Midway through the 20th century, heart disease caused one of every two deaths in the United States. While doctors traced the heart problems to clogged arteries, they didn't know what caused those clogs.
It was exactly the kind of riddle Dr. Ancel Keys loved trying to solve.
Keys already had examined why eels survived in both freshwater and saltwater and had spent 10 days at an elevation of 20,000 feet to see what the altitude did to the oxygen in his own blood. To feed soldiers in World War II, he created portable meals known as K rations (K for Keys, of course), which led to work in starvation, specifically how to reintroduce food to people after they'd been without it.
His work on heart disease would trump it all, becoming his greatest contribution to science.
Keys showed that diets rich in saturated fats led to an abundance of cholesterol in the bloodstream, which in turn becomes the root of coronary heart disease. The American Heart Association, which helped fund those studies, began urging Americans to cut back on fatty foods such as butter, eggs and red meats. The U.S. government later issued guidelines discouraging saturated fats.
A half-century after Keys' groundbreaking discoveries, his legacy continues to shine. Alas, so does ongoing criticism, from those quoted in a 1961 cover story about Keys in Time magazine to the author of a new book -- even though other rigorous scientific studies have not only supported his findings, they've expanded upon them.
"It's clear without a doubt that saturated fats raise LDL cholesterol, which we know contributes to heart disease," said Penny Kris-Etherton, Ph.D, R.D., a nutrition professor at Penn State University and the incoming chair of the American Heart Association's Nutrition Committee. "There's just no doubt about that."
Many of the studies that question Keys -- those that say saturated fats play no role in heart disease -- rely on information gathered through self-reporting. That is, the research is based on people filling out questionnaires, and hoping they gave accurate, truthful answers. Other papers have also relied on data collection methods that don't provide the desired certainty.
The most reliable research model involves scientists monitoring meals. Those studies are considered the gold standard because the data can be independently verified. These types of work have consistently shown an undeniable link between consuming saturated fat and the development of atherosclerosis, the disease process that underlies most heart disease.
"People should remember to turn to reliable sources that use evidence-based scientific findings for their recommendations," said Robert Eckel, M.D., a former AHA president and professor of medicine at the University of Colorado Anschutz Medical Campus in Aurora.
Eckel co-chaired a committee that developed the lifestyle guidelines released by the American Heart Association and American College of Cardiology in November 2013. This major scientific effort -- which involved a gathering of the nation's top scientists spending five years studying existing research -- underscored and advanced Keys' work. They recommended limiting saturated fats to about 5 or 6 percent of daily calories to lower blood pressure and "bad" cholesterol (LDL).
Keys, by the way, came up with his own antidote to saturated fats -- his version of the Mediterranean diet, one based on eating fruits and vegetables, and olive oil, and using meats, fish and dairy to accent a meal, rather than being the centerpiece.
I realize that talk of eating more of this and less of that can get confusing. I get it -- I'm as bombarded by that as you are.
Trying to keep up with it all is nearly impossible, especially since the suggestions keep changing. Look closely and you'll even find that many of the fad diets are contradictory.
So why not keep it simple?
Instead of burdening yourself with the unreasonable goal of eliminating things from your diet, aim for moderation. Set a goal of consuming less saturated fat today than yesterday. Once you're ready, try doing the same for sugar, and salt. Meanwhile, mix in a little more exercise today than yesterday.
Less of the bad, more of the good. Simple.
The best wellness advice is the advice you are willing to follow. At the American Heart Association, our experts sort through all the information available and make recommendations on what's scientifically proven to work. This is what's made us the nation's largest and oldest voluntary organization devoted to cardiovascular health, and a source you can trust. Consider the results.
While heart disease remains the No. 1 killer of Americans, the rate has plummeted, going from 50 percent (one in two) when Keys began studying fats to about 17 percent (one in six).
Keys died in 2004, a few months shy of his 101st birthday. His wife, Margaret, a biochemist who was his co-author on three books about healthy living, lived to be 97.
Good genes undoubtedly played a role in their longevity. Still, common sense says their adherence to their own work likely was a factor, too.