TUESDAY, Nov. 6, 2007 (HealthDay News) -- The high-fat, high-protein and low-carbohydrate Atkins diet may put practitioners at risk for heart disease in as little as one month, a new study suggests.
When individuals followed the maintenance phase of the diet -- without weight loss -- they experienced increased "bad" cholesterol and other markers for heart disease, experts report.
"I think the Atkins diet is potentially detrimental for cardiovascular health, if maintained for a long duration and without attempts to lose weight," said lead researcher Dr. Michael Miller, lead author of the study, director of preventive cardiology at the University of Maryland Medical Center and associate professor of medicine at the University of Maryland School of Medicine in Baltimore. "A stabilizing Atkins diet is not the way to go," he said.
It's also unclear if the popular South Beach or Ornish diets, also studied in the trial, actually promote heart health.
This was just one of several studies involving diet and nutrition slated for presentation at this week's annual meeting of the American Heart Association in Orlando, Fla.
A second study, conducted primarily among Mormons in Utah, found that routine fasting was associated with a lower risk of coronary artery disease.
And yet another trial found that moderate drinking might help ward off angina after heart attack.
"Nutrition continues to be an area of interest, and, clearly, there is conflicting information out there," said Dr. Robert Bonow, immediate past president of the American Heart Association. "With the Atkins diet, you do lose weight and experience a short-term beneficial effect on lipid parameters, but the concern would be long-term. Saturated fats are not good for heart health, and many people experience rebound weight gain which is not good."
Although much research has been done on the Atkins diet, no one has yet looked at the effects of the diet when the person is not losing weight.
"During the process of weight loss, we would expect to see a benefit on various [cardiovascular] parameters," Miller said. In other words, the weight loss that can come with these diets will help the heart.
But how does the cardiovascular system fare on a high-fat regimen when weight remains stable? "Weight loss confounds the results, and we wanted to compare these diets without that possible confounder," Miller explained.
For this trial, 18 healthy adults completed four weeks each on the Atkins (50 percent fat), South Beach (30 percent fat) and Ornish (10 percent fat) diets.
People on the Atkins diet had increased levels of LDL ("bad") cholesterol, more constricted blood vessels and an increase in blood markers for inflammation, some by as much as 30 percent or 40 percent, the researchers said.
The results were less clear for the Ornish or South Beach regimens. In those diets, markers for inflammation remained stable or dipped by up to 20 percent, the researchers found.
Another study followed up on reports from the 1970s that Mormons experience fewer deaths from heart disease.
Previous researchers had assumed that a prohibition on tobacco use among Mormons was the reason, but the current researchers hypothesized that there were additional factors at play.
Indeed, people who reported fasting regularly had a lower risk of developing coronary artery disease. The study adjusted for various factors including resting on the Sabbath, avoiding tea and tobacco, and age and body mass index.
The study did not put a time limit on fasting, but the religious teachings of Mormons do include fasting once a month for about 24 hours.
It could be that self-proclaimed fasters have better control of their diet in general, or fasting may prompt some kind of protective biological mechanism, said Benjamin Horne, senior author of the study, director of cardiovascular and genetic epidemiology at Intermountain Medical Center and adjunct assistant professor of biomedical informatics at the University of Utah in Salt Lake City.
Still, the study has raised more questions than it has answered, including whether to fast at all and for how long, he said. Horne warned that diabetics, in particular, should not start fasting until more is known.
A final study, this one of almost 2,500 individuals, confirmed that moderate alcohol consumption (one to two drinks daily) was associated with a reduced risk of angina one year after having a heart attack, compared to both abstinence or heavy alcohol consumption. Drinking too much (more than four drinks a day) was associated with an increased risk of angina, said researchers from St. Luke's Hospital in Kansas City.
How does one find the healthiest lifestyle in the midst of all this information?
"We recommend weight loss in a slow and consistent manner rather than a crash course," said Bonow, who is also Goldberg Distinguished professor at Northwestern University Feinberg School of Medicine, and chief of the division of cardiology at Northwestern Memorial Hospital in Chicago.
Bonow offered what he believes is a quick nutritional checklist for health: "Exercise and paying attention to calories in and out, lots of fruits and vegetables, less saturated fat, milk products should be skim, fried foods are bad, omega-3 fatty acids are good."
For more on diet and nutrition, visit the American Heart Association.