Caffeic acid (3,4-dihydroxycinnamic acid, 3,4-DA) is an organic compound found in many plants and foods, which is unrelated to caffeine. It has a high antioxidant potential and its primary source in human diet is coffee. Other sources are bark of Eucalyptus globulus, mushroom Phellinus linteus, apples, artichoke, berries, pears and also wine.
Caffeic acid may increase time to fatigue
Caffeic acid is used in supplements for boosting athletic performance and has shown promise in reducing the fatigue associated with exercise, however research is limited. Animals administered with caffeic acid (3,4-dihydroxycinnamic acid) had higher exercise tolerance, reduced blood lactate, and markers of hepatic oxidation .
Caffeic acid’s derivative caffeic acid phenethyl ester (CAPE) has been shown to protect against hyperthermal stress induces by prolonged exercise .
More evidence is needed to rate caffeic acid for exercise-related performance.
Antioxidant activity of 3,4-Dihydroxycinnamic Acid
Antioxidant potential of caffeic acid has been shown in vitro and also in vivo [3,4]. Besides its antioxidant properties one animal study also showed significant reduction of the blood glucose after caffeic acid ingestion . Therefore, caffeic acid demonstrates significant potential as an antidiabetic agent by an attenuation of liver glucose output and enhancement of adipocyte glucose uptake, insulin secretion, and antioxidant capacity.
Data on the absorption of caffeic acid in humans is lacking. Therefore, Olthof and others  evaluated absorption of caffeic acid in cross-over study. Results showed that 95 ± 4% of caffeic acid is absorbed.
Other uses of caffeic acid
There is some data that caffeic acid may be anti carcinogenic, however, results are mixed . Some studies even suggest it is carcinogen . It is listed as “possibly carcinogenic to humans” by the International Agency for Research on Cancer .
Caffeic acid side effects and toxicity
There is very little available data to know if 3,4-dihydroxycinnamic acid is safe when taken as a supplement.
Noaves, Rômulo D., et al. “3, 4-Dihydroxycinnamic Acid Attenuates the Fatigue and Improves Exercise Tolerance in Rats.” Bioscience, biotechnology, and biochemistry 76.5 (2012): 1025-1027.
- Chen, Yu‐Jen, et al. “Caffeic acid phenethyl ester, an antioxidant from propolis, protects peripheral blood mononuclear cells of competitive cyclists against hyperthermal stress.” Journal of food science 74.6 (2009): H162-H167.
- Olthof, Margreet R., Peter CH Hollman, and Martijn B. Katan. “Chlorogenic acid and caffeic acid are absorbed in humans.” The Journal of nutrition 131.1 (2001): 66-71.
- Jung, Un Ju, et al. “Antihyperglycemic and antioxidant properties of caffeic acid in db/db mice.” Journal of Pharmacology and Experimental Therapeutics 318.2 (2006): 476-483.
Hirose, M., et al. “Carcinogenicity of antioxidants BHA, caffeic acid, sesamol, 4-methoxyphenol and catechol at low doses, either alone or in combination, and modulation of their effects in a rat medium-term multi-organ carcinogenesis model.” Carcinogenesis 19.1 (1998): 207-212.
- International Agency for Research on Cancer. Retrieved from http://monographs.iarc.fr/ at 25. May 2013