Table 3

Geometric means (95% CI) of glycemic and inflammatory parameters by categories of black tea consumptiona

never or < 1 cup per week

2-6 cups per week

≥ 1 cup(s) per day

P trendb


Fasting plasma glucose (mmol/L)

Model-1c

4.86 (4.83 - 4.89)

4.81 (4.77 - 4.86)

4.83 (4.80 - 4.86)

0.144

Model-2

4.78 (4.72 - 4.84)

4.73 (4.66 - 4.80)

4.75 (4.68 - 4.81)

0.115

HOMA-IR

Model-1

1.55 (1.50 - 1.60)

1.49 (1.42 - 1.57)

1.61 (1.55 - 1.67)

0.141

Model-2

1.43 (1.34 - 1.52)

1.35 (1.25 - 1.45)

1.44 (1.35 - 1.54)

0.579

HOMA-beta

Model-1

101.07 (98.18 - 104.04)

105.48 (101.04 - 110.13)

103.83 (100.59 - 107.17)

0.169

Model-2

103.34 (96.79 - 110.34)

107.12 (99.69 - 115.10)

105.49 (98.70 - 112.76)

0.320

HbA1c %

Model-1

5.79 (5.76 - 5.82)

5.75 (5.71 - 5.80)

5.79 (5.76 - 5.82)

0.987

Model-2

5.73 (5.67 - 5.80)

5.71 (5.64 - 5.78)

5.72 (5.66 - 5.79)

0.698

Adiponectin: high-molecular weight (µg/ml)

Model-1

1.05 (1.01 - 1.09)

1.02 (0.96 - 1.08)

1 (0.96 - 1.05)

0.110

Model-2

1.03 (0.94 - 1.12)

1.01 (0.92 - 1.11)

1 (0.92 - 1.09)

0.327

CRP (mg/L)

Model-1

1.50 (1.41 - 1.59)

1.46 (1.33 - 1.60)

1.49 (1.40 - 1.59)

0.929

Model-2

1.34 (1.19 - 1.52)

1.28 (1.12 - 1.46)

1.32 (1.17 - 1.5)

0.730


a HOMA-IR, homeostatic model assessment-insulin resistance; HOMA-beta, homeostatic model assessment-beta cell function; CRP, C-reactive protein. Numbers of participants differ across outcomes because participants with outlier values (response values > 4 SD from mean) were excluded. Numbers were as follows: fasting plasma glucose: 2130, 723, 1221 HOMA-IR: 2148, 727, 1233, HOMA-beta: 2143, 725, 1227, HbA1c: 1758, 587, 1008 HMW adiponectin: 2097, 705, 1215; and CRP: 2082, 700, 1213.

b P-values were obtained from multiple linear regression models with median cups of tea per week (0, 4,10.5) as predictors and log transformed parameters as dependant variables.

c Model-1: adjusted for age (years), sex and ethnicity (Chinese, Malay, Indian).

Model-2: adjusted for Model 1 covariates (above) and BMI (kg/m2), physical activity level (kcal/week), education level (primary, secondary, polytechnic/diploma and university), alcohol level (non-drinkers, < 1 serving/day, and ≥ 1 serving/day), cigarette smoking (never-smokers, ex-smokers, current smokers < 10 cigarettes/d, and current smokers ≥ 10 cigarettes/d), history of dyslipidemia (yes/no), history of hypertension (yes/no), and dietary confounders i.e. energy intake (kcal), fiber (per 1000 kcal), cholesterol (per 1000 kcal), PUFA (% energy), MUFA (% energy), SFA (% energy), coffee (never/rarely, < 1 cup per day, 1-2 cup(s) per day, ≥ 3 cups/day) and alternate teas (never or < 1 cup per week, 2-6 cups per week, ≥ 1 cup(s) per day). HOMA-beta models were further adjusted for HOMA-IR.

Rebello et al. Nutrition Journal 2011 10:61   doi:10.1186/1475-2891-10-61

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