Sources Of Carbohydrates: Excess And Deficiency In Food

Carbohydrates are essential components of food that perform a wide range of functions in the body. It is not only the raw material most readily used by cells for energy, but also a structural component of many macromolecules - in particular, DNA and RNA.

Is the elimination of this class of organic compounds really shown, or is the new fashion a potential threat to the organism? What does excess food lead to and is there a relationship between their deficiency and menstrual irregularities? Let's figure it out.

Classification of carbohydrates

All carbohydrates can be divided into simple (the molecules of which are initially represented by structural units) and complex, built from monosaccharide bricks interconnected by chemical bonds.

The first do not need to be split: they, initially having a primitive structure, freely enter the bloodstream through the intestinal wall, which causes a sharp increase in the concentration of glucose in the blood, which entails increased production of insulin by the beta cells of the pancreas, a protein hormone that seeks to return elevated sugar values. in serum to the initial optimal values. We will talk about this in more detail below. This category of carbohydrates, in particular, includes:

• glucose;

• fructose;

• galactose.

From the two base blocks of the above monosaccharides, disaccharides are synthesized - this is an intermediate link between simple and complex carbohydrates. Sucrose, lactose (milk sugar), maltose (malt sugar) - all representatives of this group are also quickly absorbed (since the corresponding enzyme needs to first cleave only one chemical bond) by the epithelial lining of the small intestine and sufficiently stimulate the pancreatic islets.

Slow or complex carbohydrates are polysaccharides. Their long, branched chains contain a huge number of simple sugar molecules linked together. Considering their imposing size, it becomes obvious that they need a long enzymatic treatment before the actual absorption process, which, in turn, mediates a smoother increase in serum glucose concentration and distinguishes them favorably from other compounds. These are, first of all, the components that make up vegetables, cereals and legumes, as well as dietary fiber, which is especially rich in greens.

Functions of carbohydrates

1. Energy is the simplest substrate that cells easily and willingly send to their furnaces. In the presence of all the necessary conditions (oxygen; the absence of a deficiency of those vitamins whose coenzyme forms are involved in catalytic reactions; as well as the proper concentration of magnesium and calcium ions, which significantly mediates the work of specific enzymes), one glucose molecule ultimately produces 38 ATP molecules. (compared to several hundred, which ensures the oxidation of lipid components such as glycerol and fatty acids).

2. In the process of the pentose phosphate pathway, one of the mechanisms of glucose utilization, the structural building blocks of nucleic acids (DNA and RNA) are formed, as well as the coenzyme form of vitamin B3 (NADPH), which largely protects red blood cells from hemolysis.

3. Reserve - is carried out by storing glycogen - a polysaccharide in the pantries of the liver, which ensures (in conditions of a decrease in the concentration of glucose in the blood) the return of its level to optimal values.

4. Carbohydrate molecules are part of many cellular receptors, thus participating in the transmission of various kinds of signals.

Metabolism of carbohydrates in the body

Understanding the metabolism of carbohydrates - the main fuel of cells (especially in the context of the traditional type of nutrition) - is the key not only to predicting certain metabolic disorders, but also an important element in the formation of a holistic picture of the disease.

The metabolism of glucose, fructose and galactose - the main representatives of monosaccharides - is quite different from each other. Let us consider some fundamentally important points of their further biotransformation in the human body.

Glucose homeostasis is one of the iron postulates of the body, the violation of which leads to very adverse consequences. So, there are parameters of the concentration of this sugar clearly set by the program, strictly regulated, first of all, by the endocrine system. In healthy people, as a rule, its level does not fall below 2.5 mmol / l and does not exceed 8 mmol / l after eating.

The central conductors that assume the duties of control are the hormones: insulin and glucagon. Possessing a polypeptide nature (that is, representing amino acid residues linked by chemical bonds) and being formed by the islets of Langerhans, which are located in the pancreas, they perform radically opposite effects.

The task of the first is to reduce the level of glucose, which naturally increased after eating, to the optimal level. This is achieved by increasing the density of a specific carrier (GLUT4) of glucose - a protein under the action of insulin, which ensures its entry into the cell - in other words, it helps to overcome the customs border in the form of a plasma membrane. This process is especially pronounced in muscle and adipose tissues. In the latter, in addition, it includes the mechanism of lipogenesis - that is, it promotes the synthesis of fat (triglycerides).

In addition, insulin actively stimulates the formation of glycogen in the liver, a reserve substrate that can cover the energy needs of the body for some time in the event of starvation.

Glucagon acts differently: all of its effects are aimed at increasing the concentration of glucose in the blood serum. So, it activates the mechanism of gluconeogenesis in hepatocytes - endogenous production of glucose is launched, the raw material for which can be various non-carbohydrate components: ketone bodies and, in particular, amino acids, obtained mainly due to the breakdown of proteins. It also acts on key enzymes that regulate glycogen catabolism - the latter is again broken down to glucose.

Fructose metabolism is very different: if only because it does not stimulate the secretion of insulin from the beta cells of the pancreas and partly thus bypasses the path of saturation, without affecting the satisfaction of hunger. Cellular ovens are also unable to utilize it as an energy source - at least without first converting it into glucose. In addition, it can go to the formation of triglycerides - this is the relationship between the excessive intake of this monosaccharide and the development of non-alcoholic fatty liver disease. So fruits also get fat - especially the internal organs.

