Bananas' Potassium Helps Boost Bone Mass
Diets rich in potassium-packed fruits such as bananas and cantaloupe, greens like kale and Swiss chard, and cruciferous vegetables including broccoli and cabbage, may help women prevent osteoporosis, especially if they love salty food. Potassium appears to counteract the increased urinary calcium loss caused by the high-salt diets typical of most Americans, thus helping to prevent bones from thinning out at a fast rate, suggests a new study which appeared in the May issue of the Journal of Clinical Endocrinology and Metabolism.
While calcium and vitamin D are well recognized as vital for strong bones, researchers have also suspected that potassium plays a role in bone health. To find out, lead researcher Dr. Deborah Sellmeyer, an assistant adjunct professor of endocrinology and metabolism at the University of California at San Francisco, and her colleagues evaluated 60 postmenopausal women, looking at the effects of a high salt diet on calcium loss and whether the addition of potassium citrate to a high salt diet could lessen salt's detrimental effects on bone.
Sellmeyer recruited 60 postmenopausal women to participate in her study. To establish a baseline, for the first three weeks, she put them on a low-salt diet — only 2 grams of salt a day — even less than the 6 grams, or 1.5 teaspoons recommended by federal health officials.
At the end of this three week low salt trial, the researchers measured the amount of calcium the women excreted in their urine, as well as a number of important markers of bone loss including urine N-telopeptide, urine cAMP, serum osteocalcin, and fasting serum PTH.
Then, for one month, the women all went on a high-salt diet — 9 grams of salt a day — an amount of salt at the high end of what Americans typically consume, Sellmeyer says.
During the high salt diet, half of the women were given potassium supplements, while half took a placebo. At the end of the high salt diet, the researchers again measured the amount of calcium the women excreted in their urine, as well as the various markers of bone turnover.
The potassium appeared to protect the bones of the women who took it, Sellmeyer says. They lost less calcium than they did on the low-salt diets, and the amount of lost protein was only slightly higher.
On the high salt plus placebo diet, the amount of calcium the women excreted in their urine increased an average of 42 mg/day from the amount they had excreted while on the low salt diet. But when the women on the high salt diet were also given potassium, their urinary excretion of calcium decreased an average of 8 mg/d.
N-telopeptide, a marker of bone turnover, increased an average of 6.4 4 nanomoles in the high salt plus placebo group, but only an average of 2.0 nanomoles in the high salt plus potassium citrate group. Other markers of bone turnover (osteocalcin, PTH, and cAMP) were not significantly altered.
The women who didn't take potassium while on the high-salt diet also lost 33% more potassium and 23% more protein.
All of which indicates that more salt consumption quickens bone decay by pulling calcium out of bones, but potassium limits the damage, Sellmeyer says. The women given potassium supplements consumed the amount of potassium found in seven to eight servings of fruits and vegetables, according to Sellmeyer.
She does not believe women should take potassium supplements, which are now available only by prescription, but that results of her study provide yet more evidence for the importance of a balanced diet that contains at least eight daily servings of fruits and vegetables.
"Typically, we think worrying about dietary salt is for people with high blood pressure or stroke. This brings in another group of people who are at risk," Sellmeyer says.
An estimated 44 million Americans over the age of 50 have osteopenia (bone thinning) or suffer from osteoporosis — porous, brittle bones at a significantly increased risk for fracture — according to the National Osteoporosis Foundation.
Although women are at higher risk due to their smaller stature and thus lower bone mass, men who like to sprinkle on the salt or who eat a lot of processed foods — the vast majority of which are high in sodium — can also lose bone mass, along with height and strength, as they grow older.
Eating lots of potassium-rich fruits and vegetables is a delicious form of bone insurance. While many people associate potassium only with bananas, according to the World's Healthiest Food's stringent criteria, a wide variety of other foods are even better sources of this bone-building mineral.
To learn more about this vitally important mineral, click potassium. To learn more about any of these potassium-rich members of the World's Healthiest Foods, including quick and easy cooking and serving ideas, simply click on the highlighted name of the food in the above list.
This summer, treat your bones as well as your tastebuds by grilling crimini mushrooms, fennel, eggplant and tomato along with some tuna or halibut. Then top off your meal with a slice or two of cool cantaloupe topped with strawberries, or if you prefer a creamy warm dessert, try grilling some banana sliced lengthwise and sprinkled with cinnamon.
Want some great recipes that will provide quick, easy and delicious ways to enjoy foods rich in potassium more frequently as part of your healthy way of eating? Take a look at the World's Healthiest Foods' Recipes containing these foods. Simply, click on the Recipe Assistant, select the foods for which you'd like some recipes from the Healthy Foods List, and click on the Submit button. A list containing links to all our recipes containing the foods chosen will appear immediately below.