Tagged Oils and Fats

No Health Benefit to Replacing Fat With Carbs

Photo

Low-fat diets that are high in carbohydrates are unlikely to improve your health, a new study shows.

Researchers came to the conclusion after studying the eating habits and health behaviors of 126,233 men and women who completed health questionnaires every two to four years for up to 32 years. Then they calculated the effect of replacing just 5 percent of saturated fat calories with another type of fat or carbohydrates.

The study, in JAMA Internal Medicine, found that replacing 5 percent of daily calories from saturated fats (mainly animal fat) with foods high in monounsaturated fat, such as olive oil and avocados, was associated with a 27 percent reduction in total mortality and reduced death from cardiovascular disease, cancer and neurodegenerative disease.

A similar switch from saturated fat to polyunsaturated fats, such as the omega-3 and omega-6 fatty acids in fish and walnuts, was associated with a 13 percent reduction in total mortality and a 29 percent reduction in death from neurodegenerative diseases.

But replacing saturated fats with carbohydrates, such as sugars and refined grains, did not confer any health benefits.

“Not all fats are created equal,” said the senior author, Dr. Frank B. Hu, a professor of nutrition at the Harvard T.H. Chan School of Public Health. “We should eat more good ones from fish and avocados, instead of animal fats. And second, the low-fat, high-carbohydrate diet is not beneficial for improving health and longevity.”

Diet High in Saturated Fats May Be Linked to Dense Breasts

Photo

Teenage girls who eat a diet high in saturated fat are at increased risk of developing dense breasts, a study concludes. Dense breasts contain more fibrous and connective tissue than normal and are a risk factor for breast cancer.

Researchers studied 177 girls, ages 10 to 18 at the start of the study, who periodically filled out dietary recall questionnaires. The scientists measured breast density by M.R.I. when the members of the group were 25 to 29 years old. The study is in Cancer Epidemiology, Biomarkers & Prevention.

Average dense breast volume in those in the lowest quarter for saturated fat intake was 16.4 percent, compared with 21.5 percent for those in the highest quarter.

Consumption of unsaturated fats had the opposite associations — the higher the consumption of unsaturated fats, the lower the average dense breast volume.

“We looked only at the associations of breast density with fat intake,” said the senior author, Joanne F. Dorgan, an epidemiologist at the University of Maryland School of Medicine. “Whether this will then be related to an increase in breast cancer later in life, we don’t know. But breast density itself is associated with increased risk.”

The authors controlled for many health factors, but they acknowledge that unknown variables could have affected their results.

“This is all observational data,” Dr. Dorgan said, “and needs to be confirmed before we can make health recommendations.”

A Decades-Old Study, Rediscovered, Challenges Advice on Saturated Fat

A four-decades-old study — recently discovered in a dusty basement — has raised new questions about longstanding dietary advice and the perils of saturated fat in the American diet.

The research, known as the Minnesota Coronary Experiment, was a major controlled clinical trial conducted from 1968 to 1973, which studied the diets of more than 9,000 people at state mental hospitals and a nursing home.

During the study, which was paid for by the National Heart, Lung and Blood Institute and led by Dr. Ivan Frantz Jr. of the University of Minnesota Medical School, researchers were able to tightly regulate the diets of the institutionalized study subjects. Half of those subjects were fed meals rich in saturated fats from milk, cheese and beef. The remaining group ate a diet in which much of the saturated fat was removed and replaced with corn oil, an unsaturated fat that is common in many processed foods today. The study was intended to show that removing saturated fat from people’s diets and replacing it with polyunsaturated fat from vegetable oils would protect them against heart disease and lower their mortality.

So what was the result? Despite being one of the largest controlled clinical dietary trials of its kind ever conducted, the data were never fully analyzed.

