No Science is Settled

“The science is settled” is a frequently heard refrain today, usually applied to the issue of climate change.  President Obama said in his State of the Union address on January 28, 2014, “The debate is settled. Climate change is a fact.” Those who would question that the science is settled are now labeled “climate deniers”, a grotesquely misappropriated description that implies such people are in the class of those who would deny the Holocaust perpetrated upon the Jewish people.

Charles Krauthammer, highly respected syndicated columnist for The Washington Post, responded to the president’s assertion saying, “There is nothing more anti-scientific than the very idea that science is settled, static, impervious to challenge.” As a Harvard trained medical doctor, Krauthammer is certainly qualified to render an opinion on science.

He points to recent changes in the scientific literature as an example. For years we have been told by scientists that mammograms help reduce breast-cancer deaths. But a recent massive randomized study of 90,000 women followed for 25 years – an unusually comprehensive research project – concludes that mammograms may have no effect on breast-cancer deaths. They concluded one out of five of those diagnosed by mammogram receives unnecessary radiation, chemotherapy, or surgery.

Does this mean we should stop doing mammograms? Hardly, but it does mean we should be wary of our previous conclusions of the value of mammograms and need to continue to study our methods of screening for this common deadly cancer in women. The science of mammograms is not settled.

Recently I read in The Orlando Sentinel that researchers are now challenging earlier conclusions that the population of great white sharks is declining. The article, by Barbara Liston, says, “A new look at research on great white sharks in part of the Pacific Ocean indicates that the population is likely growing and not endangered, according to an international research team.” The findings are in stark contrast to the impressions of a 2011 Stanford University study that led to petitions by conservationists to add white sharks to state and federal endangered lists. This is no great surprise to those who follow the scientific literature. New studies frequently challenge old conclusions as we learn more about the world of science we live in. The science of great white sharks is not settled.

Perhaps most surprising, however, is an article that graces the cover of the June 23, 2014 edition of Time magazine that carries the bold headline: Eat Butter. Scientists labeled fat the enemy. Why they were wrong.” Inside the pages of this liberal-leaning magazine, the article entitled Don’t Blame Fat by Bryan Walsh tells us that scientists have been wrong for years on the best diet to prevent the scourges of heart disease, high blood pressure, strokes, and diabetes.

In 1977, a Senate committee led by Senator George McGovern published its landmark “Dietary Goals for the United States” which urged Americans to eat less high-fat red meat, eggs and dairy and more fruits, vegetables, and especially carbohydrates. By 1980 the USDA issued its first dietary guidelines to avoid cholesterol and fat of all kinds. The National Institutes of Health recommended all Americans over the age of 2 cut fat consumption. Later the same year the government announced the conclusions of a $150 million study, which said: Eat less fat and cholesterol to reduce your risk of a heart attack.

As one who lived through that era and trained in medical school at the time, I can easily recall the guilt we all felt when we had bacon and eggs for breakfast or a steak topped with Hollandaise sauce for dinner. To assuage our guilt we ate our baked potatoes without sour cream or butter and switched to frozen yogurt instead of ice cream. Low-fat diets became the rage and manufacturers scrambled to produce low-fat renditions of their butter, milk, yogurt, cheese, or any other product with high fat content. Our diets became blander but we convinced ourselves we were going to live longer with less chance of a heart attack.

But now the results of this nearly forty-year dietary change are in and the experiment was a failure. The prevalence of Type 2 diabetes increased 166% from 1980 to 2012. Nearly one in ten American adults has the disease, costing the health care system $245 billion a year, and an estimated 86 million people are pre-diabetic. It is true that deaths from heart disease have fallen but this is attributed mostly to improvements in emergency room care, less smoking, and widespread use of cholesterol-lowering drugs like statins. Yet cardiac disease remains the country’s number one killer.

“Americans were told to cut back on fat to lose weight and prevent heart disease,” says Dr. David Ludwig, the director of the New Balance Foundation Obesity Prevention Center at Boston’s Children’s Hospital. “There’s an overwhelmingly strong case to be made for the opposite.”

Walsh rightly points out that changing the culture will not be an easy task. The low-fat diet craze of the last forty years has produced mega-changes in the agricultural and food processing industries. It will require similar changes if the culture is to adjust to this new understanding of the impact of our diet on our health and risk of heart attack.  “This is a huge paradigm shift in science,” says Dr. Eric Westman, the director of the Duke Lifestyle Medicine Clinic, who works with patients on ultra-low carb diets. “But the studies to support it do exist.”

What do these studies tell us? The new research suggests it’s the over consumption of carbohydrates, sugar, and sweeteners that is chiefly responsible for the obesity and Type 2 diabetes epidemics that we are seeing now in our population. Carbohydrates are the new villains like fatty foods were the old ones. Refined carbohydrates, like white bread, rice, and potatoes, and low-fat crackers and pasta, are believed to cause changes in our blood chemistry that result in storage of calories as fat rather than maintaining an even level of blood sugar. The result is increased hunger that leads to more consumption that leads to more storage of fat.

“The argument against fat was totally and completely flawed,” says Dr. Robert Lustig, a pediatrician at the University of California, San Francisco, and the president of the Institute for Responsible Nutrition. “We’ve traded one disease for another.”           

The Low Fat Theory

Perhaps no one was more instrumental in convincing us that low-fat diets were the cure for heart disease than Dr. Ancel Keys. He first came to prominence during World War II when he was assigned the task by the military to develop imperishable food rations to be carried by the troops in the field of combat. These “K rations” were the regular diet of every soldier throughout the war. Following the war, the country was seized with a fear of heart attacks after President Dwight Eisenhower suffered one in 1955 while in office.

Keys believed the culprit was high cholesterol that caused clogging of the arteries with plagues that produced heart attacks. He reasoned that lowering the intake of cholesterol would lower the incidence of heart attacks. Then he traveled in the 1950s and ‘60s to find support for his hypothesis by studying the diets in other countries. Upon completion of these trips he published his landmark Seven Countries Study that concluded that people who ate a diet low in saturated fat had lower levels of heart disease.  Keys found himself on the cover of Time magazine in 1961 telling Americans to reduce the fat calories in their diet by a third if they wanted to avoid heart disease. Many believed at that time that the science of fat intake and heart disease was settled.

Walsh explains the impact of Keys:

“Keys’ work became the foundation of a body of science implicating fat as a major risk factor for heart disease. The Seven Countries Study has been referenced close to 1 million times. The vilification of fat also fit into emerging ideas about weight control, which focused on calories in vs. calories out. Everyone assumed it was all about the calories. And since fat contains more calories per gram than protein or carbohydrates, the thinking was that if we removed fat, the calories would follow.”

Now it becomes clear that there were problems with Keys’ research from the start. Apparently he cherry-picked his data, leaving out those countries that didn’t support his hypothesis like France and West Germany that had high-fat diets but low rates of heart disease. “It was highly flawed,” says Dr. Peter Attia, the president and director of the Nutrition Science Initiative, an independent obesity-research center. “It was not on the level of epidemiology work today.”

Which only goes to prove that science is never settled. Our finite understanding of an infinite universe will never be complete. As we learn more and live longer we increase our comprehension but we can never be complacent enough to say, “The science is settled.” True scientists always recognize the need for more research and more analysis, no matter what the science being studied. When I began medical school, the professor in my first lecture admonished us that we could never stop learning because “half of what we teach you today will be eventually proven wrong. We just don’t know which half.”  This is an important lesson everyone should remember the next time anyone accuses you of being a “science denier”.

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