Sunday, April 7, 2019

Retrospective #51: Dietary Cholesterol

Pay attention - dietary cholesterol is the cholesterol you eat. Serum cholesterol is the cholesterol in your blood. They are not only different; they are largely independent of each other. The following excerpt from Wikipedia gets “into the weeds” a bit, but if you want to learn about cholesterol in food, it is necessary to provide a framework.
“While the absolute production quantities vary with the individual, group averages for total human body content of cholesterol, with the U.S population, commonly run about 35,000 mg (assuming lean build; varies with body weight and build) and about 1,000 mg/day ongoing production. Dietary intake plays a smaller role, 200-300 mg/day being common values; for pure vegetarians, essentially 0 mg/day, but this typically does not change the situation very much because internal production increases to largely compensate for the reduced intake” (emphases added).
Assuming a “lean...body build” for the U.S. population is a dubious proposition, as must be obvious to the casual observer. My body is certainly not lean. Neither do I eat just 200-300mg/day of cholesterol. I typically eat 600-650 mg/day. But, the USDA/HHS Dietary Guidelines for Americans (age 2 and older) urged us, until 2015, to eat no more than 300mg/day (200mg with CVD risk factors). Then, on December 14, 2014, the Dietary Guidelines Advisory Committee announced that “…cholesterol is NO LONGER a nutrient of concern for overconsumption.” Finally!
To make sense of all this consider 1): Most societies wean at 3 or 4, and breast milk is 55% fat, mostly saturated, and loaded with cholesterol? “Mother's milk is especially rich in cholesterol and contains a special enzyme that helps the baby utilize this nutrient. Dr. Mary Enig (deceased), the doyenne of lipid chemistry and the author of the definitive biochemistry guide, “Dietary Fats,” said, “Babies and children need cholesterol-rich foods throughout their growing years to ensure proper development of the brain and nervous system.”
And 2): the abstract of, “Diabetes and insulin in regulation of brain cholesterol metabolism,” from the Joslin Diabetes Center and Harvard Medical School, published in Cell Metabolism (2010 Dec 1; 12(6):567-79), begins,  “The brain is the most cholesterol-rich organ in the body, most of which comes from in situ synthesis,”
Yet, many people have deprived themselves for decades of cholesterol-rich foods (shrimp, eggs, butter, cream, liver, marbled steaks) in an effort to comply with the government’s public health guidelines. And many still do!
And 3): Perhaps the most compelling evidence is that vegetarians, who eat 0g/day of dietary cholesterol, have serum cholesterol levels similar to omnivores. Why? “…because internal production increases to…compensate for the reduced intake.” Vegetarians avoid eating cholesterol-loaded foods altogether “but this typically does not change the situation very much.” They have completely given up eating animal-based foods – no cholesterol whatsoever – for a different reason, perhaps, but they did not thereby lower their serum cholesterol “very much.”
The reason, as the numbers In the Wiki-quoted paragraph above note, is that most cholesterol, typically 80-90% of what is contained within the body, is created and controlled by internal production by every cell in the body. As described in Retrospective #24,”… cell structure relies on fat membranes to separate and organize intracellular water, proteins and nucleic acids, and cholesterol is one of the components of all animal cell membranes.”
The Wikipedia entry on atherosclerosis continues: “For many, especially those with greater than optimal body mass and increased glucose levels, reducing carbohydrate intake (especially simple forms), not fat and cholesterol, is often more effective for improving lipoprotein expression patterns [cholesterol panel], weight and blood glucose.“
Unfortunately, Ancel Keys, the father of the (infamous) Lipid Hypothesis, is little known for having said very late in his life, “Cholesterol in the diet doesn't matter at all unless you happen to be a chicken or a rabbit.” “There’s no connection whatsoever between cholesterol in food and cholesterol in blood. And we’ve known that all along.
Given that we were born to drink mother’s milk, and our brain is mostly cholesterol, eating cholesterol-rich foods strikes me as both natural and healthy.  Quoting from the 1970s TV ad, “It’s not nice to fool Mother Nature.”

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