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The link between high blood pressure and salty snacks or sodium-rich processed foods has been known for a long time, but now we can add sugar to the list of suspects.
Specifically, sugar-sweetened drinks – soft drinks, fruit drinks, lemonade, fruit punch. Americans drink two 12-ounce servings of these sugary drinks a day, on average.
A new study in Circulation suggests that kind and quantity of liquid refreshment is one reason why 131 million Americans have high blood pressure or pre-hypertension. That's roughly half the population.
The good news is, the study shows that reducing your intake of sugar-sweetened drinks even a modest amount can lower blood pressure enough to reduce your risk of heart attack and stroke.
Dr. Liwei Chen of Louisiana State University and her colleagues looked at 810 adults with pre-hypertension (blood pressure readings between 120/80 and 139/89) and Stage I high blood pressure (140/90 to 159/99). Study participants got randomly assigned to three different groups, with different levels of dietary advice and counseling.
Those who reduced their intake of sugary drinks by just six ounces – half-a-serving – had a small but significant drop in blood pressure, even when the researchers accounted for other changes, such as weight loss.
Blood pressure didn't change when people cut their intake of artificially sweetened drinks or caffeinated beverages without sugar. But researchers did find an association between blood pressure and other sources of dietary sugar – another clue that sugar is the culprit.
Study authors calculate that a 12-ounce reduction in daily sugary-beverage consumption can lead to a 1.8-point drop in systolic blood pressure (the pressure with each heart contraction) and a 1.1-point reduction in diastolic pressure (when the heart relaxes). Doesn't sound like much, but it's enough to make a difference in heart disease and stroke incidence.
Other research suggests that a 3-point drop in systolic blood pressure produces an 8 percent reduction in strokes and a 5 percent drop in heart attacks. That would require eliminating 24 ounces of sugar-sweetened drinks a day, or two servings – a bit less than the average U.S. daily intake.
Scientists aren't sure why sugar drives up blood pressure. Maybe it's because sugar activates the sympathetic nervous system, which initiates the fight-or-flight response.
Or perhaps more sugar intake causes the body to hold onto sodium.
A third possibility is that sugar increases blood levels of uric acid, a waste product that may cause blood vessels to contract or may act on the kidneys to increase blood pressure.