Monday, September 27, 2010

5. The Metabolc Syndrome

The metabolic syndrome is a term used to encapsulate a complex set of markers associated with increased risk to heart disease. The profile includes (1) insulin resistance and dysfunctional glucose metabolism in muscle cells, (2) excess triglycerides in the blood serum, (3) high levels of LDL, particularly small dense LDL, the worst kind, (4) low levels of HDL (the "good" cholesterol) and reduced cholesterol content within the individual HDL particles, (5) elevated blood pressure, and (6) obesity, particularly excess abdominal fat. I have argued previously that this syndrome is brought on by a diet that is high in empty carbohydrates (particularly fructose) and low in fats and cholesterol, along with a poor vitamin D status [Seneff2010]. While I still believe that all of these factors are contributory, I would now add another factor as well: insufficient dietary sulfate.

I have described in a previous essay, my interpretation of obesity as being driven by a need for abundant fat cells to convert glucose to fat because the muscle cells are unable to efficiently utilize glucose as fuel. With sulfur deficiency comes the answer as to why muscle cells would be defective in glucose management: they can't come up with enough cholesterol sulfate to seed the lipid raft needed to import the glucose.

An alternative way to ovecome a muscle cell's defective glucose metabolism is to exercise vigorously, so that the generated AMPK (an indicator of energy shortage) induces the GLUT4 to migrate to the membrane even in the absence of insulin [Ojuka2002]. Once the glucose is inside the muscle cell, however, the iron-sulfate mechanism just described is dysfunctional, both because there's no cholesterol sulfate and because there's no hydrogen peroxide. Additionally, with intensive exercise there's also a reduced supply of oxygen, so the glucose must be processed anaerobically in the cytoplasm to produce lactate. The lactate is released into the blood stream and shipped to the heart and brain, both of which are able to use it as fuel. But the cell membrane remains depleted in cholesterol, and this makes it vulnerable to future oxidative damage.

Another way to compensate for defective glucose metabolism in the muscle cells is to gain weight. Fat cells must now convert glucose into fat and release it into the blood stream as triglycerides, to fuel the muscle cells. In the context of a low fat diet, sulfur deficiency becomes that much worse a problem. Sulfur deficiency interferes with glucose metabolism, so it's a much healthier choice to simply avoid glucose sources (carbohydrates) in the diet; i.e. to adopt a very low-carb diet. Then the fat in the diet can supply the muscles with fuel, and the fat cells are not burdened with having to store up so much reserve fat.

Insulin suppresses the release of fats from fat cells [Scappola1995]. This forces the fat cells to flood the bloodstream with triglycerides when insulin levels are low, i.e., after prolonged periods of fasting, such as overnight. The fat cells must dump enough triglycerides into the bloodstream during fasting periods to fuel the muscles when the dietary supply of carbohydrates keeps insulin levels elevated, and the release of fats from the fat cells is repressed. As the dietary carbs come in, blood sugar levels rise dramatically because the muscle cells can't utilize it.

The liver also processes excess glucose into fat, and packages it up into LDL, to further supply fuel to the defective muscle cells. Because the liver is so preoccupied with processing glucose and fructose into LDL, it falls behind on the generation of HDL, the "good" cholesterol. So the result is elevated levels of LDL, triglycerides, and blood sugar, and reduced levels of HDL, four key components of the metabolic syndrome.

The chronic presence of excess glucose and fructose in the blood stream leads to a host of problems, all related to glycation damage of blood stream proteins by glucose exposure. One of the key proteins that gets damaged is the apolipoprotein, apoB, that's encased in the membrane of the LDL particles. Damaged apoB inhibits the ability of LDL to efficiently deliver its contents (fat and cholesterol) to the tissues. Fat cells again come to the rescue, by scavenging the broken LDL particles (through a mechanism that does not require apoB to be healthy), taking them apart, and extracting and refurbishing their cholesterol. In order to function properly, the fat cells must have intact ApoE, an antioxidant that cleans up oxidized cholesterol and transports it to the cell membrane for delivery to HDL particles.

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