Numerous studies demonstrate the negative correlation between food antioxidant content and biomarkers such as glucose, cholesterol and triglycerides, the concentration of oxidized LDL in the bloodstream as well as waist measurement and belly fat alongside a positive correlation to HDL levels.(1)

Coffee is a mixture that comprises close to one thousand different chemicals, including carbohydrates, fats, vitamins, minerals, alkaloids, diterpenes (cafestol and kahweol), dietary fibers as well as antioxidants such as polyphenols, chlorogenic acid and caffeic acid.(2)

Coffee is a rich dietary source of antioxidants such as the polyphenols: chlorogenic acid and caffeic acid. Chlorogenic acid is an ester compound of caffeic acid and quinic acid. The antioxidant activity in these polyphenols is high. A 200ml cup of coffee contains 70-350 mg of chlorogenic acid and 35-175 mg of caffeic acid. Studies show that about 33% of the chlorogenic acid and 95% of the caffeic acid is absorbed in the intestines. The chlorogenic acid that is not absorbed reaches the colon, where it is hydrolyzed by the colonic bacteria and the metabolites are absorbed into the bloodstream. A study published in Am J Clin Nutr in 2006 rates coffee as sixth in the list of foods that have the highest content of antioxidants per serving.(3)

In recent years, a growing number of studies demonstrate the protective effects of coffee against various diseases, including: type 2 diabetes (adult diabetes), heart disease, certain types of cancer, various liver conditions, metabolic syndrome and subclinical inflammation, Parkinson’s disease, dementia and Alzheimer’s and even general mortality. Some of the mechanisms that are suggested as explanations for the protective effects of coffee relate to the antioxidant activity of coffee.(2)
Many studies show a high antioxidant activity in such polyphenols within the framework of in vitro experiments but only recently researchers were also able to prove the existence of high antioxidant activity by conducting in vivo experiments.‎ ‎In a study that was published this year (2011), the researchers created an ischemic intestine model and found that the chlorogenic acid and caffeic acid of coffee displayed a strong antioxidant activity in the damaged cells.(4)
Another study published in 2011 specifically examines the effect of instant coffee on the antioxidant activity of enzymes in rats. Apparently, the activity of antioxidant enzymes (catalase, superoxide dismutase, glutathione peroxidase and more) of the coffee group was higher.(5) A similar study that was also conducted on rats showed that coffee drinking had reduced the oxidizing of fats in brain membranes and also reduced the concentration of oxidants in this area following an increase the activity of the antioxidant enzymes. These findings account for the improved brain functions and the prevention of age-related diseases.
In an additional study that was published recently (2011), an interventional experiment was conducted, in which 33 healthy individuals were instructed to drink 3 cups of coffee a day over a period of 4 weeks. During this period, blood samples were taken from the participants, which demonstrated that the daily drinking of coffee has reduced the oxidative damage, as measured on the basis of various markers.(7)

In conclusion, it appears that the antioxidants in coffee play a key role in the protective effects of coffee against a variety of chronic diseases where oxidative stress is a significant risk factor. Drinking 3 cups of coffee a day improves the antioxidant balance of the body and is beneficial to our health.

Bibliography:
1.‎ ‎Hermsdorff H.H.M. et al.‎‎ ‎Nutrition & Metabolism 2011; 8:59-67‎.‎
2.‎ ‎Higdon J.V. & Balz F.‎‎ ‎Clin Rev Food Sci Nutr 2006; 46:101-23‎.‎
3.‎ ‎Am J Clin Nutr 2006; 84:95-135‎.‎
4.‎ ‎Sato Y. et al.‎‎ ‎Int J Pharm 2011; 403:136-8‎.‎
5.‎ ‎Choi E.Y. et ak.‎‎ ‎Nutrition 2011‎.‎
6.‎ ‎Abreu R.V.‎‎ ‎Pharmacol Biochem Behav 2011; 99:659-64‎.‎
7.‎ ‎Bakuradze T. et al.‎‎ ‎Mol Nutr Food Res 2011;55: 793-7‎.‎