Diet debate: Maybe it's just time to give up that soda

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Pam Panchak, Post-Gazette
James Henderson switched from soft drinks to juice and water two years ago, added exercise, an improved diet and Lipitor and has lowered his cholesterol from 500 mg/dl to 220.
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James Henderson, 32, of Braddock, liked soft drinks. He'd drink three or four cans a day of Pepsi or Mountain Dew, sometimes a root beer.

But Mr. Henderson, who works for the Port Authority, had a big problem, his doctor said. His blood cholesterol level was more than 500 milligrams per deciliter. People with a blood cholesterol level of 240 mg/dl or higher are at high risk for heart disease. James Henderson was a heart attack waiting to happen.

"He is an interesting case because he has two different problems," said Mr. Henderson's doctor, Dr. Oscar Marroquin, a cardiologist at UPMC Presbyterian. "His diet was poor and he didn't get enough exercise. But he also has a familial type of cholesterol that causes bad cholesterol to be high."

Cholesterol is a soft, waxy substance found in the fats in the bloodstream and in the cells of the body. It's used to form cell membranes and some hormones. About 80 percent of our cholesterol is manufactured by our bodies. The remaining 20 percent comes from what we eat.

There are three components to cholesterol, Dr. Marroquin said.

Triglycerides are the chemical form in which most fat exists in food and in the body. Triglycerides in the blood come from eating fatty food. Triglycerides also are manufactured by the liver from excess carbohydrates, which will be stored as body fat. A "normal" person will have a triglyceride level of less than 150 mg/dl, the American Heart Association says.

Cholesterol and other fats can't dissolve in blood. They have to be transported to and from cells by lipoproteins. The most important lipoproteins are low density lipoprotein (LDL) and high density lipoprotein (HDL). Levels of LDL and HDL in the blood can point to either health risks or health benefits.

LDL is the bad cholesterol. If too much of it circulates in the blood, it can build up on the walls of the arteries bringing blood to the heart and the brain, eventually clogging them. An LDL level of 160 mg/dl or more is dangerously high.

HDL is the good cholesterol, because it is thought to carry cholesterol away from the arteries and back to the liver.

"Triglycerides make HDL small and dense, so they get easily cleared by the urine," Dr. Marroquin said.

Generally speaking, the higher your HDL rating, the better. An HDL of less than 40 mg/dl in men, 50 mg/dl in women increases the risk of heart disease.

Eating too much of the wrong kinds of food raises triglyceride levels and suppresses good cholesterol, Dr. Marroquin said. Soft drinks are a big culprit, he said.

"The combination of not being very active plus the soft drinks contributed to a great majority of [James Henderson's] problem," Dr. Marroquin said. "When one drinks very sugary drinks they oftentimes get turned into triglycerides very quickly."

Mr. Henderson has lost 14 pounds since he came to Dr. Marroquin two years ago (he's currently 5 feet, 9 inches tall and 206 pounds). His blood cholesterol has dropped from more than 500 mg/dl to 220.

This is partly due to exercise: "I do calisthenics every other day," Mr. Henderson said. And partly due to other changes in his diet: "I've cut back on cheese, fried food, fast food, and snack foods like potato chips," he said.

Dr. Marroquin also put Mr. Henderson on Lipitor, a drug that lowers cholesterol by blocking an enzyme in the liver that makes cholesterol. When the liver manufactures less cholesterol, it uses more of it from the blood, lowering levels of cholesterol in the blood.

But both Dr. Marroquin and Mr. Henderson think much of his dramatic improvement is due to largely forsaking soft drinks.

"I might have a can or two of pop a week," Mr. Henderson said. "I mostly drink water and juice."

Drinking more than one soft drink a day seems to be associated with a substantially increased risk of heart disease, according to a study published last month in Circulation, the journal of the American Heart Association.

"In those who drink one or more soft drinks daily, there was an association of increased risk of developing metabolic syndrome," said Dr. Ramachandran Vasan of the Boston University School of Medicine, senior author of the Framingham Heart Study.

Metabolic syndrome is a cluster of risk factors for diabetes and cardiovascular disease, including a bulging waistline, high blood pressure, low levels of good cholesterol, and high fasting glucose levels. Having three or more of these risk factors greatly increases the likelihood of contracting diabetes or suffering a heart attack.

Those who drank one or more soft drinks a day were 48 percent more likely to have metabolic syndrome (which is defined as having three or more of the risk factors listed in the paragraph above) than those who eschew soft drinks, the Framingham researchers said. They were 31 percent more likely to become obese; 25 percent more likely to develop high blood triglycerides, and 32 percent more likely to have low levels of good cholesterol.

The most startling finding in the study was that it didn't seem to matter whether the soft drinks consumed were the regular sugary drinks, or diet sodas.

"We were struck by the fact that it didn't matter whether it was a diet or regular soda that participants consumed, the association with increased risk was present," Dr. Vasan said.

"We don't see any difference," said Dr. Ravi Dhingra of the Harvard Medical School, the lead author of the study.

Many people who consume large amounts of diet soda have otherwise poor eating habits.

"The biggest issue with diet soda is it makes people think 'I'm off the hook,' " said Leslie Bonci, director of sports medicine nutrition for UPMC. "Nobody has ever lost a significant amount of weight drinking diet soda."

Drinking diet soda actually can make you gain weight, Ms. Bonci said, because "it's still a sweet taste as far as the body is concerned. Sweet is a stimulus for eating."

But Dr. Dhingra said the researchers controlled for total calorie intake, so this couldn't explain why diet sodas seem as bad for you as sugary sodas.

"We adjusted in our analyses for saturated fat and trans fat intake, dietary fiber consumption, total caloric intake, smoking and physical activity, and still observed a significant association of soft drink consumption and risk of developing metabolic syndrome and multiple metabolic risk factors," he said.

Perhaps the caramel in diet as well as regular soft drinks promotes insulin resistance and lowers good cholesterol, Dr. Dhingra said.

But he emphasized he was speculating. "All we can demonstrate right now is an association. We have not proven causality."

Ms. Bonci was skeptical. "Frankly, I find it hard to believe that a diet soda in and of itself should be a stimulant for the metabolic syndrome," she said. "It's not a source of calories. Zero grams of carbohydrates just does not cause an increase in blood glucose."


Jack Kelly can be reached at jkelly@post-gazette.com or 412-263-1476.


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