Abstract
Purpose: This study investigated the effects of Coleus Forskohlii (CF) on body composition, and determined
the safety and efficacy of supplementation. Methods: In a double blind and randomized manner, 23 females
supplemented their diet with ForsLean™ (250 mg of 10% CF extract, (n=7) or a placebo [P] (n=12) two times
per day for 12-wks. Body composition (DEXA), body weight, and psychometric instruments were obtained at 0,
4, 8 & 12 weeks of supplementation. Fasting blood samples and dietary records (4-d) were obtained at 0 and 12-
wks. Side effects were recorded on a weekly basis. Data were analyzed by repeated measures ANOVA and are
presented as mean changes from baseline for the CF and placebo groups, respectively. Results: No significant
differences were observed in caloric or macronutrient intake. CF tended to mitigate gains in body mass (-
0.7±1.8, 1.0±2.5 kg, p=0.10) and scanned mass (-0.2±1.3, 1.7±2.9 kg, p=0.08) with no significant differences in
fat mass (-0.2±0.7, 1.1±2.3 kg, p=0.16), fat free mass (-0.1±1.3, 0.6±1.2 kg, p=0.21), or body fat (-0.2±1.0,
0.4±1.4 %, p=0.40). Subjects in the CF group tended to report less fatigue (p=0.07), hunger (p=0.02), and
fullness (p=0.04). No clinically significant interactions were seen in metabolic markers, blood lipids, muscle
and liver enzymes, electrolytes, red cells, white cells, hormones (insulin, TSH, T3, and T4), heart rate, blood
pressure, or weekly reports of side effects. Conclusion: Results suggest that CF does not appear to promote
weight loss but may help mitigate weight gain in overweight females with apparently no clinically significant
side effects. Journal of the International Society of Sports Nutrition. 2(2):54-62, 2005
Key Words: Weight Management, Nutritional Supplement, Lipolysis, Obesity, Herbs
Introduction
Coleus forskohlii ( C F ) i s a p l a n t n a t i v e t o I n d i a .
Since ancient times, plants of the Coleus species have
been used as an herbal medicine to treat various
disorders of the cardiovascular, respiratory,
gastrointestinal, and central nervous systems (1).
Forskolin has been isolated from the roots of the
India-based Coleus Forskohlii . One of the most
common species that contains forskolin is Coleus
Forskohlii Briq. Coleus forskohlii Briq. belongs to
the family Labiatae, better known as the mint family.
Chemically, it is a plant rich in alkaloids, which are
considered to have a high probability of influence on
the biological systems (2).
Forskolin is a diterpene that acts directly on
adenylate cyclase (3). Adenylate Cyclase is an
enzyme that activates Cyclic Adenosine
Monophosphate, or Cyclic AMP (cAMP) in the cell.
Cyclic AMP promotes the breakdown of stored fats
in animal and human fat cells (4). It regulates the
body’s thermogenic response to food, increases the
body’s basal metabolic rate, and increases utilization
of body fat. It may also release fatty acids from
adipose tissue, which results in increased
thermogenesis, loss of body fat, and theoretically
increased lean body mass (5). Forskolin increases
cAMP accumulation, and therefore stimulates
lipolysis. So, with high concentrations of forskolin,
cAMP and lipolysis increase (4). Enhanced lipolysis
increases fat degradation and fat usage as a fuel in the
body (3). This may promote fat and weight loss. It is
thought that supplementing with forskolin may
enhance fat loss without loss of muscle mass (6-8).
55
A previous proof-of-concept preliminary study was
conducted to test the effects of CF on body
composition (5). The study used a population of six
overweight, but otherwise healthy, women (BMI >
25) who ingested forskolin twice daily for eight
weeks. Each subject maintained her previous daily
physical exercise and eating habits. The results of the
study showed a significant decrease in the mean
values for body weight and fat content using
bioelectrical impedance (BIA) methodology. Lean
body mass significantly increased compared to
baseline. No side effects were reported. This
preliminary study showed that, given 25 mg of
forskolin twice a day, overall body weight could
improve by increasing lean body mass and by
decreasing weight from body fat (5).
A recent study conducted by Godard and colleagues
(6) evaluated the effects of forskolin supplementation
(250 mg of a 10% CF extract taken twice a day for
12-weeks) in overweight and obese men (BMI > 26)
on body composition, testosterone, metabolic rate,
and blood pressure. The study consisted of thirty
participants randomized, in a double-blind, placebo-
controlled (forskolin n = 15, placebo n = 15) manner
for 12 weeks. Body composition determined by
DEXA was affected due to significant decreases in
fat percentage and fat mass when compared to the
placebo group (p ≤ 0.05). Bone mass changes
occurred in the forskolin group (p ≤ 0.05) when
compared to the placebo group. The results of lean
body mass revealed an increased trend when
compared to the placebo group (p = 0.097). In
addition, increases in serum free testosterone
occurred in the forskolin group compared to the
placebo group (p ≤ 0.05). This study showed that
body composition decreased, bone mass increased,
and serum free testosterone increased. Thus, it was
concluded that forskolin use could possibly be used
as a therapeutic agent for weight management and
treatment in obese men (6).
