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Insulin and insulinemic index.
A constant level of glucose concentration in the blood is maintained with the help of pancreatic hormones - insulin and glucagon.
Insulin is a protein hormone that is formed by beta cells, the so-called pancreatic islets.
The intensity of insulin release depends on many factors, but above all - on the level of glucose (sugar) of blood. The action of insulin is aimed at reducing the glucose content in the blood, increasing its permeability of the cell membranes of various tissues.
The biochemistry of our body is designed so that as soon as sugar (glucose) enters the blood, the level of insulin rises. Glucose must be disposed of directly in the cells. Scientists suggest that our distant ancestors food rich in carbohydrates, came across quite rarely and seasonally. Nature compensatory provided for uncontrolled synthesis of insulin to ensure the full absorption of the most effective "fuel" in reserve. That is why, having consumed carbohydrates, whether you like it or not, you are launching an evolutionarily ancient biochemical reaction of synthesis and deposition of energetic material on a rainy day. Initially, by entering the blood, insulin contributes to the conversion of glucose into glycogen, but when there is not enough space for glycogen in the liver and muscles, glucose is directly converted into fats, which are deposited in the “bins” of subcutaneous fat. This pipeline synthesis of fats literally does not stop with the constant flow of glucose (sugar) into the blood.
At the same time, insulin has the peculiarity of causing an incessant feeling of hunger, a feeling of malnutrition, and a person becomes so accustomed to suppress this condition by ingesting carbohydrate foods that it becomes dependent on her as on drugs. A condition when you need to eat something carbohydrate every 2-3 hours to feel normal. Moreover, often in the "overdose" of carbohydrates from the islet of the pancreas will be thrown an excessively large amount of insulin. As a result, in half an hour the level of glucose will again decrease, and quite sharply. A condition that is called reactive hypoglycemia. It is accompanied by weakness, a decrease in physical and mental performance, and most importantly, the appetite sharply increases again, demanding another “dose”.
As is known, in India and China the elite used exotic drugs. Among these drugs was what we today call food sugar. This drug is very similar to today's cocaine. Perhaps the effect of sugar as a drug is somewhat exaggerated. But there are some obvious similarities between them: sugar, like cocaine, is a plant extract purified to a chemically pure state, i.e. does not contain vitamins, minerals, proteins or fiber.
Think about it!
It has long been observed that with the use of different types of products, the concentration of glucose in the blood, and, consequently, the response insulin release increases in varying degrees and at different speeds. This allowed Dr. David Jenkins, a professor at the University of Toronto in Canada, to introduce the concept of the glycemic index for the first time in 1981. The ability of carbohydrates to cause an increase in blood sugar levels (hyperglycemia) is determined by the glycemic index. This index will be the higher, the higher the hyperglycemia caused by the breakdown of carbohydrates, while the glycemic glucose index is taken to be 100. The higher this index in foods, the greater the amount of sugar in the blood when they are consumed.
David Jenkins thus tried to determine what kind of food is most favorable for people with diabetes. Later, the term was popularized by M. Montignac, and in 1997, scientists at Harvard University, led by Walter Willett, studied the relationship between food consumption with a high glycemic index and the risk of type 2 diabetes (insulin-independent), found that this relationship is right is proportional.
And very recently, Janette Brand-Miller from the University of Sydney, noticed that in some cases the pancreas secretes too much insulin in response to the consumption of certain types of foods with a low glycemic index. And then she introduced, in addition to the glycemic index, which characterizes the rate of increase in the level of glucose in the blood, the new index, insulinenemic, which characterizes the rate of insulin release in response to food. This indicator more accurately reflects the real picture and, by the way, it turned out that in most cases both these indexes correspond to each other - the more one, the bigger the other. In normal practice, the glycemic index describes the rate of rise in blood sugar levels in response to the consumption of the amount of a product containing 50 g of carbohydrates. Jeanette Brand-Miller took a slightly different approach.
First, for the product to compare, she took not glucose, but white bread. Its glycemic index is conventionally taken as 100.
Secondly, for experiments and for calculating both the insulinemic and glycemic indexes, it was not portions of the product containing 50 g of carbohydrates, but portions of products giving the same amount of energy: 1000 kilojoules (240 kcal.).
