Are Egg Yolks Good or Bad?
February 29, 2016
Story at-a-glance
−
-
Egg yolks provide valuable vitamins (A, D, E and K),
omega-3 fats and antioxidants, much of which is not
found in egg whites
-
The cholesterol in egg yolks is not associated with high
blood cholesterol levels or heart disease
-
The yolk is arguably the healthiest part of the egg and
should be consumed lightly cooked or raw (provided it’s
free-range and organic)
By Dr. Mercola
Egg white omelets and other yolk-free recipes have become
synonymous with “healthy” to many. But if you toss out your egg
yolks, you’re also tossing out some of the most nutritious parts of
the egg.
For instance, egg yolks (but not whites) contain vitamins A, D, E
and K along with
omega-3 fats. Compared to the whites, egg yolks also contain
more beneficial folate and vitamin B12. The yolks also contain far
more of the nutrient choline than the whites, and all of
the antioxidants lutein and zeaxanthin.
Egg yolks have been unfairly vilified for decades because they
contain cholesterol and saturated fat. But contrary to the
prevailing nutritional dogma that such dietary components need to be
avoided, the cholesterol and saturated fat in animal foods like egg
yolks are quite beneficial for your health.
Cholesterol-Rich Foods Tend to Be Among the Best for Your Health
Many of the healthiest foods happen to be rich in cholesterol (and
saturated fats). Cholesterol has been demonized since the early
1950s, following the popularization of
Ancel Keys, Ph.D.'s flawed research.
But cholesterol has many health benefits. It plays a key role in
regulating protein pathways involved in cell signaling and may also
regulate other cellular processes,1
for instance.
It's already known that cholesterol plays a critical role within
your cell membranes, but research suggests cholesterol also
interacts with proteins inside your cells, adding even more
importance. Your body is composed of trillions of cells that need to
interact with each other.
Cholesterol is one of the molecules that allow for these
interactions to take place. For example, cholesterol is the
precursor to bile acids, so without sufficient amounts of
cholesterol, your digestive system can be adversely affected.
It also plays an essential role in your brain, which contains
about 25 percent of the cholesterol in your body. It is critical for
synapse formation, i.e. the connections between your neurons, which
allow you to think, learn new things, and form memories.
Eating Cholesterol-Rich Foods Doesn’t Lead to High Cholesterol
One egg yolk contains about 210 milligrams (mg) of cholesterol,
which is why public health agencies have long suggested Americans
limit their intake.
This is a highly flawed recommendation on multiple levels; for
starters,
“high” cholesterol does not cause heart disease, and beyond
that, eating cholesterol-rich food doesn’t cause your cholesterol
levels to increase.
Cleveland Clinic cardiologist Dr. Steven Nissen estimates that
only 20 percent of your blood cholesterol levels come from your
diet. The rest of the cholesterol in your body is produced by your
liver, which it makes because your body needs cholesterol.
One survey of South Carolina adults found no correlation of blood
cholesterol levels with so-called "bad" dietary habits, such as
consumption of red meat, animal fats, butter, eggs, whole milk,
bacon, sausage, and cheese.2
Consumption of more than six eggs per week also does not increase
your risk of stroke and ischemic stroke, for instance.3
Egg Yolks Have Little to No Impact on Cholesterol Levels for Most
People
Further, eating two eggs a day does not adversely affect
endothelial function (an aggregate measure of cardiac risk) in
healthy adults, supporting the view that dietary cholesterol may be
far less detrimental to cardiovascular health than previously
thought.4
According to Chris Masterjohn, who received his Ph.D. in
nutritional sciences from the University of Connecticut:5
"Since we cannot possibly eat enough cholesterol to use
for our bodies' daily functions, our bodies make their own. When
we eat more foods rich in this compound, our bodies make less.
If we deprive ourselves of foods high in cholesterol —
such as eggs, butter, and liver — our body revs up its
cholesterol synthesis. The end result is that, for most of us,
eating foods high in cholesterol has very little impact on our
blood cholesterol levels.