The present study was needed to further investigate
the effectiveness of CF. Aside from its potential
health and therapeutic benefits, additional research
was needed to assess its role in the management of
body composition, and to determine the safety and
efficacy of supplementation. It was also of interest to
the investigator how forskolin affects general
markers of health (i.e. heart rate, blood pressure, and
blood variables). This study took a more
comprehensive approach to explore the role that
forskolin supplementation has on body composition,
fat loss, and general markers of health.
Methods
AND MATERIALS
Subjects. Nineteen (19) moderately overweight (BMI
of 25 - 35) female subjects between the ages of 18
and 40 participated in the study. An initial
entry/familiarization session was held during which
subjects completed personal and medical histories,
and signed Informed Consent Statements. A general
medical exam was given that included evaluating the
medical history, performing a general physical
examination, and evaluating whether the subjects met
entry criteria to participate in the study. Entry criteria
were based on age, BMI, and the presence of any
medical condition deemed unsuitable for
participation by the examining physician. Table 1
presents the experimental protocol/testing schedule
that was conducted.
Table 1. Overview of Research Design
Entry
Baseline 0
week (T1)
4 week
(T2)
8 week
(T3)
12 week
(T4)
Phone
interview
Familiarization
session
General
medical exam
by a registered
nurse to
determine
qualifications
to participate
in study.
Blood
Collection
* Clinical
Chemistry
* Thyroid
Panel
* Fasting
Insulin
Total Body
Water
DEXA Body
Comp
HR/Blood
Pressure
Dietary
History
Questionnaires
Total Body
Water
DEXA Body
Comp
HR/Blood
Pressure
Questionnaires
Total Body
Water
DEXA Body
Comp
HR/Blood
Pressure
Questionnaires
General
Medical Exam
Blood
Collection
* Clinical
Chemistry
*Thyroid
Panel
* Fasting
Insulin
Total Body
Water
DEXA Body
Comp
HR/Blood
Pressure
Dietary
History
Questionnaires
Pre-Supplementation / Baseline Testing. Subjects
recorded all food intake on dietary record forms for
four days (4-d) prior to pre-supplementation testing.
Subjects were instructed to refrain from exercise for
48 hours and to fast for 8 hours prior to pre-
supplementation testing. Subjects then reported for
the initial battery of assessments, which included an
appetite questionnaire, a psychological mood
inventory, and the following measurements: body
weight, total body water, body composition, resting
heart rate, and blood pressure. Subjects then donated
approximately 30 milliliters (6 teaspoons) of blood.
Supplementation Protocol . After baseline testing,
subjects were randomly and blindly assigned to
ingest Forslean™ or a matched placebo for 12 weeks.
The Forslean™ forskolin extract and appropriate
placebo were prepared by Sabinsa Corporation
(Piscataway, NJ)
. Capsules were provided in a 2-
piece hard shell capsule form, and delivered in
blindly labeled bottles containing 60 capsules each.
56
Each capsule contained 250 mg of the extract
standardized for 10% forskolin, or a suitable placebo.
Participants were instructed to take one capsule in the
morning and one in the evening, a half an hour before
a meal for 12 weeks.
Post-Supplementation Assessments . Subjects were
instructed to provide weekly reports to the research
nurse in order to monitor safety and side effects.
Subjects who did not provide a weekly report were
called by the research nurse to determine whether
they had experienced any unexpected problems
and/or adverse events. Following 4 and 8 weeks of
supplementation, subjects returned to have the same
initial battery of assessme nts performed minus the
blood draw and dietary history. After 12 weeks of
supplementation, subjects returned to repeat all
baseline tests (including dietary history and blood
draw).
PROCEDURES
Medical Monitoring. Subjects who met eligibility
criteria were informed to report any unexpected
problems or adverse events they encountered during
the course of the study. The subjects were contacted
on a weekly basis to determine if they experienced
any unexpected problems and/or adverse events. If
clinically significant side effects were reported, the
subjects were to discuss the problem with the
supervising physician to determine whether any
medical treatment was needed and/or whether the
subject could continue in the study. If so, the subject
would be referred to obtain medical treatment from
his/her personal physician. New findings and/or
medical referrals of unexp ected problems and/or
adverse events would be documented, placed in the
subjects research file, and reported to the University
of Memphis IRB committee.