Several years ago, Christopher E. Ramsden, a medical investigator at the National Institutes of Health, learned about the long-overlooked study. Intrigued, he contacted the University of Minnesota in hopes of reviewing the unpublished data. Dr. Frantz, who died in 2009, had been a prominent scientist at the university, where he studied the link between saturated fat and heart disease. One of his closest colleagues was Ancel Keys, an influential scientist whose research in the 1950s helped establish saturated fat as public health enemy No. 1, prompting the federal government to recommend low-fat diets to the entire nation.

“My father definitely believed in reducing saturated fats, and I grew up that way,” said Dr. Robert Frantz, the lead researcher’s son and a cardiologist at the Mayo Clinic. “We followed a relatively low-fat diet at home, and on Sundays or special occasions, we’d have bacon and eggs.”

The younger Dr. Frantz made three trips to the family home, finally discovering the dusty box marked “Minnesota Coronary Survey,” in his father’s basement. He turned it over to Dr. Ramsden for analysis.

The results were a surprise. Participants who ate a diet low in saturated fat and enriched with corn oil reduced their cholesterol by an average of 14 percent, compared with a change of just 1 percent in the control group. But the low-saturated fat diet did not reduce mortality. In fact, the study found that the greater the drop in cholesterol, the higher the risk of death during the trial.

The findings run counter to conventional dietary recommendations that advise a diet low in saturated fat to decrease heart risk. Current dietary guidelines call for Americans to replace saturated fat, which tends to raise cholesterol, with vegetable oils and other polyunsaturated fats, which lower cholesterol.

While it is unclear why the trial data had not previously been fully analyzed, one possibility is that Dr. Frantz and his colleagues faced resistance from medical journals at a time when questioning the link between saturated fat and disease was deeply unpopular.

“It could be that they tried to publish all of their results but had a hard time getting them published,” said Daisy Zamora, an author of the new study and a research scientist at the University of North Carolina at Chapel Hill.

The younger Dr. Frantz said his father was probably startled by what seemed to be no benefit in replacing saturated fat with vegetable oil.

“When it turned out that it didn’t reduce risk, it was quite puzzling,” he said. “And since it was effective in lowering cholesterol, it was weird.”

The new analysis, published on Tuesday in the journal BMJ, elicited a sharp response from top nutrition experts, who said the study was flawed. Walter Willett, the chairman of the nutrition department at the Harvard T.H. Chan School of Public Health, called the research “irrelevant to current dietary recommendations” that emphasize replacing saturated fat with polyunsaturated fat.

Frank Hu, a nutrition expert who served on the government’s 2015 dietary guidelines committee, said the Minnesota trial was not long enough to show the cardiovascular benefits of consuming vegetable oil because the patients on average were followed for only about 15 months. He pointed to a major 2010 meta-analysis that found that people had fewer heart attacks when they increased their intake of vegetable oils and other polyunsaturated fats over at least four years.

“I don’t think the authors’ strong conclusions are supported by the data,” he said.

To investigate whether the new findings were a fluke, Dr. Zamora and her colleagues analyzed four similar, rigorous trials that tested the effects of replacing saturated fat with vegetable oils rich in linoleic acid. Those, too, failed to show any reduction in mortality from heart disease.

“One would expect that the more you lowered cholesterol, the better the outcome,” Dr. Ramsden said. “But in this case the opposite association was found. The greater degree of cholesterol-lowering was associated with a higher, rather than a lower, risk of death.”

One explanation for the surprise finding may be omega-6 fatty acids, which are found in high levels in corn, soybean, cottonseed and sunflower oils. While leading nutrition experts point to ample evidence that cooking with these vegetable oils instead of butter improves cholesterol and prevents heart disease, others argue that high levels of omega-6 can simultaneously promote inflammation. This inflammation could outweigh the benefits of cholesterol reduction, they say.

In 2013, Dr. Ramsden and his colleagues published a controversial paper about a large clinical trial that had been carried out in Australia in the 1960s but had never been fully analyzed. The trial found that men who replaced saturated fat with omega-6-rich polyunsaturated fats lowered their cholesterol. But they were also more likely to die from a heart attack than a control group of men who ate more saturated fat.

