For years, experts have been dancing the limbo with blood pressure and cholesterol, routinely lowering the bar in the quest to prevent heart attacks, strokes, heart failure, and other cardiovascular conditions. Two articles in the August 2011 Harvard Heart Letter explore healthy targets for blood pressure and harmful low-density lipoprotein (LDL) cholesterol.

High blood pressure (also known as hypertension) slowly damages arteries. It is a key contributor to heart attack and stroke. Low blood pressure is harmful in more immediate ways. It can cause blurry vision, confusion, dizziness, fainting, and falls. Among healthy people, a good blood pressure is under 120/80. For people with hypertension, lowering blood pressure to 120/80 may be a good goal, but is usually more trouble than it's worth. That's why most people with hypertension aim for a target under 140/90.

Cholesterol is a different story. The average American has an LDL of around 120 milligrams per deciliter of blood (mg/dL). That's substantially above the 50 to 75 mg/dL that our hunter-gatherer ancestors probably had. Findings from clinical trials support the idea that lowering LDL to the neighborhood of 70 mg/dL can halt or even reverse the steady spread of artery-clogging atherosclerosis.

Two expert panels commissioned by the National Heart, Lung, and Blood Institute are in the process of updating the guidelines that doctors use to diagnose and treat high blood pressure and high cholesterol. The reports are due next year. It will be interesting to see if they continue to lower the bar for cholesterol.

Read the full-length articles: "What's the best target for blood pressure when it is high?" and "Sliding scale for LDL: How low should you go?"