If you've been diagnosed with high blood pressure, your doctor has likely prescribed a low-sodium diet. The recommended intake for dietary sodium is 1,500 milligrams per day, with an upper limit of 2,300 milligrams per day for people who are not at risk for high blood pressure based on age, medical history or ethnicity. The average American takes in 3,400 milligrams per day, about three-quarters of which comes from processed and restaurant foods rather than from the actual salt shaker.
Sticking to a low-sodium diet in this country is not easy. It's not just a matter of avoiding unhealthy foods like cured, processed meats (bacon, sausages) and fast food meals. It can also mean avoiding some nutritious foods like whole-wheat bread, cottage cheese, vegetable soups, olives and calorie-controlled frozen dinner entrees. And after all that effort, at the end of the day, reduced-sodium diets on their own aren't always enough to reduce the risk of stroke from high blood pressure.
This may be due to the fact that traditional emphasis on reducing dietary sodium leaves out the other half of the body's fluid-balance equation: potassium.
Potassium is sodium's natural foil—the yang to sodium's yin. Sodium causes the kidneys to retain excess fluid in the body; potassium coaxes the kidneys to excrete sodium into the urine. Indeed, a growing body of research supports an inverse relationship between potassium intake and blood pressure levels or risk of cardiovascular events like heart attack or stroke.
Most recently, a 2011 meta-analysis of 10 separate studies, including a combined 260,000 people, showed that for every 1,000-milligram increase in dietary potassium, the risk of ischemic stroke decreased by 11 percent. Additional research has shown that people who consume higher sodium intakes relative to their potassium intakes were more than twice as likely to die of heart attacks compared to people who ate the two nutrients in the greatest balance
And yet, despite this robust body of evidence, the message of "more potassium" seems to get drowned out by the louder message of "less sodium."
The recommended intake of potassium for healthy adults without kidney disease is 4,700 milligrams per day. The average American gets about 2,640 milligrams per day—or only about 56 percent of the target level. This widespread shortcoming in dietary potassium is symptomatic of a broader deficit in the average American diet: fruits and vegetables. As it turns out, fruits and veggies—especially dark green and bright orange ones—are among the best sources of dietary potassium.
But even if salads aren't your thing, there are plenty of creative ways to increase your potassium intake. Here are my picks for the most delicious potassium-rich food combos to add to your diet rotation in support of efforts to reduce blood pressure through diet.
• Tropical coconut water smoothie: One cup of plain coconut water contains 600 milligrams of potassium (13 percent of the daily value) in exchange for a reasonable 46 calories and 6 grams of natural sugar. For a liquid potassium powerhouse, blend 1 cup of coconut water with 1 small banana and 1 cup of frozen mango chunks. The combo has about 240 calories and 25 percent of your daily potassium needs.
• White beans and spinach: White beans and dark greens are a classic combo of Mediterranean cuisine. These nutritional dynamos both happen to contain a high amount of potassium: 1 cup of the beans has almost 1,200 milligrams of potassium (25 percent of the daily value), and 1 cup of cooked spinach has about 840 milligrams (18 percent of the daily value). For a super-fast and delicious Mediterranean side dish à la Martha Stewart, sauté a small chopped onion and 2 cloves of chopped garlic in olive oil until translucent. Then, toss in 2 cans of no-salt-added white beans, drained and rinsed well. Once the mixture is heated through, add an 11-ounce bag of pre-washed spinach, well chopped, and ¼ cup of white wine vinegar. Once the spinach is wilted, season with dried thyme and pepper.
• Plain, low-fat yogurt and dried plums: Skip the high-sodium cheeses, and get your potassium-rich dairy from yogurt or milk instead. For a cup that overfloweth with potassium, sweeten a 6-ounce container of plain, low-fat yogurt with 3 pitted and diced dried plums (It sounds better than "prunes," don't you think?); they're among the very best sources of potassium. This snack clocks in at 170 calories and contributes 600 milligrams of potassium (13 percent of the daily value) to your daily tally.
• Butternut squash and asparagus: A 1 cup serving of frozen, puréed butternut squash delivers about 320 milligrams of potassium without any added sodium—or effort. Place it alongside five large spears of grilled asparagus, and these vibrant accompaniments to whatever chicken, fish or meat dish is on the dinner menu will deliver a flavorful 11 percent of your daily value for potassium.
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• Roasted Patatas Bravas: This well-known Spanish appetizer of crispy potatoes in a piquant tomato sauce is a hidden treasure trove of potassium: A small potato (5 ounces) paired with ½ cup of canned, crushed tomatoes delivers 23 percent of the daily value—over 1,000 milligrams! Recipes abound online for versions of Patatas Bravas that call for roasting—rather than frying—the potato chunks. The dish's signature tomato sauce is generally made with some combination of onions, garlic, tangy vinegar, smoky paprika and/or Tabasco sauce—a deep bench of strong flavors that precludes the need to add much—if any—salt. Look for no-salt-added versions of canned tomato products when shopping for ingredients—they are easy to find.
It's essential to note that potassium targets should be reached through foods—not supplements like potassium salts, whose concentrated doses of potassium can interact with certain medications or cause dangerous electrolyte imbalances. Also, adding more potassium to your diet doesn't buy you free license with salt; absolute sodium intake matters for stroke risk, too.
Since so much of the salt in our diets comes from restaurant or convenience meals, however, you need not banish the salt shaker from your home. You're likely to be better off using the salt shaker to (conservatively) season a cooked-from-scratch meal in place of pre-salted convenience foods or restaurant meals.
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Tamara Duker Freuman, MS, RD, CDN, is a NYC-based registered dietitian whose clinical practice specializes in digestive disorders, Celiac Disease, and food intolerances. Her personal blog, www.tamaraduker.com, focuses on healthy eating and gluten-free living.