Humans have probably eaten eggs for as long as humans have been humans.
When records of egg consumption began in 1945, people in the United States ate, on average, around one egg every day.
But, about 50 years ago, there was a sharp drop in egg consumption. This was due to a fear that eggs might increase cardiovascular risk. This fear suppressed sales for decades.
Now, after years in the doghouse, eggs are making a welcome comeback.
In the U.S., consumption has increased by 15% in the last 20 years, with a similar uptick in the United Kingdom.
In this feature, we’ll ride the egg consumption rollercoaster. It’s a tale of scientific fisticuffs, the dogged persistence of industry, and an achingly slow shift in official guidelines.
The wonder of eggs
The humble chicken egg is a nutritional powerhouse — and we don’t say that lightly. It contains a wide range of micronutrients, including all essential trace elements.
Beyond their abundant nutrients, eggs are versatile, have a long shelf life, and tend to be widely available at a relatively low cost. What’s not to love?
As scientists continue to study this humble foodstuff, they’re finding clues that eggs might contain useful antimicrobial, antioxidant, and anti-inflammatory compounds.
Despite eggs’ impressive list of attributes, they’ve had a rough ride. Below, we’ll find out why.
The fall from grace
Throughout human history, eggs have provided much-needed calories and nutrients. But as scientists learned more about nutrition and health, the mood began to change.
And in 1968, the American Heart Association (AHA) decreed that people should eat at most three eggs per week.
At the time, this decision made sense: High blood cholesterol levels are associated with heart disease, and eggs contain a good dose of cholesterol.
So, experts assumed that cutting down on your egg count would reduce your cholesterol intake and, therefore, reduce your heart disease risk.
We now know that’s not the case — and we’ll get to it later — but the advice seemed sensible and was easy to follow. So, people in the U.S. stopped eating as many eggs.
Although this feature mostly focuses on the U.S., European countries put similar egg guidelines in place at around the same time.
The status quo
Why did scientists think consuming high-cholesterol foods was bad? Broadly, the evidence came in three flavors.
First, animal studies showed that high-cholesterol diets increased blood cholesterol levels leading to atherosclerosis: a buildup of a fatty substance on the walls of arteries.
Second, scientists found evidence that, on a population level, people who consumed high-cholesterol diets had higher rates of cardiovascular disease.
And third, clinical studies showed that eating cholesterol increased cholesterol levels in the blood.
These three strands combined make a compelling case.
So, cholesterol entered the public consciousness as the latest nutritional baddy, and stores stocked up on products boasting “low cholesterol” or “no cholesterol.”
However, the devil is in the detail, as we’ll see shortly.
The backlash from ‘Big Egg’
Eggs are a big business, and there’s nothing big businesses like less than losing money. So, egg producers decided to fight science with science — Big Egg started publishing research papers.
Eventually, they formed the Egg Nutrition Center, with a mission to “support America’s egg farmers and increase demand for eggs and egg products.”
The low-fat, low-cholesterol approach to reducing heart disease was widely accepted in scientific circles, although the data were controversial. And even at the time, not everyone agreed.
Now, Big Egg needed to dive into the controversy and attempt to disprove it.
The razor of scrutiny
So, what about the three lines of evidence we mentioned earlier? Although they seem watertight, none stood up to scrutiny.
For instance, some cholesterol studies in animals were carried out in herbivores, which are particularly sensitive to dietary cholesterol, compared with omnivores like humans.
And when scientists did use more suitable animals, they often gave them much larger quantities of cholesterol than a human would eat in the real world.
As for the population-level research, the original studies did find convincing correlations between high levels of dietary cholesterol and heart disease. But correlation doesn’t equal causation.
And when scientists conducted similar, more detailed analyses that accounted for a broader range of factors, they found that dietary cholesterol wasn’t the culprit.
This points to a key challenge when looking at single foods in large-scale trials: People don’t just eat one food or compound in isolation — the foods in question are part of a whole dietary pattern.
In this case, because cholesterol primarily comes from animal products, people who consume a lot of cholesterol often also consume a lot of meat and dairy.
And people who eat higher levels of animal products, in general, eat fewer plant-based foods, which itself increases cardiovascular risks.
