Most medication side effects are irritating, harmful, or downright deadly. Here's one that is good for you: stronger bones. Thiazide diuretics, beta blockers, and ACE inhibitors, all used to control blood pressure and ease the heart's workload, also appear to protect bones from breaking.
Studies here and there have looked at the link between blood pressure drugs and bones. Canadian and Spanish researchers combed medical journals for such reports and combined the best of them into a single huge study, a technique known as a meta-analysis. This one included 54 studies representing more than 900,000 participants. It was published in the October 2006 Journal of Internal Medicine.
Diuretics flush excess fluids and minerals from the body by stimulating the kidneys to make more urine. This lowers blood pressure by relaxing blood vessel walls. Thiazide diuretics increase the excretion of both sodium and chloride.
These drugs are good for bone in two ways. Under their influence, the kidneys hang on to calcium instead of releasing it into the urine. This extra calcium can be used to build or strengthen bone. Thiazide diuretics also rev up osteoblasts, a family of cells responsible for building bone.
In the meta-analysis, people who used a thiazide diuretic were 14% less likely to have had a broken hip, wrist, or other bone than those who didn't use one.
The heart and blood vessels are covered with tiny molecular triggers known as beta adrenergic receptors. When activated by stress hormones released by the sympathetic nervous system, they constrict blood vessels, speed up the heart rate, and increase the force of each heartbeat. Beta blockers jam these receptors, allowing blood vessels to relax. This lowers blood pressure, making it easier for the heart to pump blood. Beta blockers also ease the heart's workload by slowing the heart rate and reducing the force of the heart's contractions.
The meta-analysis showed that beta blockers decrease fracture risk by 14%.
ACE inhibitors block the production of angiotensin II, a hormone that makes arteries constrict. With less angiotensin II in circulation, blood vessels relax and blood pressure declines.
Angiotensin II and its relatives also stimulate the activity of osteoclasts (a family of cells that break down bone) and influence the body's calcium stores. Either of these actions can weaken bone.
In the meta-analysis, use of an ACE inhibitor was linked with a 19% reduction in the chances of breaking a bone.
Other heart drugs and bones
Blood pressure drugs aren't the only ones linked with better — or worse — skeletal health:
Statins. Some studies show that the use of a cholesterol-lowering statin may cut the chances of breaking a bone by one-third, though other studies show no effect.
Nitrates. In one large study, people who used nitroglycerin or another type of nitrate to ease chest pain (angina) had 11% fewer fractures than those who didn't use a nitrate.
Warfarin. Using warfarin for more than a year ups the chances of breaking a bone.
First things first
Blood pressure isn't the only connection between the skeleton and the cardiovascular system. Inflammation and other factors that are bad for the heart and blood vessels aren't so good for the bones, either. And there is mounting evidence that people with fragile bones or those who lose more than a couple inches of height as they age are more likely to also have cardiovascular disease or to die early.
In the other direction, many of the things proven to keep your heart and arteries in good shape are also good for your bones. Exercise is at the top of the list. Eating a lot of fruits and vegetables, getting enough vitamin D, and not smoking follow close behind.
Intriguing as the hypertension drug findings are, no one is recommending taking a thiazide diuretic, beta blocker, or ACE inhibitor to protect bones. Take them to keep blood pressure in check or ease your heart's workload. That's plenty — any other benefits are gravy.
May 2007 update