Ron Krauss, the former chairman of the American Heart Association’s dietary guidelines committee, said the new research was intriguing. But he said there was a vast body of research supporting polyunsaturated fats for heart health, and that the relationship between cholesterol-lowering and mortality could be deceiving.

People who have high LDL cholesterol, the so-called bad kind, typically experience greater drops in cholesterol in response to dietary changes than people with lower LDL. Perhaps people in the new study who had the greatest drop in cholesterol also had higher mortality rates because they had more underlying disease.

“It’s possible that the greater cholesterol response was in people who had more vascular risk related to their higher cholesterol levels,” he said.

Dr. Ramsden stressed that the findings by he and his colleagues should be interpreted cautiously. The research does not show that saturated fats are beneficial, he said: “But maybe they’re not as bad as people thought.”

The research underscores that the science behind dietary fat may be more complex than nutrition recommendations suggest. The body requires omega-6 fats like linoleic acid in small amounts. But emerging research suggests that in excess linoleic acid may play a role in a variety of disorders including liver disease and chronic pain.

A century ago, it was common for Americans to get about 2 percent of their daily calories from linoleic acid. Today, Americans on average consume more than triple that amount, much of it from processed foods like lunch meats, salad dressings, desserts, pizza, french fries and packaged snacks like potato chips. More natural sources of fat such as olive oil, butter and egg yolks contain linoleic acid as well but in smaller quantities.

Eating whole, unprocessed foods and plants may be one way to get all the linoleic acid your body needs, Dr. Ramsden said.

Making a Case for Eating Fat

Photo

Credit

Photo

Credit Mark Hyman

For years Dr. Mark Hyman was a vegetarian who kept his intake of dietary fat to a minimum. Whole-wheat bread, grains, beans, pasta and fruits and vegetables made up the bulk of his diet, just as the federal government’s dietary guidelines had long recommended. But as he got older, Dr. Hyman noticed something that bothered him: Despite plenty of exercise and a seemingly healthy diet, he was gaining weight and getting flabby.

At first he wrote it off as a normal part of aging. But then he made a shift in his diet, deciding to eat more fat, not less – and the changes he saw surprised him.

He lost weight, his love handles disappeared, and he had more energy. He encouraged his patients to consume more fat as well, and many of them lost weight and improved their cholesterol. Some even reversed their Type 2 diabetes.

Today, as the director of the Cleveland Clinic’s Center for Functional Medicine, Dr. Hyman has become an outspoken advocate about the health benefits of eating fat. He promotes it on talk shows, educates other doctors, and has even managed to wean his close friend Bill Clinton off of his previously prescribed low-fat vegan diet.

Now in a new book called “Eat Fat, Get Thin,” Dr. Hyman takes a deep dive into the science behind dietary fat, making sense of decades of confusing health recommendations and building a case for why even saturated fats, which have long been vilified, belong in a healthy diet. Dr. Hyman argues that Americans have been misled about the benefits of fat because of a disconnect between nutrition science and food policy. In the book he challenges the nutrition orthodoxy while also exploring the food industry’s outsize influence on official health recommendations.

Recently, we sat down with Dr. Hyman to discuss his thoughts on the gap between nutrition science and health recommendations, the reason you should always plan your meals, and why he never leaves home without a stash of “emergency foods” in his backpack. Here are edited excerpts from our conversation:

Q.

Why did you write “Eat Fat, Get Thin”?

A.

I wrote it because we’ve been suffering from 40 years of bad advice about fat that’s led to the biggest obesity and diabetes epidemic in history. The myth that fat makes you fat and causes heart disease has led to a total breakdown in our nutritional framework. I felt it was important to tell the story of how fat makes you thin and how it prevents heart disease and can reverse diabetes. I think people are still very confused about fat.

Q.

In the book you argue that nutrition recommendations are often contradictory. How so?

