I just read an article on MedPageToday.com that states...
"People who eat eggs every day may substantially increase their risk of type 2 diabetes, researchers here said.
Men with the highest level of egg consumption -- at seven or more per week -- were 58% more likely to develop type 2 diabetes than those who did not eat eggs, and women were 77% more likely to become diabetic if they ate at least an egg a day, Luc Djouss??, M.D., D.Sc., of Brigham and Women's Hospital and Harvard, and colleagues reported online in Diabetes Care.
Levels of egg intake above one a week also incrementally increased diabetes risk in both men and women (both P<0.0001 for trend), the researchers said."
I'm always skeptical of "observational" studies that rely on questionnaires and polling from a limited population (in this case, male and female doctors).
The article itself is quite confused as is states, "Eggs are a major source of dietary cholesterol (about 200 mg per egg) and add about 1.5 g of saturated fat each to the diet, both of which would be expected to increase diabetes risk" and then goes on to say, "Adjustment for dietary cholesterol attenuated the association between diabetes and egg consumption, whereas saturated fat was not associated with type 2 diabetes and did not alter the diabetes-egg link."
Is this another case of bad science and bad science reporting (which is my thought) or is there actually some physiological explanation/reason why eggs might lead to diabetes?
asked byTony_Fed (19479)
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on September 24, 2011
at 02:43 AM
This would be correlative data, which is good for a hypothesis but can't establish causation. So if this is to be used as anything other than a reason to go to a controlled trial then it would be bad science. But this study isn't bad science, it is what it is: epidemiology. It is people who wish to use this as evidence that eggs cause insulin resistance that are the dumb ones. I mean you just proved that yourself by posting a study in which eggs were not associated with diabetes risk. If we are to use these sorts of studies as anything other than a hypothesis we will inevitably run into a logical contradiction that both eggs cause diabetes and do not cause diabetes. And in fact this is an example of very good science, because they discuss the limitations and contradictions of the notion. They referenced a controlled trial where they gave obese subjects on a low carbohydrate diet 3 eggs or no eggs a day and there was no difference in fasting glucose. Now maybe that could only manifest itself with more carbs, but the one controlled trial in humans that they noted was not supportive of the hypothesis that eggs cause insulin resistance.
Eggs are generally seen as an unhealthy food amongst the public and so you can expect the most health-conscious people to eat the least of them and the least health-conscious people to eat more of them, on average in a population, especially amongst doctors. They did control for some relavent confounding factors, but they didn't really control for the tendency to eat at fast food restaurants, snack foods rich in oxidized fats, sugar-containing foods and beverages, etc. It is probably the case that those eating more eggs are also eating more junk. Older people are less likely to see eggs are unhealthy, and there are studies that do not show an increased risk of diabetes with higher egg consumption in elderly people http://www.ncbi.nlm.nih.gov/pubmed/20534749
Their proposed biological explanation is dietary cholesterol itself, however they didn't supply a biological mechanism by which it could happen. In the comments section of that news article, a lady named Evelyn Tribole who runs the interesting blog http://omega-6-omega-3-balance.omegaoptimize.com/ comments
"Evelyn Tribole, MS, RD - Nov 22, 2008 Eggs contain a significant amount of the omega-6 fatty acid, arachidonic acid. While this potent fatty acid is a polyunsaturated fat, excessive consumption of omega-6 fats have been linked with many chronic diseases, including diabetes and insulin resistance."
I am guessing that she proposed that dietary arachidonic acid, causes excessive inflammation by upregulating production of the eicosanoids it produces, and the enhanced inflammatory cascade will cause insulin resistance, possibly through excessive expression of tumor necrosis alpha on the insulin receptor substrate 1 (maintains insulin receptor sensitivity), although maybe there are other mechanisms as well. Inhibiting inflammation does indeed improve insulin sensitivity, so it makes sense at face-value. However this isn't necessarily the way things work in the body. Just because you eat arachidonic acid doesn't mean it is going to automatically be turned into inflammatory messengers, that is not really how it works. In fact eggs have been shown to be anti-inflammatory in the context of a low carbohydrate diet http://www.fasebj.org/cgi/content/meeting_abstract/21/6/A1062-d (I see no reason why not in a higher carbohydrate diet) and so we would expect the opposite. Or perhaps it is a problem in the absence of omega-3 fats to control the anti-inflammatory signaling. Oftentimes nutrient deficiencies can make certain things harmful that aren't harmful otherwise, like a "high-fat" diet causing insulin resistance in rats is prevented by fish oil http://www.ncbi.nlm.nih.gov/pubmed/3303333
Egg quality should be taken into account. These are probably junk eggs most of the time. There is a night and day difference between the good ones and the bad ones. I wouldn't be surprised if the junk eggs caused health problems, although I'm not sure if they do. Degree of cooking can be a factor as well. Highly oxidized dietary cholesterol can cause inflammation in rats, so perhaps frying eggs is a problem but soft-boiling them is not. I would expect the amount of antioxidants in the yolk to play a role, which would mean that better quality eggs would make a difference. Better quality eggs have some omega-3, which is important in regulating inflammation, so I would like to see controlled trials with the best quality eggs.
So, umm, I dunno. pastured eggs are so damn nutritious and good for the brain, I'll keep eating them unless I get diabetes, but my insulin sensitivity is great.
