Standard laboratory reference ranges represent average populations and not optimal levels. In the 1960s, for instance, the upper reference range for cholesterol was 300 mg/dL (milligrams per deciliter). This number was based on a statistical calculation indicating that it was โ€œnormalโ€ to have total cholesterol levels as high as 300 mg/dL. Of course, it was also considered โ€œnormalโ€ for men to have fatal heart attacks at a relatively young age. As greater knowledge accumulated about the risk of heart attack and high cholesterol, the upper limit reference range has gradually dropped to 200 mg/dL (American Family Physician 2001; ADVANCEDATA 1977).

Blood test reference ranges are not the only measures that fail to provide physicians and patients with optimal numbers. For example, high blood pressure (hypertension) is defined medically as a blood pressure reading of 140/90 (read as โ€œ140 over 90โ€) or greater. Yet a diastolic blood pressure reading (the second number in a blood pressure readingโ€”90 in this example) higher than 80 mmHg (millimeters of mercury) is associated with an increased risk of stroke. A high percentage of people older than age 60 have diastolic readings higher than 80 mmHg, and this is the age group most vulnerable to stroke (Hansson L et al 1998). If your physician checks your blood pressure and says it is โ€œnormal,โ€ Life Extension advises you to ask what the optimal range is. Optimal blood pressure is defined as 115/75. In fact, the risk of cardiovascular disease doubles with each increase of 20/10 mmHg, starting at 115/75 mmHg. It is important to know that midlife hypertension predisposes people to stroke later in life, so keeping blood pressure readings within optimal ranges is important at any age.