And finally, we get to the egg studies in humans. These had issues, too: They often used unrealistic quantities of cholesterol. For instance, one study had participants eat six eggs per day for 6 weeks.
Also, the scientists in these early studies focused on total blood cholesterol levels. We now know that it’s not the total amount that matters for your health.
Instead, it’s the levels of “good” and “bad” cholesterol and the ratio between them.
Systematically, the egg industry published studies that decisively cleared eggs’ (and dietary cholesterol’s) bad name.
Today we know that, at regular intakes, dietary cholesterol has little influence over levels of cholesterol in your blood.
Surely the powers that be would change their recommendations under the weight of this new evidence. Wouldn’t they?
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The brick wall of dogma
By 1995, the major sources of health recommendations in the U.S., including the AHA and the Dietary Guidelines for Americans, all agreed: You shouldn’t consume more than 300 milligrams of cholesterol per day.
And because one large egg has more than 186 mg, they suggested that people eat no more than three eggs a week.
Once a figure becomes enshrined in this way — despite it being a fairly arbitrary figure — it’s very difficult to get it changed.
Although the weight of scientific evidence was swinging in eggs’ favor, they were still stuck on the naughty step.
Big Egg needed to rethink.
The ‘do no harm’ approach
Egg producers realized that just showing that eggs weren’t harmful wasn’t enough. So, they switched gears. They set out to show that restricting egg intake was causing harm.
In doing so, they used a multi-pronged attack. These were some of their main arguments:
High nutritional value
Eggs contain a wide range of key nutrients. Also, they’re relatively cheap, widely available, and versatile. By convincing people to eat fewer eggs, the current dietary recommendations were hitting people with lower incomes the hardest.
Egg promoters published research showing that people who consumed eggs took in more nutrients than those who didn’t.
They fill you up
The egg industry published studies showing that eggs could keep you fuller for longer.
And they argued that replacing the once-common breakfast egg with high-carb, nutrient-light breakfast cereals was damaging.
Essentially, they argued that cutting out eggs would be more likely to cause obesity than reduce the risk.
Older adults and muscle loss
Another line of argument involved older adults, for whom a loss of muscle mass can be an issue. Research has shown that consuming more protein can help limit this loss.
The egg industry suggested that eggs were a good source of protein that was also cheap, easy to chew, and simple to prepare — all important factors for many older adults.
Big Egg carried out research into compounds in eggs called xanthophylls. They argued that these compounds could protect eye health and reduce the risk of certain diseases.
In the early 2000s, only around 1 in 10 people were consuming enough choline, which is an essential nutrient.
And guess what? Eggs are rich in choline. Depriving people of this nutrient could be damaging to their health, egg promoters argued.
The tide slowly turns
The dogged efforts of egg producers started paying off. More and more good quality evidence rolled in showing that eating an average of one egg a day wasn't linked to heart disease in healthy people.
Slowly, minds were changed.
In 2002, the AHA dropped their 2–3 eggs per week recommendation. They no longer singled out eggs at all.
However, they kept the 300 mg of cholesterol per week guideline, while institutions in other parts of the world, including the U.K. and Australia, discarded it.
Over time, researchers demonstrated repeatedly that moderate levels of dietary cholesterol don’t meaningfully increase levels of bad cholesterol in the blood.
And finally, in 2014, the AHA announced that there wasn’t enough evidence “to determine whether lowering dietary cholesterol reduces [’bad’ cholesterol].”
The following year, the Dietary Guidelines for Americans dropped the 300 mg of cholesterol recommendation.
So, after almost half a century, eggs were firmly back on the menu.
So, can I eat six eggs every day?
In conclusion, eggs are cheap and packed full of nutrients. But, as with everything in life, moderation is key.
Eating an average of one egg a day is likely to be good for you, but if you’re cramming in six every day, there may be some risks attached.
Also, if you already have high cholesterol or eat a diet that contains a lot of cholesterol from other sources, it might be best to eat fewer than one egg a day.
And if you have diabetes, speak with your doctor before changing your diet.
Overall, though, eggs are a delicious addition to a well-rounded, diverse diet.
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