Eggs are again linked to heart problems — though the study has problems

Though eggs are back on the menu, some are trying to rewrite the script.

egg red background
Photo by REVOLT on Unsplash
  • A new study at Northwestern University found a link between egg consumption and cardiovascular disease and all-cause mortality.
  • The research relied on self-reporting at the beginning of observation, with no follow-up reporting.
  • Correlation is likely, not causation, as larger studies have found the opposite to be true.

Here we go again.

Few foods have taken a beating like eggs. From the world's "perfect food" to leading one down a certain path to a heart attack, eggs have somehow become as polarizing as politics.

In 2017, Harvard suggested that an egg a day shows no increase in your risk of a heart attack, stroke, or any other type of cardiovascular disease. This is not without caveats: three a week is probably the upper level for those suffering from diabetes; cutting down consumption if you've already experienced a heart attack (or if you smoke) is wise.

Based on similar research, the U.S. government removed limits related to egg consumption on its dietary guidelines. Dietary cholesterol seemed not to be the devil many assumed. Eggs were back on the plate. Faux egg concoctions dwindled. Yolk advocates reclaimed their trophy as more (but not all) restaurants dropped egg white omelettes from their menus.

Now a new study, conducted by researchers at Northwestern University's Department of Preventive Medicine — it was published this month in the medical journal JAMA — claims that high consumption of dietary cholesterol (or eggs) increases your risk of both cardiovascular diseases (CVD) and all-cause mortality.

Are eggs good for you?

Data collection for this paper covered 29,165 participants over 31 years — each participant was followed for an average of 17.5 years. A total of 5,400 CVDs were logged. Specifically: 2,088 coronary artery problems, 1,897 heart failures, 1,302 strokes, and 113 deaths from CVDs. The total number of deaths (all-cause mortality) during this period was 6,132.

The researchers were backtracking to discover participant diets; food logs were not kept. The study is based on self-reporting, which was conducted only at the beginning of the research. Thus, two serious problems: self-reporting without regular tracking can vary widely; their diets might have changed dramatically over the course of 17-plus years. If you claim you eat two eggs a day, then a year later drop eggs altogether, this was not taken into account.

The group's results were derived from tracking 300 mg increases in daily cholesterol intake. (One large egg has 186 mg, all of which are in the yolk.) For every 300 mg added, a 3.24 percent increase in the chance of suffering from CVD and 4.43 percent increase in dying from anything was observed.

To break this down to round numbers, associate professor Norrina Allen, who participated in the study, notes that consuming two eggs per day increases your likelihood of developing heart disease by 27 percent. She also says that the study, being observational, does not include other factors that could play a role in developing CVD, though the team did factor in age, sex, ethnicity, smoking and drinking habits, and exercise levels — again, all self-reported.

When Bruce Y. Lee was a member of the National Academies of Science, Medicine, and Engineering in 2017, he served on a committee that recommended a multi-factor approach to better understand the relationship between diet and health. As an analogy, he writes that during a rocket launch, engineers take into consideration more than one or two weather factors when determining whether or not to conduct the mission.

Turkish men show unsold eggs at Rami Dried Food and Vegetable Market in Istanbul. Photo credit: Ali Ozuler / AFP / Getty Images

This is a constant problem with health studies. For example, Gary Taubes noted that research decrying the macronutrient, fat, never considered the amount of carbohydrates participants were eating, which seriously skewed the results. Fans of ketogenic diets use the same argument to defend their dietary approach.

Lee says that a holistic mindset should be applied with all nutritional research, noting the eggs are excellent sources of "protein, vitamin D, choline, lutein, and zeaxanthin." Focusing exclusively on cholesterol levels while negating the benefits might steer people away from a food that could prove beneficial.

Lee also takes note of a study involving half-million Chinese adults, which showed moderate egg consumption is "significantly associated with lower risk of CVD, largely independent of other risk factors."

Which is all to say that moderation, as with everything, is key. Will an egg a day keep the doctor away? Perhaps. Should you be careful if you suffer from problems such as hypercholesterolemia (genetic high cholesterol)? Absolutely. But does this imply that everyone needs to avoid eggs? Highly doubtful.

Fourteen eggs a week might simply be overkill, especially since you can get the micronutrients elsewhere. Skipping them altogether doesn't appear to be the right move either. Until more isolated research, involving actual dietary tracking and not self-reporting, takes place, headlines about the dangers of eggs need to be taken with a grain — okay, a pinch — of salt.

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COVID and "gain of function" research: should we create monsters to prevent them?

Gain-of-function mutation research may help predict the next pandemic — or, critics argue, cause one.