In seventy percent of the population, foods rich in
cholesterol such as eggs cause only a subtle increase in
cholesterol levels or none at all. In the other thirty percent,
these foods do cause a rise in blood cholesterol levels.
Despite this, research has never established any clear
relationship between the consumption of dietary cholesterol and
the risk for heart disease … Raising cholesterol levels is not
necessarily a bad thing either."
U.S. Dietary Guidelines Remove Dietary Cholesterol Limit
If you’re still worried about the cholesterol in egg
yolks, take a look at the newly released 2015 U.S. Dietary
Guidelines. As recently as 2010, U.S. dietary guidelines described
cholesterol-rich foods as “foods and food components to reduce.”6
They advised people to eat less than 300 milligrams (mg) per day,
despite mounting evidence that dietary cholesterol has very little
to do with
cholesterol levels in your body.
The latest guidelines have finally removed this misguided
suggestion, and they even added egg yolks to the list of suggested
sources of protein. Dietitian Lisa Drayer told CNN:7
"If you connect the dots together scientifically, we
don't believe there is a strong influence between dietary
cholesterol and blood cholesterol … So the government advice is
catching up to the science."
The long-overdue change came at the advice of the Dietary
Guidelines Advisory Committee (DGAC), which finally acknowledged
what the science shows, which is that “cholesterol is not considered
a nutrient of concern for overconsumption.”8
Dr. Luc Djoussé, an associate professor at Harvard Medical School
and Brigham and Women’s Hospital, who has conducted research on
heart disease and eggs, further told TIME, “Dietary cholesterol does
not translate into high levels of blood cholesterol.”9
More Research Shows Eating Eggs Doesn’t Raise Heart Risks
According to a new study published in the American Journal of
Clinical Nutrition, even carriers of the ApoE4 gene, which makes
them highly susceptible to heart disease, egg and cholesterol intake
was not associated with an increased risk of coronary
artery disease.10
The men in the study consumed an average of 2,800 mg of
cholesterol a week via their diets, more than 25 percent of which
came from eating an average of four eggs a week. No association was
found between the consumption of cholesterol or eggs and heart
disease, either in ApoE4 carriers or non-carriers.
Carotid artery thickness, which is a measure of atherosclerosis,
was also not associated with cholesterol consumption.11
Jyrki K. Virtanen, Ph.D. an adjunct professor of epidemiology at the
University of Eastern Finland and the study’s lead author, told The
New York Times:12
“Moderate intake of cholesterol … doesn’t seem to
increase the risk of heart disease, even among those people at
higher risk.”
On the contrary, separate research found dietary cholesterol from
eggs led to increases in beneficial HDL (high-density lipoprotein)
cholesterol.13
This is the "good" cholesterol that helps keep cholesterol away
from your arteries and remove any excess from arterial plaque, which
may help to prevent heart disease.
Superstar Nutrients Are Plentiful in Egg Yolks
When you eat egg yolks, you’re providing your body with valuable
nutrients, including the following:
Choline
Choline is a B vitamin known for its role in brain
development. It’s a precursor to the neurotransmitter
acetylcholine, which plays a role in both muscle control and
memory. Choline is also important for the health of your cell
membranes and has anti-inflammatory properties.
An estimated 90 percent of the U.S. population may be
deficient in choline.14
Some of the symptoms associated with low levels include memory
problems, lethargy and persistent brain fog. Your body can only
synthesize small amounts of this nutrient, so you need to get it
from your diet. One egg yolk contains nearly 215 mg of choline.
Lutein and Zeaxanthin
Lutein and zeaxanthin are carotenoids. Zeaxanthin is an
antioxidant carotenoid found in your retina, but it cannot be
made by your body, so you must get it from your diet. Lutein is
found in your macular pigment, which helps protect your central
vision and aids in blue light absorption.
Both zeaxanthin and lutein are also found in high
concentrations in your macula lutea, the small central part of
your retina responsible for detailed central vision.15
Together, they're believed to serve two primary roles that are
particularly valuable for your vision health:
- To absorb excess photon energy
- Quench free-radicals before they damage your lipid
membranes
While there's no recommended daily intake for lutein and
zeaxanthin, studies have found health benefits for lutein at a
dose of 10 mg per day, and at 2 mg/day for zeaxanthin. One egg
yolk contains about 0.2 mg of lutein and zeaxanthin.
