Cholesterol in food is not the danger it’s been made out to be 06/02/2020
For decades, we've heard that food containing cholesterol is bad for your health. But it's just not true.
The good news: you can happily and healthfully enjoy many foods high in both nutrients and cholesterol, notably eggs, pasture-raised meat, and shellfish.
We need cholesterol, which is built into the membrane of all of our cells. We also need cholesterol to make hormones and turn sunlight into Vitamin D, among other functions.
Your body, specifically your liver, makes most of the cholesterol you need, with only a small amount coming from food, and a delicate mechanism maintains your blood cholesterol levels. When you eat less cholesterol, your liver makes more. When you eat more, your liver makes less. This means that for most people, eating high-cholesterol foods won't affect blood cholesterol levels (Berger et al, 2015, Fernandez, 2012).
So how did we get the idea that cholesterol in food is always dangerous? A bit of history will clear up the confusion.
How recommendations about cholesterol have evolved.
In 1968, the American Heart Association recommended eating no more than 300 mg a day of cholesterol, and only 200 mg if you had a high risk of heart disease. As part of that regime, you were allowed only three whole eggs a week.
It seemed to make sense that dietary cholesterol could end up clogging your artery walls, since plaque, the waxy substance that narrows arteries, is made up of cholesterol as well as fat and other substances.
The theory went back to the American scientist Ancel Keys, who noticed that heart disease dropped sharply in Europe after World War II, when food was scarce. Could leaner diets with fewer cholesterol-containing animal-based foods have made the difference? He presented his ideas to the World Health Organization in 1955.
But just a year later, Keys himself observed that there wasn't a direct relationship between diet and blood cholesterol. He published a paper citing several studies showing that "in adult men the serum cholesterol level is essentially independent of the cholesterol intake over the whole range of natural human diets. It is probable that infants, children and women are similar" (Keys et al. 1956).
Over time, new research followed up on Keys' 1956 observations and medical recommendations evolved. Finally, by 2015, the new (still current) dietary guidelines for Americans dropped the idea of a maximum amount of cholesterol we should eat.
In between, scientists developed a better picture of how cholesterol works. If you've had a lipid profile test, you may have heard of "good" cholesterol, the number called HDL on your test, which stands for high-density lipoproteins, and "bad" cholesterol, labeled LDL, for low-density lipoproteins. (But so-called "bad" cholesterol isn't necessarily bad, as you'll learn in a future article).
Lipoproteins are molecules, think of them as submarines, that carry cholesterol around your body. The LDLs carry it from your liver to other cells. HDLs carry it the other way, to the liver, from which it leaves your body. The ratio of LDL/HDL is believed to be a key marker of heart disease risk.
About a quarter of the population seems to be more sensitive to dietary cholesterol, and food can raise their blood levels for LDL cholesterol (Fernandez, 2012). But even in this group, called "hyper-responders," HDL cholesterol also rises, and their ratio may be fine.
You've also probably been told if you have high triglycerides, another kind of fat.
The current wisdom is that high triglycerides and low levels of HDL cholesterol in your blood are signs of increased heart disease risk. The 2018 guidelines published in the Journal of the American College of Cardiology established acceptable, borderline, and high measurements for adults. The ideal is 60 or higher HDL, less than 100 LDL (or below 70 if you have heart coronary artery disease) and less than 100 triglycerides (Grundy et al, 2018).
But do you need to avoid all cholesterol-rich foods to achieve that ideal? Not at all. Carbs are more likely to be your problem. In a study comparing the cardiovascular effects of low-carb and low-fat diets, it was the low-carb diet that most improved heart risk numbers (Bazzano et al. 2014). In a small study of the effect of a diet with 20-30 percent calories from protein (the American average is 15 percent), volunteers with obesity and diabetes saw big increases in HDL cholesterol (Pedersen et al. 2013).
Consuming some high-cholesterol high-protein foods actually can be a strategy to improve your heart health.
Healthful, cholesterol-rich foods include:
- Shellfish. The American Heart Association recommends eating two servings of seafood a week, especially high-omega 3 fish like salmon and sardines. Shellfish counts, too. Some people avoid shrimp because they fear its cholesterol content. But eating shrimp every day has been shown to lower triglycerides, while keeping the HDL/LDL ratio steady (De Oliveira e Silva et al, 1996).
- Pasture-raised beef. Processed meat is linked to heart disease, but several large studies have found no tie otherwise between red meat and heart disease (Rohrman et al. 2013). In fact, a large Korean study found that eating a moderate amount of unprocessed meat was linked to less heart risk (Park et al. 2017). Eating pasture-raised steak is a good way to up your protein intake, and obtain more nutrients and omega-3 fatty acids than you'd get from feedlot cows.
- Eggs. Remember that old rule of no more than three eggs a week? One study put people with metabolic syndrome on a calorie-restricted diet, but had half the group eat three whole eggs a day and the other half a yolk-free substitute. The egg-eaters saw greater improvements in their lipoprotein profile (Blesso et al. 2012).
Yes, your mother might have been horrified to see you tuck into a three-egg salmon omelet plus coffee with whole milk, but your great-grandmother would have thought it was a wonderful, healthful meal.
Turns out, great-grandma was right, about that at least, not necessarily about the towering stack of pancakes! Times change, science advances, and your heart may thank you for it.
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