Dietary Inventories . Subjects recorded all food and
fluid intake on dietary record forms. Dietary intake
was assessed using the Food Processor III Nutrition
Software (Version 7.5) (Salem, OR).
Appetite Scale. Appetite was assessed using a visual
analogue scale ranging from low to high (9). This
scale was used to record appetite, hunger, fullness,
satisfaction, energy, and quality of food.
Psychometric Inventory . Mood changes were
assessed by the Profile of Moods States (POMS)
inventory ( San Diego, CA ) . T h e P O M S i s a
validated, standardized self-rating scale consisting of
57 items that measures six identifiable mood states;
Tension-Anxiety; Depression-Dejection; Anger-
Hostility; Vigor-Activity; Fatigue-Inertia;
Confusion-
Bewilderment. A 5-point scale is used from 0 = not
at all to 4 = extremely (10).
Total Body Weight. Prior to each assessment, height
was measured with the shoes removed using standard
anthropometrics. Total body weight was also
measured with the shoes removed using a calibrated
electronic scale with a precision of +/-0.02 kg
(Healthometer, Bridgeview, IL ). The scale was
calibrated by placing cer tified 25-kg weights and
balancing the scale.
Total Body Water . Total body water was estimated
using the Valhalla Scientific Bioelectrical Impedance
Analyzer ( Model 1990B, San Diego, CA ), which
measures bio-resistance of water and body tissues
based on a minute low-energy, high frequency
transmitted through the body. The analyzer was
calibrated internally to a st andard electrical current
by pressing the calibration key located on the unit.
After calibration was completed, subjects were
placed in a supine position with the arms slightly bent
at the elbows and palms facing down. The arms and
hands were not to contact the body, and the legs were
not allowed to touch each other. The subjects were
instructed to remove the right shoe and sock. The
laboratory technician sterilized the area where the
electrodes were to be placed with a Kendall
Webcol™ alcohol prep saturated with 70% isopropyl
alcohol. Electrodes were placed on the posterior
aspect of the hand and wrist, and on the anterior
aspect of the foot and ankle.
Body Composition & Bone Density . Body
composition was determined using a calibrated
Hologic 4500W dual-energy x-ray absorptiometry
(Bedford, MA ) with the Hologic version V7, Rev F
software ( Waltham, MA ). The dual-energy x-ray
absorptiometry (DEXA) segments regions of the
body (right arm, left arm, trunk, right leg, and left
leg) into three compartments for determination of fat,
soft tissue (muscle), and bone mass. The scanned
bone, fat, and fat-free/soft tissue mass for each region
were subtotaled to determine whole body values.
Percent body fat was calculated by dividing the
amount of measured fat mass by total scanned mass.
Day–to-day reliability studies of hip, spine, and
whole body scans on men and women show the
DEXA used in this study to be a highly reliable and
precise method for determining variations in body
composition segments (11). Test-retest reliability
studies performed on male and athletes with this
DEXA machine yielded a mean deviation for total
BMC and total fat free/soft tissue mass of 0.31% with
a mean intra-class correlation of 0.985 (11). Quality
57
control (QC) calibration pr ocedures were performed
on a spine phantom ( Hologic X-CALIBER Model
DPA/QPR-1 anthropometric spine phantom ) prior to
each testing session. In addition, weekly calibration
procedures were performed on a density step
calibration phantom. Testing was performed by
certified radiology technicians who properly
positioned the subjects in a supine manner on the
DEXA table and executed testing according to
standard procedures.
Heart Rate & Blood Pressure . Heart rate was
determined by palpitation of the radial artery
according to procedures outlined in the ACSM’s
Guidelines for Exercise Testing and Prescription
(12). Blood pressure was assessed in the supine
position after resting for 5-min with a mercurial
sphygmomanometer ( Trimline by PyMah
Corporation, Somerville, NJ ) using standard
procedures.
Blood Samples. Subjects observed an overnight eight
(8) hour fast prior to reporting to the lab to donate
blood. Approximately 6 teaspoons of venous blood
(30 milliliters) were obtained through venipuncture
of an antecubital vein in the forearm using standard
phlebotomy procedures. Samples were collected into
one (1) 10 mL Vacutainer SST™ gel and clot
activator tube, and two (2 ) 5mL Vacutainer Brand K
3
EDTA™ sterile interior tu bes. Trained laboratory
technicians centrifuged the blood samples at 5000 rev
x min
-1 for 10 minutes in a Biofuge 17R Centrifuge
(Heraeus Inc., Germany ). Serum from one SST tube
was transferred into Costar microcentrifuge tubes
(Corning Incorporated, Corning, NY ) using plastic
disposable Falcon™ transfer pipets ( Becton
Dickinson) and frozen at -80º Celsius for subsequent
analysis. Serum from the remaining SST and EDTA
tubes were transferred into two (2) separate 10 mL
plain sterile tubes. The whole blood was diluted with
2 mL of saline solution. Both serum and whole blood
samples were refrigerated and sent to Quest
Diagnostic Labs ( Ann Arbor, MI) for clinical
analysis.
