Just because a beverage is labeled "diet" doesn't mean it's good for you. Researchers are linking low-calorie drinks to a number of medical issues, from an increased waistline to stroke. Is this just another health scare? Lifescript's Health Detective gets to the bottom of this bubbling issue.
Choosing a diet drink over a high-calorie beverage feels good. Righteous, even, But don't pat yourself on the back just yet. In recent years, many studies have suggested that diet sodas might harm your health.
Findings from a study published in Trends in Endocrinology & Metabolism in 2013 found that artificial sweeteners are linked to obesity; they may increase the risk for diabetes, metabolic syndrome and cardiovascular disease; and they may also increase the risk of learning difficulties.
When the body responds normally to sugar, it signals that an intake of both calories and sugar has occurred so the body can release the hormones needed to prepare," according to the study's lead author, Susan Swithers, Ph.D., a professor of the department of psychological sciences and ingestive behavior research center at Perdue University in West Lafayette, Ind.
"This prevents big spikes in blood sugar, and those same hormones are thought to have direct effects on feeling full."
The consumption of sweet-tasting but non-caloric or reduced-calorie food and beverages interferes with the body's normal responses, the study suggests. And blunting those responses could cause people to overeat and experience higher blood sugar levels, which could lead to type 2 diabetes.
What's diet sodas' role in the above health issues and others, such as osteoporosis, heart disease and kidney problems? That's the $21 billion question--the amount Americans spend on low-calorie drinks annually.
"There's a connection between diet soda and negative health outcomes," Swithers says. But it's unclear whether the drinks are directly responsible, or if people with health issues or unhealthy behaviors just happen to consume more of them, she adds.
Lifescript's Health Detective found that women who drink these beverages daily could have reason to worry. Here's the truth about how diet soda can affect your health.
WEIGHT GAIN--It may seem counterintuitive that zero-calorie beverages could make you pack on pounds, but the research bears this out time and again. Beverages in general don't provide the feeling of fullness or satisfaction as solid foods, because the body doesn't register liquid calories the same way it does calories from solid food, according to the Harvard School of Public Health. This may prompt you to eat even after having a high-calorie drink.
Sweet-tasting soft drinks--whether they're sweetened with sugar or a calorie-free substitute--may stimulate the appetite for other sweet, high-carbohydrate foods. But because people consider soda a drink and cookies a dessert, they're more likely to limit food than beverages, even though the soda may contain more sugar.
Then there's the "Big Mac, fries and diet soda" theory. Wishful thinkers who believe a diet soda will counterbalance a high-calorie meal end up consuming more than they should.
"People use diet sodas as an excuse to eat poorly," says Ramachandran Vasan, M.D., professor and chief of preventative medicine and epidemiology at Boston University School of Medicine.
Those who drink more low-calorie beverages tend to eat foods with more saturated and trans-fats, exercise less and eat fewer fruits and vegetables, he adds.
OSTEOPOROSIS--For many women, nothing refreshes after a workout like a diet drink. But this could be undoing exercise's benefit to her bones. About 40 million Americans, most of whom are women, are at risk for osteoporosis, a condition in which bones become brittle and vulnerable to fracture, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases.
What is the link between diet drinks and bone loss? Phosphoric acid, a flavoring agent that increases blood acidity. It's a major component in many types of soda, but cola tends to have more.
Phosphorus itself is an important bone mineral, but excess amounts may lead to bone loss because the body tries to neutralize excess acid by taking calcium from bones. Some experts also believe that people replace calcium-rich beverages like milk with diet sodas, leading women to take in lower levels of the bone-building nutrient.
"Your calcium requirements increase after age 50," says osteoporosis expert Robert Heaney, M.D., a professor of medicine at Creighton School of Medicine in Omaha, Neb. Women of any age should have 3 servings of dairy products per day for optimal calcium intake, whether they drink soda or not, he advises.
HEART DISEASE--Drinking two or more diet drinks a day may increase the risk of heart disease, including heart attack and stroke, in otherwise healthy postmenopausal women, according to a study by researchers at the University of Iowa. The findings of the study of nearly 60,000 women in the Women's Health Initiative Observational Study were published in the Journal of the American College of Cardiology earlier in 2014.
Women who consume two or more diet drinks a day are 30% more likely than those who never or rarely do to have a cardiovascular event and are 50% more likely to die from related disease.
This is one of the largest studies on this topic, and our finding are consistent with some previous data," says Ankur Vyas, M.D., a fellow in cardiovascular disease at University of Iowa Hospitals and Clinics, and the study's lead investigator.
METABOLIC SYNDROME--Forty-seven million Americans have metabolic syndrome, although many may not know it, according to the American Heart Association. It's linked to several health conditions. Metabolic syndrome isn't a disease. It's a cluster of risk factors for heart disease and diabetes, including a large waistline, high levels of triglycerides, low levels of HDL (good) cholesterol, high blood pressure and high-fasting blood sugar.
KIDNEY DISEASE--If you drink two or more diet sodas daily, you could double your risk of decreased kidney function, according to results from the Nurses' Health Study, one of the largest and longest-running investigations of factors influencing women's health. It surveyed 3,000 nurses over 11 years.
Your kidneys serve several important purposes, including filtering waste products from blood and regulating blood pressure.
Kidney function decreases with age, says researcher Julie Lin, M.D., assistant professor at Harvard Medical School and kidney specialist at Brigham and Women's Hospital in Boston.
The study found that the "rate of kidney function loss was three times faster in women who drank diet soda compared with aging alone."
Drinking one diet soda daily didn't decrease kidney function. Drinking two or more diet sodas, though, appeared to cause problems.
One theory: Diet sweeteners could lead to kidney scarring, Dr. Lin says. Further studies are needed.
So what should you do when you feel the urge for a fizzy drink? Try a zero-calorie fruit-flavored seltzer. But read the label to be sure it contains natural flavors only and is free of the artificial sweeteners you want to avoid.