Journal of Medicinal Plants Research Vol. 2(7), pp. 154-158, July, 2008
Available online at http://www.academicjournals.org/JMPR
ISSN 1996-0875© 2008 Academic Journals
Full Length Research Paper
Morinda citrifolia L. (noni) improves athlete endurance:
Its mechanisms of action
'Afa K. Palu
*, R. D. Seifulla
and. Brett J. West
Tahitian Noni International Research Center, American Fork, Utah 84003 USA.
Moscow Scientific and Practical Center of Sports Medicine, 105120, Moscow, Zemlyanoy Val St., 53
Accepted 10 July 2008
The ability of noni juice to improve endurance in athletes was evaluated clinically. A placebo-controlled
clinical trial with TAHITIAN NONI® Juice (TNJ) was conducted in 40 highly-trained athletes. Drinking 100
mL of TNJ twice daily increased endurance (time-to-fatigue) by 21%, and improved antioxidant status as
measured by a 25% decrease in blood chemiluminescence. Chemical analyses by multiple laboratories
and drug-urine screening of human volunteers reveal that TNJ does not contain any illegal drugs or
substances prohibited by the World Anti-doping Agency. The collective results indicate that TNJ
improves endurance via potent antioxidant effects. The results warrant human clinical trials to assess
the dosages and the feasibility of using TNJ by athletes participating in strenuous sports such as
football, rugby, ice hockey, soccer and basketball.
Key words: Noni, Morinda citrifolia, antioxidant, free radicals, endurance,
Morinda citrifolia L. commonly known as noni, from the
family Rubiaceae, has been used in Polynesia for over
2000 years for food, medicine and dyeing of traditional
clothes. Its medicinal usage has been purported to in-
clude the amelioration of diabetes (suka), gout (kauti),
high blood pressure (toto ma’olunga), cancer (kanis or
kahi), boils (hangatmaki), and other skin and internal ail-
ments (Wang et al., 2001; Palu, 2004; Palu et al., 2008).
Traditionally, noni fruit juice was also consumed after a
long voyage to help strengthen and restore vigor to the
body (Thaman, 1990, 1992). Interestingly, the numbers of
athletes who use TNJ as part of their nutritional regimen
are growing, and include reports of increases in recovery
time and endurance. However the mechanisms respon-
sible for these effects have not been elucidated.
MATERIALS AND METHODS
In these studies the commercial Brand TAHITIAN NONI
(TNJ) was obtained from the manufacturer (Tahitian Noni Interna-
tional, 737 East 1180 South, American Fork, Utah 84003 USA).
*Corresponding author. E-mail: firstname.lastname@example.org. Fax: 1 (801)
234-1030; Tel: 1 (801) 234-3624.
Endurance clinical trial
Forty volunteers (32 males and 8 females), who were highly-train-
ed, middle- to long- distance runners (1500 - 10000 m), were enroll-
ed in the study. Each participant received a pre-experimental medi-
cal examination, including ECG, heart rate, blood pressure, and
The volunteers were divided into 2 groups of 16 males and 4 fe-
males each: a TNJ group, ages 18 - 27; and a placebo group, ages
19 - 26. Athletes assigned to the TNJ group consumed 100 mL of
TNJ twice daily, 30 min before meals, for 21 days. Those in the
placebo group consumed blackberry juice, following the same dose
and consumption schedule as the TNJ group.
