Potassium: Milligrams Can Help Manage Millimeters of Mercury

The July-August issue of Food Insight featured Part I of a 3-part series on blood pressure management.  Part I, “Dietary Approaches to Stop Hypertension—A Little DASH Will Do,” briefly discussed potassium as an important aspect of the DASH Diet for managing blood pressure.  This article, Part II, will expand on the role of potassium in a heart-healthy diet.

Americans Don’t Ponder Potassium

Ask anyone on the street what potassium is and why it’s important to get recommended amounts. More than likely, they will either tell you they don’t know or say that it has something to do with food but are unsure exactly how it benefits health.  In fact, data from the 2012 IFIC Foundation Food & Health Survey shows that only 28 percent of consumers consider whether a product contains potassium when purchasing a food or beverage.  Many people are unfamiliar with the role of potassium in diet and health, so a little bit of information could make a big difference, especially due to potassium’s importance for managing hypertension; a condition that affects 3 out of every 10 adults in the US.

Benefits and Sources

Potassium is a naturally occurring mineral and an electrolyte found in many foods. It’s also an essential nutrient.  For your body to perform well, it’s imperative to take in enough potassium.  Many vital bodily functions, such as stabilizing the amount of water in our cells, maintaining electrolyte balance, and ensuring healthy joints and skeletal and smooth muscle contraction, require potassium.  Potassium also impacts cardiovascular health by controlling the electrical activity of the heart and lowering blood pressure, especially among people who have or are at risk of having elevated blood pressure.

Potassium can be found in many types of food—literally, everything from soup to nuts.  Potassium- containing foods include many dairy foods, meat, poultry and fish, beans, nuts, fruit and fruit juices, and vegetables.  It’s important to note that cooking methods impact potassium levels. For example, dry cooking methods can preserve potassium content while boiling vegetables in water promotes potassium loss.

The food source most often associated with potassium is bananas.  One medium banana contains 422 mg or almost 10 percent of the Adequate Daily Intake (AI) for adults), but bananas make up only about 2 percent of the potassium consumed in the US.  According to Adam Drewnowski, PhD, noted nutrition scientist, “High-potassium foods (vegetables, dried fruit) are not necessarily the major sources of potassium in the American diet.”  “In reality,” Drewnowski continued, “once you take consumption frequency into account, the major sources of potassium are coffee, milk, and white potatoes.” (NHANES 2005-06)

The Price of Potassium

Like many purchasing decisions, price is one of the most important factors that consumers consider when it comes to food—only taste impacts food decisions more.  However, “it \[potassium\] can be an expensive nutrient” says Drewnowski.  Fortunately, there are less costly ways to consume more potassium.  In his recent research, “potatoes and citrus (fruit and juices) were the least expensive sources.”

Potatoes (and especially their skins) are a potassium powerhouse and a vegetable to include in the diet rather than avoid.  Per standard portion, baked white potatoes offer more potassium than any other food source (738 mg of potassium and 128 calories) and baked sweet potatoes are not far behind their white counterparts (542 mg of potassium and 103 calories).  While this is good news for shoppers on the lookout for potassium “bargains,” it’s also important to be mindful of how cooking method (e.g., baking versus frying) and the addition of traditional toppings (e.g., butter, sour cream, brown sugar, or bacon) may alter the total caloric content of the dish.

Sodium, Potassium, and Heart Health

The 2010 DGA recommends consuming less than 2,300 mg of sodium per day.  Certain populations are recommended to further reduce daily sodium intake to 1,500 mg.  Yet the overwhelming majority of Americans aren’t in step with official dietary guidelines when it comes to sodium.  Specifically, 95.2 percent of those recommended to consume less than 2,300 mg don’t meet this goal.  Adhering to a 1,500 mg sodium diet appears even more difficult with 98.8 percent exceeding this recommendation.  The average American eats more than 3,300 mg of sodium daily.  Conversely, more than 98 percent of US adults fail to get the recommended 4,700 mg of potassium per day. 

Clearly, Americans consume more sodium and less potassium than is recommended.  However, recent data suggest that our sodium intake from all sources has not changed significantly since 1988-1994, but our potassium intake is in decline.  As a result, the 2010 DGA identified potassium as a “nutrient of concern in American diets.” Simultaneously meeting sodium and potassium guidelines continues to be a challenge, both for consumers and public health officials.  A recent publication from Dr. Drewnowski and colleagues examines this important dilemma.

Strong evidence supports potassium’s role in heart health.  It is known to lower blood pressure and have a positive effect on salt sensitivity, an independent risk factor for hypertension and heart disease. In fact, consuming foods high in potassium directly counteracts the blood pressure response to sodium.  Properly managing blood pressure is critical for good health, but can be challenging.  Fortunately, there are many ways that individuals can play an active role in managing their blood pressure, including maintaining a healthy weight, adopting a DASH eating plan, eating a lower-sodium diet, engaging in regularly physical activity, moderating alcohol consumption, and increasing knowledge and intake of potassium-rich foods.