CHAPTER EIGHT-INSULIN-The Root of All Evil?
I can make this complicated or I can make this simple. After all, I am a doctor. Since I like to keep things simple, we will stick to keeping it simple. Ahhh, Insulin, what can I say about insulin that has not already been said? Well, actually, a lot.
First off, let me be the first to tell you to be afraid of insulin, be very, very afraid. It is actually insulin that controls how and when sugar will be changed into cholesterol and fat. So the more insulin we secrete the more cholesterol and fat we make. And as a little aside insulin also increases our risk of developing and spreading cancer, which I will explain later. So now you must be wondering,” What is insulin and where does it come from?"
Insulin is referred to as a polypeptide hormone. Hormones come in many shapes and sizes. Some are made up of proteins others are created from cholesterol. That is correct, cholesterol is necessary for the development of many very important hormones. I mentioned this before. Testosterone, estrogen, and cortisol are but a few. Without these hormones, we die. So, without cholesterol, well, I am sure you get it…
A hormone brings messages that control the activities of our cells. They are very important for normal cellular function. We are taught in biology classes that the main role of insulin is to allow sugar to get into the cell. This is true. Without insulin sugar has a very difficult time getting into cells.
The pancreas in response to the presence of carbohydrates secretes insulin. So, whenever we eat carbohydrates and/or food containing sugar the pancreas will squirt out insulin. Now it is true that one of insulin's roles is to help sugar get into cells; but insulin does a lot more. A whole lot more.
As I started to mention above it is insulin that controls many of the very important steps which allow our bodies to make cholesterol. Insulin also sends the signals for us to make more triglycerides. And it is the presence of insulin which prevents us from losing weight.
All doctors know that in medical language insulin is referred to as an anabolic hormone. Anabolic simply means growth promoting. Some of my readers will recognize anabolic as preceding the word steroid, such as anabolic steroids used by athletes. And it means the same thing there; anabolic steroids promote growth.
The reason insulin is anabolic is because, again, it sends all the signals to our body’s cells to make fat and to prevent us from losing weight. Insulin controls key enzymes for cholesterol synthesis most notably HMG CoA reductase (also known as 3-hydroxy-3-methylglutaryl CoA reductase). When insulin is present it will tell this enzyme to make more cholesterol.
Remember insulin is secreted every time we eat carbohydrates (unless you are a Type I diabetic, which I will discuss a little later). Insulin will then tell the very thing that helps make cholesterol, HMG CoA reductase, to make more cholesterol. Oh yeah, do not forget that our bodies actually use sugar to make cholesterol.
So let me make this perfectly clear. Not only by eating carbs are we giving the body what it needs to make cholesterol; when the body secretes insulin in response to carbohydrates, the insulin actually speeds up cholesterol production. When we eat carbs we are giving the body everything it needs to make more cholesterol.
Now this HMG CoA reductase thing is not just a way for me to show off and say big words. It is very important for cholesterol production. In biochemical language we refer to this enzyme as the rate-limiting step in cholesterol synthesis. This is a fancy way of saying that once this enzyme gets started it is going to finish what it started doing and there aint no turning back. So once insulin encourages this enzyme to work it will make cholesterol no matter what.
For our body's sake it is better that it sees as little insulin as possible. The only way to have any effect on insulin's presence is by lowering the carb intake. That is it. There's no other way to really, truly have an effect on insulin levels in the blood other than by lowering your carb intake.
Lower your insulin level and you lower the activity of that HMG thing. Oh, and something else. Remember when I mentioned a little while ago that eating cholesterol lowers your body’s production of cholesterol. Guess how it does it? Well, when you eat cholesterol it actually combines with the HMG CoA reductase and tells it not to work as hard. The cholesterol in the foods we eat actually turns off the enzyme that makes itself. But it does not stop there. The cholesterol in the foods we eat will also tell the cells which make cholesterol to make less of the very enzyme that makes itself.
So eating less carbs helps by not giving the body what it needs to make cholesterol. Lowering the carb intake also means less insulin secretion. Less insulin secretion, less stimulation and production of HMG. Less stimulation and production of HMG, less cholesterol production.
