It is generally required that you fast for 9 to 12 hours before a cholesterol blood test. Neither eating nor drinking anything but water before the test generally yields the most accurate results. Although 1 small cup of black coffee shortly before having blood drawn will probably have little effect on the test results, always follow the pretest instructions because strict fasting may be particularly important in certain situations.
Perhaps One Small Cup
A study in the July 2005 issue of "Annals of Pharmacotherapy" reported that drinking a 6-ounce cup of coffee 30 to 60 minutes before having blood drawn for a cholesterol test had little effect on the results. In this study, 2 different types of coffee were consumed: black coffee and coffee with nondairy creamer and sugar. While drinking both types slightly raised the cholesterol, the increases were minor and unlikely to influence decisions regarding whether treatment is needed.
Fasting in General
A December 2012 study in "JAMA Internal Medicine" examined fasting in general -- not just coffee consumption -- and concluded that, for most people, fasting or not fasting did not significantly affect cholesterol results. Nevertheless, fasting may be particularly important for people with high triglyceride levels because elevated triglycerides can interfere with the way some cholesterol tests are performed. Fasting is also important when very accurate cholesterol results are needed, such as in people at high risk for heart disease. Despite studies suggesting that it may not be necessary for everyone, fasting for at least 9 hours before a cholesterol test remains the general recommendation. Do not consume anything except water unless your doctor or the testing laboratory says that it is permitted.