Pay attention - dietary cholesterol is the cholesterol you eat. Serum cholesterol is the cholesterol in your blood. They are not only distinct; they are largely independent of each other. The following excerpt from Wikipedia gets “into the weeds” a bit, but 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.”
Assuming a “lean (body) build” for the U.S. population is a dubious proposition, as must be patently obvious to even the casual observer. My body is certainly not lean. Neither do I eat just 200-300mg/day of dietary cholesterol. I typically average 600-650 mg/day. I know this from the days (years, actually) when I tracked carefully. But, the HHS/USDA Dietary Guidelines for Americans age 2 and older urge us to eat no more than 300mg daily (200mg with CVD risk factors). Does this make any sense when we consider that 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. Babies and children need cholesterol-rich foods throughout their growing years to ensure proper development of the brain and nervous system,” says Dr. Mary Enig, the doyenne of lipid chemistry and the author of the definitive biochemistry guide, “Dietary Fats.”
“The brain is the most cholesterol-rich organ in the body, most of which comes from in situ synthesis,” begins the abstract of a paper, “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).Yet, many people have deprived themselves for decades of cholesterol-laden foods (shrimp, eggs, butter, cream, liver, even a marbled steak) in an effort to comply with the government’s public health guidelines. What a pity (for them)!
Perhaps the most telling statement in the quoted paragraph, however, is that vegetarians have serum cholesterol levels similar to omnivores “…because internal production increases to largely compensate for the reduced intake.” Vegetarians have avoided eating cholesterol-loaded foods altogether “but this typically does not change the situation very much.” Admittedly, they completely gave up eating animal-based foods – meaning they ate absolutely no cholesterol – for a different reason, 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% within the body, is created and controlled by internal production by all the cells in the body, with typically slightly greater relative production by hepatic (liver) cells. As described in The Nutrition Debate #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. More on cholesterol within this blog can be found at The Nutrition Debate #25 , “Understanding Your Lipid Panel,” and The Nutrition Debate #45 , “Do You Need to Lower Your Cholesterol?”
But get this: “For many,” the Wikipedia entry on atherosclerosis continues, “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 (i.e. cholesterol), weight and blood glucose values. For these reasons, medical authorities much less frequently promote the low dietary fat concept than was common prior to about the year 2005.” That’s certainly been true for me, as I have reported here with my own example (n = 1). Since switching to a high fat/high cholesterol, moderate protein and very low carbohydrate diet about 10 years ago, my HDL has doubled and my triglycerides have dropped by two-thirds, while my LDL has been constant and my T. Chol. has risen only slightly. Remember the common laboratory formula for serum cholesterol: T. Chol. = LDL + HDL + TG/5.
Finally, Ancel Keys, the father of the (infamous) Lipid (saturated fat/heart disease) Hypothesis, is equally famous in some circles for having said later in life, according to Malcolm Kendrick, author of “The Great Cholesterol Myth,” “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, it strikes me as pretty natural and healthy to eat cholesterol rich foods. As the ‘70s margarine commercial said, “It’s not nice to fool Mother Nature.”© Dan Brown 5/6/12