Semantic pratfall and puzzling paradox draw one savvy reader’s cogent comments
by Craig Weatherby
We received a welcome query and critique from reader Kris Johnson of northwest Ohio, who wrote in response to an article I researched and authored last week, titled “Dietary Fat May Affect Kids’ Memories.”
I thank Mrs. Johnson for her sharp eye and mind, as one correction was needed.
Here is Mrs. Johnson’s email, edited a bit for space:
“Something is wrong with the logic here: Whoever heard of getting your calories from cholesterol...?
“[And] I wonder why they would find negative results with increased cholesterol consumption, since cholesterol is essential for proper brain development. Maybe because it [the cholesterol the children were eating] is associated with poor quality meat that is low in omega-3's?
“…if the kids were getting more PUFA, they were maybe getting the omega-3's they were needing—though probably with a big dose of omega-6's leading to other problems they didn't look for.”
Here is our reply, also edited a bit
Dear Ms. Johnson:
Thank you for your email. You are correct that my words—"children who got more of their calories from cholesterol"—were misleading in that they conflated cholesterol intake with calorie intake stemming from dietary cholesterol, which is an oxymoron. It should have read: "children who consumed more cholesterol."
As a steroid alcohol, cholesterol does store potential energy, but is not metabolized to produce energy (calories).
I also agree that the study, like most such observational studies, may not have taken into account all possible confounding factors, such as the ones you mention.
While it is true that cholesterol is an essential physiological factor for nerve and brain function, the body has little difficulty producing all it needs, and virtually all of the cholesterol in the brain is produced in the brain.
And, while most researchers consider high intake of dietary cholesterol a risk factor for senile dementia and AD, the evidence is inconsistent, and the problem with cholesterol (if there is one) may be a dysfunction of the lipid transport system in the brain, rather than cholesterol per se. It may be that high dietary cholesterol somehow impairs the brain's lipid transport system, directly or indirectly. Further research will clarify matters, one hopes.
- Panza F, D'Introno A, Colacicco AM, Capurso C, Parigi AD, Capurso SA, Caselli RJ, Pilotto A, Scafato E, Capurso A, Solfrizzi V. Cognitive frailty: Predementia syndrome and vascular risk factors. Neurobiol Aging. 2005 Jul 13; [Epub ahead of print]
- Reiss AB. Cholesterol and apolipoprotein E in Alzheimer's disease. Am J Alzheimers Dis Other Demen. 2005 Mar-Apr;20(2):91-6. Review.
- Ledesma MD, Dotti CG. The conflicting role of brain cholesterol in Alzheimer's disease: lessons from the brain plasminogen system. Biochem Soc Symp. 2005;(72):129-38. Review.