A complete 31-panel clinical chemistry profile was
run on serum samples using the Technicon DAX
model 96-0147 automated chemistry analyzer
(Technicon Inc., Terry Town, NY ) following standard
clinical procedures. This panel consisted of muscle
enzymes [creatine kinase, phosphorus, calcium]; liver
enzymes [direct bilirubin, total bilirubin, gamma
glutamyl transferase (GGT), lactate dehydrogenase
(LDH), alkaline phosphatase, AST (SGOT), ALT
(SGPT)]; lipid profile [triglycerides, total cholesterol,
high-density lipoprotein-cholesterol (HDL-C), low-
density lipoprotein-cho lesterol (LDL-C),
cholesterol/HDLC ratio, glucose], electrolytes
[sodium, potassium, chloride, carbon dioxide, urea
nitrogen (BUN), creatinine, BUN/creatinine ratio],
protein status [uric acid, total protein, albumin,
globulin, albumin/globulin ratio], and whole blood
cell counts [hemoglobin, hematocrit, red blood cell
counts, white blood cell counts (basophils, absolute
basophils, eosinophils, absolute eosinophils,
monocytes, absolute monocytes, lymphocytes,
absolute lymphocytes, neutrophils, absolute
neutrophils), platelet count, mean corpuscular volume
(MCV), mean corpuscular hemoglobin (MCH), mean
corpuscular hemoglobin co ncentration (MCHC), red
cell distribution width (RDW)]. Cell counts with
percent differentials were run on whole blood
samples using a Coulter STKS automated analyzer
(Coulter Inc., Hialeah, FL ) using standard
procedures.
Frozen serum samples were sent to the Department of
Physiology at East Tennessee State University to
assay thyroid stimulating hormone (thyrotropin),
thyroxin, total thyroxin, and fasting insulin. A
chemistry profile was run on these samples using an
Immulite Mark 5 HSS ch emiluminescence random
access immunoassay analyzer ( Diagnostic Products
Corporation, Los Angeles, CA ) following standard
procedures. These analyzers were calibrated daily to
controls according to manufacturer recommendations
and federal guidelines for clinical diagnostic
laboratories. Test to test reliability of performing
these assays ranged from 2 to 6% for individual
assays with a average variation of ±3%. Samples
were run in duplicate to verify results if the observed
values were outside contro l values and/or clinical
norms according to standard procedures (13).
Analysis of these blood parameters helped determine
the safety effects of this nutritional supplementation
formulation on general markers of clinical health
status and selected hormones.
DATA ANALYSIS
A 2 (groups) x 4 (times) analysis of variance
(ANOVA) test with repeated measures on the second
factor was performed on five variables: total body
weight, total body water, body composition, appetite
surveys, and psychological mood state inventories. A
2 X 2 ANOVA test with repeated measures on the
second factor was performed on the diet logs and the
clinical profiles for the blood samples. Type I error
was controlled at 0.05 for all of the data analysis
58
Table 2. Four-day total dietary intake for the CF and P groups.
Variable Group Week 0
(T1)
Week 8
(T3)
Week 12
(T4) Significance
Fat
(g/kg/d)
CF
P
281.5±87.5
337.0±124.2
243.2±69.0
310.1±99.1
187.0±55.8
219.0±86.3
Group
Time
Group x Time
0.153
0.002
0.696
Carbohydrates
(g/kg/d)
CF
P
959.1±278.7
959.7±253.6
903.5±227.9
953.3±269.2
777.5±303.2
831.5±184.1
Group
Time
Group x Time
0.719
0.025
0.676
Protein
(g/kg/d)
CF
P
293.8±112.0
318.5±143.5
270.8±93.0
290.7±129.9
242.8±80.7
282.1±77.6
Group
Time
Group x Time
0.525
0.213
0.831
Energy Intake
(kcal/kg/d)
CF
P
7458±1920
8087±2310
6833±1259
7772±2165
5690±1927
6435±1475
Group
Time
Group x Time
0.299
0.007
0.919
Table 3. Selected hematological markers for the CF and P groups.
