The Skeptical Cardiologist

Are Pasture-Raised Hen Eggs More Heart Healthy Than Conventional Eggs

Eggs (and dietary cholesterol) should no longer be restricted in a heart-healthy diet as the skeptical cardiologist has pointed out here.
But if we’re eating eggs should they come from “pasture-raised” (or grass-fed or pastured) hens?
The arguments for choosing hens that can roam freely and eat bugs, clover, and grass from the ground beneath them are of four types:
1. Ethical. The vast majority of eggs come from hens that are kept in a small cage most of their life and are never allowed to see the light of day or engage in their normal activities. This is inhumane.
2. Esthetic. Eggs from pasture-raised hens (PRH) taste better.
3. Health. PRH eggs are more nutritious because of the better food ingested by PRH and the manner in which they live and are treated.
4. Environmental. PRH operations are more sustainable and contribute less toxins and antibiotics to the environment.

Ethical Arguments

PETA gives a horrific description of what factory farm hens endure here. Here’s an excerpt:

“hens are shoved into tiny wire “battery” cages, which measure roughly 18 by 20 inches and hold up to 10 hens, each of whom has a wingspan of 32 inches. Even in the best-case scenario, each hen will spend the rest of her life crowded in a space about the size of a file drawer with four other hens, unable to lift even a single wing.
The birds are crammed so closely together that these normally clean animals are forced to urinate and defecate on one another. The stench of ammonia and feces hangs heavy in the air, and disease runs rampant in the filthy, cramped sheds. Many birds die, and survivors are often forced to live with their dead and dying cagemates, who are sometimes left to rot.”

PETA and vegans advocate not eating any animals or animal products. They have an inherent bias against omnivorous diets and their interpretation of the nutritional science always reflects that.
I sympathize with the plight of factory farms hens, but it is very difficult to martial scientific arguments in the area of the ethical treatment of animals.

 Nutritional Differences

A brief Google search yields dozens of websites which proclaim that PRH eggs are far more nutritious and better for you than conventional eggs. When a source for this claim is listed it comes from one of two studies:
1. Mother Earth News (Oct/Nov 2007). Mother Earth News is not known for its scientific rigor, but they did publish an analysis of the nutritional content of eggs from 14 farms with PRH and compared it to what the USDA had published for the nutritional content of conventional eggs.
Let me just say that this “study” would never be published in a reputable scientific journal due to flaws in the study design. For one thing, the PRH eggs should have been compared to conventional eggs analyzed at the same time in the same way in a blinded fashion. Also, there is no statistical analysis of the data.
Here is how Mother Earth News summarizes their findings:
These amazing results come from 14 flocks around the country that range freely on pasture or are housed in moveable pens that are rotated frequently to maximize access to fresh pasture and protect the birds from predators. We had six eggs from each of the 14 pastured flocks tested by an accredited laboratory in Portland, Oregon.
PRH eggs compared to the conventional eggs had
• 1/3 less cholesterol
• 1/4 less saturated fat
• 2/3 more vitamin A
• 2 times more omega-3 fatty acids
• 3 times more vitamin E
• 7 times more beta carotene
You can see the data in this PDF (PRH eggs versus conventional nutrients.)
Eggs were vilified during the heyday of the anti-fat movement because of their cholesterol and saturated fat content. We now know that neither one of these macronutrients causes heart disease; so the fact that PRH eggs have less of them is irrelevant. In addition, no other study has replicated the findings with respect to cholesterol and saturated fat content.
The higher levels of Vitamin A, Vitamin E and beta-carotene make sense given the differing food intake of PRH compared to factory hens, but again, there is nothing to suggest Americans aren’t consuming plenty of these vitamins in other foods. In addition, studies looking at supplementing diet with Vitamin E and beta-carotene have shown no overall health or cardiovascular benefits.
2.2010 paper by Karsten, et al. in Renewable Agriculture ad Food Systems.
This study is a legitimate peer-reviewed scientific study published in a reputable scientific journal by researchers who did not have any obvious bias or conflict of interest.. Bias can run both ways in these types of studies, as any research supported by the conventional egg industry would receive pressure to find no difference between conventional and PRH eggs. However, studies funded by advocates of PRH eggs would be hoping to find significant benefits of their eggs.
The 2010 study  found:
“Compared to eggs of the caged hens, pastured hens’ eggs had twice as much vitamin E and long-chain omega-3 fats, 2.5-fold more total omega-3 fatty acids, and less than half the ratio of omega-6:omega-3 fatty acids (P<0.0001).”
Of the nutrient differences reported between PRH and conventional eggs the omega-3 differences are the most intriguing. Both of these studies found a doubling of omega-3 fatty acids in PRH eggs, which are generally considered the healthiest of all fatty acids. The second study found a lower ratio  of omega-6:omega-3 in the PRH eggs. The relative benefits of omega-6 and omega-3 fatty acids in the diet is a topic of considerable controversy in the scientific literature right now but, in general, recommended diets like the Mediterranean feature higher omega-3 to omega-6 ratios than standard Western diets.
There are no studies looking at the differing effects of consuming PRH versus conventional eggs on biomarkers or outcomes in humans.
Thus, we have no idea whether the overall package of nutrients delivered in the PRH eggs would improve blood pressure, cholesterol parameters or markers of inflammation or whether they could lower your risk of heart attack or stroke.


