SUNDAY, Nov. 13 (HealthDay News) -- Drinking two or more sugar-sweetened beverages a day may boost a woman's risk for developing heart disease and diabetes -- even if this habit isn't causing her to pack on extra pounds, a new study says.

Sugary sodas and other sweetened beverages are frequent targets in the war on obesity. Many efforts, such as taking these drinks out of vending machines in schools, are aimed at reducing exposure to these beverages and the empty calories they provide. However, the new study suggests that the risks posed by sugar-sweetened sodas and flavored waters may be independent of weight gain.

Middle-aged women who drank two or more sugary beverages a day were close to four times as likely to have high levels of dangerous blood fats called triglycerides and impaired blood sugar levels (known as "prediabetes'), when compared with women who drank less than one sugar-sweetened beverage a day.

What's more, women who drank two or more sodas a day also had more belly fat, but not necessarily more weight. Belly fat, or abdominal obesity, poses greater health risks than fat in other areas of the body because it lies deep inside and can produce hormones and other substances that negatively affect blood pressure, cholesterol and insulin production.

Add these perils together and you've got so-called metabolic syndrome, a cluster of risk factors that has been linked to heart disease, diabetes and stroke.

The study findings were presented Sunday at the American Heart Association's annual meeting, in Orlando, Fla.

A related study presented Sunday found that people with heart failure who have low levels of vitamin C fare worse than their counterparts who get enough vitamin C from foods.

In the beverage study, Christina Shay, an assistant professor at the University of Oklahoma Health Sciences Center, and her colleagues assessed the drinking habits of nearly 4,200 women and men aged 45 to 84 from various ethnic groups via questionnaires. None of the participants had heart disease when the study began in 2002. The researchers measured weight gain, waist circumference, cholesterol levels, triglycerides and glucose (blood sugar) during three follow-up exams conducted over a five-year span. They also looked to see who had been diagnosed with type 2 diabetes during this time frame.

Women who drank more than two sugary drinks a day had more risks for heart disease and diabetes than women who drank less than one soda or sweetened beverage each day -- even in the absence of weight gain.

The same findings were not seen among men. There's no consensus on why sugar-sweetened beverages did not affect men in the same way, but it may be that women require less energy for metabolism than men, Shay said. "They have smaller bodies, less muscle mass and need fewer calories than men," she said, adding that a 130-calorie soda accounts for a bigger chunk of a woman's daily energy than it does for men. "It is possible that men need more sodas to see an effect," she said.

The bottom line is that cutting back on sugar-sweetened beverages is an easy way to improve health, said Dr. Stacey Rosen, the associate chairman of cardiology at Long Island Jewish Medical Center in New Hyde Park, N.Y.

"Our soda habit is something we have total control over," Rosen said. "There are a lot of things that keep us healthy that are hard work and difficult, but cutting back on sweetened drinks isn't one of them. We are not talking about doing an hour of exercise or buying expensive organic foods."

"Simple dietary choices can have a critical role in determining risk for cardiovascular disease," she added. "And remember -- women often make food choices for their entire family, so the impact of this may be more widespread.

In the vitamin C study, people with heart failure who had low levels of vitamin C were 2.4 times more likely to have higher blood levels of high sensitivity C-reactive protein (hsCRP), a marker of inflammation that has been linked to heart disease risk. And those people with low vitamin C and high hsCRP levels were nearly twice as likely to be hospitalized or die from heart failure when compared to counterparts who had higher levels of vitamin C and lower levels of hsCRP.

The study included 212 people with heart failure who were 61 years old, on average. They were asked to keep a food diary for four days, and their diary entries were verified by a nutritionist. Researchers analyzed vitamin C intake using a computer program. The study participants were also asked to take a blood test to measure their hsCRP levels. An hsCRP level greater than 3 milligrams per liter of blood was considered elevated, the researchers said.

Vitamin C, a potent antioxidant, may help cool inflammation in the body, while a lack of the nutrient may allow inflammation levels to go unchecked, study author Grace Song, an assistant professor in the department of nursing at the University of Ulsan in Korea, told reporters at the meeting.

Vitamin C is plentiful in many healthful fruits and vegetables, including bell peppers, broccoli, cauliflower, kale, lemon juice, oranges, papaya, and strawberries. Studies have shown that adding supplements of vitamin C or other antioxidants does not improve outcomes in people being treated for heart failure, said American Heart Association President Dr. Gordon F. Tomaselli.

But people who eat diets rich in vitamin C foods may be healthier than those who don't, said Tomaselli, chief of cardiology at Johns Hopkins University. "Vitamin C in the diet may be a marker of a healthy lifestyle," he said.

Dr. Clyde W. Yancy, chief of cardiology at Northwestern University's Feinberg School of Medicine in Chicago, urged caution before jumping to any conclusions about vitamin C, however. "There is a benefit to a heart-healthy lifestyle, but it is not clear if vitamin C is independently associated with better outcomes among people with heart failure," he said.

Yancy agreed with Tomaselli that eating a diet rich in vitamin C may help contribute to healthy lifestyle, which includes better adherence to heart-failure treatment regimens.

Research presented at medical meetings should be considered preliminary until it has been published in a peer-reviewed journal.

More information

Get the facts on metabolic syndrome by visiting the American Heart Association.