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- Ginseng (Panax spp., Araliaceae)
- Glycemic Control
- Systematic Review/Meta-analysis
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Date:
06-15-2018 | HC# 111772-594
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Re: Ginseng Aggregate Data Analyses Show Evidence of Modest yet Significant Benefit for Improving Fasting Blood Glucose
Shishtar
E, Sievenpiper JL, Djedovic V, et al. The effect of ginseng (the genus Panax) on glycemic control: a systematic
review and meta-analysis of randomized controlled clinical trials. PLoS One. September 29,
2014;9(9):e107391. doi: 10.1371/journal.pone.0107391.
Diabetes
is a global epidemic, and ginseng (Panax spp.,
Araliaceae) is a popular complementary and alternative medicine that has shown
promise in type 2 diabetes. However, systematic reviews of ginseng's effects on
blood glucose parameters have not been conclusive. The purpose of this
systematic review and meta-analysis was to evaluate the effect of ginseng on
glycemic control in people with and without diabetes.
The
authors' search of the MEDLINE, EMBASE, CINAHL, and CENTRAL databases from
inception through July 3, 2013, used the following terms and variations
thereof, in ways to maximize useful results from each database: panax, ginseng,
ninjin, renshen, shinseng, jen adj shen, schinseng, ginsenoside(s), glucose
tolerance test, OGTT, hemoglobin A, glycosylated, HBA1C, fructosamine, insulin,
glucose, hyperglycemia, hyperglycaemia, glycaemia, hyperinsulin, dysglycemia,
diabetes mellitus, "diabetes millitus [sic],"
HOMA, glycemia, gly, albumin, diabetes, metabolic syndrome, homeostasis model
assessment, hyperglycemic, hyperglycaemic, type1/ or type 1 diabetes, type2/ or
type 2 diabetes, gestational/ or gestational diabetes, and prediabetic state/
or prediabetes. (Please see Table S1 for the complete search strategy.)
Eligible
studies were at least 30 days long and evaluated the effect of oral ginseng (all
species of the genus Panax) supplementation
on at least one of the four following glycemic control metrics in people with
and without diabetes: fasting blood glucose (FBG), fasting plasma insulin
(FPI), glycated hemoglobin (HbA1c), and homeostasis model assessment of insulin
resistance (HOMA-IR). Excluded trials tested multi-herbal preparations, did not
have a suitable control, or did not provide satisfactory data on endpoints.
Fifteen
reports encompassing 16 trials and 770 participants with a median age of 51
years were included in the analysis (FBG: 16 trials, n = 770; FPI: 10 trials, n
= 349; HbA1c: nine trials, n = 264; HOMA-IR: seven trials, n = 305). Half of
the trials were conducted in Asia and half (25% each) in North America or
Europe. Table 1 summarized the following trial data: subject characteristics;
age; body mass index; setting; glucose (mmol/L); insulin (pmol/L); HbA1c (by
percent); HOMA-IR; design; comparator; follow-up time; methodological quality
score (MQS); funding sources; manufacturer; and ginseng form, preparation,
dose, and species.
Eleven
trials (68.8%) used parallel designs and five (31.3%) used crossover designs. Asian
ginseng (P. ginseng) was studied in
75% of trials, American ginseng (P. quinquefolius)
in 18.8%, and the remainder was unspecified. The intervention in all trials was
powdered ginseng in capsules. Preparations included Korean red ginseng (P. ginseng), American ginseng, or P. ginseng
whole root/rootlets or extracts; two trials did not include this information. Thirteen
trials (81.2%) used a placebo as the comparator, two (12.5%) used a control
group that did not receive ginseng, and one (6.25%) used fermented soy (Glycine max, Fabaceae) bean. The average
follow-up was eight weeks. The median MQS was 8 and most trials (n = 11) were
high quality (MQS ≥ 8).
Compared
to control, ginseng significantly reduced FBG (mean difference [MD] = −0.31
mmol/L, P = 0.03). Subgroup analyses revealed that the presence of diabetes
impacted ginseng's FBG-lowering effect (between-group MD = −0.96, P = 0.001).
Studies of those with diabetes had an MD of −0.84 mmol/l (95% confidence
interval [CI], −1.22 to −0.46), while studies of those without had an MD of
0.11 mmol/l (95% CI, −0.19 to 0.42). A linear association between baseline FBG
and treatment differences in FBG was seen in the continuous meta-regression
analyses (P = 0.001).
There
was no statistically significant difference between ginseng and control for
FPI, HbA1c, or HOMA-IR, but subgroup analysis revealed a significant reduction
in HbA1c in parallel trials compared to crossover trials (MD = 0.22%, P =
0.01). Significant study heterogeneity was found in the analyses of FBG (P <
0.001), HbA1c (P = 0.002), and HOMA-IR (P < 0.001). Funnel plot analyses
revealed there may have been publication bias in favor of "small and/or
imprecise studies with FBG and HbA1c reducing effects … ." but
neither Egger's nor Begg's test confirmed this.
The
authors state their study is limited by relatively short trial duration,
subject heterogeneity (those with and without diabetes), and different ginseng
preparations. The decrease in FBG was greater in those with diabetes,
suggesting ginseng supplementation may be more beneficial in people with higher
FBG. Inadequate washout and participant glycemic control, as well as relatively
short trial duration, may explain why HbA1c improvement was seen only in
parallel trials. The included trials had insufficient data on safety, ginseng
dose equivalents, and ginsenoside profiles to include these in the
meta-analysis.
The
authors conclude that ginseng significantly and modestly decreased FBG in
people with and without diabetes. More data are needed from larger and longer
randomized controlled trials focusing on ginseng's effect on HbA1c and FBG.
The
study was part of author Shishtar's master's thesis; Shishtar was supported by
a fellowship from the Embassy of the State of Kuwait. Please see the exhaustive
paragraph "Competing Interests" for information on the authors' affiliations.
—Heather Anderson, MD
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