A Closer Look at the China Study: Eggs and Disease

18 06 2010

Ah, eggs: Incredible and edible, as the commercial goes. A quintessential staple of American breakfasts, loaded with protein, packed with cholesterol. Bodybuilders chug ‘em down en masse, and raw foodists sometimes experiment with them—but could they raise your risk of disease, as T. Colin Campbell claims all animal foods do? Let’s take a look at the original China Study data and find out.

Egg consumption in rural China

There’s no doubt about it: Eggs aren’t exactly a staple in China. In the China Project counties, egg consumption ranged from zero grams per day to 14.8 grams per day, which is the equivalent of about two or three chicken eggs per week. Not a lot. Although the data is still relevant, whatever we find here only reflects modest egg consumption—not a daily four-egg-omelet habit, for instance.

Unfortunately, we don’t have much information on what kind of eggs these people were eating. You wouldn’t guess it by strolling through an American supermarket, but chickens are, in fact, not the only birds that lay edible eggs. (Shocking, eh?) In China, meals can include eggs from ducks, quail, geese, pigeons, and other poultry, along with those of chickens. And rather than our familiar omelets and souffles, Chinese cuisine embraces things like salted duck eggs (which are soaked in brine for a month) and century eggs (which are soaked in a mixture of ash, salt, clay, lime, and rice straw for a few months—’til the yolks turn green and the eggs develop a delightful ammonia smell).

Alas, the only variable we have in the China Project data is “egg intake,” so we can’t see if particular types of eggs or preservation methods have different effects than others. An unfortunate limitation indeed. But we’ll work with what we’ve got.

In China, egg consumption tied in with a number of other variables. The folks who ate eggs tended to also have low triglycerides (-42), got a larger portion of their total calories from fat (+37), loved them some sea veggies (+41), indulged in a bit of processed starch and sugar (+33), piled on the soy sauce (+45), used a fair amount of soybean, cottonseed, sesame, and peanut oil (+32), gulped down the beer (+38), and smoked cigarettes (+34). Like fish eaters, eggy folks worked more often in industry than in agriculture (+37 and -49, respectively). Whew! Lots of variables there.

Here’s what egg-related correlations look like without adjusting any variables. Again, I’ll just be discussing the statistically significant ones.

NEGATIVE CORRELATIONS (more eggs = fewer of these diseases)

Liver cirrhosis: -46***
Peptic ulcer: -43**
Diseases of the blood and blood-forming organs: -35*
Death from all causes: -33*
Digestive disease other than peptic ulcer: -30*
Hypertensive heart disease: -28
Oesophageal cancer: -26*
Death from all non-cancer causes: -26

It’s questionable how many of these ailments (apart from heart disease and blood-related woes) are even related to diet, so I won’t gush over these happy correlations too much. Things like liver cirrhosis are probably related more to hepatitis B infection, peptic ulcers are linked to the bacterium Helicobacter pylori, and digestive diseases (whatever those consists of) could be related to infection or parasites. But I will say that eggs, in the modest amounts the Chinese consumed, don’t appear to tarnish heart health in any way. Along with hypertensive heart disease, other cardiovascular problems have inverse or neutral correlations with egg intake (-21 for rheumatoid heart disease, -13 for myocardial infarction, and -8 for stroke).

POSITIVE CORRELATIONS (more eggs = more of these diseases)

Colorectal cancer: +35*
Colon cancer: +34*
Rectal cancer: +30*

Look familiar? It should. If you’ll recall, we saw high rates of colorectal cancers (colon and rectal) with meat in an earlier post—a trend that turned out to be related to schistosomiasis infection, not meat itself. And as it just so happens, egg intake correlates strongly with schistosomiasis as well, at the statistically significant rate of +40. Could that pesky little parasite be causing colorectal cancers in egg eaters?

Yep, that’s right… graph time! You know you love it.

Here we have three charts mapping the correlation between eggs and rectal cancer, colon cancer, and all colorectal cancers—using only the counties free from schistosomiasis infection.

Voila; we no longer have a statistically significant correlation between eggs and any form of colorectal cancer. As you can see, even our counties with the highest egg consumption didn’t have considerably more or less of these cancers than the eggless populations.

In conclusion:

We can’t say too much about eggs one way or another, simply because our data pool is limited and we lack some pertinent info—like what kinds of eggs these people ate and in what form. However, based on what we do know from the China Project, there’s no reason to think eating a couple of eggs per week (hopefully organic and free-range) would have any negative health repercussions. More than that may be fine, too; we just can’t say for sure based on this data alone. In fact, egg consumption may even offer benefits for heart health and “diseases of the blood and blood forming organs,” as the variable is titled.