Update: a controlled trial of dietary supplementation with omega-3-enriched eggs reported a drop in plasma glucose. http://www.ncbi.nlm.nih.gov/pubmed/18991244
on September 25, 2011
at 02:47 AM
If this study is talking about these:
then I totally believe it.
on September 24, 2011
at 01:27 AM
This was actually a result of two prospective cohort studies, considered the 'strongest' observational study design. Subjects reported egg consumption specifically. The confusing nature of the MedPage article could be due to poor reporting. However, what that sentence on saturated fat is saying is that in this particular study, adjusting for saturated fat consumption did not change the association between egg consumption and diabetes risk (i.e. even after accounting for consumption of saturated fat from other food sources, egg consumption was still associated with diabetes). Cholesterol, in this case, did account for some of the risk of diabetes, since adjusting for it attenuated the association between egg consumption and diabetes risk.
There may be other factors not adjusted for that were potential confounders, of course. But that's an issue with all epidemiological studies.
EDIT: it's highly likely smoking and other factors related to diabetes were accounted for (I'd have to Pull the original article, but these are very well-known cohort studies and I'm sure that standard confounders were included in their regression model). That isn't to say the study wasn't flawed somehow. But reading the MedPage article and the source article's abstract aren't sufficient to determine what biases may have affected the results.
EDIT 2: sorry FED, I didn't mean to sound critical of you! Just tired of bad reporting. I agree it written in a way that's confusing. The sentence is trying to say that we'd expect saturated fat to have an effect based on prior studies but in this particular study an association between saturated fat and diabetes was not observed. Because this link isn't there, saturated fat fails to meet one of the criterions for being a confounder, and so it does not have an effect on the association between egg consumption an diabetes. I am a cancer epidemiologist and am appalled at how studies are often communicated in broader media. As for epi evidence, remember where we get a lot of data that is in favor of the paleo lifestyle. Many are epi studies (note: cohort studies provide estimates of relative risk, which differs from correlation, which is strictly the relationship between two continuous variables). Many are even animal studies, which are great for understanding mechanisms but not necessarily predictive of what will be observed in humans. And randomized controlled trials are not always definitive or even valid. They are also subject to biases. Many aren't conducted for a sufficient length of time to observe the outcome of interest. Issues of changing risk over time can result in a different relative risk depending on at the time point that is being observed. All epi studies should be considered carefully, whether they support our beliefs or not. That's what drives us to do better and better science. :-)
on September 24, 2011
at 01:33 AM
You might have the same type of confounders as you do with saturated fat ??? people who continued to eat eggs in the middle of the cholesterol scare were the type of people to ignore health advice in general ??? smoke, not exercise, etc...
It would be interesting to control for the other unhealthy behaviors and see if the choline in the eggs were protective against type 2 diabetes.
on September 24, 2011
at 01:06 AM
It may simply be that foods which use eggs as an ingredient eg cake and other baked goods were also included as part of the overall egg consumption tally. Studies claiming to link red meat and diabetes do this all the time, when it is the foods that are incidental to red meat consumption which are the real hazard eg the bun vs the hamburger.
Also, considering the medical-field demographic, it seems likely that the health conscious would be more likely than the general population to avoid eggs due to conventional wisdom on cholesterol, leaving those unconcerned with their health to get back to their breakfasts of double french toast with extra syrup.
Edit: eggs are commonly prepared in a variety of ways. I wonder if the methods which created more oxidised cholesterol (scrambling) or which used more vegetable fats (frying) could have had any bearing on the results. Equally, another confounding factor is that eggs can vary significantly in size and nutritional content eg more omega 6, less vitamin e e.t.c.
on September 24, 2011
at 11:08 PM
Let me guess, people who have diabetes need to eat low carb in order to avoid insulin shots, and as part of that, because they're not eating cereals, bagels, pastries, or donuts for breakfast they eat more eggs than those who don't. Therefore people who eat more eggs are more likely to have diabetes? D'oh!
Correlation is NOT Causation.
on September 24, 2011
at 04:09 AM
My answer....I use to dip like 3-4 pieces of bread into my egg yolks in the morning. So, food association/carrier yadda yadda yadda......
on November 16, 2011
at 07:50 PM
This study seems to contradict another one reported on Reuters. The studies were done by the same doctor
on January 28, 2016
at 10:15 AM
Here are 7 articles from the more research focused paleo bloggers out there:
Chicken eggs are a good source of selenium, vitamin A, D and the B vitamins. Some people report sensitivity to them. probablyhealthy-dot-com
Peter Attia – What I actually eat.
4 eggs, 0.5 avocado, 3.5 oz cheddar, 3 oz red onion, 2 oz walnuts, 2 oz cashews, 4.5 oz chicken thigh, 2 tbsp butter
I do indeed eat three eggs with cheese, bacon and sausage for breakfast every morning
On page 205 of “The Paleo Solution” Robb speaks to his concerns about eggs and autoimmunity, saying he digs this food but “doesn’t recommend eating eggs for breakfast every day for the rest of your life.” He says this clearly in the context of how well tolerated eggs are for particular persons.
They’re an excellent source of highly assimilable protein and vitamins like A, choline, K2, and folate, and they can be a good source of omega-3s if the hen’s diet is right.
Chicken eggs are generally a nutritious food and are a good source of selenium, vitamin A, vitamin D and the B vitamins, some minerals and lutein as Barbara indicated.”
“So, should everybody include eggs in their diet on a daily basis? Not necessarily,…, in the wild, bird eggs only appear seasonally. Hence, pre-agricultural humans could have never consumed two eggs for breakfast every morning of the year similar to some westernized people, but rather only occasionally for a few brief weeks or months.”
Chris MasterJohn Meeting the Choline Requirement — Eggs, Organs, and the Wheat Paradox
“In America, at least, it would appear that lots of us need lots of egg yolks and liver.”
The persistent myth that cholesterol causes heart disease has scared many of us away from eating eggs on a regular basis. But there is absolutely no research that links egg consumption to heart disease.