A.

This year, for example, the U.S. Dietary Guidelines for the first time removed their longstanding restrictions on dietary fat. But they still have recommendations to eat low-fat foods. They say total fat is not an issue, but you should drink low-fat milk and eat low-fat dairy and other low-fat foods. It’s a schizophrenic recommendation from the government, and it’s the same with other professional organizations such as the American College of Cardiology and the American Heart Association. There’s a mismatch between the science and the government and professional recommendations.

Q.

What’s driving this disconnect?

A.

I think the government based its recommendations on some very flawed science, which took hold. It became policy that was turned into the dietary guidelines and the food pyramid that told us to eat six to 11 servings of bread, rice, cereal and pasta a day and to eat fats and oils sparingly. It’s very hard to overturn dogma like that. It’s embedded in our culture now. It’s embedded in food products. The food industry jumped on the low-fat bandwagon, and the professional associations kept driving the message. Unfortunately the science takes decades to catch up into policy and into practice. And I’m trying to close that gap by bringing awareness to the latest science on how fats and carbs work in your body.

Q.

You reviewed hundreds of studies while writing this book. What is your conclusion on saturated fat?

A.

It’s a huge area of controversy. But large reviews of randomized trials, observational research and blood-level data have all found no link between saturated fat or total fat and heart disease. Yet there are still recommendations to limit saturated fat because it raises total cholesterol and LDL cholesterol. But it also raises HDL, and it increases cholesterol particle size, so you actually get a net benefit.

Q.

What do you say to scientists who argue that saturated fat does in fact cause heart disease?

A.

I think the challenge with the research is that a lot of the data combines saturated fat in the context of a high-carbohydrate diet. The real danger is sweet fat. If you eat fat with sweets – so sugar and fat, or refined carbohydrates and fat – then insulin will rise and it’ll make you fat. But if you eliminate the refined carbs and sugar, that doesn’t happen. I think saturated fats can be bad in the context of a high-carbohydrate diet. But in the absence of that, they’re not.

Q.

What foods do you eat and recommend to your patients?

A.

What I eat is a cross between paleo and vegan diets. It combines elements of the two, so I call it a “pegan” diet. It’s low in sugars and refined carbs, and it’s very high in plant foods. About 70 to 80 percent of your diet should be plant foods. It should also include good-quality fats like nuts and seeds, olive oil, avocado, coconut oil and fatty fish. It should basically include whole, fresh food that’s unprocessed and high in fiber and phytonutrients. I always say that vegetables should make up 50 to 75 percent of your plate.

Q.

In a world where fast food is everywhere, wouldn’t that be fairly difficult for most people?

A.

It’s actually very easy to eat well if you just know what to do. The reason most people don’t succeed is they don’t plan their food. They plan their vacations, they plan their kitchen redesign, but they don’t plan out what they’re eating, and that’s a recipe for failure. I always think through how and where I’m going to get my food every day of every week. I also carry with me a set of emergency food so that I’m never in a food emergency.

Q.

What are the “emergency foods” that you carry?

A.

I have to protect myself from myself because I’ll eat whatever if I’m hungry in an airport. So I always carry packets of almond butter, cashew butter, an Evolution bar, a Bulletproof bar, a Tanka bar and a KIND bar. I basically have fat and protein as my snacks, and I have enough food in my bag to last an entire day so I don’t make bad choices.

Q.

We talked a lot about fat. But what is one overarching message you would most like people to understand?

A.

I think we have to get rid of the prevailing dogma that all calories are the same, and that we just need to exercise more and eat less, which is what the food industry and the government promote. The truth is that you can’t exercise your way out of a bad diet. Metabolism is not a math problem. It’s a hormonal problem. Food is not just energy. It’s information. It’s instructions that turn on or off different switches in your body that regulate hunger and metabolism. Obesity is not about how much you eat. It’s about what you eat. If you just focus on quality, not calories, then the quantity takes care of itself.