Variable Group Week 0
(T1)
Week 12
(T4) Significance
White Blood
Cells
(thous/cum)
CF
P
6.5±1.8
5.9±1.7
7.9±2.3
5.1±1.7
Group
Time
Group x Time
0.030
0.366
0.007
Absolute
Lymphocytes
(cells/mcl)
CF
P
2161.2±433.6
2084.4±511.4
2771.0±643.2
1945.8±447.5
Group
Time
Group x Time
0.051
0.043
0.003
Calcium
(mg/dl)
CF
P
9.1±0.1
9.3±0.2
9.3±0.4
9.1±0.2
Group
Time
Group x Time
0.894
0.904
0.030
ALT (SGPT)
(U/L)
CF
P
11.8±4.6
22.5±10.1
11.4±3.4
22.0±13.8
Group
Time
Group x Time
0.020
0.036
0.000
Uric Acid
(mg/dl)
CF
P
4.2±0.9
3.9±1.1
3.8±1.0
4.4±1.4
Group
Time
Group x Time
0.006
0.724
0.003
Absolute
Neutrophils
(cells/mcl)
CF
P
3791.9 ±1273.0
3270.7±1251.3
4467.7±
1737.2
2732.5±596.0
Group
Time
Group x Time
0.042
0.787
0.027
procedures. Tukey least significant difference (LSD)
post-hoc procedures were conducted when a
significance level was observed. Delta values were
calculated on body composition variables to further
highlight significant changes that occurred during the
study.
Results
Nutritional Intake . Table 2 presents four day total
nutritional intake data for the CF and P groups. No
significant group interactions ( p>0.05) were
observed in mean relative daily energy intake,
carbohydrate intake, protein intake, or fat intake.
However, daily intake for the energy, carbohydrate,
and fat variables significantly decreased ( p < 0.05 )
from Week 0 to Week 12.
Medical Safety Analysis. Table 3 presents significant
blood markers obtained throughout the study. These
hematological responses were measured for the
analysis of the safety of the supplement on general
markers of health. The results of the analysis
indicated a significant group interaction in white
blood cell levels ( p=0.007), absolute lymphocyte
levels ( p=0.003), absolute neutrophils ( p = 0. 027),
calcium levels ( p=0.03), ALT ( p=0.000), and uric
acid ( p=0.003) for the CF group. Additionally, a
significant group effect ( p < 0.05 ) was observed in
red blood cell count, % hematocrit, MCV, MCH,
59
Table 4. Body composition and bone density values for the CF and P groups
Variable Group Week 0
(T1)
Week 4
(T2)
Week 8
(T3)
Week 12
(T4) Significance
Body
Weight
(kg)
CF
P
87.2±12.4
86.1±12.5
86.8±12.1
86.1±15.3
86.5±12.8
87.1±14.3
86.6±13.0
87.4±13.4
Group
Time
Group x Time
0.987
0.492
0.121
Bone
Mineral
Area
(cm
2)
CF
P
1772±94
1846±116
1772±121
1861±110
1755±127
1855±106
1781±130
1844±120
Group
Time
Group x Time
0.148
0.929
0.756
Bone
Mineral
Content
(g)
CF
P
1781±202
1872±237
1788±206
1874±223
1759±226
1874±232
1803±223
1870±242
Group
Time
Group x Time
0.412
0.663
0.601
Bone
Mineral
Density
(g/cm
2 )
CF
P
1.0±0.08
1.0±0.08
1.0±0.07
1.0±0.07
0.9±0.07
1.0±0.08
1.0±0.07
1.0±0.08
Group
Time
Group x Time
0.923
0.367
0.578
Fat Mass
(kg)
CF
P
33.82±8.00
31.27±7.22
33.77±8.38
31.69±7.94
33.66±8.17
32.20±8.70
33.61±8.37
32.36±8.22
Group
Time
Group x Time
0.638
0.336
0.161
Lean Mass
(kg)
CF
P
44.65±5.75
46.40±6.18
44.40±4.88
46.47±6.45
44.69±5.44
47.01±5.97
44.59±5.53
47.05±5.62
Group
Time
Group x Time
0.446
0.168
0.212
Lean +
BMC
(kg)
CF
P
46.43±5.88
48.27±6.36
46.18±5.01
48.35±6.63
46.45±5.57
48.88±6.16
46.40±5.66
48.92±5.81
Group
Time
Group x Time
0.440
0.154
0.211
Total Mass
(kg)
CF
P
80.25±12.42
79.54±12.70
79.96±11.93
80.04±13.60
80.11±12.59
81.08±13.81
80.017±12.7
81.28±13.01
Group
Time
Group x Time
0.948
0.139
0.080
Body Fat
(%)
CF
P
41.8±4.7
39.0±3.7
41.8±5.0
39.5±4.0
41.6±4.4
39.2±4.6
41.6±4.8
39.3±4.3
Group
Time
Group x Time
0.243
0.923
0.395
Body
Water
(%)
CF
P
43.9±4.0
46.1±3.2
44.1±3.6
46.1±3.6
45.5±3.8
46.1±3.2
45.3±4.3
47.3±5.2
Group
Time
Group x Time
0.289
0.200
0.802
total bilirubin, glucose, BUN/creatinine ratio, and
cholesterol/HDL ratio within the P and CF groups. A
significant decrease was noted in all of the values
except for total bilirubin, which significantly
increased within both groups. The cholesterol/HDL
ratio also significantly increased within the P group.
