Scientists Understand Heart Disease Better, Still Give Bad Advice

Calling fast food "high fat" is true, but misleading. Image courtesy of avlxyz.

New research from UC Davis sheds light on how triglycerides induce atherosclerosis—the hardening of artery walls that causes heart disease—particularly in individuals with abdominal obesity. Unfortunately, however, the researchers credit the fat in the fast food meal they used to induce the triglyceride spike, while letting the more likely culprit, orange juice, completely off the hook.

In the study, researchers fed a fast food meal (two breakfast sandwiches, hash browns and orange juice, as noted in the press release) to people with either normal or elevated blood triglycerides. Triglycerides correlate strongly with risk of heart disease and are a better predictor of cardiovascular risk than total or LDL cholesterol.

After eating the horrible meal, triglycerides rose and LDL cholesterol was transported into cells in the artery wall, a process that leads to artery hardening and heart disease. This effect was worsened in the presence of cytokines, which are known to cause inflammation and correlate with a larger waist size.

The implication is that poor diet choices become more dangerous as a person's metabolic health declines, making good nutrition an even greater priority for people with abdominal obesity.

“The new study shows that eating a common fast food meal can affect inflammatory responses in the blood vessels," said the lead researcher, Anthony Passerini, and the effect seems to be worse in those with chronic inflammation and larger waists.

But why do they extrapolate and claim that this problem is caused by dietary fat?

The authors describe the fast food meal as “high-fat”, but neglect that it is also high in processed carbohydrates (two buns and hash browns) and fructose, the fruit sugar present in orange juice. Fructose is converted to triglycerides in the liver and is the most effective way to increase triglyceride levels.

Not only is fructose from the orange juice the most likely cause of the triglyceride effect, but it is particularly unlikely the fat had an impact. High-fat, low-carbohydrate diets have been used to treat high triglycerides since the 1960s, even at levels as high as 65% of calories from fat. In the current study the fat in the fast food meal represented only 47% of calories.

Though the fast food meal used by the researchers undoubtedly matches the “typical western diet,” it is unlikely that the fat content is responsible for elevating triglycerides and the risk of heart disease that comes with them.

A better message for people worried about triglycerides: watch your sugar.

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