A Story with Bearing: Cholesterol
By Michael Pickering
Years ago our friend Peggy told us that her doctor had prescribed a diet devoid in cholesterol, as her blood test indicated worrisome numbers. The doctor recommended that all of the usual suspects be excluded from her diet, such as egg yolks and butter, but it was all to no avail. Regardless of how long she maintained the exclusive diet, her blood numbers did not budge. So, she decided to experiment with her own dietary exclusions. One of her first experiments was targeted at a food everyone who knows Peggy is well aware that she is addicted to – milk chocolate. It was only then that her blood cholesterol numbers improved.
While it is true that one’s diet is an important factor in the level of cholesterol in one’s blood, the amount of cholesterol in one’s diet is not germane. Unlike the essential amino acids and minerals which must be harvested from the diet, the cholesterol in our blood is synthesized inside our bodies from smaller synthons (many acetates, a popular biosynthetic mode, see flavonoids).
So the issue isn’t whether cholesterol is in one’s diet, but rather how cholesterol is behaving in one’s blood.
The key link between the importance of diet and the behavior of cholesterol in one’s blood is the amount and type of fat you ingest. Highly saturated fats have the most negative impact on the solubility of cholesterol in the blood.
Blood chemistry is necessarily dominated by water soluble processes. Magnesium, sodium, citrate, and all manner of water soluble nutrients must course around freely. However, cholesterol is not water soluble, even though it must move as freely through our veins. The body’s solution is to cloak the cholesterol with a hydrophobic interior (cozy coat) with a hydrophilic exterior (sort of like a 1960’s Bill Blass coat with the mink on the inside and the satin on the outside).
These water taxis are called LDL and HDL: low density lipoproteins and high density lipoproteins. Our body considers the HDL to be better than the LDL because, among other things, it’s easier to void. Tom Scheve’s description of the reason for this in his article for Discovery Health, entitled “What’s the difference between LDL and HDL Cholesterol” eloquently expresses my own musings:
When the lipoprotein has more protein than cholesterol [HDL], it resembles a Ferrari, gunning through your body without stopping until the cholesterol arrives at your liver, where it’s converted into bile acids. […] When the lipoprotein has more cholesterol than protein [LDL], however, this makes for a rickety ride, and that jalopy doesn’t get too far. Cells have special receptors that bind tightly to these lipoproteins as they pass. This LDL sputters down the road, careening off the arteries, running into things and leaving bits all over the place. While the HDL Ferrari sees a pileup and nimbly speeds around it, the LDL jalopy crashes right into it, adding to the jumble of tangled fenders and tailpipes (or platelets and plaque).
The overall solubility of cholesterol in the blood is governed by a ternary phase diagram. Maintaining these three components in the proper ratio crates a zone of solubility in the triangle. If the diet (the source of phospholipids and fats) biases the ratio out of the soluble zone, the cholesterol precipitates with the fenders and tailpipes. And like all solids in a moving fluid, they deposit in the zones of slowest flow. In a vascular system the slowest flow is in the arteries.
The lipids (fats) in our diet can be broadly sorted into two categories: 1) naturally occurring, and 2) man-made. Obviously the naturally occurring fats and oils are derived from plants and animals. The man-made fats are partially hydrogenated vegetable oils. The saturation level determines the melting point and viscosity regardless of the source. So highly unsaturated lipids like sesame oil have a low melting point and viscosity and so are inappropriate for frying, whereas poly-saturated lard and butter have a high melting point and viscosity, and are well suited for frying. Similarly, an award-winning pie crust can be made with lard or butter, but not with unsaturated oil. Partial hydrogenation thus controls the melting point of the fat and establishes its suitability for any particular application.
However, a side reaction also occurs during the hydrogenation: isomerization. Natural unsaturation tends to be cis-configuration but hydrogenation isomerizes the bonds to trans-configuration.
Our wild type diet is clearly designed around whole grains as the staple, a source uniquely rich in unsaturated (cis-) fats, phospholipids, and protein. The goal is to manage the trace chemistry in our blood, the hydrophobic components. So the lesson is: eat as little saturated (mostly animal) fat as you can tolerate, eat whole grains and exclude all partially hydrogenated vegetable oil. Read the label!
So while the amount of cholesterol present in a milk chocolate bar (24 g) is comparable to that of a tablespoon of butter (30 g), the two had very different effects on Peggy’s blood work. Cocoa fat is among the most saturated of the vegetable oils. The melting point is so high that the bars are wax-like at room temperature. The chocolate was in effect creating an excess of LDL jalopy wreckage in Peggy’s blood stream, by causing the LDL and HDL levels to get out of whack.
The cholesterol had no bearing.
Editor’s Note: Always consult a physician first. The views presented herein are strictly editorial in nature.