We’re finally catching up to Canada: while our neighbors to the north removed dietary limits on cholesterol from their nutritional guidelines years ago, we are just coming around, with our new dietary guidelines likely suggesting that cholesterol is no longer a problem nutrient.. The evidence has been pretty one sided for quite some time – eating cholesterol doesn’t cause heart disease. Period. And now our guidelines are likely to reflect the best of our current scientific understanding, at least when the scope is limited to just cholesterol.
To understand how cholesterol became so inappropriately vilified, it helps to understand a bit about why we used to think it was a bad guy in terms of heart disease. In the medical world, you can learn a lot from autopsies. Studying how people die teaches us about disease and helps us come up with ideas about how to prevent and treat it. If you look at the arteries of someone who died of a heart attack, you see plaques that have built up in some of their coronary arteries (the blood vessels that supply the heart). These plaques have cholesterol in them, which would seem to implicate cholesterol as a causative agent of heart disease. But biology isn’t so simple – we don’t just simply eat cholesterol that gets dumped into the arteries around our heart.
Every cell in our body needs cholesterol to function
Its presence is necessary for cell membranes to function and for hormones to be synthesized. But cholesterol isn’t soluble in water; just like oil and water separate, cholesterol and water separate in a similar way, so it can’t travel through blood without help. And that’s where lipoproteins come into play – these are proteins that can carry cholesterol through the blood to the organs where it needs to go. I’m sure you’ve heard of LDL and HDL, the “bad” cholesterol and the “good” cholesterol, respectively. These aren’t different types of cholesterol, they’re different lipoproteins that carry cholesterol. To oversimplify a very complex process, LDL is the carrier that tends to drop off cholesterol at the arteries while HDL tends to pick it up and take it away. LDL litters and HDL is the trash man.* What we’ve learned is that eating cholesterol doesn’t lead to LDL dropping more cholesterol off in our blood vessels. And eating cholesterol certainly doesn’t lead to more heart attacks or strokes.
So our guidelines are catching up to the science. And this is a good thing, even if its happening slowly. It’s just unfortunate that the cholesterol dogma has become such a big part of pop nutritional science. We’ve gotten to the point where everyone knows that cholesterol is bad for you. Just google “low cholesterol diet” and see how many supposedly reputable sources will tell you how to enjoy cholesterol free meals that are “heart healthy.” It’s a real tragedy that inaccurate ideas have become so ingrained in our cultural understanding because of dietary guidelines released in the 1970s that were based on incomplete and unsettled science. I’m glad that we’re moving forward on this one, and I hope that it doesn’t take too long for cholesterol to be acquitted in the court of public opinion.
*This is an oversimplification a much more nuanced and complex process, but this model can be helpful for a cursory understanding of the process of heart disease