Nantz MP, Rowe CA, Bukowski JF, Percival SS. Standardized capsule of Camellia sinensis lowers cardiovascular risk factors in a randomized, double-blind, placebo-controlled study. Nutrition. 2009;25: 147-154.

Tea (Camellia sinensis) consumption has been linked with beneficial health effects for centuries. Many studies, mostly observational in nature, have shown that tea consumption has positive effects on bones and the cardiovascular system and has antiaging effects; however, other studies have consistently shown no health benefits. Studies showing positive and negative health effects have all been limited by confounding variables, which are inherent in observational studies involving free-living human subjects, and by inconsistencies in the constituent compounds and storing and brewing methods of tea. Most studies of tea have focused on a family of compounds known as catechins; however, tea also contains the compound L-theanine, the concentration of which varies from 0.6 to 2.38 g/100 g of tea depending on the cultivar. L-Theanine has been shown to decrease blood pressure (BP) in rats, and epigallocatechin-3-gallate (EGCG) has been shown to relax vascular smooth muscle cells in culture; however, these effects have not been studied in humans. The authors hypothesized that the intake of standardized amounts of L-theanine and EGCG would decrease cardiovascular disease (CVD) risk factors in healthy humans. The objective of the present study was to evaluate whether a standardized decaffeinated green tea product decreases BP, serum lipid concentrations, oxidative stress, and markers of chronic inflammation. Healthy men (n = 52) and women (n = 72) aged 21 to 50 years were enrolled in a double-blind, placebo-controlled, parallel study in which they were randomly assigned to consume tea compounds (CSC; n = 61) or placebo (n = 63) for 3 months. The study was conducted at the University of Florida, Gainesville. The CSC product (Cardio Guard®; Cardio Guard, LLC; Orlando, Florida) used contains 100 mg of L-theanine and 200 mg of a decaffeinated catechin green tea extract providing polyphenols, catechins, EGCG, and trace amounts of caffeine, approximating the ingestion of 10 cups of decaffeinated green tea daily. The subjects were instructed to take 2 capsules daily, 1 in the morning and 1 in the evening, for 3 months. Fasting blood samples were collected at baseline (day 0) and on day 21 for the measurement of serum lipids, serum amyloid- (a marker of chronic inflammation), and serum malondialdehyde (a marker of oxidative stress). BP was measured at baseline, 3 weeks, and 3 months. One hundred seventeen subjects completed the study. Systolic and diastolic BP decreased significantly (P < 0.05) in the CSC group, by 5 and 4 mm Hg, respectively, after 3 weeks. The significant systolic BP-lowering effect of CSC was still evident after 3 months, although it was lower after 3 months (3-mm Hg decrease from baseline) than after 3 weeks. The significant decrease in diastolic BP observed after 3 weeks was no longer evident at 3 months. Neither CSC nor the placebo had a significant effect on high-density-lipoprotein cholesterol or triacylglycerols in the study group as a whole or in any of the subgroups or on total and low-density-lipoprotein (LDL) cholesterol in the study group as a whole. However, total and LDL cholesterol decreased significantly (P < 0.05) by 10 and 7 mg/dL, respectively, in men in the CSC group after 3 weeks. Serum amyloid- decreased by 42% in the CSC group after 3 weeks, and serum malondialdehyde was 11.9% lower in the CSC group than in the placebo group after 3 weeks. The adverse events reported were mild, infrequent, and transient. The results of this study indicate that the daily consumption of CSC capsules for 3 weeks significantly decreased both systolic and diastolic BP, but only the significant decrease in systolic BP was maintained over the 3-month study period. The mechanism responsible for the BP-lowering effect likely involves several factors; however, neither the effects of L-theanine nor of EGCG individually or in combination have been studied in humans with hypertension. Furthermore, CSC decreased LDL-cholesterol concentrations and markers of oxidative stress and inflammation, elevated concentrations of which are independent risk factors for CVD. The authors suggest that additional research be conducted to determine the mechanisms of action responsible for these beneficial health effects and suggest that "CSC may be an option for people who have mild to moderate high BP, elevated LDL cholesterol, elevated markers of inflammation, or a combination of these three CVD risk factors." —Brenda Milot, ELS dow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;}

