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Dear Mark: Raw Eggs

Posted By Mark Sisson On February 15, 2010 @ 9:15 am In Health,Nutrition | 225 Comments

A glassful of raw eggs incites mixed reactions for many of us. It’s routine for some and revulsion for others. Commonly associated with bodybuilders and boxers (the Rocky scene) who want to bulk up, a lot of folks who fit neither category include them on a regular basis for simple nutritional reasons. However, there’s more to the picture, as this reader’s email suggests.

Dear Mark,

I have searched the site to see if there is any pros/cons of eating raw eggs. I know in the past, CW says that eating raw eggs can create a biotin deficiency in our bodies. I like having a couple of raw eggs in my whey protein drink after a workout. Do you have any information that would be helpful in the use of raw eggs?

Eggs [7] in general are a nutritional (and wholly Primal!) powerhouse with impressive supplies of selenium, iodine, phosphorus, molybdenum, choline, lutein, vitamins A, B2, B5, B12, E, D and K. Add to this a healthy 5.5 grams of protein, 20% of your RDA for tryptophan and essential fatty acids. But what’s the specific draw to raw eggs?

A lot of folks choose to eat raw eggs because some nutrients can be diminished by heating. (Although this is true of cooking just about anything, cooking also makes certain nutrients more bioavailable – hence the constant pull and push between the raw foodists and traditional cooks.) Some people feel any change in the chemical structure is to be avoided. Others don’t. Although some vitamins (like vitamins C, B6 and B9) are more fragile and lose potency during heating (the more/longer heat, the more loss), other nutrients are enhanced. As reader Tuscoyote noted in the forum a few months ago, researchers have found that egg protein is more bioavailable when heated [8]. (Thanks for the NPR link, Tuscoyote!) Here’s the study [9] referenced in that interview. The study showed that egg protein is more digestible (94% versus 55-64%) when heated, probably due to alteration of the protein’s structure and the ability of digestive enzymes to infiltrate peptide bonds. Whether you eat your eggs heated or raw (or a little of both) in part depends on your goal in eating them to begin with.

As for drawbacks, there’s the well-circulated salmonella risk, which isn’t the dire prospect it’s often made out to be. The risk has been estimated as 1 in 10,000 [10] (CDC) or 1 in 30,000 [11] (Risk Analysis journal). And though washing eggshells can reduce much of the risk, it doesn’t eliminate it entirely. Salmonella can be present in the yolk [12] due to infection in the hen’s reproductive tissue.

Of course, not all eggs are created equal [13] when it comes to salmonella or nutrition. Not only are organic, free range eggs more nutrient-dense, one study found them to be significantly less contaminated than battery cage hens [14]. Hens that graze and eat a natural diet as well as have more space to roam (to avoid living in feces) are naturally healthier. While the survey determined a quarter of battery cage groups to be contaminated, only 5% of those that were both organic and free range showed contamination. (Free-range, non-organic came up at 6.5%.) Simple refrigeration can keep any salmonella bacteria from multiplying, which minimizes the risk of actual illness from contaminated eggs. In those who are very young, pregnant or immune-compromised, salmonella risk is more of a consideration.

As you mention, eating raw eggs carries the eventual risk of a biotin deficiency. Although egg yolk is actually a rich source of biotin, the white contains avidin, a glycoprotein that bonds with biotin, preventing the nutrient’s absorption. Avidin is generally inactivated when cooked, which makes the biotin in the yolk fully available for absorption by the body. You don’t have to rule out raw eggs by any means. I wouldn’t advise eating them daily for long stretches of time without a biotin supplement (supported within a B-complex intake, since these vitamins work synergistically). If you’re eating them just a few times a week, the risk for deficiency isn’t as great, but I would still do a supplement or at least make sure I was getting a hefty amount of biotin rich food (swiss chard, tomatoes, carrots, liver and others) the days I eat raw eggs. As a compromise, some folks will just eat the raw yolks alone and cook up the whites later.

All that said, raw eggs can be part of your Primal fare. (There are advantages to cooked eggs, but it’s however you enjoy them.) If you like raw eggs, I’d say have at it – with the above info in mind. If you would rather cook them, I’d suggest going easy on the heat to avoid overcooking. Some folks suggest choosing cooking methods that leave the egg yolk intact and soft (like sunny side up or poached) because of concerns about oxidizing the cholesterol. I’m not too concerned about the small amount that might result from my breakfast routine. For myself, I take a middle road (mostly for taste). Sometimes I do my omelets, but just as often these days I’ll poach them so the egg white is cooked and yolk runny. Just had two for breakfast in fact.

Let me know your take on raw versus runny versus fully cooked. For those who go raw or not, how do you eat them? Thanks for all your questions and comments, and keep ‘em coming!


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[8] egg protein is more bioavailable when heated: http://www.npr.org/templates/story/story.php?storyId=112334465&ft=2&f=510221

[9] study: http://jn.nutrition.org/cgi/content/full/128/10/1716

[10] 1 in 10,000: http://www.cdc.gov/ncidod/dbmd/diseaseinfo/salment_g.htm

[11] 1 in 30,000: http://www.ncbi.nlm.nih.gov/pubmed/12022671?dopt=Abstract

[12] can be present in the yolk: http://www.ncbi.nlm.nih.gov/pubmed/8155476

[13] not all eggs are created equal: http://www.marksdailyapple.com/egg-purchasing-guide/

[14] significantly less contaminated than battery cage hens: http://www.worldpoultry.net/news/salmonella-levels-in-poultry-higher-in-battery-eggs-id2162.html

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