Assay for quantitative determination of glutathione and glutathione disulfide levels using enzymatic recycling method Nature Protocols Fasting for blood work typically involves avoiding food and drink (except water) for eight to twelve hours to ensure accurate results, particularly for tests like glucose, cholesterol, and triglycerides. It is important Blood Test Guidelines in Dubai: 8 Tests That Require Fasting ServiceMarket Blog Fasting requirements for Chemistry tests.