Tea (Camellia sinensis) consumption has been linked with beneficial health effects for centuries. Many studies, mostly observational in nature, have shown that tea consumption has positive effects on bones and the cardiovascular system and has antiaging effects; however, other studies have consistently shown no health benefits. Studies showing positive and negative health effects have all been limited by confounding variables, which are inherent in observational studies involving free-living human subjects, and by inconsistencies in the constituent compounds and storing and brewing methods of tea. Most studies of tea have focused on a family of compounds known as catechins; however, tea also contains the compound l-theanine, the concentration of which varies from 0.6 to 2.38 g/100 g of tea depending on the cultivar. l-Theanine has been shown to decrease blood pressure (BP) in rats, and epigallocatechin-3-gallate (EGCG) has been shown to relax vascular smooth muscle cells in culture; however, these effects have not been studied in humans. The authors hypothesized that the intake of standardized amounts of l-theanine and EGCG would decrease cardiovascular disease (CVD) risk factors in healthy humans. The objective of the present study was to evaluate whether a standardized decaffeinated green tea product decreases BP, serum lipid concentrations, oxidative stress, and markers of chronic inflammation.

Healthy men (n = 52) and women (n = 72) aged 21 to 50 years were enrolled in a double-blind, placebo-controlled, parallel study in which they were randomly assigned to consume tea compounds (CSC; n = 61) or placebo (n = 63) for 3 months. The study was conducted at the University of Florida, Gainesville. The CSC product (Cardio Guard®; Cardio Guard, LLC; Orlando, Florida) used contains 100 mg of l-theanine and 200 mg of a decaffeinated catechin green tea extract providing polyphenols, catechins, EGCG, and trace amounts of caffeine, approximating the ingestion of 10 cups of decaffeinated green tea daily. The subjects were instructed to take 2 capsules daily, 1 in the morning and 1 in the evening, for 3 months. Fasting blood samples were collected at baseline (day 0) and on day 21 for the measurement of serum lipids, serum amyloid-a (a marker of chronic inflammation), and serum malondialdehyde (a marker of oxidative stress). BP was measured at baseline, 3 weeks, and 3 months.

One hundred seventeen subjects completed the study. Systolic and diastolic BP decreased significantly (P < 0.05) in the CSC group, by 5 and 4 mm Hg, respectively, after 3 weeks. The significant systolic BP-lowering effect of CSC was still evident after 3 months, although it was lower after 3 months (3-mm Hg decrease from baseline) than after 3 weeks. The significant decrease in diastolic BP observed after 3 weeks was no longer evident at 3 months. Neither CSC nor the placebo had a significant effect on high-density-lipoprotein cholesterol or triacylglycerols in the study group as a whole or in any of the subgroups or on total and low-density-lipoprotein (LDL) cholesterol in the study group as a whole. However, total and LDL cholesterol decreased significantly (P < 0.05) by 10 and 7 mg/dL, respectively, in men in the CSC group after 3 weeks. Serum amyloid-a decreased by 42% in the CSC group after 3 weeks, and serum malondialdehyde was 11.9% lower in the CSC group than in the placebo group after 3 weeks. The adverse events reported were mild, infrequent, and transient.

The results of this study indicate that the daily consumption of CSC capsules for 3 weeks significantly decreased both systolic and diastolic BP, but only the significant decrease in systolic BP was maintained over the 3-month study period. The mechanism responsible for the BP-lowering effect likely involves several factors; however, neither the effects of l-theanine nor of EGCG individually or in combination have been studied in humans with hypertension. Furthermore, CSC decreased LDL-cholesterol concentrations and markers of oxidative stress and inflammation, elevated concentrations of which are independent risk factors for CVD. The authors suggest that additional research be conducted to determine the mechanisms of action responsible for these beneficial health effects and suggest that "CSC may be an option for people who have mild to moderate high BP, elevated LDL cholesterol, elevated markers of inflammation, or a combination of these three CVD risk factors."