Chlorogenic Acid

Chlorogenic acid is a member of the polyphenol family, specifically a hydroxycinnamic acid derivative formed when caffeic acid is joined to quinic acid through an ester bond ^[1]. Its molecular formula is C16H18O9, corresponding to a molar mass of about 354 grams per mole ^[1]. In plants it serves as an intermediate in the production of lignin, the material that stiffens cell walls, and it contributes to defense and pigmentation ^[1]. Its name comes from Greek words meaning light green, a reference to the greenish color that appears when the compound is oxidized, and not to any chlorine content, of which it has none ^[1].

The term chlorogenic acid is often used loosely to cover a whole family of related esters ^[1]. Closely related isomers include neochlorogenic acid and cryptochlorogenic acid, while compounds bearing more than one caffeic acid unit are called isochlorogenic acids, among them cynarine ^[1]. These compounds occur throughout the plant kingdom ^[1]. Coffee is the most familiar dietary source, and unroasted, or green, coffee beans are particularly rich in chlorogenic acid, although roasting degrades much of it; other notable sources include potatoes, eggplant, apples, peaches, prunes, hibiscus, and bamboo shoots ^[1][4].

Because roasting reduces chlorogenic acid, extracts made from green coffee beans are prepared and standardized for their chlorogenic acid content and sold as dietary supplements, typically in capsule form and marketed for weight, blood sugar, and blood pressure support ^[1][3]. Chlorogenic acid is also of interest to food science as a natural antioxidant ^[4].

Interest in chlorogenic acid is closely tied to research on coffee and green coffee extract ^[2][3]. Population studies have linked regular coffee drinking, which delivers substantial chlorogenic acid, with lower risk of conditions such as type 2 diabetes, and controlled trials of green coffee extract have reported modest improvements in some measures of the metabolic syndrome, including waist circumference, triglycerides, blood pressure, and fasting blood glucose ^[2][3]. Reviewers emphasize, however, that the effects observed are generally small, that study quality varies, and that the ideal amounts and long-term value are not settled ^[3][4]. Encyclopedic and regulatory summaries note that evidence for specific health claims, such as lowering blood pressure, is still insufficient ^[1].

Chlorogenic acid is consumed safely in everyday amounts as a normal part of coffee, fruits, and vegetables ^[2]. In the United States it has not been approved as a food additive nor formally recognized as safe in concentrated form, and green coffee extracts are sold under dietary supplement rules rather than as approved medicines ^[1]. Concentrated supplements also carry the caffeine and other compounds present in coffee extracts, so people sensitive to caffeine should take that into account ^[2].

Generally well tolerated. High doses may cause GI upset, and green coffee extracts often contain caffeine, which can cause jitteriness and affect sleep. Some concern exists about high-dose chlorogenic acid raising homocysteine transiently. People sensitive to caffeine should check the product's caffeine content.