A paper published in JAMA (the esteemed Journal of American Medical Association) in March 2019 has made a lot of headlines. Let’s look into the details of the study.
Structure of the Study
This study is a meta-analysis of six different US based prospective cohort studies. A prospective cohort study means that collections of people, who have many things in common, are followed over time focusing on one key difference among them.
29,615 participants over a 17 year period on average
Data collected between 1985 and 2016
Data was self reported by the participants
45% of the participants were men
31% of the participants were black
The study controlled for confounding factors such as demographics, socioeconomic conditions, and behavioral factors.
Goal of the Study
To study the effects of how the level of dietary cholesterol, specifically via eggs, impacts cardio-vascular disease (CVD) and overall human health.
Findings
17% increased risk in CVD for each daily 300 milligrams of dietary cholesterol
18% increased risk in premature death for each daily 300 mg of dietary cholesterol
6% increased risk for CVD for each ½ egg consumed daily
8% increased risk for premature death for each ½ egg consumed daily
Criticisms of the Study
The data is all self reported so you have to trust the information the participants are providing
The study is observational, so you cannot conclude any cause and effect relationships, only associations
The dietary data was gathered only at the beginning of the study and not throughout the study, so changes in participants' dietary patterns over the average of 17 years is not factored into the results
Professional Commentary on the Study
“...the results are surprising because here even a half-egg a day makes a difference. This study seems to find a much stronger association than what has previously been found.”
--Frank Hu, PhD, Professor of Nutrition and Epidemiology, Harvard School of Public Health
“Compared with the meta-analyses and reviews previously published, this report is far more comprehensive, with enough data to make a strong statement that eggs and overall dietary cholesterol intake remain important in affecting the risk of CVD and more so the risk of all-cause mortality.”
--Robert Eckel MD, Professor of Medicine, University of Colorado
“This study takes into account the general quality of the diet and adjusts for it. We really were focused on the independent effects of eggs and dietary cholesterol. For example, healthier people tend to eat more eggs because they feel there’s a lot of protein in them, but even for healthy people on healthy diets, the harmful effect of eggs and cholesterol was consistent.”
“You do want to reduce the number of eggs, especially egg yolks, as part of a healthy diet. But we don’t want people to walk away thinking they shouldn’t eat any eggs. That’s not the right message.”
--Norrina Allen, PhD, Lead Author of the Study
Personal Commentary on the Study
The last quote by the study’s lead author is representative of the confused and conflicted advice that result from corrupting industry influence and government mandates to promote certain foods.
As an example, The Dietary Guidelines for Americans 2015 - 2020 which is published by the US Department of Health and Human Services states the following
“we should eat as little cholesterol as possible while consuming a healthy eating pattern”
However, in the scientific report that accompanies this very same set of guidelines, it is stated:
“cholesterol is not a nutrient of concern for overconsumption”
In one final example of complete confusion, the USDA prohibits eggs as being advertised healthy, nutritious, or even safe because even a single egg has more cholesterol and saturated fat than the USDA guidelines consider to be healthy.
One way to cut this confusion is err on the side of caution and perform a risk/benefit analysis. What do you hope to gain from eating eggs? Is there anything helpful that eggs provide which cannot be obtained from a non-controversial source? The only two I can think of are B-12 and vitamin D. Considering 40% of the general population is considered to be B-12 deficient and B-12 supplementation is starting to be recommended broadly, this is a moot point.
Personally, spending time in the sun (or supplementing with vitamin D), and taking a B-12 supplement is a far better alternative than what the Adventist Health Studies show when comparing Ovo-Lacto eaters with vegans:
The Bigger Picture that is Lost in the Press
When you see the stories about this study in the press, they all seem to focus on whether *eggs* are healthy, or should we stop eating *eggs*. This is missing an important point of the study. Eggs are simply a proxy used for dietary cholesterol in general. The method by which you ingest the dietary cholesterol is irrelevant to the conclusions drawn. In fact, the study emphasizes this, when the authors state the following:
“the associations between egg consumption and incident CVD and all-cause mortality were no longer significant after adjusting for dietary cholesterol consumption”
I take this to mean that eggs, in and of themselves, do not contribute to CVD or all-cause mortality more or less than if you consumed the same amount of dietary cholesterol via other animal products. The results of this study are just a damning for eggs as they are for animal products in general because of this fact.
Sources:
https://jamanetwork.com/journals/jama/article-abstract/2728487
https://jamanetwork.com/journals/jama/article-abstract/2728465
https://oembed.libsyn.com/embed?item_id=9008525
https://health.gov/dietaryguidelines/2015/guidelines/chapter-1/healthy-eating-patterns/