For the study, researchers compared cholesterol testing results of 300,000 people from Denmark, Canada, and the U.S. In both the U.S. and Canada, fasting for eight hours before a test is required. In Denmark, however, it is not.
Patients who are scheduled for a lipid profile test should fast (except for water) for 12-14 hours before the blood sample is drawn. If the patient's cholesterol is to be fractionated, he or she also should avoid alcohol for 24 hours before the test. http://www.healthatoz.com/healthatoz/Ato...
Typically at least a 12-hour fast is required for cholesterol and triglyceride screenings. Vitamin levels and glucose tests usually only require an eight-hour fast. Following the guidelines is important to make sure your blood sample is not influenced by food or drink. What is Allowed? Water is allowed even when fasting.