Another Reason to Skip the Soda: High Blood Pressure

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There’s plenty of evidence that guzzling sugared drinks like sodas can harm your health. The extra calories can lead to obesity and contribute to heart problems and diabetes. Now researchers say the sweet beverages may boost blood pressure as well.

The risk is not entirely new, but the size of the relationship came as a surprise to the researchers, who published their findings in Hypertension: Journal of the American Heart Association. Led by Ian Brown, in the department of epidemiology and biostatistics at Imperial College London’s School of Public Health, the group found that for every extra sugared beverage consumed, blood pressure — a ratio of systolic and diastolic pressure in the vessels — rose by an average of 1.6 mm Hg and 0.8 mm Hg respectively. While that may not seem like much, says Brown, when you consider that many children and adults down several cans of soda or sweetened fruit juices a day, the numbers can creep up. (More on Do the Chemicals That Turn Soda Brown Also Cause Cancer?)

The study involved close to 2,700 subjects aged 40 to 59 years in both the U.S. and the United Kingdom. The volunteers dutifully reported what they ate and drank over a four-day period, answered questions about their lifestyle and then provided urine for a detailed analysis. Those who drank more than one serving a day of sugar-sweetened beverages consumed nearly 400 more calories daily than those who didn’t drink these products, and had higher body mass index measures than those who avoided the drinks.

The extra calories in and of themselves could contribute to elevated blood pressure, since obesity is a risk factor for hypertension; it puts the heart under greater strain to pump enough blood to feed the body’s cells. But there may be other ways that excess sugar strains blood vessels. Previous studies suggest that the glucose and fructose from beverages can boost levels of uric acid, a breakdown product of certain foods, which is normally cleared by the kidneys. Too much uric acid interferes with blood vessels’ ability to dilate and expand to accommodate greater blood flow, thus causing a rise in pressure. In addition, it may also be possible that excess sugar causes the body to retain more water, and the added volume of liquid in the system can also drive blood pressure up.

Sodium may be playing a role in all of this as well, says Brown. His team found that while there wasn’t much difference in the amount of sodium excreted by those drinking a lot of sugared beverages compared to those drinking fewer, there was a small group of participants whose urine contained high levels of sodium. Because much of the sodium we eat is released from the body, either as waste or through perspiration, the elevated amounts suggest that these subjects were eating more sodium, and in these individuals, the relationship between excess sugars from beverages and higher blood pressure was even greater. (More on Diet Soda May Lead to Stroke Risk? Really?)

“There may be some synergistic effect between sugar and sodium and their effect on blood pressure,” says Brown. “So the take home message is that there may be additional benefits if you reduce both the amount of sugar-sweetened beverages you drink and your salt intake at the same time, than if you did either on its own,” he says.

The data are among the first to hint that simply lowering sodium in the diet may not be enough to prevent hypertension. Sugars can contribute to blood pressure peaks as well, and, says Brown, it makes sense to consider a “more holistic approach to nutrition in controlling blood pressure.” That means following the familiar recommendations of avoiding foods that are high in sugar, salt and fat and focusing on eating more fruits, vegetables and lean meats.

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