Researchers in South Korea said this association was regardless of coffee type (black coffee or 3-in-1 coffee) in women. They did not find a significant association between coffee type and MetS in men.
MetS is a group of metabolic abnormalities including atherogenic dyslipidemia, elevated blood pressure, and plasma glucose.
They published the findings in the journal, Nutrients.
The study recruited a subset of participants (n=14,132) from the Health Examinees (HEXA) study of more than 160,000 participants aged 40 to 69 years.
Coffee consumption patterns were assessed using a two-day, 24-hour recall data.
Black coffee was defined as coffee powder or extracts, with added water but no other ingredients. 3-in-1 coffee was defined as instant coffee drinks containing coffee powder, creamer, and sugar.
MetS was defined according to the updated National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III).
Participants who satisfied at least three of the five criteria were diagnosed with MetS: modified waist circumference (WC) ≥ 90 cm in men or ≥ 80 cm in women; blood triglyceride (TG) level ≥150 mg/dL; blood high-density lipoprotein cholesterol (HDL-C) level <40 mg/dL in men or <50 mg/dL in women; systolic blood pressure (BP) ≥130 mmHg or diastolic BP ≥85 mmHg; and fasting blood glucose (FBG) level ≥100 mg/dL.
More coffee, less risk for women
The study reported that women who consumed more than one serving of black coffee per day had a significantly lower prevalence of MetS (p=0.0089), increased WC (p=0.0138), and reduced HDL-C (p<0.0001) compared to non-coffee consumers and those who consumed ≤1 serving/day.
Women who consumed more than one serving/day of 3-in-1 coffee also had a significantly lower prevalence of elevated TG (p=0.0010) and reduced HDL-C (p<0.001) compared to non-coffee consumers and those who consumed ≤1 serving/day.
The study found that in women, as total coffee intake increased, the prevalence of MetS (>1 serving/day: p=0.0436) and some components, such as elevated TG (>1 serving/day: p=0.0007) and reduced HDL-C (>1 serving/day: p<0.0001), significantly decreased.
In men, there was no significant association between coffee type and MetS. Individuals who consumed more than one serving/day of coffee had a 19% lower prevalence of elevated BP (p=0.0101) compared to non-coffee consumers.
Researchers said the differences between the genders may be due to, “These differences might result from differences in lifestyle factors between men and women. For example, lifestyle factors such as alcohol consumption and smoking status were less heterogeneous in women (mostly non-smokers and non-drinkers). Thus, there was a possibility that the effects of dietary factors might have been more significant in women than men.”
Coffee and insulin
In the present study, there was a significant inverse association between coffee consumption and prevalence of elevated TG.
Researchers explained that coffee consumption has been reported to prevent insulin resistance by altering physiological signals related to food intake and intestinal hormone secretion.
In particular, polyphenols in coffee such as chlorogenic acids (CGAs) reduce intestinal glucose absorption, resulting in reduced glucose-dependent insulinotropic polypeptide (GIP) and increased glucagon-like peptide 1 (GLP-1) levels, which can improve insulin sensitivity.
Strengths and limitations
A strength of the study was its use of a two-day, 24-h recall to estimate participants’ usual coffee consumption, which can reduce effects of bias results such as in the case of FFQ. “Previous studies used a food frequency questionnaire (FFQ) to assess coffee consumption, which showed recall bias, leading to underestimation of true coffee consumption. Moreover, the use of FFQ with closed-ended response categories causes nondifferential misclassification that could bias study results.”
This study has several limitations. First, its cross-sectional nature meant that causal associations could not be confirmed. Second, it did not include the amounts of caffeine, added sugar, and creamer in the statistical model.
In South Korea, the prevalence of MetS increased significantly from 24.9% in 1998 to 31.3% in 2007.
In the present study, women who consumed more than one serving/day of any type of coffee had a significantly lower prevalence of MetS or its components compared to non-coffee consumers and those who consumed ≤1 serving/day.
However, researchers warned that these results do not imply that high coffee consumption should be encouraged.
“Excessive coffee intake is undesirable because high caffeine intake has adverse effects, such as general toxicity, cardiovascular effects, and effects on bone status and calcium balance in healthy adults.
Although the results suggested that regardless of coffee type, coffee might play a preventive role in the development of MetS, researchers recommend that further prospective studies and well-designed randomised controlled trials should be conducted to demonstrate the preventive effects of coffee intake on MetS and its components.
“The Association between Coffee Consumption Pattern and Prevalence of Metabolic Syndrome in Korean Adults”
Authors: Seong-Ah Kim and Sangah Shin