I have been eating PRH eggs whenever possible for the last few years and I swear they taste better than conventional eggs. In preparation for this post, I had decided that a blinded tasting of eggs would be needed to support my totally subjective assessment of PRH egg superiority.

However, it turns out that several blinded tasting egg comparison have already been done and the results are quite shocking to me.

The Food Lab at Serious Eats (which, by the way is dedicated to “unraveling the mysteries of home cooking through science”)  had 8 tasters  taste scrambled eggs prepared from PRH eggs, conventional hen eggs and various omega-3 supplemented eggs

One half of the tasters found no difference in taste between the various kinds of eggs, but those who did favor an egg favored the PRH eggs and the higher omega-3 eggs. The yolks of the PRH eggs and omega-3 eggs were more on the “intensely orange” end of the spectrum.

Did the more orange yolks taste better or were the tasters biased by the more intense color?

The tasting was repeated, this time with the color of the eggs masked by adding green food coloring. In this color-blind tasting:

“most people could not taste any difference in the eggs. Those who did taste a difference picked a totally different batch of eggs—this time, there was no clear winner, and no discernible trends based on how the eggs were produced or levels of omega-3’s”

A food writer for the Washington Post did a similar taste test, this time with actual blind folds, and although she was convinced that the eggs from her backyard hens would be superior, a panel of six tasters could find no difference between hers, conventional eggs, and organic eggs.

Although these taste tests haven’t been published in peer-reviewed scientific journals, they are likely as close as we are going to get to the truth. The fact that the organizers of the tests were biased towards PRH eggs tasting better but found no difference means almost certainly, alas, that there is no taste superiority for PRH eggs.

Are PRH Eggs Worth The Extra Cost?

Ultimately, this is a question for each individual. True PRH eggs cost upwards of 5 dollars per dozen compared to around 2$ per dozen (prior to the recent avian flu outbreak).

It is hard to justify that cost based on nutritional, health or taste considerations as I’ve shown.

Chelsea Pearson, communing with her hens

My oldest  daughter, Chelsea Pearson, has, along with thousands of other city dwellers, begun raising chickens in her backyard.  In addition to collecting delicious eggs from the hens, she has become attached to them and finds them to be interesting and enjoyable pets.

After weighing the ethical and environmental concerns despite the absence of conclusive health benefits or taste superiority I have elected to continue paying a premium for PRH eggs.

I have the financial resources to justify this decision but for those without such resources I totally  understand a decision to eat conventional eggs.

Eggstatically Yours,


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