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- Green Tea (Camellia sinensis)
- Obesity
- Mineral Levels
| Date:
09-14-2012 | HC# 061211-456
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Re: Green Tea Supplementation Alters Mineral Status and Improves Lipid and Glucose Profiles in Obese Patients
Suliburska
J, Bogdanski P, Szulinska M, Stepien M, Pupek-Musialik D, Jablecka A. Effects
of green tea supplementation on elements, total antioxidants, lipids, and
glucose values in the serum of obese patients. Biol Trace Elem Res. May 15, 2012; [epub ahead of print]. doi:
10.1007/s12011-012-9448.z.
Obesity
is associated with many adverse health effects, including the development of
many chronic diseases. Studies have shown abnormalities in mineral status,
increased oxidative stress, and metabolic imbalances are associated with obesity.
So-called "functional foods," such as green tea (Camellia sinensis; GT), are reported to reduce the risk of many
health problems associated with obesity. The compounds in GT that are most
likely responsible for these effects are polyphenolics, especially catechins
such as epigallocatechin-3-gallate (EGCG). Although polyphenolics are reported
to interact with minerals and alter their distribution throughout the body, few
studies have explored the effects of GT on obesity and mineral status. Thus, the
aim of this randomized, double-blind, placebo-controlled study was to assess the health effects of obese patients
supplemented with GT extract (GTE) by analyzing serum mineral concentrations and
obesity-related parameters, such as body mass index (BMI), blood pressure,
total antioxidant status (TAS), lipid profiles, and glucose concentrations.
A
total of 46 obese patients (23 men and 23 women) aged 30-60 years, with a BMI
≥30 kg/m2, and without health conditions that would confound the
study, were enrolled in the trial. All patients received one 379 mg GTE capsule
(Olimp Laboratories; Dębica, Poland) per day, containing 208 mg EGCG, or
placebo (cellulose) with their morning meal for 3 months. All subjects
maintained an isocaloric diet (kept same calorie diet throughout the study) and
continued previous eating and physical habits during the study. Anthropometric (body)
measurements, blood pressure, and blood collection were taken at baseline and
after 3 months of treatment. Biochemical studies were conducted on blood
samples to measure mineral status and other obesity-related parameters.
There
were no significant differences between the 2 groups at baseline. However, after
3 months of treatment with GTE, in comparison to the placebo, a significant
reduction of total cholesterol (TC) (P<0.01), triglycerides (TG) (P<0.01),
low-density lipoprotein (LDL) cholesterol (P=0.02), BMI (P=0.03), and waist
circumference (P=0.04) was observed, while a significant increase was observed
in TAS (P<0.01) and zinc (P=0.03) levels. In comparison to baseline
measurements, only the 3-month GTE group resulted in significant changes in the
measured parameters. GTE treatment resulted in a significant reduction in TC (P=0.034),
TG (P=0.042), LDL cholesterol (P=0.035), glucose (P=0.043), and iron (P=0.048) levels;
and a significant increase in high-density lipoprotein (HDL) cholesterol (P=0.044),
TAS (P=0.048), zinc (P=0.037), and magnesium (P=0.047) levels.
Moreover,
before treatment a significant positive correlation was found between calcium
and BMI (P=0.042) and a negative correlation was found between copper and TG (P=0.038).
After treatment, a significant positive correlation was observed between iron
and BMI (P=0.023) and between magnesium and HDL cholesterol (P=0.023), while a
significant negative correlation was found between magnesium and glucose
(P=0.002).
The
authors conclude that supplementing obese patients with 3 months of GTE resulted
in a change in serum mineral status, which included a significant improvement
of zinc and magnesium content, but reduced iron levels. Furthermore, the authors
summarize that treatment with GTE produced favorable effects on BMI, lipid
profile, glucose, and TAS. Although the health implications of this study are
for the most part positive, the reduction of serum iron may be of concern. Many
of the polyphenolics in GT can function as iron chelators, which may prevent
absorption of iron and possibly compound the effects of low serum iron that may
result from obesity-related inflammation.1 Thus, more studies are
needed that assess the safety levels of GT polyphenolics in obese patients. Additionally,
the authors suggest larger-scale studies with longer observation times are
needed to support the data in this study. —Laura M. Bystrom,
PhD
Reference
1Tussing-Humphreys LM,
Liang H, Nemeth E, Freels S, Braunschweig CA. Excess adiposity, inflammation, and
iron-deficiency in female adolescents. J
Am Diet Assoc. 2009:109(2):297-302.
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