How You Store and Cook Your Eggs Matters

How many eggs we should eat, and whether or not we should even eat eggs at all, is a subject of much debate. 


For example: “In conclusion, consumption of eggs may increase risk of developing a lethal form of prostate cancer among healthy men.”  (Source)


Versus: “Our analyses provided no evidence of a significant influence of egg consumption on prostate cancer incidence and mortality.”  (Source)


As I often state, find me a scientific study that says one thing and I’ll find you a study that says the opposite. Thus has science, so often co-opted by industry, become unreliable. One really has to do their own research and temper everything with good old fashioned common sense.


As a brief response to the above conflicting studies, I will point out that a high dietary intake of omega 6 fatty acids is linked to many disease states, including cancer. Commercial chickens are fed a diet high in corn and soybean meal, both of which create an egg high in omega 6’s. (Chicken and pork meats are also high in omega 6, but beef is not, as cattle process their food differently.)


So one solution is to ensure that your diet avoids foods high in omega 6’s (mostly seed oils and processed foods containing these oils), and includes a good amount of omega 3 fatty acids. Also, there are now eggs available that are high in omega 3 due to feeding those chickens a different diet.




Some of this questioning the healthfullness of consuming eggs began with the demonization of cholesterol. This was not long ago revealed to be a ploy by the sugar industry, aided by corrupt scientists from Harvard who were paid to blame cholesterol and saturated fats for heart disease in the 60s, when sugar was actually the culprit. (Source)


Now we are aware that cholesterol is not the demon it was once made out to be, and we know that in fact the body requires cholesterol for the production of the sex hormones and to protect the brain from aging (“The brain contains the highest level of cholesterol in the body; it contains approximately 20% of whole body cholesterol”.) (Source)


Given this undue fear of cholesterol, we were often advised to eat only the egg white if we were going to consume large amounts of eggs as a primary protein source. And while it is true that there is about 3.6 grams of protein in one large egg white, there is again as much in the yolk, so eating the whole egg almost doubles our protein intake. But there is more to it than that. The healthy fats and other nutrients including choline, lutein, zeaxanthin, selenium, and vitamin D, are all found in the yolk but not in the white of the egg.


But wait, there’s more.


Whole Eggs Vs. Egg Whites During Resistance Training


In 2021, a study published in the Journal of Strength and Conditioning Research, concluded that whole eggs were superior to egg whites when used as a post-workout protein load. 


Thirty young men were given either three whole eggs, or six egg whites (providing roughly the same amount of total protein), immediately following resistance training. This carried on at three sessions per week for 12 weeks. At the end of the study the group who ate the whole eggs showed better fitness gains than the egg white group, including a greater change in lean body mass and improvement in strength and testosterone levels.


“Postexercise whole egg ingestion increases knee extension and handgrip strength, testosterone, and reduces body fat percentage compared with postexercise egg white ingestion, despite no group differences in muscle mass, in resistance-trained young males. Whole egg consumption may be preferable during RT programs geared toward the improvement of muscular strength and body fat percentage.”   (Source)


Now let’s have a look at another couple of contentious egg issues. How are they best stored and cooked?


Preserving the Vitamin D Content


Researchers from Newcastle University, in the UK, analysed vitamin D enriched eggs in order to determine how the vitamin D content was affected by cooking and storage methods. They compared eggs stored in a fridge to the equivalent of those left out on the kitchen countertop, along with five different ways of cooking the eggs.


First, I’d like to point out that the researchers opened with, “We know that more than 90% of the British population is not getting enough dietary vitamin D and there is an urgent need to develop foods that will solve this problem”.


Which confirms my continuous promotion of the idea that virtually everyone living in the modern world (with a few exceptions), needs to supplement with vitamin D.


The comment about “developing foods” refers to the eggs they subjected to this study, which were enriched with vitamin D via the hens’ diet. To further ensure the end consumer was gaining the most benefit from these vitamin D rich eggs they studied storage and cooking methods.


Tom Hill, Professor of Nutrition, and lead researcher, provided this conclusion: “We found that if you want to retain more of the vitamin D in your eggs then you are better to keep them out of the fridge at ambient temperature, such as on the kitchen worktop. And when it comes to the cooking method, scramble or poach them is best to retain most of the vitamin.


Just out of general interest, here are the ratios of vitamin D preservation based on each cooking method: Scrambled eggs (109%); Microwaved (109%); Poached (93%); Hard boiled (80%); Fried eggs (78%).   (Source)  (Don’t ask me how you get more than 100%: I am not a scientist. Common sense tells me that 100% should be the maximum, but, whatever.)


How Much Vitamin D is in an Egg?


Most of the protein in an egg is found in the white, and the fat, vitamins, and minerals are found mostly in the yolk. As mentioned at the beginning, vitamin D is also found in the yolk of the egg. So just how much vitamin D can we acquire from an egg?