Credit: Guillermo Legaria via Getty Images
Coronavirus

This article was originally published on our sister site, Freethink.

"I was intrigued," says Ron Fouchier, in his rich, Dutch-accented English, "in how little things could kill large animals and humans."

It's late evening in Rotterdam as darkness slowly drapes our Skype conversation.

This fascination led the silver-haired virologist to venture into controversial gain-of-function mutation research — work by scientists that adds abilities to pathogens, including experiments that focus on SARS and MERS, the coronavirus cousins of the COVID-19 agent.

If we are to avoid another influenza pandemic, we will need to understand the kinds of flu viruses that could cause it. Gain-of-function mutation research can help us with that, says Fouchier, by telling us what kind of mutations might allow a virus to jump across species or evolve into more virulent strains. It could help us prepare and, in doing so, save lives.

Many of his scientific peers, however, disagree; they say his experiments are not worth the risks they pose to society.

A virus and a firestorm

The Dutch virologist, based at Erasmus Medical Center in Rotterdam, caused a firestorm of controversy about a decade ago, when he and Yoshihiro Kawaoka at the University of Wisconsin-Madison announced that they had successfully mutated H5N1, a strain of bird flu, to pass through the air between ferrets, in two separate experiments. Ferrets are considered the best flu models because their respiratory systems react to the flu much like humans.

The mutations that gave the virus its ability to be airborne transmissible are gain-of-function (GOF) mutations. GOF research is when scientists purposefully cause mutations that give viruses new abilities in an attempt to better understand the pathogen. In Fouchier's experiments, they wanted to see if it could be made airborne transmissible so that they could catch potentially dangerous strains early and develop new treatments and vaccines ahead of time.

The problem is: their mutated H5N1 could also cause a pandemic if it ever left the lab. In Science magazine, Fouchier himself called it "probably one of the most dangerous viruses you can make."

Just three special traits

Recreated 1918 influenza virionsCredit: Cynthia Goldsmith / CDC / Dr. Terrence Tumpey / Public domain via Wikipedia

For H5N1, Fouchier identified five mutations that could cause three special traits needed to trigger an avian flu to become airborne in mammals. Those traits are (1) the ability to attach to cells of the throat and nose, (2) the ability to survive the colder temperatures found in those places, and (3) the ability to survive in adverse environments.

A minimum of three mutations may be all that's needed for a virus in the wild to make the leap through the air in mammals. If it does, it could spread. Fast.

Fouchier calculates the odds of this happening to be fairly low, for any given virus. Each mutation has the potential to cripple the virus on its own. They need to be perfectly aligned for the flu to jump. But these mutations can — and do — happen.

"In 2013, a new virus popped up in China," says Fouchier. "H7N9."

H7N9 is another kind of avian flu, like H5N1. The CDC considers it the most likely flu strain to cause a pandemic. In the human outbreaks that occurred between 2013 and 2015, it killed a staggering 39% of known cases; if H7N9 were to have all five of the gain-of-function mutations Fouchier had identified in his work with H5N1, it could make COVID-19 look like a kitten in comparison.

H7N9 had three of those mutations in 2013.

Gain-of-function mutation: creating our fears to (possibly) prevent them

Flu viruses are basically eight pieces of RNA wrapped up in a ball. To create the gain-of-function mutations, the research used a DNA template for each piece, called a plasmid. Making a single mutation in the plasmid is easy, Fouchier says, and it's commonly done in genetics labs.

If you insert all eight plasmids into a mammalian cell, they hijack the cell's machinery to create flu virus RNA.

"Now you can start to assemble a new virus particle in that cell," Fouchier says.

One infected cell is enough to grow many new virus particles — from one to a thousand to a million; viruses are replication machines. And because they mutate so readily during their replication, the new viruses have to be checked to make sure it only has the mutations the lab caused.

The virus then goes into the ferrets, passing through them to generate new viruses until, on the 10th generation, it infected ferrets through the air. By analyzing the virus's genes in each generation, they can figure out what exact five mutations lead to H5N1 bird flu being airborne between ferrets.

And, potentially, people.

"This work should never have been done"

The potential for the modified H5N1 strain to cause a human pandemic if it ever slipped out of containment has sparked sharp criticism and no shortage of controversy. Rutgers molecular biologist Richard Ebright summed up the far end of the opposition when he told Science that the research "should never have been done."

"When I first heard about the experiments that make highly pathogenic avian influenza transmissible," says Philip Dormitzer, vice president and chief scientific officer of viral vaccines at Pfizer, "I was interested in the science but concerned about the risks of both the viruses themselves and of the consequences of the reaction to the experiments."