There was a significant time effect ( p 0.05)
were observed in the blood lipid profile,
hemodynamic, hormone, insulin variables, or weekly
reports of side effects. All values remained within
normal clinical parameters.
Body Composition . Table 4 presents body
composition data obtained during each of the four
testing trials, and Figure 1 presents mean changes in
body composition data from Week 0 to Week 12.
There were no significant differences ( p>0.05) in
body weight , bone mineral area, bone mineral
density, fat mass, lean mass, % body fat, or % body
water observed between the two groups. In addition,
there was no significant interaction (p>0.05) amongst
the groups in body composition. Group trends
occurred in total mass (p=0.08).
Psychological Profiles. A significant time effect was
noted for tension/anxiety ( p = 0. 006) in the
psychological analysis of mood. Group trends
occurred in fatigue ( p = 0.07 ) between P and CF
from Week 0 to Week 12. No other significant
differences were observed.
Appetite Profiles . Table 5 presents the appetite data
obtained during each of the four testing trials. There
were no significant changes observed in appetite,
60
-1000
-500
0
500
1000
1500
2000
2500
3000
1234
Trials (Weeks)
Fat (g)
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
1234
Trials (weeks)
% Body Fat
Figure 1. The upper left panel depicts changes in DEXA total scanned mass (g), the upper right panel illustrates changes in DEXA fat-
free mass (g), the lower left panel highlights differences in DEXA lean mass (g), and the lower right panel shows changes in DEXA %
body fat from Week 0 to Week 12 for CF (♦) and P (■).
amount of energy, or over all quality of food. The
analysis indicated a significant time effect ( p =
0.026) in satisfaction from food in both groups from
Week 0 to Week 12. There was a significant decrease
observed in the feelings of fullness variable ( p =
0.04) for group CF from Week 0 to Week 12.
Discussion
The major findings of this study were: 1.) 12-weeks
of CF supplementation (250 mg of a 10% CF extract
taken two times per day) did not promote weight loss
but may have helped mitigate weight gain in free-
living overweight females; and, 2.) CF
supplementation did not adversely affect markers of
health status. However, some interesting findings
were observed that warrant additional research. The
following discusses the results of this study in greater
detail.
Dietary Intake . The subjects involved in the study
recorded all food and fluid intake during Week 0 and
Week 12 of the testing sessions. Significant decreases
were seen in carbohydrate, fat, and energy intake for
both groups over time. No significant differences
were observed between CF and P, which suggest that
supplementation had no significant effect on diet.
The changes over time could reflect subject efforts to
decrease food intake in an attempt to assist in the
weight loss process. It is possible that more group
differences could have been observed if a specific
diet were implemented into the study. This would
allow for the effects of supplementation to be more
closely monitored.
Medical Safety Analysis . One purpose of this study
was to determine the safety effects of forskolin
supplementation on general markers of health. This
was measured by monitoring changes in heart rate
and blood pressure taken during each testing session,
and serum and whole blood samples collected during
Week 0 and Week 12 of the study. Previous
research indicated that CF causes an increase in heart
rate and a decrease in blood pressure (14-15).
However, the results of this analysis showed that
supplementation had no significant effect on either
variable. The blood samples collected were assayed
for muscle and liver en zymes, lipid profile,
electrolytes, protein status, thyroid hormones, fasting
insulin, and whole blood cell counts. Significant
changes were observed from Week 0 to Week 12 in
Group CF in white blood cell count, absolute
lymphocyte count, absolute neutrophil count, calcium
levels, ALT, and uric acid levels. Supplementation
-1 000
-500
0
500
10 0 0
150 0
2000
2500
3000
12 34
T rials (Weeks)
Total Mass (g)
-1500
-1000
-500
0
500
1000
1500
1234
Trials (Weeks)
Fat Free Mass (g)
61
Table 5. Appetite markers for the CF and P groups.
