The debate as to whether coffee is a benefit or risk for some patients just got clarified further with an American Heart Association (AHA) study showing that heavy coffee consumption increases the risk of mortality from cardiovascular disease (CVD) in people with severe hypertension, whereas green tea does not.

It is worth looking at the details of this study, and to review the results from other new coffee studies. Information on how coffee affects people with diabetes and rheumatoid arthritis (RA) will be helpful to HCPs as they advise their patients. 

 

Coffee vs tea effect on CVD mortality

 

A new study published in the Journal of the American Heart Association has provided some concerning results on coffee drinking. 

This large prospective, observational Japanese study of more than 18,000 participants looked at the impact of coffee vs green tea consumption on CVD mortality among people with various levels of hypertension.

Teramoto M, Yamagishi K, Muraki I, et al. Coffee and green tea consumption and cardiovascular disease mortality among people with and without hypertension. JAHA. 2023;12(2):e026477.

 

 

In contrast, green tea consumption was not associated with an increased risk of CVD mortality across any hypertension category. 

This is the first study to find a positive association between heavy coffee consumption and CVD mortality among people with severe hypertension.

The authors also state that heavy coffee consumption should therefore be avoided by people with severe hypertension.

 

Metabolic syndrome and rheumatoid arthritis 

 

A study from China looked at the association between coffee consumption and metabolic syndrome severity among 1,094 participants with self-reported RA in the NHANES database.

Wang S, Han Y, Zhao H, et al. Association between coffee consumption, caffeine intake, and metabolic syndrome severity in patients with self-reported rheumatoid arthritis: National Health and Nutrition Examination Survey 2003–2018. Nutrients. 2023;15(1):107.

 

 

The authors note that RA has historically been associated with a higher incidence of metabolic syndrome and insulin resistance due to the associated hyper-inflammatory state involved. Metabolic syndrome refers to a constellation of factors that include central obesity, hypertension, high triglycerides, and low levels of high-density lipoprotein cholesterol (HDL-C).

The authors of the study theorized about the mechanisms for the positive effects of daily coffee intake on metabolic syndrome in the patients with RA. The beneficial effects, they wrote, might be due to effects of coffee on BMI, blood pressure, and insulin resistance. In the study, the investigators did not find any significant differences between caffeinated and decaffeinated coffee. 

 

Effect on development of diabetes 

 

News about how coffee drinking may affect the development of diabetes comes from a study conducted by an international team of investigators.

Yang J, Tobias DK, Li S, et al. Habitual coffee consumption and subsequent risk of type 2 diabetes in individuals with a history of gestational diabetes - a prospective study. Am J Clin Nutr. 2022;116(6):1693–1703.

 

 

 

The study focused on women with a history of gestational diabetes, who are known to be at higher risk for type-2 diabetes later in life. The study was designed to determine whether greater habitual coffee drinking would be associated with a lower risk of type-2 diabetes among these women.

This was a prospective study in which 4,522 participants were followed for 26 years. Overall, type-2 diabetes developed in 979 participants. Consumption of caffeinated coffee was found to be inversely related to the risk of type-2 diabetes. In addition, greater caffeinated coffee consumption was associated with lower fasting insulin and C-peptide concentrations. 

 

Investigations into the health effects of coffee could be aided by analyzing urine samples for specific metabolites as biomarkers for coffee consumption. Although incorporating routine urine samples into multiyear studies could be a logistical challenge, the approach has merit. This is because a urine biomarker for coffee consumption has been found, according to a study published in Food Chemistry.

Lang R, Beusch A, Dirndorfer S. Metabolites of dietary atractyligenin glucoside in coffee drinkers' urine. Food Chem. 2023;405(Pt B):135026.

 

 

The urine for the investigation was obtained from individuals who self-reported their coffee consumption (which can be unreliable).

The researchers identified three metabolites that are products of substances formed in large quantities during coffee roasting, but are rarely found in any other foods. In addition, the biomarkers can be detected in very small amounts of urine, making them appealing for use in future clinical research.