8 weeks	21.6	1.84	—	—
Promthep, 2015	Right hand (kg/wt)			Kaempferia parviflora 180 mg/day vs placebo	Baseline	0.65	0.09	0.63	0.07	Significantly 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 4
					4 weeks	0.7	0.09	0.66	0.07
					8 weeks	0.68	0.1	0.63	0.07
					12 weeks	0.65	0.08	0.62	0.07
	Left hand (kg/wt)			Kaempferia parviflora 180 mg/day vs placebo	Baseline	0.62	0.08	0.6	0.08	Significantly enhanced at week 8 (difference from the placebo group in the same week)
					4 weeks	0.65	0.1	0.62	0.07
					8 weeks	0.64	0.08	0.59	0.08
					12 weeks	0.61	0.08	0.57	0.07
30-Second chair stand test (seconds)
Wattanathorn, 2012				Kaempferia parviflora 25 mg/day vs placebo	Baseline	18.33	2.58	19.13	2.79	No significant effects
					4 weeks	19	2.77	19.26	1.43
					8 weeks	20	3.11	18.93	1.7
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	18.6	2.52	—	—	Significantly increased at week 8 compared with baseline
					4 weeks	19.6	2.13	—	—
					8 weeks	20.66	2.28	—	—
6-Minute Walk Test (m)
Wattanathorn, 2012				Kaempferia parviflora 25 mg/day vs placebo	Baseline	571.26	33.68	567.33	33.52	No significant effects
					4 weeks	570.33	38.32	598.73	31.57
					8 weeks	575.53	36.04	571.26	32.05
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	572.8	32.65	—	—	Significantly increased at week 8 compared with either baseline or placebo
					4 weeks	575.46	34.29	—	—
					8 weeks	601.26	33.7	—	—
Tandem stance test (seconds)
Wattanathorn, 2012	Opened eye
		Right leg is in front		Kaempferia parviflora 25 mg/day vs Placebo	Baseline	161.8	11.16	164.8	12.34	No significant effects
					4 weeks	164.06	9.63	163.06	10.35
					8 weeks	162.26	8.93	165.06	9.8
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	164	10.5	—	—	No significant effects
					4 weeks	166.6	6.81	—	—
					8 weeks	168.46	6.9	—	—
		Left leg is in front		Kaempferia parviflora 25 mg/day vs placebo	Baseline	111.93	7.77	112.33	11	No significant effects
					4 weeks	112.33	11.39	110.66	10.01
					8 weeks	111.8	10.16	109	10.2
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	108.2	11.32	—	—	No significant effects
					4 weeks	109.33	13.62	—	—
					8 weeks	111.8	13.31	—	—
	Closed eye
		Right leg is in front		Kaempferia parviflora 25 mg/day vs placebo	Baseline	31.86	10.12	33.8	9.22	No significant effects
					4 weeks	32.6	7.44	30.8	10.74
					8 weeks	32.73	7.67	31.66	10.41
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	31.26	11.09	—	—	No significant effects
					4 weeks	31.86	9.33	—	—
					8 weeks	33.4	8.94	—	—
		Left leg is in front		Kaempferia parviflora 25 mg/day vs placebo	Baseline	20.93	3.41	18.8	3.6	No significant effects
					4 weeks	21.33	3.79	19.86	5.01
					8 weeks	21.26	3.19	21.2	4.57
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	20.46	4.24	—	—	No significant effects
					4 weeks	21.26	4.58	—	—
					8 weeks	22.06	3.93	—	—
A sit-and-reach test (cm)
Promthep, 2015				Kaempferia parviflora 180 mg/day vs placebo	Baseline	17.98	4.6	16.14	4.93	Significant difference compared with the baseline score at week 4 (both the treatment and placebo groups)
					4 weeks	16.43	5.15	14.64	4.92
					8 weeks	16.88	5.19	14.61	5.24
					12 weeks	18.28	5.1	17.01	4.55
A back-and-leg strength test (kg/wt)
Promthep, 2015				Kaempferia parviflora 180 mg/day vs placebo	Baseline	2.77	0.54	2.45	0.39	No significant effects
					4 weeks	2.68	0.55	2.45	0.51
					8 weeks	2.77	0.55	2.44	0.4
					12 weeks	2.79	0.59	2.53	0.52
A 40-yard technical test (seconds)
Promthep, 2015				Kaempferia parviflora 180 mg/day vs placebo	Baseline	11.61	0.07	11.99	0.86	Significantly decreased at week 12 compared with the baseline
					4 weeks	12.06	1.16	12.34	1.33
					8 weeks	11.5	0.74	11.46	0.75
					12 weeks	10.08	0.47	10.47	0.9
A 50-metre sprint test (seconds)
Promthep, 2015				Kaempferia parviflora 180 mg/day vs placebo	Baseline	6.24	0.31	6.29	0.37	No significant effects in both groups. No significant differences between the groups
					4 weeks	6.26	0.31	6.33	0.49
					8 weeks	6.37	0.26	6.5	0.5
					12 weeks	6.33	0.24	6.47	0.52
A cardiorespiratory fitness test VO2 max (mL/kg/min)
Promthep, 2015				Kaempferia parviflora 180 mg/day vs placebo	Baseline	45.09	9.88	45.09	9.96	Significantly increased cardiorespiratory fitness, as indicated by VO2 max values at week 12. No significant difference between the groups
					4 weeks	46.95	7.61	47.85	10.08
					8 weeks	49.4	8.4	48.34	7.17
					12 weeks	51.05	8.4	47.1	8.45
Pain indicators
Chalee, 2010	Pain severity			Kaempferia parviflora 7% w/w vs analgesic cream	Baseline	8.11	0.99	8.15	1.09	Significantly decreased at week 4 compared with the baseline (both the treatment and placebo groups). No significant difference between the groups
					4 weeks	6.8	0.76	6.87	0.65
	Circumference of knee joint (cm)				Baseline	37.91	2.75	37.15	3
					4 weeks	37.03	2.56	36.3	2.64
	Range of motion of knee joint (range of motion)				Baseline	110.57	9.45	109.39	10.66