An example of some products, the insulinemic response of the body to which is stronger than glycemic:
(The first digit is glycemic, the second digit is the insulinemic index of foods by J. Brand-Miller).
• Croissant - 74 and 79
• Cake - 65 and 82
• Cookies "Donuts" - 63 and 74
• Cookies "Cookies" - 74 and 92
• Mars bars - 79 and 112
• Peanuts - 12 and 20
• Yoghurt - 62 and 115
• Ice cream - 70 and 89
• Potato chips - 52 and 61
• White bread - 100 and 100
• French loaf - 71 and 74
• Beef - 21 and 51
• Fish - 28 and 59
• Bananas - 79 and 81
• Grapes - 74 and 82
• Apples - 50 and 59
• Oranges - 39 and 60
These figures I give only for general comparison. There are whole lists and tables of such products, but they are needed, rather, by dietitians, as the very concept of the glycemic and insulinemic index of foods is very relative.
These indices may change under the influence of various factors. These factors include culinary processing of products, as well as the interaction of various products with each other. Patients suffering from obesity, it is enough to have a general idea of the mechanisms of influence of various products on insulin production and to take into account these indices for only a few types of the most frequently used products.
Many of my patients often ask me a question: “Why can we eat fruits containing fructose, and fructose itself is strictly prohibited in its pure form?”
Fructose is found in a wide variety of fruits and honey, as well as the so-called “inverse syrups”. Because of its low glycemic index (31 relative to white bread) and strong sweetness, it has long been considered an alternative to sucrose. Unlike glucose, fructose can penetrate from the blood into the cells of tissues without the participation of insulin. For this reason, it is recommended as the safest source of carbohydrates for diabetics.
Some fructose enters the liver cells, which convert it into glucose, so fructose is also able to raise blood sugar levels, although to a much lesser extent than other simple sugars. But fructose is much faster than glucose, it can turn into fat!
In experiments on rats, researchers at the University of Florida found that fructose is one of the links in the biochemical chain reaction that leads to an increase in body weight and the development of other signs of metabolic syndrome, the precursor of type II diabetes.
Fructose increases the level of uric acid in the blood, which reduces the activity of insulin, which regulates the process of storing and consuming carbohydrates in the body.
Frequent increases in uric acid can cause the development of metabolic syndrome, including obesity, elevated levels of cholesterol in the blood and, as a result, high blood pressure.
And all because fructose - natural sugar contained in fruits (although some fruits, such as oranges and grapes also contain a large amount of glucose) - are processed in the liver not into glycogen (a special substance that goes to cover the energy costs caused by muscular work ), and in fat! Once in the body, fructose passes a special enzyme, fructokinase-1. And he is responsible for the processing of carbohydrates into the body of energy and decides what to turn the carbohydrates into: glycogen or fat. Complex carbohydrates, such as oatmeal, pasta, wild rice, once ingested, are converted mainly to glycogen, and in this form are deposited in the liver and muscles. This happens as long as there is free space in the “stores” of your body, and only then these carbohydrates will be processed into fat (according to scientific data, the human body is able to save about 250,400 grams of carbohydrates in the form of glycogen). Fructose is the liver almost completely turns into fat, which, getting into the blood, is immediately absorbed by fat cells.
Little of! When it enters the blood, glucose usually passes unhindered through the liver - this kind of filter of the body is sent straight from there to the muscles. What happens if a part of the fructose obtained by your body gets into the liver and turns into glycogen? And the fact that your wise body itself will say "no" to any other incoming carbohydrates and block their flow, both in the liver and in the muscles through the liver. As a result, unclaimed complex carbohydrates will not be transformed into precious muscle glycogen, which is capable of providing a powerful burst of energy, but into a hated fat!
Recently, in a study published in the journal Hepatology, rats were fed sugar solution containing glucose in one case and fructose in another. Feeding rats with fructose led to two serious consequences: an increase in fat production in the liver and a decrease in the efficiency of protein leptin (among other functions, leptin is responsible for fat metabolism).
The study revealed that some of the negative properties of fructose were the result of a deterioration in the function of the receptor, known as alpha polyphosphoric acid. This receptor is present in the human body, and its activity in humans is less than in rats. As a result, one of the authors of the study suggested that the effect of fructose on humans should have even worse effects than those observed in rats. It seems that there is every reason to believe that the use of fructose can contribute to the growth of obesity, observed in the world.
