Bone basics.

Potassium citrate--which is found primarily in fruits and vegetables--appears to boost bone density by neutralizing excess acid in the body.

Swiss researchers gave 169 people who were over 65 either a placebo or enough potassium citrate to supplement their diets with 2,400 milligrams of potassium a day. Both groups also got calcium (500 mg) and vitamin D (400 IU) every day. None of the participants had bone density low enough to require treatment for osteoporosis.

After two years, the potassium takers had higher spine, flip, arm, and leg bone density than the placebo takers, and the potassium citrate neutralized excess acid excretion.

Potassium citrate was also good for bones when U.S. researchers gave 52 men and women over 55 either a placebo or potassium citrate at a medium or higher dose (2,400 or 3,600 mg of potassium a day). Each participant also got calcium (630 mga day) and vitamin D (400 IU a day). After six months, those taking the higher dose of potassium lost less calcium than the placebo group. (The medium-dose group was in between.)

What to do: Eat more fruits and vegetables. Most people have excess acid in their blood because the typical American diet is rich in grains and animal protein, both of which generate acids in the body. Our bones release calcium to neutralize the excess acid, which can lead to osteoporosis (brittle bones) as we age (see Nov. 2010, cover story). Why not take potassium citrate pills? Fruits and vegetables not only supply potassium, but may also replace the extra grains that most people eat. What's more, the people in these studies had to go to the trouble of taking six to nine potassium citrate pills a day.

J. Clin. Endocrin. Metab. DOI:10.1210/jc.2012-3099 and J. Bone Minel: Res. DOI:10.1002/jbmr.1764.