Photo: rob_rob2001 (flickr)
Everybody calm down. Bacon did not just become a new vitamin.
A new study released this week in the Annals of Internal Medicine concluded that previous studies had failed to demonstrate that saturated fats – the cheesy, meaty, bacony kind – are any better or worse than so-called “better” fats, like the ones in fish, nuts and vegetable oils. But many nutrition and medical experts are worried people will jump to dangerous conclusions that contradict longstanding warnings.
The study doesn’t even mention bacon, but it did crunch data from 45 studies and 27 trials that encompass a total of more than 600,000 participants in 18 countries. Researchers found no significant difference in the risk of heart disease between subjects who ate more saturated fats than poly- and monosaturated fats. The study didn’t produce any additional data of its own, it just analyzed existing studies.
What the study concluded:
- When considered as a whole, previous studies did not adequately link increased saturated fat consumption with increased coronary risk.
- Eating more omega-3 and omega-6 fatty acids did not reduce coronary risk.
- Trans fats are still terrible. Increased consumption is linked to heart disease.
- High-carbohydrate, sugary diets are terrible. Excessive carbs are liable to promote artery-clogging cholesterol – and increase the risk of heart attacks and stroke.
A Chilly Reception
The study has stirred up tensions in the public health community over contradictory research and media messages. Critics charge that the group’s analysis is out of context, and its premise is flawed.
Dr. David Katz, the director of the Prevention Research Center at the Yale University School of Medicine, said the study did not take into account participants who replace their saturated fats with refined carbohydrates – swapping one poison for another.
“When diets change, what matters is how do they change? What did you eat more of and what happens to the overall pattern and quality of your diet?” he said. Katz added that he’s concerned about the impact of confusing messages on public health.
“Each time this happens, we’re set back. The opportunity to take what we do know, apply it, and improve the human condition is forestalled.”
Dr. Eric Rimm, an epidemiologist at the Harvard School of Public Health, told Medwire that the study’s findings were not placed in proper context “because it likely represents the result of when you exchange saturated fat in your diet for refined grain. Thus, saturated fat is no better or worse than eating white bread. We have known that for decades, so [it] is not new.”
On the findings about omega-3 and omega-6 fatty acids, Rimm was more cutting, saying his colleagues had discovered a flaw in the research that indicates “the results are in serious question.”
Each time this happens, we’re set back. The opportunity to take what we do know, apply it, and improve the human condition is forestalled.
The American Heart Association is one of several key organizations leading the campaign to curb intake of saturated fats. They even invented cartoon characters “Bad Fats Brothers,” whose nicknames “Sat” and “Trans,” are mnemonics to remember that saturated and trans fats are the right ones to limit. The new study takes those guidelines to task.
Linda Van Horn, an AHA spokesperson from Northwestern University Feinberg School of Medicine in Chicago, also found the study’s approach too broad.
“The meta-analyses were derived primarily from observational, cross-sectional and or mixed method studies that varied greatly in study design, analysis and power,” she said in an email interview. “In order to truly test the question, it requires a prospective, randomized trial comparing representative populations that eat the recommended diet versus those who do not with outcome measures focused on cardiovascular risk factor development, incidence of hypertension, insulin resistance, hyperlipidemia, etc. and then of course cardiovascular and all cause mortality.”
Such studies would “require billions of dollars and decades to complete,” the organization said in a release on Monday. “It is virtually impossible to achieve this so we must settle for the best and well controlled smaller randomized control trials,” Van Horn said.
The study has its supporters. Dr. Eric Westman, associate professor of medicine at Duke University and the director of the Duke Lifestyle Medicine Clinic, welcomes fresh challenges to guidelines on saturated fat intake.
“We need evidence to limit fat in guidelines, because the science doesn’t support that it’s bad.”
Westman recommends a low carbohydrate, high-fat, high protein diet for some patients, and authored the book New Atkins for a New You.
“I think what we’re dealing with is what’s called a paradigm shift. And there’s always reluctance in changing paradigms. There’s a whole industry around low fat, and that industry can either catch up or squelch it.”
Dr. Douglas Zipes, a cardiologist and professor emeritus of medicine at Indiana University-Purdue University Indianapolis, said though the study’s findings seem compelling, diet is only one of many complicated factors in determining the risk of heart disease and stroke.
“We’ve been wrong from our armchair many times in the past, making assumptions of what seems logical,” he said. But the article takes a “healthy swipe” at the conclusion that certain fats raise health risks, he said. “Guidelines are living documents.”
He plans to continue advising his patients to exercise and watch their diet.
“This [research] in no way says that you’re free to go to McDonalds and pig out seven days a week,” Zipes said. “I can understand the frustration of the public who doesn’t have the scientific insight to look into these things. But that’s medicine, and that’s science. Things change.”