Therefore, fructose is not considered a healthy dietary supplement. The use of large quantities of soft drinks containing fructose, more contributes to obesity than the use of other sweeteners.
At one time such work was carried out: the researchers offered experimental mice a choice of water, fructose solution and fructose soft drinks. In mice - lovers of fructose drinks, a more significant weight gain was observed even with a decrease in the total diet. In these mice, not only weight gain was noted, but, most dangerously, this increase was 90% due to adipose tissue.
It is also proved that some hormones that respond to glucose (leptin, insulin, etc.) do not perform their normal functions when fructose is consumed. The appearance of obesity is explained not only by the high caloric content of fructose, but also by changes in metabolism that contribute to the accumulation of fat.
Let's imagine two oranges. One we just cleaned, eat, and squeeze out the other juice and drink it.
What happens when this juice gets into our stomach, and then the intestines. The fructose contained in it in liquid form is instantly absorbed and converted into glucose. If we just eat an orange, our body will have to spend time and effort to extract fructose from it. In this case, its entry into the blood will not be as rapid as from the juice. Insulin for utilization of the glucose formed then will be released gradually and gradually.
Fans of fructose should also be aware that it is high in calories like sugar — 2.5 times sweeter than glucose and 1.7 times sucrose. For this reason, a number of experts associate the obesity epidemic in the United States with the use of fructose.
We have been talking so much about carbohydrates and their ability to influence insulin production, which inadvertently raises the question of what is the relationship between insulin production and fat accumulation.
It turns out that in humans the process of accumulating or not accumulating fat in the body is directly related to the release of this wonderful hormone. Insulin is secreted by the pancreas and plays a vital role in the metabolism, promoting the penetration of nutrients into the cell. And although its main natural purpose is to remove carbohydrates from the blood, in some cases it is directly involved in the deposition of fat. Why and how does this happen? Let's figure it out.
So, the body's normal reaction to an increase in blood glucose is insulin secretion, which affects glucose (that is, sugar), helping it to penetrate into the body's tissues. It's good. Glucose immediately satisfies the body’s energy needs. And it's great! It seems that's all !? Blood sugar "decreased" - insulin should not stand out anymore.
But as it turned out, some people always have too much insulin in their blood. This is associated with a loss of sensitivity to it by the receptors of the body (insulin resistance). Remember what I wrote at the beginning of this chapter.
Sometimes heredity, sometimes chromium deficiency is to blame, but more often - the love of sweet life, that is, easily digestible carbohydrates. For several years of constant consumption of a huge number of products with a high glycemic or insulinemic index, the pancreas learns to throw out endless streams of insulin, and the body loses sensitivity to it over time. At the same time, even despite the decrease in glucose (sugar) in the blood, insulin continues to be released into the blood, since its regulation is violated.
A fairly simple and fairly accurate criterion for determining the presence of pancreatic pathology and loss of sensitivity to insulin receptors is associated with the distribution of fat. It is defined as the ratio of the lengths of the waist and hip circumferences. However, as was established in recent studies, more accurately, the abdominal fat accumulation situation is characterized by the size of the waist circumference itself.
Dr. Gerald M. Riven and his colleagues at the Stanford University School of Medicine have suggested that a BMI (body mass index) and waist circumference may be equally effective in identifying patients with insulin resistance. In this case, the risk group can include those patients whose waist circumference in men exceeded 94 cm, and in women 80 cm. Do you want to measure your waist? I'll wait. Although for many the big question is where to look for this very waist.
Scientists rated 260 apparently healthy volunteers, 133 of whom were classified as having obesity. They found that insulin sensitivity and the associated metabolic cardiovascular risk factors are directly related to an increase in obesity, regardless of what was used as an overweight index — BMI or waist circumference.
So, suppose you have a hidden or apparent resistance (insensitivity) to insulin. At the same time, the blood has a constantly high concentration of this hormone, and you decided to pamper yourself with, say, a cream cake. What will happen? What will happen is that - immediately satisfying the energy needs at the expense of sugar, your body will immediately try to put fat (fat cream) in reserve. And he will do it very successfully due to the huge amount of the same insulin. After all, the body fat depot is huge. As this happens on a more subtle level, I will try to explain in an easy way.
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Insulin and insulinemic index.
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