High sodium: potassium ratio increases cardiovascular risk
By David Dunaief, M.D.
We need sodium in our diets in modest amounts; however, many Americans overconsume it. Meanwhile, potassium, which we also need, is underconsumed.
More than 90 percent of people consume far too much sodium, with salt being the primary culprit (1). Sodium is found in foods that don’t even taste salty. Bread and rolls are the primary offenders. Other foods with substantial amounts of sodium are cold cuts and cured meats, cheeses, pizza (which has both bread and cheese), fresh and processed poultry, soups, meat dishes, pastas and snack foods. Foods that are processed and those prepared by restaurants are where most of our consumption occurs (2).
By contrast, only about 2 percent of people get enough potassium from their diets (3). According to one study, we would need to consume about eight sweet potatoes or 10 bananas each day to reach appropriate levels. Why is it important to reduce sodium and increase potassium? A high sodium-to-potassium ratio increases the risk of cardiovascular disease by 46 percent, according to the study, which looked at more than 12,000 Americans over almost 15 years (4). In addition, both may have significant impacts on blood pressure and cardiovascular disease.
To improve our overall health, we need to tip the sodium-to-potassium scales, consuming less sodium and more potassium. Let’s look at the evidence.
Two studies illustrate the benefits of reducing sodium in high blood pressure and normotensive (normal blood pressure) patients, ultimately preventing cardiovascular disease, including heart disease and stroke.
The first used the prestigious Cochrane review to demonstrate that blood pressure is reduced by a significant mean of −4.18 mm Hg systolic (top number) and −2.06 mm Hg diastolic (bottom number) involving both normotensive and hypertensive participants (5). When looking solely at hypertensive patients, the reduction was even greater, with a systolic blood pressure reduction of −5.39 mm Hg and a diastolic blood pressure reduction of −2.82 mm Hg.
This was a meta-analysis (a group of studies) that evaluated data from randomized clinical trials, the gold standard of studies. There were 34 trials reviewed with more than 3,200 participants. Salt was reduced from 9 to 12 grams per day to 5 to 6 grams per day. These levels were determined using 24-hour urine tests. The researchers believe there is a direct linear effect with salt reduction. In other words, the more we reduce the salt intake, the greater the effect of reducing blood pressure. The authors concluded that these effects on blood pressure will most likely result in a decrease in cardiovascular disease.
In the second study, a meta-analysis of 42 clinical trials, there was a similarly significant reduction in both systolic and diastolic blood pressures (6). This meta-analysis included adults and children. Both demographics saw a reduction in blood pressure, though the effect, not surprisingly, was greater in adults. Interestingly, an increase in sodium caused a 24 percent increased risk of stroke incidence but, more importantly, a 63 percent increased risk of stroke mortality. The risk of mortality from heart disease was increased as well, by 32 percent.
In an epidemiology modeling study, the researchers projected that either a gradual or instantaneous reduction in sodium would save lives (7). For instance, a modest 40 percent reduction over 10 years in sodium consumed could prevent 280,000 premature deaths. These are only projections, but in combination with the above studies they may be telling. The bottom line: Decrease sodium intake by almost half and increase potassium intake from foods.
Potassium’s positive effects
When we think of blood pressure, sodium comes to mind, but not enough attention is given to potassium. The typical American diet doesn’t contain enough of this mineral.
In a meta-analysis involving 32 studies, results showed that as the amount of potassium was increased, systolic blood pressure decreased significantly (8). When foods containing 3.5 to 4.7 grams of potassium were consumed, there was an impressive −7.16 mm Hg reduction in systolic blood pressure with high blood pressure patients. Anything more than this amount of potassium did not have any additional benefit. Increased potassium intake also reduced the risk of stroke by 24 percent. This effect was important.
The reduction in blood pressure was greater with increased potassium consumption than with sodium restriction, although there was no head-to-head comparison done. The good news is that potassium is easily attainable in the diet. Foods that are potassium-rich include bananas, sweet potatoes, almonds, raisins and green leafy vegetables such as Swiss chard.
Lowering sodium intake may have far-reaching benefits, and it is certainly achievable. We need to reduce our intake and give ourselves a brief period to adapt — it takes about six weeks to retrain our taste buds, once we reduce our sodium intake. We can also improve our odds by increasing our dietary potassium intake, which also has a substantial beneficial effect, striking a better sodium-to-potassium balance.
(1) Am J Clin Nutr. 2012 Sep;96(3):647-657. (2) www.cdc.gov. (3) Am J Clin Nutr. 2012 Sep;96(3):647-657. (4) Arch Intern Med. 2011;171(13):1183-1191. (5) BMJ. 2013 Apr 3;346:f1325. (6) BMJ. 2013 Apr 3;346:f1326. (7) Hypertension. 2013; 61: 564-570. (8) BMJ. 2013; 346:f1378.
Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, visit www.medicalcompassmd.com or consult your personal physician.