Green Tea & Fat Metabolism

1. Green Tea & Fat Metabolism MacKenzie Stark Macronutrient Metabolism 12-6-12

2. The Obesity Epidemic • Obesity is currently viewed as one of the most serious health problems of the 21st century. • Obesity is a medical condition in which an individual has excess body fat in relation to lean body mass. • Defined as having a BMI of 30 or higher. • Associated with T2DM, CVD, hypertension, and certain cancers.

3. Green Tea Components • During the past 10 years, green tea has been studied for its potential as a natural agent for weight loss. • Green tea contains polyphenol components, also known as catechins. • The most abundant catechin in green tea leaves is epigallocatechingallate (EGCG). • Researchers have proposed that EGCG may have an anti-obesity effect.

4. Fatty Acid Synthesis • Fatty acid synthesisis the creating of fatty acids from acetyl-CoA and malonyl-CoA precursors. • Acetyl-CoA is carboxylated to malonyl-CoA by the enzyme acetyl-CoA carboxylase (ACC). • Malonyl-CoA can then feed into the fatty acid synthase system. • Series of enzymatic reactions occur and the end product is palmitic acid. • Fatty acids are stored as triglycerides in adipose tissue.

5. Acetyl-CoA carboxylation to Malonyl-CoA

6. Fatty Acid Synthase System

7. The Effect of Catechins • The exact mechanism of catechins on fatty acid synthesis is inconclusive. • However, researchers have proposed that catechins have the ability to inhibit the action of ACC. • This would reduce the production of malonyl-CoA. • The reduction in malonyl-CoA would directly decrease fatty acid synthesis • Malonyl-CoA is a highly regulated molecule in fatty acid synthesis, and it inhibits carnitinepalmitoyltransferase I. • Relieving inhibition of CPT1 allows more fatty acids to enter the mitochondrial matrix and effectively increases Beta-oxidation of fatty acids.

8. Clinical Trial 1 • This study consisted of 30 volunteers-15 were put in the experimental group and 15 in the control group. • Between the ages of 20 and 50, with a BMI greater or equal to 24 kg/m2. • Experimental group consumed two 325 mL of a green tea beverage each day containing 267 mg catechins and 18 g of inulin powder. • Control group consumed two 325 mL of a green tea beverage each day containing 81 mg catechins. • Each group ate three meals provided by the hospital, and all other foods and beverages that contained catechins, polyphenols or caffeine were prohibited. • Study lasted eight weeks, where the first six weeks were the experimental weeks, and the last two weeks were a follow-up period. • Body weight, BMI and fat mass were measured in each group at the third, sixth and eighth week.

9. Results • There was a significant reduction in body weight, BMI and fat mass in the experimental group compared to the control group at the third and sixth week. • These differences were maintained during the two week follow-up period. • The mean BMI in the control group was 26.7 at baseline and remained the same after six weeks. • The mean BMI of the experimental group was 27.3 at baseline and decreased to 26.6 after six weeks. • Results show that catechin-rich green tea plus inulin may have beneficial effects in people who are overweight or obese.

11. Clinical Trial 2 • The second study consisted of 240 Japanese men and women with visceral fat-type obesity between the ages of 25 and 55. • The control group received one 340 mL green tea beverage daily with 96.3 mg catechins and 75 mg caffeine. • The experimental group received one 340 mL green tea beverage daily with 582.8 mg catechins and 72.3 mg caffeine. • Dietary intake was not monitored, but food products and/or medications known to influence lipid or CHO metabolism were prohibited. • The study started with a two week run in period and a 12 week treatment period. • Each subject visited the medical institution at four week intervals to have their anthropometrics and biochemical labs recorded.

12. Results • After the 12 week trial, the results showed a significant decrease in body weight, BMI, body fat ratio, body fat mass, waist circumference, and hip circumference in the experimental group. • Lean body mass significantly increased over time. • Total fat area, visceral fat are, and subcutaneous fat area all significantly decreased in the experimental group compared to the control group. • The mean BMI decreased by 0.6 in the experimental group, and there was no change in BMI in the control group after 12 weeks. • Results suggest that continuous ingestion of catechins in high amounts reduces body fat and might prevent obesity.

14. Discussion • Both studies suggested that green tea catechins ingested in high amounts increase fat loss in overweight or obese individuals. • However, the exact mechanism regarding the effect of catechins on fat metabolism is inconclusive and further studies are needed. • Several limitations to each study. The first study added inulin. Inulin is a naturally occurring soluble fiber. Inulin can give you a feeling of fullness and suppress your appetite. Could this account for the weight loss? • Green tea contains caffeine, which has been studied for its effect on weight loss. Synergy effect? • The dosage of catechins in the experimental groups was very high. Equivalent to 8-10 cups of green tea daily. What’s the best way to ingest high amounts of catechins?

15. Conclusion • Catechins found in green tea appear to aid in the reduction of fat. • Green tea catechins appear to be safe, as no adverse reactions were seen in either study. • A natural and effective supplement that can be used to support weight loss in overweight or obese individuals.

16. Questions?