Next up is the last of our animal products: dairy.

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17 responses

18 06 2010
meatnpotatoesforlife

Dayum! I be lovin’ this series. Nerdistanis, ftw! As an aside, I heard an interview with Randy Roach, the author of an absolutely brilliant tome called muscle, smoke & mirrors that recommends raw egg yolks with juice ( I think this may be based on Aajanous’ ideas) espesh if it’s even remotely sugary like carrot, beets etc. Juice + raw yolks = sustained energy. Eggsquisite, your writing that is!

20 06 2010
neisy

Eggsellent comment, fellow Nerdistani! ;)

I’m not familiar with Randy Roach (though it sounds like I’ll have to check him out). If I recall, raw egg yolk/juice mixtures are also recommended on the “Wai” diet (http://www.waiworld.com/waidiet/thewaidiet.html). I haven’t tried eggs with juice, but I’ve put egg yolks in smoothies and they definitely do add some staying power.

Thanks for stopping by! :)

20 06 2010
A Closer Look at the China Study: Dairy and Disease « Raw Food SOS: Troubleshooting on the Raw Food Diet

[...] What the China Study says about eggs and disease [...]

21 06 2010
Sue

I’ll keep eating my one egg white a day. Thanks, Neisy!

11 07 2010
Monte Diaz

http://www.naturalnews.com/025815_eggs_health_cholesterol_levels.html

http://www.timesonline.co.uk/tol/life_and_style/health/article5705038.ece

Left and right the egg is being vindicated.

“In 2006, Dr. Maria Luz Hernandez of the University of Connecticut’s Department of Nutritional Sciences looked at the effect consuming eggs has on cholesterol levels. Her findings revealed that in two-thirds of people, consuming 2-3 eggs per day had virtually no effect on serum cholesterol levels. In the other one-third of people, both HDL and LDL levels rose equally, and the increase in LDL was due to particles simply getting bigger, not more numerous. This type of rise in serum cholesterol levels actually does little to increase a person’s risk for health problems such as heart attacks.”

14 07 2010
Neet Ielasi

i am enjoying eggs again,after nearly 7 years raw vegan,my body cried out for change with illness and developing disease.How good wholefoods can help a body to regenerate it’s wonderful.Thanks Denise for your continued wonderfulness ;)

11 11 2011
living123

wondering, do u mean being raw vegan led to ur body developing illnesses and diseases? because that’s quite shocking….

22 01 2012
SK

It’s only shocking because of the way the raw vegan movement censors the long term results of the diet. Once your body has run out of fat soluble vitamins A, D, K and long chain essential fatty acids, EPA and DHA, you’re basically done for.
My advice, go raw vegetarian if you want to stay completely raw and remain healthy

30 07 2010
justwantthetruth

It would be appropriate of you to mention “Free Range Eggs”. Ever been to a battery farm….you will never ever eat an egg again if you saw the way your hen lives (death all around them, diseases, living in their own crap, etc) just to give you a poisoned egg!

20 08 2010
380 Million Eggs Have Been Recalled

[...] What I really love about this page is that on the bottom right under "Possibly related posts" it has a link to one of Denise Minger's China Study take-down posts called "A Closer Look at the China Study: Eggs and Disease"! [...]

15 05 2011
Forks Over Knives Review | Ready State Fitness

[...] A Closer Look at the China Study: Eggs and Disease (Associations the “eggs” variable has with various diseases in China.) [...]

22 09 2011
28 11 2011
‘The China Study’ and ‘Forks over Knives’, links to critiques | Julianne's Paleo & Zone Nutrition Blog

[...] A Closer Look at the China Study: Eggs and Disease (Associations the “eggs” variable has with various diseases in China.) [...]

21 09 2012
30 01 2013
Jeremy

Y’all need to look up choline and how important a nutrient it is. Eggs are a great source of choline.

23 05 2013
RR

Eggs are not the only source of choline. Do not be fooled into the myth that animal based foods are the only source for minerals and vitamins or the best. “More does not mean better, it just means more.”

5 06 2014
Doug

Hi Denise,

In 2013, 30 Chinese companies were producing poisoned 100 year eggs. They were producing over 300,000 tonnes per year.

“Thirty preserved egg companies are being shut down for using industrial copper sulphate, a toxic chemical, to expedite the egg-festering process. South China Morning Post reports:
Industrial copper sulphate usually contains high levels of toxic heavy metals, including arsenic, lead and cadmium”

Might have messed up the egg results a bit, don’t you think.

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