Wednesday, April 09, 2008

Egg study flawed

Bonnie - the American Journal of Clinical Nutrition published a study in their April issue showing that middle-aged males who eat more than seven eggs per week were at a modestly greater risk for all-cause mortality and greatly increased risk in diabetics. While we have professed our love for this journal for years, and still do, we are scratching our heads over the publishing of this study. The authors, as well as the accompanying editorial, all but apologizes that they study was performed. Nevertheless, Reuters picked up on the story and the media will probably run with it.

There were so many limitations. Here are the important points:
  • First of all, of the 21327 participants who were followed over 20 years, only 8 percent ate more than one egg per day. That is a very small cohort. The most important thing to note is that less frequent intake (less than one egg per day) DID NOT INFLUENCE RISK for all-cause mortality. How many of us eat eggs every day?

  • The study suffers from lack of detailed dietary information, such as, how were the eggs prepared (fried, scrambled, hard-boiled, in egg salad)? This is extremely important when taking into account all-cause mortality.

  • The participants with higher egg intake were older, had higher BMI (body mass index), smoked more cigarettes, drank more alcohol, were less physically active, and had a higher prevalence of hypertension and diabetes. Think this may have contributed to all-cause mortality?

  • Egg consumption in any amount was NOT associated with increased risk of heart attacks, strokes, or cardiovascular disease.

  • The authors profess that they did not track the amount of calories and major nutrient intake of the participants, where as other egg studies did.
In short, the chances are very high that the terrible lifestyle choices in the participants who ate more than 7 eggs per week (diabetic and non-diabetic) contributed to the all-cause mortality than the eggs themselves. I suspect (because the researchers did not take this into account) that these participants ate their eggs in the Standard American Breakfast way: prepared in butter accompanied by pancakes or waffles, hash browns or toast, etc. It is shocking to me that the numbers were not higher!

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