The endurance of all athletes was measured by a treadmill run
with increasing workload (stepwise every min), until muscle fatigue
(time-to-fatigue). The time-to-fatigue was measured pre-study and
at day 21. Total protein, urea, glucose, hemoglobin, lactate, and
other blood measurements were made at the same intervals. Addi-
tionally, super-weak chemiluminescence (counts per min, relative to
baseline data) of unsaturated fatty acids (spontaneous chemi-lumi-
nescence) was determined with an LKB chemiluminometer (LKB
Instruments, Sweden), using an established protocol (Rozhkova et
al., 2003). The chemiluminescence method measures photons
emitted after the excitation of fatty acids that occurs during electron
transfer. The data were analyzed by multivariate statistical
Drug screen test
TNJ was evaluated in a pilot study consisting of 6 healthy adult
volunteers (5 males and 1 female), with no recent history of drug
Table 1. Treadmill run-time-to-fatigue in min (mean ±
Group Pre-study Day 21
Placebo 11.4 ± 0.6 11.5 ± 0.7
TNJ 12.1 ± 0.9 14.6 ± 0.9
*P < 0.05
Table 2. Relative blood chemiluminescence (counts per
min) superweak spontaneous chemiluminescence (mean
± standard deviation).
Group Pre-study Day 21
Placebo 97.3 ± 6.3 108.1 ± 7.7
TNJ 101.2 ± 7.2 75.4 ± 6.2*
*P < 0.05
abuse, and who each consumed 125 mL of TNJ daily. Urine sam-
ples were collected from the volunteers within 24 h. Each sample
was tested for the presence of THC, benzoylecgonine, phen-
cyclidine, opiates, methamphetamines, methadone, amphetamines,
barbiturates, benzodiazepines, and tricyclic antidepressants, using
a RapidCheck® 10 Panel Drug Test immunoassay, according to
manufacturer’s instructions without modifications (Craig Medical
Distribution, Vista, CA).
TNJ antidoping screening
TNJ was evaluated by three different agencies (ConsumerLab.com
in the US, China Doping Control Center, and Anti-doping Center
Moscow). Tests were conducted for the presence of more than 170
chemicals and compounds which are banned under the guidelines
of the World Anti-doping Agency.
Endurance, antioxidant, and exercise performance
effects of TNJ
Endurance test results (time-to-fatigue) are shown in
Table 1, blood chemiluminescence is compared in Table
2, and banned substances are listed in Table 3.
Endurance in the TNJ group was increased by 21%, after
21 days of supplementation. There was no change in any
blood measurements of the TNJ group. Blood lactate did
not increase in this group, indicating that the improved
endurance was not due to increased energy consump-
tion. Conversely, chemiluminescence decreased by
approximately 25%, suggesting that the increased time-
to-fatigue was achieved due to significant antioxidant
activity. No allergic responses, or other side effects, were
observed in those who drank TNJ. No significant changes
in any measurements were observed in the placebo
group, with the exception of an increase in blood lactate.
Even though the increase suggests an increase in energy
expenditure, no improvement in endurance occurred in
Palu et al. 155
the placebo group.
TNJ drug screen test
No drugs or their metabolites were found in any of the
urine samples collected from both female and male
volunteers that consumed 124 mL of TNJ daily.
TNJ antidoping screening
ConsumerLab.com (2005) reported that TNJ passed its
antidoping screening and that no banned substances
(beta-blockers, diuretics, narcotics, anabolic steroids, sti-
mulants or masking agents) were detected. Similarly,
reports from Moscow Anti-doping Centre and China
Doping Control Center verified that TNJ does not contain
any of the banned substances listed by the World Anti-
A stream of research shows that high-intensity exercise
generates and increases oxygen-free radicals and other
reactive-oxygen species (ROS) (Duarte et al., 1993;
Heunks et al., 1999; Ji, 1999; Oba et al., 2002; McAnulty
et al., 2004). This type of exercise contributes to an imba-
lance of the body’s ROS, and its antioxidant defense (Ji,
1999). Further, heavy exercise results in an increase of
blood-glutathione oxidation, a marker of oxidative stress
in healthy subjects (Sastre et al., 1992; Gomez-Caberara
et al., 2003).
TNJ’s antioxidant effect was first discovered and
reported by Wang and Su (2001), from in-vitro studies.
This discovery brought a new perspective into the health
benefits of noni, especially regarding its effect on
increasing energy, recovery time, and endurance in ath-
letes, part of which is attributed to its antioxidant property.