					4 weeks	117.43	5.86	116.21	6.62
	Modified WOMAC score				Baseline	40.31	6.63	39.97	6.02
					4 weeks	39.29	5.84	39	5.5
Energy expenditure
Matsushita, 2015	Energy expenditure change (kJ/day)
		All		Kaempferia parviflora 100 mg/day vs placebo	Baseline	6213	143	6196	150	No significant in the placebo group but significant difference between the groups at 30 and 60 minutes, difference from baseline and maximal rise at 60 minutes
					60 minutes	6442	212	NR	NR
		High-brown adipose tissue		Kaempferia parviflora 180 mg/day vs placebo	Baseline	6076	184	6103	184	No 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 minutes
					60 minutes	6427	234	NR	NR
		Low-brown adipose tissue		Kaempferia parviflora 180 mg/day vs placebo	Baseline	6418	223	6334	261	No significant effects
					60 minutes	NR	NR	NR	NR
Erectile response
Wannanon, 2012	Penile circumference (cm)
		Resting state		Kaempferia parviflora 25 mg/day vs placebo	Baseline	9.4	0.79	9	0.73	No significant effects
					1 month	9	0.79	8.7	0.59
					2 months	9.4	0.79	8.8	0.59
					Delayb	9.15	3.1	9.15	3.1
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	9.2	0.69	9	0.73	After 1 and 2 months of treatment, significant increase in the length and width of penis when compared with the placebo treated group
					1 month	10.2	0.79	8.7	0.59
					2 months	10.15	0.79	8.8	0.59
					Delay b	9.65	2.71	9.15	3.1
		Erection state		Kaempferia parviflora 25 mg/day vs placebo	Baseline	10.9	3.87	11.5	3.87	No significant effects
					1 month	10.5	3.68	10.6	3.1
					2 months	11.5	4.26	11.8	2.71
					Delay b	11.7	3.1	11.7	2.71
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	10.8	4.26	11.5	3.87	After 1 and 2 months of treatment, significant increase in the width when compared with the placebo treated group
					1 month	12.1	4.26	10.6	3.1
					2 months	11.9	4.26	11.8	2.71
					Delay b	11.7	0.39	11.7	2.71
	Penile length (cm)
		Resting state		Kaempferia parviflora 25 mg/day vs placebo	Baseline	9.7	4.26	9.95	7.55	No significant effects
					1 month	9.65	3.87	9.9	3.49
					2 months	10.9	3.87	10	3.1
					Delay b	10.6	3.49	10.25	0.07
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	9.4	4.07	9.95	7.55	After 1 and 2 months of treatment, significant increase in the length when compared with the placebo treated group
					1 month	11.25	3.49	9.9	3.49
					2 months	11.1	2.71	10	3.1
					Delay b	10.65	3.49	10.25	0.07
		Erection state		Kaempferia parviflora 25 mg/day vs placebo	Baseline	12.5	5.27	13.1	4.96	No significant effects
					1 month	12.95	4.03	12.2	3.87
					2 months	13.1	4.34	12.4	4.18
					Delay b	13.55	3.87	13.2	2.79
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	12.9	4.34	13.1	4.96	After 1 and 2 months of treatment, significant increase in the length when compared with the placebo treated group
					1 month	13.75	4.34	12.2	3.87
					2 months	13.9	4.03	12.4	4.18
					Delay b	13.5	4.65	13.2	2.79
	Latency time (mins)
		Erection state		Kaempferia parviflora 25 mg/day vs placebo	Baseline	10.9	13.94	11.6	12.39	No significant effects
					1 month	8.6	12.39	11.7	11.81
					2 months	8	12.39	10	10.65
					Delay b	7.8	0.59	10.9	12.78
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	10.4	9.3	11.6	12.39	Significantly decreased the response latency to sexual erotic stimuli and still showed the significant changes during the delay period
					1 month	5.5	7.17	11.7	11.81
					2 months	5.5	6.58	10	10.65
					Delay b	7.4	6.2	10.9	12.78
	Serum hormones concentrations
		Testosterone (ng/mL)		Kaempferia parviflora 25 mg/day vs placebo	Baseline	4.11	1.56	4.14	0.92	No significant effects
					Single dose	4.79	4.63	5.28	2.76
					1 month	5.11	3.13	5.92	5.49
					2 months	4.64	1.22	5.65	1.23
					Delay b	5.71	2.38	5.14	0.92
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	4.11	1.3	4.14	0.92	No significant effects
					Single dose	4.89	2.63	5.28	2.76
					1 month	4.26	0.83	5.92	5.49
					2 months	5.74	2.6	5.65	1.23
					Delay b	6.06	3.19	5.14	0.92
		FSH (IU/L)		Kaempferia parviflora 25 mg/day vs placebo	Baseline	8.8	4.29	7.88	4.34	No significant effects
					Single dose	7.35	4.23	6.73	2.54
					1 month	7.23	5.37	6.52	5.51
					2 months	7.96	3.32	5.95	2.34
					Delay b	8.81	5.12	5.88	3.34
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	7.53	2.92	7.88	4.34	No significant effects
					Single dose	6.14	2.26	6.73	2.54
					1 month	6.29	2.25	6.52	5.51
					2 months	6.01	2.79	5.95	2.34
					Delay b	7.03	2.35	5.88	3.34
		LH (IU/L)		Kaempferia parviflora 25 mg/day vs placebo	Baseline	7.25	5.9	7.14	5.62	No significant effects
					Single dose	8.12	2.72	7.59	3.21
					1 month	7.04	5.34	7.3	4.24
					2 months	8.48	4.64	7.82	2.34
					Delay b	8.72	4.67	8.14	3.23
				Kaempferia parviflora 90 mg/day vs placebo	Baseline	6.99	4.37	7.14	5.62	No significant effects
					Single dose	7.65	1.88	7.59	3.21
					1 month	8.55	3.64	7.3	4.24
					2 months	7.41	4.67	7.82	2.34
					Delay b	8.82	4.44	8.14	3.23

