Potassium-Rich Foods Can Help Offset High Salt Diet Contribution To Osteoporosis

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Source:   University Of California - San Francisco

(http://www.ucsf.edu/)

Date:   Posted 5/27/2002

Potassium-Rich Foods Can Help Offset High Salt Diet Contribution To

Osteoporosis

Eating potassium-rich foods such as bananas, tomatoes and orange juice can

help prevent osteoporosis for postmenopausal women by decreasing calcium

losses, according to a UCSF study.

In postmenopausal women the consumption of excessive salt has been shown to

increase the level of bone minerals excreted through urine, although salt

does not seem to effect younger women or men in a similar fashion, said

study author Deborah Sellmeyer, MD, UCSF assistant adjunct professor of

endocrinology and metabolism. While the benefits of dietary calcium and

vitamin D for preserving bone density have long been established, the UCSF

study is the first to examine the role of potassium in preventing bone

density loss exacerbated by a high-salt diet.

Osteoporosis affects an estimated 44 million Americans, mostly women. It

causes bones to become fragile and more likely to fracture. The National

Osteoporosis Foundation estimates that 55 percent of Americans aged 50 and

older are at risk for the largely preventable disease. " For women at risk of

osteoporosis, eating more fruits and vegetables is a simple way to help

prevent the adverse effects of a typical American high salt diet, " said

Sellmeyer.

Although no studies have directly measured the level of dietary salt

necessary to adversely affect bone mineral excretion, Americans eat twice as

much salt (sodium chloride) as they should, according to the National

Institutes of Health (NIH). The NIH recommends consumption of no more than 6

grams, or about 1 1/2 teaspoons, of salt daily for cardiac health.

In the UCSF study, 60 healthy postmenopausal women were placed on a low salt

diet (two grams / day) for an initial three weeks while their level of

excreted calcium was measured. The level of excreted NTX, a bone protein,

was also measured. A higher NTX level indicates that more bone is being

broken down, or reabsorbed, leaving women at increased risk for fractures.

At the end of three weeks, all the participants were placed on a high salt

(9 grams/ day) diet. Half were given a potassium supplement and half were

given a placebo. For four more weeks they continued the high salt diet. At

the study¹s end, researchers were able to compare each woman¹s low and high

salt diet results individually. They were also able to compare the loss of

calcium and NTX between the placebo group and the group receiving potassium.

Calcium loss increased 33 percent for women taking the placebo, but

decreased four percent in the potassium citrate group.

For women taking the placebo, NTX excretion increased 23 percent, but in

women taking potassium citrate, it increased only 7.5 percent, suggesting

that their bones were remaining healthier than the bones of women receiving

only placebo. " When they went from a low salt diet to a high salt diet plus

potassium, there was no change, " said Sellmeyer. But increased dietary salt

increased urinary calcium excretion in the women who received only placebo,

and their enhanced calcium excretion was associated also with increases in

NTX, suggesting skeletal effects, the authors said.

The potassium dosage used in the test was 3.5 grams daily, or about the

amount in 10 bananas. Other potassium-rich foods include spinach, melon, and

potatoes. Since most dietary salt comes from processed food, the authors

said the total sodium and chloride content of one¹s diet is important to

consider.

The study was funded by the National Institutes of Health and published in

the May issue of the Journal of Clinical Endocrinology and Metabolism.

Additional authors are Schloetter, MS, RD, research dietitian in the

UCSF General Clinical Research Center and Sebastian, MD, UCSF

professor of medicine.

May is National Osteoporosis Prevention Month.