by Zina Kroner, DO
Yes, carbs can indeed elevate cholesterol. This sentence is not a typo.
Assume that you have an unfavorable cholesterol profile (low HDL, high triglycerides and low LDL). The typical scenario is as follows: You have high cholesterol, you pursue a million dollar workup with your cardiologist, including a stress test, EKG, blood work, etc, and the ultimate recommendation is to follow the Dean Ornish Diet. This diet was based on a five year intervention study called the Lifestyle Heart Trial which followed 48 men with heart disease and told them to exercise, manage stress, stop smoking, get psychological help, and go on a high fiber, low fat and low calorie diet. Of the 48 men, 20 actually completed the study, where all the recommendations were adhered to.
The results showed that there was actually some reversal of heart disease! The bottom line that was extracted from this study was that a low fat diet helps to reverse heart disease. Seldom were the other factors addressed. Since then, most patients have been advised by their cardiologists and internists to stay on a diet of this nature.
Thereafter, many have tried to comply with the low fat diet and noticed that cholesterol was not dropping. Hmmm… Let’s look at the science to figure this out.
I am going to break this one down to the nitty gritty details, so beware.
How Carbs Actually Elevate Cholesterol
You are eating your whole grain toast or dairy item in the morning with fruits, pasta for lunch and a rice dish with a protein for dinner. Your desserts are always fresh or dried fruits. You are drinking juices with your meals. Once the digestive juices are appropriately secreted and the food is churned, the necessary nutrients are absorbed through the intestinal walls. Glucose (derived from carbs), amino acids (derived from proteins), and fatty acids ( derived from fats) are passed through a corridor (the portal vein) and enter the liver.
The pancreas is paying very close attention to the molecules passing through this corridor into the liver.
It gets quite excited when it sees glucose and quickly shows its affection by secreting insulin. Insulin does several things:
It stimulates the production of cholesterol. Many of you have heard of statin drugs. They work by inhibiting an enzyme called HMGcoA reductase. Insulin stimulates this enzyme! How can it be possible for your cholesterol to go down if the foods that you are eating stimulate the very enzyme that cholesterol reducing drugs are trying to decrease?
Insulin slows down an amino acid called carnitine. Carnitine is important because it functions to shepherd the fatty acids into the part of the cell where they will be converted into usable energy. Insulin can therefore harbor weight gain by not allowing the fatty acids to be converted into energy effectively, via the mechanism of carnitine.
Insulin causes cells in the liver, muscles and fat to take up glucose. In the liver, the glucose is stored as glycogen. Here is the interesting part… There is not that much glycogen in the liver, so whatever sugar the liver is unable to hold is spilled over to another processing system. The glucose is packaged neatly into triglycerides. Yes, the ones associated directly with cardiovascular disease. This was the bottom line, ladies and gents. VLDL (very low density lipoprotein ) is then stimulated by the liver and LDL, the bad cholesterol) is made. Whew!
When there is not much glucose in he body, as in the case in a lower-carb diet, there is no signal to release the insulin. Insulin is absent (or low), glucose is not taken up by the cells and triglycerides are not manufactured from the spillover of glucose. Therefore, the above process is not as robust. With low insulin levels, the body begins to use fat as an energy source since it does not have the glucose. Using fat as an energy source is one of the mechanisms of weight loss. Let’s pause for the “ahaa” moment.
So there it is, eat low carb and see the weight come off and cholesterol decrease. A common mistake is that patients eat BOTH low and high carb simultaneously. They also focus on meats that are not lean. They come into my office telling me about all the healthy proteins they have been eating. Only problem is that they are having tons of rice or pasta along with a small amount of fatty protein. Taking the above mechanism of action into consideration, this is truly counterintuitive,.
Please reread the mechanism several times. Once you understand it, you will be able to intelligently change your diet. Being informed is crucial.