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 ⁴⁶, ⁴⁷ indicated that Kaempferia parviflora showed no acute improvement in either repeated sprint performance or endurance exercise. However, other 2 studies ³⁴, ³⁸ 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 ². This might be explained by the increased blood flow effect of Kaempferia parviflora ⁴⁸. A previous study demonstrated that Kaempferia parviflora supplementation could increase blood flow to the organs due to vasorelaxation induction ⁴⁹. This partly was mediated through cyclooxygenase and nitric oxide–dependent pathways ⁴⁹ and Kaempferia parviflora also showed anti-inflammatory effects ⁵⁰. Therefore, the combination effect of increased blood flow and anti-inflammatory effects may facilitate muscle strength ³⁴.

Kaempferia parviflora effect on erectile dysfunction

Only one randomized controlled trial compared Kaempferia parviflora with placebo in human subjects on erectile response ⁵¹. 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 ⁵¹. 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 ⁵². Thus, abundance of endothelial nitric oxide synthase in endothelium of penile vasculature and sinusoidal endothelium within the corpora carvernosa might increase penile erection ⁵³.

Kaempferia parviflora effects on pain

A study by Chalee ⁵⁴ 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 ⁵⁵, 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 ⁵⁶. A previous study found that the components of Kaempferia parviflora extract activate hormone-sensitive lipase in adipocyte ⁵⁷. 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 ¹³. 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 ⁵⁸. A study by Matsushita et al ⁵⁸ 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 ¹.

Fitnox, a sports nutritional supplement, is a unique blend of Kaempferia parviflora methoxyflavones, pomegranate peel polyphenols, and Moringa oleifera leaf saponins ²⁹. 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 ⁵⁹. 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 ⁶⁰.

Kaempferia parviflora side effects

Administration with 1.35g of Kaempferia parviflora daily does not produce any adverse effects ⁶¹. 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 ⁶², ⁶⁰. 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 ⁶³.

An animal study of Kaempferia parviflora extract on chronic toxicity was conducted ⁶⁴. 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 ⁶⁴. The results showed that the histopathological study of visceral organs revealed no remarkable lesions related to the toxicity of Kaempferia parviflora extract ⁶⁴. There has only been one reported case of anaphylaxis caused by black ginger in a dietary supplement ⁶⁵.

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