INSULIN: THE MASTER KEY TO A LONG HEALTHY LIFE

The mention of insulin reminds one of blood sugar and diabetes. Although insulin has a first order effect on blood sugar, it has a second order effect on several other metabolic functions. We all know that centenarians (people living to be 100 and beyond) come from many regions of the world and they have varied lifestyles. Some are even tobacco users and smokers but there are 3 consistent things that are common among all of them and that is they all have low insulin, low blood sugar and low triglyceride levels. Among all three factors insulin is the common denominator. So keeping low insulin levels in the blood is the key to a long life span. Let’s go a little deeper to understand why this is the case.

Whenever we eat something our blood glucose level rises. Glucose if left free in the blood is a dangerous thing. It can stick to proteins and destroy their ability to regenerate our cells (that’s why diabetics don’t heal a wound) and in severe cases lead to kidney damage and blindness. So the glucose has to be converted into energy or stored. The way glucose is converted to energy is by first converting to glycogen and then getting stored and used up in the muscles during physical activity. The excess glucose gets stored in the cells as fat.

To counteract the presence of glucose in the blood the pancreas release insulin and as soon as insulin acts on glucose in starts storing it, preferentially as glycogen and later as fat. This is why having more muscle helps raise the metabolic rate as it leaves less glucose for fat conversion. The liver also releases fat into the blood stream as triglycerides for energy conversion but triglycerides just like glucose are also dangerous if left unchecked in the blood (high levels of triglycerides have been linked to coronary heart disease). So the other role of insulin is to signal the liver to stop the release of triglycerides into the blood stream after a meal.

Eating a high GI meal causes a sudden spike in the glucose levels and the pancreas over compensate by releasing a large quantity of insulin into the blood stream. We all remember learning to ride a bike as children or learning to drive a car as youngsters. Think of blood glucose as the road and your pancreas as the driver and insulin as the steering wheel. As a novice driver you remember that every time you hit a sharp right turn you overcompensated by turning the steering wheel too far to the right and then had to quickly turn left to stay on the road and vice versa. But you had no trouble driving on a straight or slightly curved road. As you got better at driving you of course navigated the sharp turns as well, but in the case of our pancreas/insulin system the driver (pancreas) never gets better at controlling the steering wheel (insulin) as it hits the sharp turns (sudden glucose spikes). As a result of this overcompensation there is insulin left behind in the blood after all the glucose has been stored and put away. Insulin like any other chemical is also toxic if it starts acting on cells (rather than on glucose). As a result of this the cells down-regulate their insulin receptor activity once they detect free insulin in the blood stream, making them insulin resistant. So the next time around the pancreas have to release even more insulin to get the same effect. Over time the pancreas give up and stop producing insulin and the person becomes diabetic. Also not all cells are equally resistive (or sensitive) to the action of insulin. The liver is the easiest to become resistant followed by muscle cells and then followed by fat cells. So you can see the fat cells are the least insulin resistant meaning they are most receptive to the storage mechanism of Insulin. Ideally one would want the opposite to be true, i.e., the fat cells to be the most insulin resistive and the muscle and liver cells be the most insulin sensitive.

Ok, so we know that high insulin levels cause preferential fat gain and if that’s not reason enough to give up your high GI foods how about the fact that high insulin level is one of the prime reasons for high blood pressure, osteoporosis and some forms of breast and colon cancer? Ok so you think I am trying to scare you. Well let’s see how insulin is responsible for all of the above so called chronic diseases of aging.

We all know by now that insulin’s role is in storing excess nutrients into the cells. So insulin is also responsible for storing magnesium, but if your cells become resistant to insulin you can’t store magnesium and lose it through urination. The role of intra-cellular magnesium is to relax the cells and lack thereof causes the cells to constrict. This also happens in your blood vessels as they become magnesium deficient. So what results is high blood pressure.

Another problem that occurs with insulin resistance is osteoporosis. Insulin is like the master key that controls all the other anabolic hormones like growth hormone, testosterone and progesterone. In insulin resistance the production of these hormones is hampered. Bones and muscles are both built by the command of these hormones so with the lack of them, bone building is reduced and the amount of Calcium excreted in urine is increased.

Lastly, insulin has been shown to favor cellular proliferation. What does this mean? It means insulin can help cancerous cells to grow and multiply. In two pretty conclusive studies [1, 2] a strong correlation has been shown between insulin levels and the incidence of breast and colon cancer.

But wait it’s not all that bad. The good thing is insulin levels are very sensitive to exercise and diet. So these are the two variables that are in your control which in turn can help you control your insulin levels and the sooner you take action the farther in life you will get (literally). A low carbohydrate, no sugar diet is the best way to keep your insulin levels low. Also eating small meals throughout the day is a good way to keep steady blood glucose levels and this gives your pancreas time to react and release optimum levels of insulin into your blood to counteract the glucose. It’s easier for the pancreas to make small adjustments to the insulin levels to counteract small fluctuations of blood glucose (from a low GI diet), rather than over compensate large amounts of glucose (from a high GI diet) with even larger amounts of insulin. The other thing one can do is to increase the insulin sensitivity of the muscle cells. Remember earlier I talked about how the muscle and liver cells become insulin resistant where as the fat cells are the last ones to become insulin resistant. This shifts the insulin storage mechanism to favor fat storage instead of glycogen storage. By exercising the muscle cells one can increase the insulin sensitivity of the muscle cells so they become more receptive to the storage mechanism of insulin. This can be accomplished by regular aerobics exercise. Resistance training has an additional benefit as it not only increases the insulin sensitivity but also increases the volume of muscle cells so it can store even more glycogen leaving less glucose behind for fat conversion.

Controlling your blood glucose levels is one of the most powerful anti-aging strategies you can implement in your lifestyle. A high GI diet and sporadically eating big meals cause a sudden surge in your blood glucose levels and as a result your pancreas produce large quantities of insulin to counteract it and this is the single most powerful factor responsible for accelerated aging.

References:

Annual meeting of American Society of Clinical Oncology, New Orleans, May 23.

National Cancer Institute 2002 September 4;94(17):1293-300