Eating a low-fat, high-carb diet has been the mainstay of heart health for decades. But for people with Syndrome X, the tables may have turned.
By Jessica M. Scully
For as many as one in four Americans, the low-fat, high-carbohydrate diet that has become nutrition gospel could increase the risk of heart disease.
According to research conducted over more than two decades and publicized over the last few years, these people may have what sounds more like a science fiction movie than a health problem: Syndrome X.
Syndrome X is a cluster of risk factors for heart disease, including high blood pressure, high levels of blood fats, low levels of good cholesterol and high levels of bad cholesterol.
"For the person with Syndrome X, the [low-fat, high-carbohydrate] diet is a disaster," said Dr. Gerald Reaven, the Stanford University School of Medicine professor who coined the name Syndrome X, also known as insulin resistance syndrome
Along with co-authors Terry Strom and Barry Fox, Reaven this year published a book on the condition called Syndrome X, Overcoming the Silent Killer That Can Give You a Heart Attack. Reaven is also the senior vice president of clinical affairs for Shaman Pharmaceuticals in South San Francisco, which produces a line of Syndrome X products. Strom works for Shaman Pharmaceuticals as well.
Reaven recommends that people who have the syndrome get 45 percent of their daily calories from carbohydrates and 40 percent from fat, primarily unsaturated.
Established health organizations including the American Heart Association (AHA) have long advocated a diet in which no more than 30 percent of calories come from fat, with less than 10 percent from saturated fat, and 55 to 60 percent or more from carbohydrates. But the AHA now says that, for some people, Reaven's diet could work.
In fact, the AHA investigated the health effects of a higher fat diet for insulin resistant people, and recently published "guidelines" targeted to medical professionals rather than patients in order to reduce confusion.
But the dietary recommendations aren't cut and dried. One dilemma is that a higher fat diet like Reaven's could make it harder for a person to lose or maintain a healthy weight, increasing the risk for both diabetes and heart disease, according the AHA.
"X" stands for...
Reaven was not too far off mark when he coined Syndrome X. As it turned out, "X" stands for variable.
People are born with different degrees of insulin resistance, according to Strom and Reaven. How much the condition affects them depends on certain lifestyle factors, including weight, physical activity and diet.
Diet and weight maintenance are important issues for most people, but they are critical to those with Syndrome X.
The bodies of people who are insulin resistant don't respond to normal levels of insulin, which in the average person would be enough to get glucose from the blood into the body's cells where it is needed for energy.
In effect, people who are insulin resistant walk around with abnormally high blood insulin levels. The excess insulin is linked to high blood pressure and high levels of blood fats that can build up and clog blood vessel walls a harbinger for heart disease
Cutting back on carbohydrates and replacing the calories with unsaturated fat lowers insulin levels because, while carbohydrate and protein stimulate the body to make more insulin, fat doesn't.
The diabetes and weight debacle
A person with Syndrome X has not only high blood insulin levels, but also high blood glucose levels, which in turn signals more insulin production. Therefore, an insulin-resistant person's pancreas pumps out more and more insulin to transfer glucose out of the bloodstream. Most of the time, the extra insulin works.
But the insulin-producing cells in about one-third of insulin resistant people burn out, resulting in Type 2 diabetes, according to a Stanford University Website on the syndrome (www.syndromex.stanford.edu).
Even if they don't get diabetes, insulin resistant people have other problems. Virtually all the risk factors for a heart attack are linked to high levels of insulin in the blood stream, Strom said.
People with insulin resistance ultimately find themselves in a pickle. Obesity aggravates both diabetes and heart disease.Those who are insulin resistant need to eat more fat to keep their insulin levels in check, but eating a higher fat diet could make it harder for them to maintain a healthy weight.
Thumbs up for fat?
The conflict between Reaven and other health professionals revolves around fat.
The AHA, in its recently updated dietary guidelines for medical professionals includes a section on the higher fat diet. The guidelines say the diet could reduce the risk of heart disease for some people, assuming the person maintains a healthy body weight.
Because a gram of fat has more than double the calories of a gram of carbohydrate or protein, someone on Reaven's diet would have to eat less food to lose weight than someone on a low fat, high-carbohydrate diet.
Dr. Ronald Krauss, who chaired the AHA committee that created the new dietary guidelines, said that concern about weight gain "was one reason we were very careful how we worded this."
"We recognize that people who go on higher fat diets are at risk of consuming excess calories and increasing body weight," Krauss said.
He added that the AHA has used 30 percent of calories from fat as a cutoff number for a healthy diet.
Some people may be able to go beyond 30 percent, though the AHA doesn't see a particular need, Krauss said.
"But we recognize people who are at a normal weight consuming this Mediterranean type cuisine could go over 30 percent, particularly if they are concerned or their physicians are concerned about insulin resistance," he said.
The association had been aware of research on insulin resistance syndrome for some time, but hadn't addressed the higher fat diet before because it was focused on other areas of heart health, Krauss said.
Recent research, combined with an increase in obesity, prompted them to act, he said.
According to Dr. Marian Parrot, American Diabetes Association vice president of clinical affairs, a diet with around 40 percent of its calories coming from fat is an acceptable option for some patients.
"Some people will have a hard time keeping their weight down with that much fat in their diet," Parrot said, adding that each person's diet must be individualized.
Reaven argues that not everyone who is insulin resistant is overweight. About 25 percent of insulin resistant people are a normal weight, Reaven said. Physical fitness plays a key part in determining the effects of Syndrome X, he said.
Strom has had to learn firsthand how the higher fat, lower carbohydrate diet works. While writing the book, she was diagnosed with Syndrome X. Since then, "I've had to add much more good fat [to my diet]," she said.
She describes the recommended diet as a common-sense Mediterranean-like diet. Most of the carbohydrates she eats are in the form of vegetables, and she has found ways to keep the higher fat content healthy, like substituting olive oil for gravy.
"It's sort of like following the advice your grandma would give you, except without the saturated fat," Strom said.
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