Previously I was told eating eggs lead to increased cholesterol, yet, news articles repeat that it’s not true. How can the conclusions be so contradicting given that it’s simply about measuring cholesterol before and after eating eggs?
I can’t help but feel suspicious knowing ‘bacons are good for the heart’ ‘doctors smoke’ were all propaganda campaigns.
In: Biology
Science is always evolving as we learn more, including nutritional science. Eggs are naturally high in dietary cholesterol. Logically one would think that dietary cholesterol would increase the cholesterol levels in your blood.
Over years we have learned that the link is not one-to-one and that saturated fat, which is also present in many high cholesterol foods, is a bigger contributor. Eggs and shellfish are the exception, at least if they are not fried.
See https://www.heart.org/en/news/2023/08/25/heres-the-latest-on-dietary-cholesterol-and-how-it-fits-in-with-a-healthy-diet
It’s extremely difficult to have a controlled long-term dietary study. People eat tons of different foods that can interfere with the studies results, so it’s nearly impossible to perfectly control for variables and see the effects of individual foods. Also, people lie a lot about what they eat, or are just bad at keeping track.
On top of that, studies are frequently funded by industries trying to force a certain outcome that benefits their industry.
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if you take someone who has never eaten eggs and feed them eggs, you measure a cholesterol spike emediatly.
but after a month or so of eating eggs, the body has dialed back its cholesterol production to compensate so its not a problem in a long term diet.
The longer the study, the harder it is to get quality measurments, so often the emmediate effects get reported much earlier than the actually relevant long term effects
Another facet to this not mentioned by other commenters: science reporting is notoriously bad. Nutrition science takes a very long time because outcomes are often measured in years, decades, or lifetimes; it is very unethical/basically impossible to control every aspect of a person’s nutrition from birth to death so we’re stuck trying to suss out the details from small correlations in hundreds of observational studies; and as with any science it has to be repeated again and again.
Here’s what happens on the science side:
1. nutrition scientists make some mechanistic speculation “since they’re high in cholesterol maybe eggs have a negative effect on our blood cholesterol”
2. they spend months, years, or decades organizing studies to confirm or deny the hypothesis
3. other scientists read the published results and attempt to replicate them or hypothesize about factors the original studies may have missed “maybe saturated fat is a confounding factor”
4. after many many many studies have been done groups like the American Heart Association or Harvard Health may make a recommendation to the general public “dietary cholesterol seems to be fine but the preponderance of evidence suggests saturated fat intake is linked to poor outcomes, so limit your saturated fat intake
The problem arises from the way the media reports on this science. See those four very slow steps listed above? Well after step 2 happens, before step 3, journalists grab the conclusion from one of these studies and turn it into an attention grabbing headline
“EGGS ARE KILLING YOU”
“EGGS ARE GREAT FOR YOU”
“CHOCOLATE THE SECRET TO LONGER LIFE”
“RED WINE IS GOOD, NO BAD, NO GOOD AGAIN”
It’s a complicated relationship with two main factors.
1. Genetics, for some people dietary cholesterol does have more of an impact on blood cholesterol.
2. Dietary cholesterol impact on blood cholesterol levels out. So for most westerners, and many studies, going from high to very high levels of cholesterol doesn’t impact blood cholesterol. But there may be a stronger relationship if you are talking about low levels of cholesterol.
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