Egg yolks are also an excellent source of healthy fat and
protein, while providing you with vitamins that many Americans are
lacking. According to Masterjohn, eating egg yolks may even be an
ideal way to resolve common
nutrient deficiencies, including vitamins A, E and B6, copper,
calcium and folate.16
What’s the Best Way to Prepare Eggs?
Eggs are so good for you that you can easily eat one dozen eggs
per week, which is actually a simple and cost-effective way to add
valuable nutrition to your diet — provided you cook them properly
or, more aptly, don’t cook them.
The best way to consume eggs, provided they come from a
high-quality source, is to not cook them at all, which is why my
advanced nutrition plan recommends eating your eggs raw. In the
beginner plan, however, eggs are still included, and you can
prepare them anyway you like them. Less "well done" eggs are vastly
preferable, such as poached, soft-boiled, or over-easy with very
runny yolks.
It’s important to consume egg yolks that are only lightly cooked,
as the heat will damage many of the highly perishable nutrients in
the yolk. Two raw egg yolks have antioxidant properties equivalent
to half a serving of cranberries (25 grams) and almost twice as many
as an apple. But the antioxidant properties are reduced by about 50
percent when the eggs are fried or boiled, and reduced even more if
they're microwaved.17
Additionally, the cholesterol in the yolk can be oxidized with
high temperatures, especially when it is in contact with the iron
present in the whites and cooked, as in scrambled eggs, and such
oxidation contributes to chronic inflammation in your body. For this
reason, scrambled eggs are one of the worst ways to prepare
eggs if you want them to be healthy.
Organic and Free-Range: Choose Your Eggs Wisely
Even before you master how to cook your eggs properly, it’s
important to choose eggs from a high-quality source.
Free-range or "pastured" organic eggs are far superior when it
comes to nutrient content, while conventionally raised eggs are far
more likely to be contaminated with disease-causing bacteria such as
salmonella.
An egg is considered organic if the chicken was only fed organic
food, which means it will not have accumulated high levels of
pesticides from the grains (mostly GM corn) fed to typical chickens.
Ideally, the chicken should have access to the outdoors where it can
consume its natural diet.
Testing has confirmed that true free-range eggs are far more
nutritious than commercially raised eggs, likely due to the
differences in diet between free-ranging, pastured hens and
commercially farmed hens. In one egg-testing project, Mother Earth
News compared the official U.S. Department of Agriculture (USDA)
nutrient data for commercial eggs with eggs from hens raised on
pasture and found that the latter typically contains:18
- 2 to 3 times more vitamin A
- 2 times more omega-3 fatty acids
- 3 times more vitamin E
- 7 times more beta-carotene
If you're purchasing your eggs from a supermarket, be aware that
labels can be very deceptive. The definitions of "free-range" are
such that the commercial egg industry can run industrial farm
egg-laying facilities and still call them "free-range"
eggs, despite the fact that the birds' foraging conditions are far
from what you'd call natural.
The Highest-Quality Egg Yolks Are Bright Orange, Not Yellow
The key to finding truly free-range, pastured eggs is to buy your
eggs locally. This is typically even preferable to organic eggs from
the grocery store. If you live in an urban area, visiting the local
health food stores is typically the quickest route to finding the
high-quality local egg sources.
You can tell your eggs are free range or pastured by the color of
the egg yolk. Foraged hens produce eggs with bright orange yolks.
Dull, pale yellow yolks are a sure sign you're getting eggs form
caged hens that are not allowed to forage for their natural diet. So
in answer to the question, “Are
egg yolks good or bad?” —the answer is a resounding good.
© Copyright 1997-2016 Dr. Joseph Mercola. All Rights Reserved.
http://articles.mercola.com/sites/articles/archive/2016/02/29/egg-yolk-benefits.aspx
|