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Sugar. Cholesterol. JAMA. Finally.

Posted Apr 23 2010 7:44pm

By Barbara Berkeley, MD

Scientists are supposed to be curious. Weren’t they once the little boys and girls who peppered their parents with a zillion questions about how the world worked? Didn’t they once want to solve the riddles of the universe?  

But then the scientists grew up and like all the rest of us, they became less open minded.  Perhaps they were influenced by powerful figures. Or perhaps they became so immersed in their own hypotheses that they stop looking at others. 

In no area has this been so true than in the reluctance of researchers to look at the negative role of sugars in our modern diet. In 1970, Ancel Keys, a professor of physiology from the University of Minnesota, published the first results of a study that would change science for decades. The Seven Countries Study was a research project that looked at diet and heart disease throughout the world.  It concluded that there was a strong association between the amount of saturated fat people ate and their cholesterol levels and subsequent chance of developing heart disease. 

The Seven Countries study has arguably been one of the most influential forces on our modern American diet. Keys was a big, loud voice in the scientific community. Beginning in the 1960s, he and others had begun convincing much of America to start eating more polyunsaturated fats and fewer saturated ones. It was around this time that my mother banned the Breakstone butter tub from our table and substituted that fabulously healthful product - margarine - made completely from corn oil. Americans stopped frying in lard and started consuming tons of vegetable oils instead. As the years went on, things got more confused. All fat became the enemy and the fat free craze was on with a vengeance. Carbs good. Fats bad. Dutifully, I switched to a diet of vegetables, grains, pasta,  and bread with fat free Entenmanns cookies for dessert. It was all completely fat free.  But, for the first time in my life, I started to gain weight as if it was going out of style. I chalked it up to being 40. My diet was obviously pristine

But holes began to appear in the Seven Countries Study. (For more on this, see Gary Taubes’ book, “Good Calories, Bad Calories”) Critics noted that Keys had omitted data from countries in which results contradicted his preferred hypothesis. At the same time, Dr. Atkins popularized a diet which had pretty much no carbohydrates.  Cholesterol levels fell on this diet. How could that be if fat raised cholesterol? For years, people like Weston Price who studied the anthropology of diet had noted that the inclusion of large amounts of carbohydrate in native diets was linked to modern disease. Yet science refused to be swayed from its single-minded pursuit of fat as villain.  Clinicians who spoke out against sugar and starch consumption, and those who wrote about it were sidelined as kooks. 

Despite the fact it is clinically obvious that cholesterol falls when patients are placed on low carbohydrate diets, other doctors still look at me as if I’m nuts if I suggest that sugar has anything to do with lipids. Even more importantly, we now know that our levels of total cholesterol are only one, very generalized,  piece of the puzzle. Equally, if not more important, are the types of lipids we have. We’ve gone beyond just the “good” cholesterol and the “bad” one. We now know recognize vital subtleties.

Bad cholesterol turns out to exist in two forms: a light, fluffy, innocuous form and an irritating, small, dense and dangerous form.  Dense LDL predisposes us to coronary disease. Standard lipid tests do not say anything about the size of LDL particles, but doctors can guess if we have them by looking at levels of two other lipids,  triglycerides and HDL. If the ratio of these two elements is above 3.8, that is a strong indication that there is small, dense LDL. We call this type of lipid profile “dyslipidemia” and it is highly correlated with vascular disease.

Are these changes entirely brought about by the fat we eat?  Absolutely not.

On April 21, 2010,  with absolutely no fanfare, the Journal of the American Medical Association published an uber-important study ( JAMA study) . Here is how the authors introduced it:  "Dietary carbohydrates have been associated with dyslipidemia, a lipid profile known to increase cardiovascular risk.  Added sugars...are an increasing and potentially modifiable component in the US diet.  No know studies have examined the association between the consumption of added sugars and lipid measures.

Isn’t it incredible that with all the research on diet and heart disease that has been going on for the past 30 years, this is the first study to directly test the possibility that sugars impact lipids?

So here’s what the study showed.   It looked at 8,495 US adults over the age of 18 who were part of our ongoing national nutritional survey (NHANES, 1999-2006).   Excluded from the study were those on cholesterol medicines or diabetics---so two of the populations that theoretically might have shown the greatest correlation of lipid levels with sugars were not considered.    The study also looked only at the added sugars people consumed, in other words, the extra sugar, high fructose corn syrup or other sweeteners that were included in the foods they ate, not at the total carbohydrate composition of their diets.  

Results: Good Cholesterol levels, which should be high, fell as the consumption of added sweeteners increased.  Triglyceride levels rose significantly, meaning that the ratio between the two went up (suggesting more dense LDL) as sweetener use did.  In women,   total LDL (bad) cholesterol rose with increased sugars as well. 

Interpretation: Sweetening agents directly affect cholesterol and triglyceride levels  (or at least are highly correlated with them). If this study is correct,  eating more sugars increases your risk of vascular disease. Finally, It’s not just about fat anymore. 

How much added sugar do we consume? On average, about 16% of our calories are coming from this completely unnecessary source. Recently, the American Heart Association jumped on the anti-sugar bandwagon with the recommendation that women consume no more than 100 calories in added sugar per day (150 calories for men). How likely is this to happen? Well, one can of coke has 140 calories from sugar. A Starbucks blueberry scone has 460 calories, 96 of which come from added sugars, and a small pack of M&Ms has about 130 calories of added sugars. Eat any one of these and you are done with sugar for the day and that doesn’t factor in the hidden sweeteners that are added to restaurant foods, canned foods, and just about everything else. How many sugars should we truly eat? In my world, the answer would be: just the sugars contained in natural foods. 

Finally, this study just skims the bare surface. It opens the door to the thought that too many sugars can be just as dangerous for your heart as too many of the wrong fats.  But the name of the game is gestalt—or totality. If we get bogged down in running after sugars as we’ve gotten bogged down in running after fats, we will find ourselves at the end of another blind alley. Each and every one of these studies confirms the very same priniciple, that the further we depart from the diet that was original to man, the more we mess things up. Clumsy attempts to “correct” the problem only reveal our ignorance. Remember that margarine my mother switched to? Turned out that it was full of corn oil, which is high in omega 6—or pro-inflammatory—fats. Also turned out that margarine was just a tub of trans-fat, one of the most dangerous substances for the heart. And all of those Americans who switched to vegetable oil?  They vastly raised the ratio of omega 6 to omega 3 fats in their diet, putting them at risk for inflammatory problems.   Is it such a fringe idea to suggest that we need to revamp our entire idea of diet to bring it back into line with what kept us healthy in the past? I certainly don’t think so.

But for today, I will celebrate the JAMA study and be glad that science has started to expand its view.  Maybe I’ll try re-reading it while eating the peculiar concoction that I’ve recently been enjoying for lunch:  some  sardines mashed up with a good mustard, a salad, and an avocado.  Lots of omega 3, completley Primarian, and not a sugar in sight. 

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