The term "caffeine" can refer to any form of caffeine from any source. “Caffeine” and “caffeine anhydrous”  appear most often on dietary supplement labels, but for all intents and purposes they’re the same thing. However, other forms of caffeine are used in some supplements, including caffeine citrate, dicaffeine malate, and pterostilbene-caffeine. These forms combine caffeine with another substance, as indicated in their names:

  • Caffeine citrate = caffeine + citric acid + sodium citrate
  • Dicaffeine malate = caffeine + malic acid
  • Pterostilbene-caffeine = caffeine + pterostilbene

Because the caffeine is combined with other substances, the proportion of caffeine is less than that of caffeine anhydrous. For example, caffeine citrate is about 50% caffeine, so if a label lists 50 mg caffeine citrate, then it contributes about 25 mg caffeine. Compare that with caffeine anhydrous, which has essentially no water—about 0.5%—the rest being caffeine. Regardless, when looking at labels, look for the total amount of caffeine per serving in a product.

Some forms of caffeine are purported to be “better” than caffeine or caffeine anhydrous, with claims they are absorbed quicker (and therefore, have a faster effect), sustain energy and alertness longer, digest more easily, or reduce the risk of “crashing.” However, there isn’t enough research on these forms of caffeine to support such claims.

Caffeine can be labeled by other names, such as 1,3,7-trimethylxanthine, or come from “hidden” sources too, such as guarana. For more information, read the OPSS article about caffeine for performance.

 

Updated 26 February 2019

References

American Regent Inc. (2018). Caffeine citrate injection, USP. Retrieved 26 February 2019 from https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=d17e3be5-514f-454a-8347-d804cd5ec37f&type=display

Hwang, J., Kim, Y. S., Shin, J. H., & Choi, B. M. (2018). Hemodynamic effects on systemic blood flow and ductal shunting flow after loading dose of intravenous caffeine in preterm infants according to the patency of ductus arteriosus. Journal of Korean Medical Science, 33(4), e25. doi:10.3346/jkms.2018.33.e25

Joy, J. M., Vogel, R. M., Moon, J. R., Falcone, P. H., Mosman, M. M., & Kim, M. P. (2016). Twelve weeks supplementation with an extended-release caffeine and ATP-enhancing supplement may improve body composition without affecting hematology in resistance-trained men. Journal of the International Society of Sports Nutrition, 13(1), 25. doi:10.1186/s12970-016-0136-9

Latosińska, M., & Latosińska, J. N. (2017). Introductory Chapter: Caffeine, a Major Component of Nectar of the Gods and Favourite Beverage of Kings, Popes, Artists and Revolutionists, a Drug or a Poison? In J. N. Latosińska & M. Latosinska (Eds.), The Question of Caffeine (pp. 1–26): IntechOpen.

Mazel, V., Delplace, C., Busignies, V., Faivre, V., Tchoreloff, P., & Yagoubi, N. (2011). Polymorphic transformation of anhydrous caffeine under compression and grinding: A re-evaluation. Drug Development and Industrial Pharmacy, 37(7), 832–840. doi:10.3109/03639045.2010.545416

National Center for Biotechnology Information. (2019). Caffeine citrate. Retrieved 26 February 2019 from https://pubchem.ncbi.nlm.nih.gov/compound/6241

Pacifici, G. M. (2014). Clinical pharmacology of caffeine citrate in preterm infants. Medical Express, 1(5), 243–250. doi:10.5935/MedicalExpress.2014.05.06

Shrestha, B., & Jawa, G. (2017). Caffeine citrate – Is it a silver bullet in neonatology? Pediatrics & Neonatology, 58(5), 391–397. doi:10.1016/j.pedneo.2016.10.003