In 2014, in response to researchers' fears and some lab incidents, the federal government imposed a moratorium on all GOF research, freezing the work.

Some scientists believe gain-of-function mutation experiments could be extremely valuable in understanding the potential risks we face from wild influenza strains, but only if they are done right. Dormitzer says that a careful and thoughtful examination of the issue could lead to processes that make gain-of-function mutation research with viruses safer.

But in the meantime, the moratorium stifled some research into influenzas — and coronaviruses.

The National Academy of Science whipped up some new guidelines, and in December of 2017, the call went out: GOF studies could apply to be funded again. A panel formed by Health and Human Services (HHS) would review applications and make the decision of which studies to fund.

As of right now, only Kawaoka and Fouchier's studies have been approved, getting the green light last winter. They are resuming where they left off.

Pandora's locks: how to contain gain-of-function flu

Here's the thing: the work is indeed potentially dangerous. But there are layers upon layers of safety measures at both Fouchier's and Kawaoka's labs.

"You really need to think about it like an onion," says Rebecca Moritz of the University of Wisconsin-Madison. Moritz is the select agent responsible for Kawaoka's lab. Her job is to ensure that all safety standards are met and that protocols are created and drilled; basically, she's there to prevent viruses from escaping. And this virus has some extra-special considerations.

The specific H5N1 strain Kawaoka's lab uses is on a list called the Federal Select Agent Program. Pathogens on this list need to meet special safety considerations. The GOF experiments have even more stringent guidelines because the research is deemed "dual-use research of concern."

There was debate over whether Fouchier and Kawaoka's work should even be published.

"Dual-use research of concern is legitimate research that could potentially be used for nefarious purposes," Moritz says. At one time, there was debate over whether Fouchier and Kawaoka's work should even be published.

While the insights they found would help scientists, they could also be used to create bioweapons. The papers had to pass through a review by the U.S. National Science Board for Biosecurity, but they were eventually published.

Intentional biowarfare and terrorism aside, the gain-of-function mutation flu must be contained even from accidents. At Wisconsin, that begins with the building itself. The labs are specially designed to be able to contain pathogens (BSL-3 agricultural, for you Inside Baseball types).

They are essentially an airtight cement bunker, negatively pressurized so that air will only flow into the lab in case of any breach — keeping the viruses pushed in. And all air in and out of the lap passes through multiple HEPA filters.

Inside the lab, researchers wear special protective equipment, including respirators. Anyone coming or going into the lab must go through an intricate dance involving stripping and putting on various articles of clothing and passing through showers and decontamination.

And the most dangerous parts of the experiment are performed inside primary containment. For example, a biocontainment cabinet, which acts like an extra high-security box, inside the already highly-secure lab (kind of like the radiation glove box Homer Simpson is working in during the opening credits).

"Many people behind the institution are working to make sure this research can be done safely and securely." — REBECCA MORITZ

The Federal Select Agent program can come and inspect you at any time with no warning, Moritz says. At the bare minimum, the whole thing gets shaken down every three years.

There are numerous potential dangers — a vial of virus gets dropped; a needle prick; a ferret bite — but Moritz is confident that the safety measures and guidelines will prevent any catastrophe.

"The institution and many people behind the institution are working to make sure this research can be done safely and securely," Moritz says.

No human harm has come of the work yet, but the potential for it is real.

"Nature will continue to do this"

They were dead on the beaches.

In the spring of 2014, another type of bird flu, H10N7, swept through the harbor seal population of northern Europe. Starting in Sweden, the virus moved south and west, across Denmark, Germany, and the Netherlands. It is estimated that 10% of the entire seal population was killed.

The virus's evolution could be tracked through time and space, Fouchier says, as it progressed down the coast. Natural selection pushed through gain-of-function mutations in the seals, similarly to how H5N1 evolved to better jump between ferrets in his lab — his lab which, at the time, was shuttered.

"We did our work in the lab," Fouchier says, with a high level of safety and security. "But the same thing was happening on the beach here in the Netherlands. And so you can tell me to stop doing this research, but nature will continue to do this day in, day out."

Critics argue that the knowledge gained from the experiments is either non-existent or not worth the risk; Fouchier argues that GOF experiments are the only way to learn crucial information on what makes a flu virus a pandemic candidate.

"If these three traits could be caused by hundreds of combinations of five mutations, then that increases the risk of these things happening in nature immensely," Fouchier says.

"With something as crucial as flu, we need to investigate everything that we can," Fouchier says, hoping to find "a new Achilles' heel of the flu that we can use to stop the impact of it."

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Sex & Relationships
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