Variable Group Week 0
(T1)
Week 4
(T2)
Week 8
(T3)
Week 12
(T4) Significance
Appetite CF
P
4.8±0.3
5.1±0.8
4.7±1.4
4.1±1.6
4.4±1.1
4.3±1.4
4.5±0.7
5.1±1.1
Group
Time
Group x Time
0.829
0.673
0.581
Hunger CF
P
4.0±1.2
4.9±1.1
3.8±1.0
4.0±1.5
4.0±1.8
4.1±1.1
3.1±1.5
5.2±1.0
Group
Time
Group x Time
0.054
0.645
0.165
Satisfaction
from Food
CF
P
5.8±1.7
6.1±1.4
5.0±0.5
5.9±1.3
4.4±1.2
5.5±1.9
4.7±1.9
5.8±1.1
Group
Time
Group x Time
0.138
0.026
0.242
Feeling of
Fullness
CF
P
5.8±1.3
6.3±1.3
4.7±0.9
5.9±1.7
5.0±2.1
6.1±1.8
4.1±1.3
6.4±1.5
Group
Time
Group x Time
0.040
0.086
0.042
Amount of
Energy
CF
P
5.9±2.0
5.8±1.2
5.2±1.3
6.0±1.2
5.5±2.5
5.9±1.4
5.5±1.9
5.8±1.7
Group
Time
Group x Time
0.611
0.781
0.785
Overall
Quality of
Food
CF
P
4.8±1.5
5.2±1.4
5.1±1.8
5.7±1.0
4.5±1.1
5.6±1.3
4.0±1.7
5.6±1.4
Group
Time
Group x Time
0.102
0.472
0.134
resulted in an increase in calcium, white blood cell,
absolute lymphocyte, and absolute neutrophil counts.
Decreases were observed in ALT and uric acid levels.
These variables contribute to muscle, immune, liver,
and protein functions, respectively, in the body. Even
though these changes occurred, the values remained
within normal ranges and were relatively small.
Additionally, no significan t adverse events were
reported during the study that could be attributed to
the supplementation protocol. Therefore, these
findings suggest that CF supplementation does not
appear to be associated with any significant clinical
side effects.
Body Composition . This study was also conducted
with the purpose of investigating the effectiveness of
CF on the management of body composition. Body
composition was analyzed by examining measures of
body weight, body water, and bone density. Previous
research suggests that forskolin is associated with
increased lipolysis, which would increase fat and
weight loss in the body (13). The findings from the
previous pilot study suggested that supplementation
significantly decreases body weight and fat, and
significantly increases lean body mass in free living
subjects (5). The results from this study did not
replicate those findings. Additionally, results
contrast recent findings by Godard and colleagues (6)
who reported that 12-weeks of CF (250 mg of a 10%
CF preparation taken two times per day) promoted
favorable changes in body composition in overweight
men. In the present study, no significant changes
were observed in body weight, fat content, or lean
body mass. However, statistical trends were found in
total scanned mass, which could suggest some
alleviation in weight gain among overweight
subjects. Overall, CF had no effect on the fat free or
fat mass of the female subjects used in the study. It is
possible that more group differences could be seen if
controls for exercise and/or diet were incorporated
and/or the study was conducted in a larger
population.
Psychological Analysis . A psychometric inventory
was used to analyze mood changes during each of the
four testing sessions of the study. This analysis
measured potential changes in six different mood
states: tension-anxiety, depression-dejection, anger-
hostility, vigor-activity, fatigue-inertia, and
confusion-bewilderment. The results of this
psychological inventory revealed that regular
ingestion of the supplement produced no significant
alteration in mood, except for the decrease in tension-
anxiety over time. This decrease could be associated
with the possible effects of supplementation on body
weight, which is an issue that often leads to tension-
anxiety. Trends were observed in fatigue levels.
Subjects taking the supplement appeared to
experience less fatigue over the course of the study.
Because there were no controls for physical activity
in this study, only speculation can explain the
changes that occurred. It is possible that those in CF
engaged in less activity with the idea that
supplementation would increase weight loss.
62
Appetite Analysis. An appetite invent ory was used to
assess variables of appetite during each of the four
testing sessions of the study. This inventory
measured changes in hunger, appetite, satisfaction
from food, fullness, and overall quality of food. No
significant differences were observed in appetite,
hunger, energy, or overall quality of food. This shows
that the eating desires for both groups were
maintained. However, the significant time effect in
satisfaction from food found in CF and P suggests
that both groups received less enjoyment from the
food consumed. There was also a significant decrease
noted in feelings of fullness in CF from Week 0 to
Week 12. Even though appetite and hunger were not
significantly affected by supplementation, it is
possible that because CF re ceived less satisfaction
from food that less food was eaten.
Summary. In conclusion, this study was performed in
an attempt to further inves tigate the effectiveness of
CF on body composition and general markers of
health. The findings suggest that 12-weeks of CF
supplementation in free-living subjects have limited
effects on body composition and no apparent
clinically significant side effects. However, CF has
the potential to positively influence the loss and
management of overall body weight possibly as a
means of maintaining weight after weight loss. Still,
future research is needed to further explore its
capabilities.
