Low-density lipoprotein (LDL) tests are used to help determine the risk of cardiovascular disease. LDL levels over 160 mg/dL put individuals at high risk for cardiovascular disease. Evidence that diet could exert a powerful effect on heart disease risk began to accumulate more than 50 years ago, when researchers found a strong correlation between saturated fat intake, blood cholesterol levels and the incidence of coronary heart disease. Cholesterol tests are used to estimate risk. And while cholesterol levels can vary widely among healthy individuals, the statistical evidence suggests that low levels are good and high levels are bad when it comes to being at risk for heart disease and strokes.