TNJ ergogenic effect was evaluated in mice indicating
that TNJ increased the swimming time of mice (36 to
45%) before becoming fatigued, and increased their
endurance time (59 to 128%) on a rotarod test, compared
to the control. Further, the older mice in the TNJ group
performed similarly to the younger ones in the control
group, with respect to swimming time and endurance (Ma
et al., 2007).
There has been some interest and concern regarding
the composition of herbal and dietary supplements, and
their possible influence on drug or doping tests (Winek et
al., 1993; Markowitz et al., 2004). As the use of herbal
dietary supplements increases, this issue is of paramount
importance. A pilot clinical study revealed that TNJ has
the potential to increase the ability of post-menopausal
women to perform more vigorous activities (Langford et
al., 2004). With these ergogenic effects in mind, TNJ was
evaluated for the presence of any prohibited substances.
An alkaloid screen of the juice was negative. An HPLC
156 J. Med. Plant. Res.
Table 3. Banned substances not detected in TNJ*.
Stimulants and Related Compounds Narcotics and Related Substances Anabolic Agents and Related Substances
Amfepramone urphine Androstenedione
Amphetamine Codeine Bambuterol
Bambuterol Diamorphine (heroin) Boldenone
Benzphetamine Dihydrocodeine Clenbuterol
Caffeine Hydrocodone Clostebol
Cathine/Norpseudoephedrine Hydromorphone Danazol
Cocaine Levorphanol Dehydrochlormethyltestosterone
Ephedrine Morphine Drostanolone
Etilamphetamine Nalbuphine Fenoterol
Fencamfamin Oxycodone (oxycotin) Fluoxymesterone
Fenfluramine morpho Formebolone
Fenproporex Pentazocine Formoterol
Morazone Tetrahydrocannabinol (THC) Mesterolone
based screen was also performed and detected no
alkaloids at or above the detection limits of 1 mg/L. Xan-
thine alkaloids were of particular interest, as noni belongs
to the coffee (Rubiaceae) family. Another assay, specific
to caffeine, found none at a detection limit of 50 mg/L
(Blauch and Tarka, 1983).
TNJ does not appear likely to produce false-positive
results in the immunoassay-based urine drug screens.
Blood analysis of the athletes in this study revealed that
improved endurance was not related to increased energy
consumption, but rather to other mechanisms. The ergo-
genic properties of TNJ are likely due to the nutritional
properties of the fruit, and not to any known performance-
enhancing compounds. These results are in agreement
with the earlier cited mice-test results of Ma et al, (2007).
Chemiluminescence is the phenomenon of light emis-
sion (or photon emission) from excited lipid-oxidation
products in biological matrices (Boveris et al., 1980). In
the past decade, this phenomenon has been used exten-
sively for clinical investigations (Lyamina et al., 2003),
and an indicator of oxidative stress (Costa et al., 1997). It
has also been used as an indicator of lipid peroxidation
associated with heavy exercise (Rozhkova et al., 2003; de
Souza et al., 2005). To assess the antioxidant effect of
TNJ, chemiluminescence was measured in this study for
all participants at the beginning, and again at the 21-day
conclusion. A decrease of 25% (P < 0.05) in the lipid
peroxidation was observed in the TNJ group whereas
Palu et al. 157
Table 3 (cont.)
Diuretics and related substances Masking Agents and Related Substances Beta Blockers and Related Substances
Amiloride Diuretics Acebutolo
Acetazolamide Epitestosterone Alprenolol
Bendroflumethiazide Probenecid Atenolo
Ethacrynic acid Sotalol
Banned substance list available through ConsumerLab.com (2005)
Indicates metabolites screened
in addition to parent drug.
none occurred in the placebo group. As such, TNJ
increased the antioxidant level in TNJ group by 25%.
In conclusion, TNJ has been shown to improve physical
endurance through increase in antioxidant activity. The
results of our study warrant more clinical research among
athletes from basketball, ice hockey, football, rugby and
soccer to further explore the benefits of using TNJ as part
of their daily regimens.
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