Sugar-Sweetened Drinks Linked to Elevations in Blood Pressure

March 01, 2011

February 28, 2011 (London, United Kingdom) — There is yet another reason to stay away from soft drinks, sweetened fruit juices, and sugar-loaded sports drinks: a new study has shown that there is a direct association between fructose and glucose intake and increases in blood pressure and that these sugar-sweetened beverages are associated with significant increases in systolic and diastolic blood pressures [1].

Each beverage consumed, report investigators, is associated with a 1.1-mm-Hg increase in systolic and 0.4-mm-Hg increase in diastolic blood pressure after adjustment for weight and height.

"Sugar-sweetened beverages have been linked to high blood pressure, obesity, type 2 diabetes, and heart-disease risk, and this is one more piece of evidence showing that if individuals want to drink these drinks, they should do so in moderation," lead investigator Dr Ian Brown (Imperial College London, UK) told heartwire . "Also, one of our interesting findings was that the association between sugar-sweetened beverage consumption and blood pressure was stronger in people who are consuming more sodium. We already know that salt is bad for blood pressure, but what we're finding is that if you're consuming more sodium, you appear to be, at least in this study, exacerbating the effects of these sugar-sweetened beverages."

The INTERMAP Study

The study, published online February 28, 2011 in Hypertension, is an analysis of patients included in the International Study of Macro/Micronutrients and Blood Pressure (INTERMAP). In the study, the researchers assessed the consumption of sugar-sweetened drinks, sugars, and diet beverages in 2696 healthy individuals aged 40 to 59 years old in the US and UK. Over the course of four days, participants recorded what they ate and drank and underwent two 24-hour urine collections and eight blood-pressure recordings, as well as answered questions about their lifestyle and medical history.

The mean systolic and diastolic blood pressure was 119/73 mm Hg among the US participants and 120/77 mm Hg among the participants from the UK. On average, US residents drank more sugar-sweetened and diet beverages than those from the UK, with Americans drinking nearly a full serving per day compared with 0.2 servings per day in the UK.

In a multiple linear regression analysis, there was a direct association with systolic and diastolic blood pressure. In a model that adjusted for energy intake, urinary sodium, potassium, dietary alcohol, cholesterol, and fatty-acid intake, consuming one sugar-sweetened beverage was associated with a systolic blood pressure increase of 1.6 mm Hg and a diastolic blood pressure increase of 0.8 mm Hg, adjusted down to 1.1/0.4 mm Hg when height and weight were included in the model. Diet beverage intake, on the other hand, was inversely associated with blood-pressure levels.

"If you imagine, there are probably people who are consuming two or three cans of soda a day," said Brown. "It's possible that their blood pressure could be higher by several mm Hg, and as we know, it can be difficult even with multiple drug therapies to reduce an individual's blood pressure by more than 10 mm Hg."

The American Heart Association (AHA) has published recommendations for maximum dietary intake of "added sugars," such as those found in sodas and fruit drinks. These upper limits vary by sex, age, and activity level, but the AHA puts them at 140 kcal for most American men and 100 kcal for most American women. As Brown noted, however, those who drank the sugary drinks in INTERMAP consumed approximately 400 kcal more than those who did not, and these people also had a higher body-mass index (BMI).

Interaction With Sodium

The researchers also observed a direct association with glucose and fructose consumption and blood pressure as well as a strong interaction with glucose, fructose, and sodium. In a stratified analysis, fructose- and glucose-related differences in blood pressure were observed only for participants who had higher levels of urinary sodium excretion. For example, for individuals with above-the-median 24-hour urinary sodium excretion, an increase in fructose consumption (2 standard deviations) was associated with an increase of 2.5/1.7 mm Hg systolic and diastolic blood pressure after adjustment for height and weight.

Right now, investigators aren't sure what underlying mechanism is causing the increase in blood pressure with sugar-sweetened beverages. They suspect, however, that the drinks increase serum uric-acid levels, and this in turn inhibits nitric oxide in the blood, thereby decreasing vasodilation. Although the mechanisms might not yet be clear, Brown said the data are more evidence clinicians can use in communicating to their patients the importance of following a healthy diet.

"As I look at it, this is an additional nutritional intervention that we have in our toolbox," Brown told heartwire . "The DASH trial showed that if you consume a high-vegetable, lean-meat, low-fat-dairy, no-sugar-added diet, and if you also reduce sodium, hypertensive individuals can lower their blood pressure by 8 to 10 mm Hg, which is as effective as multiple drug therapies. This is just another tool to help us reduce blood-pressure levels at the population level."

The authors report no conflicts of interest.

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