Acknowledgements
This study was conduced at University of Memphis
when the primary researchers were affiliated with
that institution. We would like to thank the subjects
who participated in this study and the laboratory
assistants in Exercise & Sport Nutrition Laboratory at
The University of Memphis who assisted in data
acquisition and researchers in the Exercise & Sport
Nutrition Laboratory at Baylor University who
assisted with data analysis and manuscript
preparation.
This study was funded in part by a research grant
from Sabinsa Corporation ( Piscataway, NJ ) in
collaboration with ImagiNutrition ( Laguna Niguel,
CA). Investigators independently collected, analyzed
and interpreted data from this study and have no
financial interest in the outcome of results reported.
Presentation of results in this study does not
constitute endorsement by researchers or their
institutions of the supplement investigated.
References
1. Agarwal, K.C., R.E. Parks. Forskolin: a potential antimetastic agent. Int J Cancer. 32:801-804, 1983.
2. Caprioli, J., M. Sears. Forskolin lowers intraocular pressure in rabbits, monkeys, and man. Lancet. 958-960, April 30, 1983.
3. Burns, T.W., Langley, P.E., Terry, B.E., D.B. Bylund, L.R. Forte, Jr. Comparative effects of forskolin and isoproterenol on the
cyclic AMP content of human adipocytes. Life Sci. 40: 145-54, 1987.
4. Litosch, I., Hudson, T.H., Mills, I., Li, S.Y., J.N. Fain. Forskolin as an activator of cyclic AMP accumulation and lipolysis in rat
adipocytes. Mol Pharmacol. 22:109-15, 1982.
5. Diterpene forskolin (Coleus forskohlii, Benth.): A Possible New Compound for Reduction of Body Weight by Increasing Lean
Body Mass Database [http://www.forlslean.com/clinical_studies.html]
6. Godard, M.P., Johnson, B.A., S.R. Richmond. Body Composition and Hormonal Adaptations Associated with Forskolin
Consumption in Overweight and Obese Men. Obesity Research. 13:1335-1343, 2005.
7. Srivasta, S.K., Khatoon, CS, Mehrotra, S, R. Mehrotra. Pharmacognistic evaluation of coleus forskohlii. Pharmaceutical Biology.
40(2):129-134, 2002.
8. Exercise and Sport Nutrition: A Balanced Perspective for Exercise Physiologists Database.
[http://www3.baylor.edu/HHPR/faculty/Kreider/Courses/PEPNutrition.pdf]
9. Flint, A., A. Raben, et al. Reproducibility, power and validity of visual analogue scales in assessment of appetite sensations in
single test meal studies. Int J Obes Relat Metab Disord. 24(1): 38-48, 2000.
10. McNair, D.M., M. Loor, L.F. Droppleman. Edits Manual for the Profile of Mood States. San Diego Educational and Industrial
Testing Service, 1992.
11. Almada, A.L., R.B. Kreider, et al. Day-To-Day Reliability in Spine, Hip, and Whole Body DEXA Scans in Men and Women.
Southeast American College of Sports Medicine Conference Abstracts. 27: 36, 1999.
12. Franklin, B., M. Whaley (Eds.). ACSM’s Guidelines for Exercise Testing and Prescription. Philadelphia: Lippincott Williams &
Wilkins; 2000.
13. Kreider, R.B., M. Ferreira, et al. Effects of Calcium β-hydroxy β-methylbutyrate (HMB) Supplementation During Resistance-
Training on Markers of Catabolism, Body Composition and Strength. Int J Sports Med. 20: 1-7, 1999.
14. Rupp, R.H., N.J. de Souza, A.N. Dohadwalla. Proceedings of the international symposium on Forskolin: Its chemical, biological
and medical potential. Organized by Hoechst Centre for Basic Research, Bombay on January 28-29, 1985. Hoechst India Limited.
15. Seamon, K.B., W. Padgett, J.W. Daly. Forskolin: unique diterpene activator of adenylate cyclase in membranes and in intact cells.
Proc Natl Acad Sci U S A. 78:3363-7, 1981.
16. Kasonia K. Preliminary screening of plant extracts used in respiratory pathology in Kivu/Zaire on isolated guinea pigs rings trachea.
Belgian Journal of Botany. 128:165-175, 1995.
17. Bauer, K. et al. Pharmacodynamic effects of inhaled dry powder formulations of fenoterol and colforsin in asthma. Clin. Pharmacol.
Ther. 53:76-83,
Text is read by the "Ask this paper" AI Q&A widget below.
Extraction quality varies by source — PMC NXML preserves structure
cleanly, OA-HTML may include some navigation residue, and OA-PDF can
have broken hyphenation. The publisher copy
(via DOI)
is the canonical version.