"Just as important as having ideas is getting rid of them."
So said the late Francis Crick, who along with James Watson worked out the basic structure of DNA in the early 1950s. His remark was quoted in a 1978 New Yorker article on the history of DNA (sometimes I get a tad behind in my reading, and this article, yellowed with age, was close to, although not at the bottom of, my "To Read" pile).
It's too bad the American Diabetes Association doesn't follow Crick's sage advice. It's hampering their progress and destroying their reputation in the minds of many people with diabetes.
Real science operates as Crick suggested. You have an idea, and you test it to see if it's true. If it is, you then try to refine your idea, or you let other people do that and you move on to a new idea.
If the experimental results show you're wrong, you reject your first idea and try to come up with a better one. You don't hang on to some old theory, for example that the earth is flat, simply because you've invested a lot in promoting that idea. If it's wrong, it's wrong. Admit it and move on.
In the early part of the 20th century, the standard treatment for all types of diabetes -- they didn't even know then that there were several different types, just "mild diabetes" (type 2) and life-threatening diabetes (type 1) -- was a low-carbohydrate, high-fat diet.
Then in the 1950s, when the results of Ancel Keys's studies appeared to show that diets with a lot of saturated fat increased risks of heart disease, the ADA started promoting low-fat diets for people with diabetes, who are at very high risk of heart disease. Because they also thought high-protein diets caused kidney disease, the only major nutrient left was carbohydrate, so the diets they supported were 60% to 70% carbohydrate.
"Make starch the star!" people were told by dieticians and ADA publications. "The more carbohydrates you eat, the better," the authors of a popular book on the glycemic index advised people with diabetes.
Of course, everyone knows it's carbohydrates that make blood glucose (BG) levels rise. But before the landmark Diabetes Control and Complications trial results reported in 1993, doctors didn't even believe that high BG levels were what caused complications. Even after that became clear, some doctors told their patients that fat intake was the central problem and that they should control BG levels with drugs, including insulin.
This low-fat mania led dieticians to suggest that people both with and without diabetes eat high-carb meals: a typical low-fat breakfast might consist of cereal, skim milk, toast (no butter), fruit, and orange juice, a veritable carbohydrate avalanche. After such meals, those with diabetes often didn't test their BG levels until just before lunch, when the tremendous peaks the carbohydrates caused had mostly come down.
Now, continuous glucose monitors are revealing the BG levels between meals on such diets, and some patients are stunned. Even people without diabetes can go quite high after such meals.
And new evidence is suggesting that glycemic variability may cause more complications than steady high BG levels.
Throughout all this time, the ADA has continued to support the low-fat, high-carb diet, although they did eventually admit that for some people without weight problems perhaps substituting some monounsaturated fat for some of the carbohydrate would be OK. And in their 2008 Clinical Practice Recommendations, they're allowing low-carb diets in the short term, for weight loss. It doesn't seem to occur to them that such diets also improve diabetes control.
Nevertheless, many -- not all -- dieticians who went to school years ago are still advising people with diabetes to follow the low-fat, high-carb diet, and the patients are wondering why their BG levels are getting worse instead of better.
Lucky patients with access to the Internet are communicating with each other and learning how to modify the recommended high-starch diets to include either more lower-glycemic-index carbohydrates like winter squash and whole grains for high-glycemic-index carbohydrates like potatoes and rice. Or they're going even further and following low-carb diets including low-carb vegetables like summer squash, broccoli, and salad.
Science is constantly evolving, and as new evidence appears, we need to modify our theories. For example, doctors used to measure total cholesterol alone. If your cholesterol went down, that was good.
Then they learned to measure HDL cholesterol and LDL cholesterol separately and discovered that high HDL was good and high LDL was bad. Some of the diets that reduced total cholesterol did so by reducing the beneficial HDL cholesterol, leaving the LDL untouched, and hence what appeared to be a good thing with the crude measurements of yesteryear turned out to be increasing the risk of heart disease.
A similar thing is occurring today with measurements of small, dense cholesterol (bad) and light, fluffy cholesterol (good). It turns out that some people can have very high cholesterol levels, but if those levels are the light, fluffy kind, they actually contribute to longevity. Bringing their cholesterol levels down to recommended levels is increasing their risks of dying young.
In 10 or 20 or 50 years, new evidence may appear that will affect the relative benefits of different kinds of diets, and when that happens we should change our theories too. (Well, in 50 years I probably won't have any theories at all.)
In the meantime, a low-fat, high-carb diet that causes huge spikes in postprandial BG levels doesn't seem to be a healthy choice for anyone, and it's high time the ADA admitted that. But they're too invested in their theories, too political, too scared to admit they were wrong.
I don't believe, as some do, that they always knew they were wrong but were promoting the high-carb diet because they were supported by the big cereal companies. I think that, like many health professionals, they were misled by the misinterpretation of the dietary studies of Ancel Keys. But at the time, the consensus was that the diet they supported was the best choice.
Today, we have new evidence, and if the ADA wants to keep anyone's respect, it's time they follow Crick's advice, admit their mistakes, get rid of their old ideas, and move on. It's time they switch their focus from politics to real science that helps real patients.
Until they do, some of us think the whole organization is not to be trusted.