When I place a patient on a low carb diet I also encourage them to eat more cholesterol, not high, simply more. Let us simplify what happens when we eat cholesterol-containing foods. More cholesterol in the diet, less stimulation and production of HMG. Less stimulation and production of HMG, less cholesterol is made. So, by eating lower carbs and more cholesterol, we make less cholesterol.
What is also very interesting is how the major drugs we docs use to lower cholesterol work. These meds are referred to as statins. The statins actually prevent HMG CoA reductase from working. By doing this these meds lower cholesterol production.
But we can have a similar and more dramatic effect when we lower the carbs and eat more cholesterol. When we eat this way we are manipulating the ability of HMG to make cholesterol and we are also telling the body to stop making HMG. The cholesterol lowering meds do not go this far. They only work on the HMG. With low carbs we lower cholesterol naturally and we can avoid medication all together.
Another question which may come up is, "How does insulin affect the TG number and our fat stores?" Well, when the pancreas in response to a carb meal secretes insulin the insulin will also interact with the enzymes responsible for fat production and utilization.
"Insulin inhibits lipolysis." (1) This is a statement found in a Biochemistry book I read more than a few times in college. This statement is so very important, yet I did not understand the profoundness of it until nine years ago. What the statement means is that insulin slows down the breakdown of fat in our body. In fact, when insulin is present our body is sent the signal to not only stop burning fat, but to make more fat. The more insulin and the more difficult it is to lose weight. And weight gain is inevitable the longer insulin is around. What keeps insulin around? Eating carbs. So if you want to make it very difficult to lose weight eat more carbs. Exactly what we do when we follow a low fat, low cholesterol diet.
Another hormone, glucagon, is also secreted by the pancreas. When this hormone is secreted it has a reverse effect than that of insulin. The more glucagon the more fat we burn and fat storage is prevented. What causes a release of glucagon? Avoidance of carbs and the consumption of protein in the diet.
It might be a good time to re-visit the whole concept of the calorie and why the calorie is irrelevant in human nutrition. Remember we discussed that calories were measured in a closed system where we knew everything about the system. I also mentioned that our bodies are open systems where it is impossible with our knowledge today to measure everything that is happening in the body. A great example of this open system concept is glucagon and insulin. Once we eat a food substance the hormones insulin and glucagon (among many hundreds, thousands? of other hormones and digestive enzymes) are secreted. The interplay between even these two hormones is complex, but just remember this; insulin makes us get fat and stay fat; glucagon sends the signal to lose fat and to not gain weight. Eat carbs and insulin is secreted and you get fat; eat less carbs and more protein, less insulin and more glucagon will be secreted, and this helps us lose weight.
There is no way to measure exactly what is happening, that is, how much glucagon was secreted versus how much insulin? Ok, well maybe we can measure in the bloodstream these two hormones, but what about the hundreds of others, what about the digestive enzymes, what about all the things we have not even discovered yet? I am getting a headache just thinking about it. Since a calorie is measured in a closed system and our bodies are open systems, again, using the term calorie to help understand any nutritional concept is like comparing apples to kites. They just are not the same. The calorie is irrelevant; do not use it, ever, unless you are a quantitative heat chemist.
We need to get into a little more detail about how insulin actually works. I said earlier that insulin is important as it allows sugar to get into our cells. Without insulin sugar cannot get into our cells very well.
As an aside, when we are exercising our muscle cells allow sugar in with very little or no help from insulin. But how exactly does insulin help sugar get into our cells?
In order for insulin to allow sugar into our cells it first binds to the outside part of the cell. This outside part is known as a cell membrane. When insulin binds to the cell membrane it sends a message to the inside of the cell. Insulin can do this because the place where insulin attaches to goes through the entire cell membrane and causes changes to the inside of the cell. These changes that occur are what allow sugar to finally get into the cell.
Since insulin is the first thing that carries the message, the message to let sugar in, it is called the first messenger. Once insulin attaches to the cell surface it sends a signal through the cell membrane causing a release of chemicals called the second messengers. It is these second messengers that eventually let sugar into the cell and it is the overuse of these second messengers that gets us into trouble. How many people know that insulin causes cell damage in and off itself? We need to examine what, exactly, these second messengers do to give the cell the message to let sugar in.