According to “Healthline”, the yolk from one large commercial egg contains about 37 IU of vitamin D. However, there are a variety of factors that can influence the amount of vitamin D an egg contains.


Sun exposure for the chicken, the vitamin D content of the chicken feed, and exposing liquid yolk to UV light will increase vitamin D in the egg. When given the same feed, pasture-raised chickens that roam outside in the sunlight produce eggs with levels 3–4 times higher.”   (Source)


In the case of the British study referred to above, eggs from The Happy Egg Company were used, whose chickens are fed a vitamin D-fortified feed. 


The enriched diet of the hens at the happy egg co. means they lay eggs with 28% more vitamin D per 100g than regular eggs. This means two large happy eggs gives you more than 94% of the European daily guideline, which is the benchmark for food labelling in the UK.” (i.e. 400 IU daily)


I checked to see if Canada had any similarly fortified eggs and found a company based in Abbotsford, B.C.. 


“Each Vitala Vita D Sunshine egg contains 200 IU of vitamin D — about 5 micrograms — or seven times the amount found in a conventional egg, according to Bill Vanderkooi, owner of Nutriva, the firm that developed the egg and feed formula that produces it, and the parent company of Vitala.”  (Source) Thus, two of these eggs would meet Health Canada’s recommended daily amount of vitamin D (400 IU). Insufficient for optimal health, in my opinion, but pretty good for food intake at one meal. 




Now, back to the idea of storing our eggs on the counter-top, at room temp. Of course this is highly frowned on by the principles of FoodSafe. 


Again according to HealthLine, eggs stored at room temp will start to decline after a few days and need to be used within 1-3 weeks, whereas eggs kept in the fridge will maintain freshness and quality for at least twice that long.


However, the FDA and Health Canada require eggs be stored and transported at a temperature below  45°F (7°C), in order to keep bacteria at a minimum. And therein lies the rub: “Once eggs have been refrigerated, they must be kept refrigerated to prevent condensation from forming on the shell if they warm up. This moisture makes it easier  for bacteria to penetrate the shell.”   (Source)


This principle does not hold true in Europe, evidently because their chickens, unlike chickens in North America, are vaccinated against salmonella, so there is little potential for the eggs to allow this bacteria to grow if they are stored at room temp. (Remember, our study on egg storage was from Europe.)


But there is one exception for us: farm-fresh eggs. If they are not washed after being layed.


You see, commercial eggs undergo a sterilization process, involving being washed in hot water, and being sprayed with a disinfectant, which kills any bacteria on the shell. But, as we all know, not all bacteria are bad (probiotics for example).


Eggs are laid with a natural coating on the shell called the “bloom” or “cuticle”. This coating is the first line of defense in keeping air and bacteria out of the egg. Eggshells are porous, so when you wash them you’re removing that natural barrier.”   (Source)


So, unwashed farm-fresh eggs can sit on the kitchen counter at room temp for a couple of weeks and still be fine and edible, and still loaded with vitamin D. But, if they’ve been washed they should be refrigerated.  


Cooking Methods


Eggs are a good source of cholesterol, which as we have established is an essential nutrient. But for many years I have heard that how eggs are cooked influences the nature of that cholesterol, and how well your body can process it.


When eggs are cooked at high temperatures, the cholesterol in them may become oxidized and produce compounds known as oxysterols. This is a concern for some people, as oxidized cholesterol and oxysterols in the blood have been linked to an increased risk of heart disease.”  (Source)


Other sources of oxidized cholesterol include commercially fried and deep-fried foods, including but not limited to, fried fish, french fries, and chicken.


Now, the recommended healthiest way to cook eggs somewhat flies in the face of the best way to preserve vitamin D. According to our study, scrambled is the best way to cook eggs based on preserving vitamin D. However, from the oxidation point of view, scrambled is the worst since when the yolk is whipped into the white of the egg the cholesterol is more easily oxidized (being more exposed to both air and heat).


Overall, shorter and lower-heat cooking methods cause less cholesterol oxidation and help retain most of the egg’s nutrients.For this reason, poached and boiled (either hard or soft) eggs may be the healthiest to eat.”


I illustrate this principle by asking that one imagine cleaning a pan after a serious scramble: often you have to vigorously scrape the egg off the frying pan: because it has oxidized. I point out that Leonardo Da Vinci painted with egg yolk, and they are still present today.   (Source)




One final point: let’s not add insult to injury by cooking our eggs in an oil that is easily oxidized, if we do scramble or fry them. And, low temperature frying (ideally sunnyside up) is not too bad, from the oxidation point of view. 


The best oils for any high temperature cooking are those that remain stable at high temperatures, most of which are saturated fats such as coconut oil, MCT oil, butter, or even lard. (Grandma was right, saving that bacon grease and using it for frying.)


(Author: All newsletters and blogs are written by Ken Peters who has worked as a nutritional consultant for the last 30 years, and as product designer for NutriStart for the last 25 years.  He has also authored two books – Health Secrets Vol. 1&2.  He may be reached at:

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