Lately, soda pop has been losing some of its fizz.
Concerns are building about sugary beverages and their association with obesity, diabetes, high blood pressure, high cholesterol and heart disease.
These concerns have fueled heated debate in New York City. In June 2012, New York Mayor Michael Bloomberg proposed a citywide ban on super-sized sodas. Then, in March 2013, a judge struck down the proposed limits, one day before they were to take effect.
One can a day?
A recent, high-profile study in the journal PLoS Medicine found that soda-pop marketers, taking a cue from the cigarette industry, are trying to subvert soda’s health risks with public-service campaigns promoting exercise and worthy community projects.
But what’s the harm in drinking soda in moderation—say, a can a day?
According to Adam Bernstein, MD, DSc, of Cleveland Clinic’s Wellness Institute, even that amount—even if it’s diet soda—can hurt your health.
“You need to try to taper off as best you can,” he says. “If you’re drinking a 20-ounce bottle of soda a day, try a 12-ounce bottle instead. If you’re drinking two sodas a day, try one.”
Daily soda linked to stroke risk
Dr. Bernstein is the lead author of a study recently published in the American Journal of Clinical Nutrition that found that daily soda consumption is directly linked to an increased risk of stroke. Consuming one can of soda per day, either sugar-sweetened or diet, increased a person’s risk of stroke over time by 16 percent.
The increase occurred regardless of whether subjects were overweight, exercised regularly, or were smokers or non-smokers. And the stroke risk increased for each additional can of soda per day that a subject drank.
With that data in hand, Bernstein recommends that all regular soda drinkers start cutting back.
Dr. Bernstein suggests “swapping out” sugar-sweetened or diet sodas for healthier beverages.
Water is best, but “we know that people drink soda for taste and a pick-me-up,” says Dr. Bernstein. “They need to find alternative beverages that have an energy boost. Some kinds of coffees or teas or seltzers or flavored waters may fill those needs.”
The science behind the soda study
Below, Dr. Bernstein explains the study’s scientific findings, noting that multiple mechanisms may explain the relationship between soda and stroke:
- The sugar in sugar-sweetened sodas may increase blood glucose and increase insulin. Over time, these may lead to glucose intolerance, insulin resistance and inflammation. Those changes in turn influence atherosclerosis (plaque buildup in arteries), plaque stability and thrombosis (clot formation), a risk factor for strokes caused by blockage of an artery.
- The fructose in sugar-sweetened soda can be converted to visceral (belly) and liver fat. This enhances lipogenesis (fat buildup and triglyceride synthesis in the blood stream). Fructose also increases uric acid in the blood, which can reduce nitric oxide in the vessel lining and increase blood pressure, a risk factor for strokes caused by blockages or hemorrhages.
- Because the body does not regulate our consumption of sugar-sweetened beverages in the same manner as foods, drinking them may lead to excess caloric intake. This is unlikely to explain our study findings, however, because controlling for energy intake in our models did not change results.
- The caramel coloring in sugar-sweetened and low-calorie colas contains advanced-glycation end products. These have been linked to inflammation, which has been linked to the initiation, growth and unstable plaques that can break off and cause strokes. An inverse (U-shaped) association has been reported between high blood pressure and caffeine, while a linear association has been reported between high blood pressure and increased soda intake. This suggests that ingredients other than caffeine in soda affect blood pressure.
- The ways in which diet or low-calorie soda may influence stroke risk are less clear than those for sugar-sweetened soda. Diet soda has recently been linked to an increased risk of vascular events (Journal of General Internal Medicine, 2012); diabetes (Diabetes Care 2009, European Journal of Nutrition, 2013) and kidney function decline (Clinical Journal of the American Society of Nephrology, 2011).
- Researchers have also begun to look at ways in which diet soda may affect “reward processing” in different parts of the brain (Physiology & Behavior, 2012) and hormone levels (Diabetes Care, 2012). Both mechanisms may help to explain the epidemiologic findings.
- For additional information, see a PDF of the study: http://ajcn.nutrition.org/cont…”