Two things relay the second message. One is a substance called IP3 (inositol 1,4,5-triphosphate) and the other is DAG (diacylglycerol). These two things come from the breakdown of something called phosphatidyl inositol 4,5-bisphosphate (also known as PIP2). (2). Now don't lose me; it really is not difficult to follow through.
To recap, insulin binds to the outer part of the cell and is referred to as the first messenger. The attachment of insulin to the outer part of the cell sends a message to the inside of the cell. The message insulin brings is to break apart PIP2 into IP3 and DAG. It is IP3 and DAG which are the second messengers.
Now this does not seem like a big deal. Heck, we need to get sugar into the cell. We would rather have it inside the cell instead of outside the cell. In fact, if sugar stays outside the cell as I have mentioned before it will start to attach to things it should not and will cause a malfunctioning of cells and then organs. This is what causes the side effects of diabetes, which we will discuss in Part 2.
Anyway, in order to get the sugar into the cell we need the help of IP3 and DAG. The problem is not with IP3. The problem lies with DAG. DAG stood for diacylglycerol, just a fancy way of saying 2 acyls and a glycerol. It is with one of these acyl things that all havoc breaks lose.
Now acyl is just a big fancy way of saying a long fat chain. So this diacylglycerol contains two long fat chains as di means two. The problem is that one of these fat chains is something called arachidonate. Arichidonate is the starting point for the creation of extremely important signaling molecules. These are known as prostaglandins, prostacyclins, thromboxanes and leukotrienes. (3) The other term we use for these signaling molecules is eicosanoids. (An excellent review of this whole process can be found in Barry Sears, The Zone.)
In fact, an enzyme known as diacylglycerol lipase breaks down DAG into arachidonate. Then the signaling molecules, the eicosanoids, can be made. My physician readers will recognize most, if not all, of these signaling molecules.
The problem with these signaling molecules is that they may not send nice messages to our cells. The prostaglandins are known to allow us to feel pain and to promote the development of clot formation by making platelets stickier. Thromboxanes have the opposite effect, they make platelets less sticky. The leukotrienes will allow us to experience a worsening of allergy symptoms, including asthma.
Arachidonate has also been implicated in sending signals for tumor (cancer) growth as well as sending signals to allow cancer to spread (metastasize). If you want to scare yourself go to your favorite search engine and perform a search of arachidonic acid and cancer. How many hits did you get? It has been known for years that arachidonate sends cancer-promoting messages to our cell’s DNA. Obviously not a good thing, but more about the cancer and carb connection later.
Let me put this all together. When we eat carbs our pancreas secretes insulin. Insulin allows us to make more cholesterol. Insulin also is anabolic in a sense that it prevents us from losing weight and helps us to gain weight. We also now know that insulin acts through a second messenger system. We also found out that one of these messengers, DAG, can be extremely dangerous. The more DAG, the more bad messages can be sent within our cells. The problem is that the more insulin we secrete the more DAG is created. But it all goes back to what? Carbs. Carbs set into motion all of these bodily processes which are not good for us.
So it is essential we do not over eat carbs. What would be considered overeating? Well, if any of you have a medical problem requiring medication, you probably should not allow yourself anymore than sixty grams a day of carbs. If you are a diabetic, then no more than twenty or thirty at the most. Remember, it is absolutely imperative that before any of you start a low carb diet, you need to find an experienced low carb doc who can watch you like a hawk. Do not, I repeat, do not under any circumstances start a low carb diet without first consulting your doc. If your doc tells you that you should not start a low carb diet-----find another doc who knows what they are talking about.
I know this has been a long chapter, but it is an important one because it shows how insulin is involved in creating some very bad things. Now do not get me wrong insulin is needed in small quantities and without it we would die. But the amounts that a typical person secretes each day are extraordinarily high. And it all goes back to carbs. It was the consumption of carbs which caused the insulin to show up in the first place. A little bit of insulin, fine. But the amount of insulin most people squirt out, well, it encourages cholesterol production, allows us to get fatter, and from the discussion above, sends signals to allow us to experience more pain and can increase our development of cancer. And this is just the tip of the proverbial iceberg. We all need to be afraid of insulin; we need to be very, very afraid.
Dr. James E. Carlson B.S.,D.O.,M.B.A.,J.D.
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