By Greg Arnold, DC, CSCS, April 30, 2013, abstracted from “Green tea supplementation increases glutathione and plasma antioxidant capacity in adults with the metabolic syndrome” in the March 2013 issue of Nutrition Research

 

Metabolic syndrome affects more than 47 million Americans. It is characterized by excess abdominal fat, blood pressure of 130/85 mmHg or higher and insulin resistance, in which insulin is not properly used to control blood sugar (1).

Free-radical damage to cells is a hallmark and a trigger of disease onset and progression (3,4). A new study suggests green tea antioxidants may support cell health in metabolic syndrome (5).

Thirty-five diagnosed participants were divided into three groups (6) for eight weeks:
A: four cups of green tea daily.
B: two green tea extract capsules and four cups of water daily.
C: controls, four cups of water daily.

Four cups supplied 928 mg of green tea and antioxidants called catechins, including 440 mg of the best-known antioxidant, EGCG. Two capsules supplied 460 mg catechins and 460 mg EGCG daily.
Participants avoided other green tea sources, supplements and drinks and kept diet, exercise and lifestyle unchanged. Blood was sampled before and after.

After eight weeks, two significant changes appeared in groups A and B versus C.
A had 28.3% higher glutathione (2394.88 versus 1866.15 micrograms/gram hemoglobin, p<0.01) and 43.75% higher antioxidant capacity (7), 2.3 versus 1.6 micromoles/L, p<0.01, compared with C.
From baseline, A’s glutathione rose 34.3% (1783.11 to 2394.88 micrograms/g Hb, p<0.02), versus an 8.4% rise in C (1720.41 to 1866.15 micrograms/g Hb).
B had 47.4% higher glutathione (2750.8 versus 1866.15 micrograms/g Hb, p<0.01) and 56.25% higher antioxidant capacity (2.5 versus 1.6 micromol/L, p<0.01) than C.
From baseline, B’s glutathione rose 44.4% over eight weeks (1904.55 to 2750.8 micrograms/g Hb, p<0.02), versus 8.4% in C.

Glutathione is an essential antioxidant component of the body’s defence system. Its deficiency is involved in aging, cardiovascular disease and cancer (8).
According to the researchers, “these results support the hypothesis that green tea may provide antioxidant protection in metabolic syndrome.” Higher glutathione levels are therefore important for cell health and protection from disease, particularly in metabolic syndrome.

 

Reference:

1.       American Heart Association Website: “Metabolic Syndrome” posted on the American Heart Association website

2.       “Metabolic Syndrome: The Costliest Disease You’ve Never Heard Of” – Medical News Today May 9, 2005

3.       Armutcu F, Ataymen M, Atmaca H, Gurel A. Oxidative stress markers, C-reactive protein and heat shock protein 70 levels in subjects with metabolic syndrome. Clin Chem Lab Med 2008;46:785–90.

4.       Roberts CK, Barnard RJ, Sindhu RK, Jurczak M, Ehdaie A, Vaziri Oxidative stress and dysregulation of NAD(P)H oxidase and antioxidant enzymes in diet-induced metabolic syndrome. Metabolism 2006;55:928–34

5.       Basu A. Green tea supplementation increases glutathione and plasma antioxidant capacity in adults with the metabolic syndrome Nutr Res. 2013 Mar;33(3):180-7. doi: 10.1016/j.nutres.2012.12.010

6.       Basu A. Green tea supplementation affects body weight, lipids, and lipid peroxidation in obese subjects with metabolic syndrome. J Am Coll Nutr 2010;29:31–40

7.       Miller NJ. A novel method for measuring antioxidant capacity and its application to monitoring the antioxidant status in premature neonates. Clin Sci 1993;84:407–12

8.       Moskaug JO. Polyphenols and glutathione synthesis regulation. Am J Clin Nutr 2005;81:277S–83S

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