By: Theresa Greenwell
Worldwide, coffee is a very popular drink. Research has supported the idea that drinking coffee can be associated with lower risks of metabolic syndrome, diabetes and coronary heart disease, but other research has shown that coffee may or may not help in endothelial dysfunction.
Inadequate functioning of the endothelial has been noted in early-stage atherosclerosis and plays a role in the development of atherosclerotic conditions. Coffee contains an abundance of compounds known as polyphenols which have antioxidant, anti-inflammatory and anti-hypertensive properties. Due to its popularity, coffee is considered the single greatest provider of dietary antioxidants in the human diet.
The exact polyphenol content and distribution in coffee is affected by how the coffee beans are roasted and prepared. Roasting coffee beans actually increases the presence of some compounds while decreasing others. One good example of how roasting can affect compound amounts involves chlorogenic acid and hydroxyhydroquinone. With coffee, the darker the roast, the lower the content of chlorogenic acid present but the greater the content of hydroxyhydroquinone. Chlorogenic acid has been associated with weight loss and improvements in endothelial function. Hydroxyhydroquinone, on the other hand appears to impair chlorogenic acid’s ability to improve endothelial function and may cause an increase in oxygen free radicals.
A recent study release in the European Journal of Nutrition (2018) looked at how varying levels of hydroxyhydroquinone and chlorogenic acid affected endothelial dysfunction. This single-blind, randomized, placebo-controlled study focused on how a one-time serving of coffee affected postprandial endothelial dysfunction in participants who already had stage 1 hypertension or were borderline. Of the 37 individuals who participated in this study, all were over 30 years of age, non-smokers, and took no other medication other than calcium blockers. Participants were divided into 2 study groups to be tested in 2 separate trials.
Participants were instructed to avoid alcohol, coffee, and foods that contained chlorogenic acid for 24 hours prior to testing. Additionally, blood pressures, flow-mediated vasodilation readings and blood samples were obtained for each person prior to any testing. Each trial consisted of giving participants a sample meal along with a coffee drink. For trial 1 the participants were given either drink A or B, while for trial 2 participants received either drink A or drink C. The 3 variations in coffee drinks were as follows: Drink A) high chlorogenic acid/low hydroxyhydroquinone; Drink B) high chlorogenic acid/high hydroxyhydroquinone; Drink C) a drink prepared with coffee flavored ingredients. Results taken at 1- and 2- hours post sample meal showed that those who had ingested drink A had reduced oxidative stress levels along with significant improvements in blood pressure and flow-mediated vasodilation. The same improvements were not seen in those who had drinks B or C.
This study showed that coffee with the right ratios of chlorogenic acid and hydroxyquinone may be beneficial for those with endothelial dysfunction. The findings of this study does show promise for the use of coffee as an adjunct to treatment for those with endothelial dysfunction. If nothing else, it may help to lead to a better dietary intervention for those with endothelial dysfunction who enjoy coffee. More research with a greater number of participants is necessary. One thing to remember is that caffeine, which is present in coffee, does elevate blood pressure and endothelial function. For these trials, caffeine content was kept at similar levels across all 3 drinks, averaging 68 mg.
Masato, K., et al. Coffee with a high content of chlorogenic acids and low content of hydroxyhydroquinone improves postprandial endothelial dysfunction in patients with borderline and stage 1 hypertension. European Journal of Nutrition. Published online January 2018.