Excess carbohydrates in food

Excess intake of carbohydrates with food is a powerful provocateur, which invariably leads subsequently to various kinds of disorders.

Insulin resistance is not only a straight road, but also a key step before a vast plateau called “type 2 diabetes”. And if earlier it was believed that this diagnosis becomes predominantly in adulthood or rather old age, now there is a significant “rejuvenation” of this pathology, which, unfortunately, cannot but be alarming. Undoubtedly, lifestyle plays a key role: fractional nutrition, rich in carbohydrates (payback for low-fat diets) and especially fast sugars (compare only the sales statistics of corn syrup in the United States, which soared dozens of times compared to the 2000s), a sedentary lifestyle life (scientists reasonably suggest that physical activity is one of the main factors preventing the development of carbohydrate metabolism disorders).

In addition, the distinction between lean patients suffering from type 1 diabetes and those prone to obesity in type 2 has also lost its relevance: a significant percentage of people, even visually thin, are susceptible to insulin resistance. They are also called “skinny fat” - despite the external (hidden by clothes) lack of fat, their proportions are far from ideal.

So, the main differences between the two diseases are far from being in the human constitution: it, as already mentioned, varies quite a bit. It is important that in type 1 diabetes, the destruction of insulin-producing cells under the action of immunocompetent cells is observed - in other words, this is an autoimmune process in which T-lymphocytes cease to distinguish between “self” and “foreign”. In its occurrence and progression, unfortunately, researchers rather give priority to viruses and mutations than to excess intake of carbohydrates.

In such patients, the appearance of antibodies to their own structures, for example, to the islets of Langerhans, is clearly visible. In addition, immunoglobulins to insulin and to glutamate decarboxylase are detected - they are quite sensitive markers that can be used to judge the degree of development of the pathology.

Type 2 diabetes mellitus, on the contrary, being a consequence of insulin resistance, develops precisely because of the excessive intake of carbohydrates, accompanied by physical inactivity. However, a genetic predisposition is not excluded here either: for example, mutations of one of the most important enzymes in glucose metabolism - glucokinase - contribute to some extent to its development.

In the context of obesity and the connection with insulin resistance, it is difficult to draw a parallel and determine which of them nevertheless serves as a trigger and which is a consequence. So, for example, it has been proven that due to the high density of receptors, visceral adipose tissue is very sensitive to adrenaline stimuli, which increases the efficiency of lipolysis - in simple words, fat burning. The free fatty acids formed in this case are sent with the bloodstream to the liver, where they not only disrupt the interaction of insulin with its cells, but also stimulate the process of gluconeogenesis - endogenous glucose synthesis is enhanced. They also have a direct toxic effect on pancreatic cells, inducing their programmed death - apoptosis.

Adipocytes also begin to secrete a large number of pro-inflammatory signaling molecules, among which, undoubtedly, interleukin-6 and tumor necrosis factor play a dominant role. Chronic inflammation develops.

In any case, based on the fact that all excess carbohydrates that are not converted to glycogen are converted to triglycerides, the continuity of sugar and lipid metabolism is evident.

Overall, given that obesity is an independent risk factor for CVD (overweight patients are more than 50% more likely than the healthy population, according to the Framingham Study), it is much easier to start , by modifying the way of life and adding to it moderate physical activity, timely complex work, than to disentangle much more serious consequences in the future.

If you still lack motivation, here are a few more adverse effects that a disturbed carbohydrate metabolism contributes to:

1. Coronary artery disease - for example, in patients susceptible to this cardiovascular pathology, fasting insulin concentration was 18% higher than in the control healthy group, as demonstrated by the published results of the Quebec study.

   Speaking about the damaging effect of excess glucose circulating through the vessels, it is impossible not to mention its ability to bind to certain sites of proteins (for example, albumin, which is the basis of such a laboratory test as determining the level of fructosamine) and lipoproteins, which partly contributes to the progression of atherosclerosis.

   The active production of free radicals also adds fuel to the fire - oxidative stress develops.

   An increase in the tone of the sympathetic system leads to an increase in the secretion of adrenaline and an increase, due to its effects, in blood pressure.

    

2. Polycystic ovary syndrome, manifested by anovulation, excessive hair growth, oily skin and acne. The violation of the menstrual cycle contributes to the increased formation of androgens by ovarian cells under the action of insulin and a decrease in the synthesis of a specific protein binding and, thus, inactivating them, by hepatocytes (SHBG).

3. An increase in the tone of the sympathetic nervous system observed in insulin resistance, as well as a slowdown in the excretion of uric acid by the renal tubules, contribute to its accumulation with the further development of gout.

Glycemic and insulin indexes

Given the significant differences in the chemical structure of various representatives of this class of organic compounds, we recommend focusing your diet on “complex” carbohydrates: their slow absorption, due to the preliminary need for enzymatic cleavage of long, branched carbon chains, also causes a much smoother (compared to simple sugars) secretion of insulin with the absence of pronounced hypoglycemia in the future.

You should also take into account indicators such as:

• Glycemic index (GI) - reflects the change in the concentration of glucose in the blood serum after eating certain foods.

• Insulin index - characterizes the production and secretion of insulin in response to a particular food component.

I must say that these indices do not always coincide: for example, dairy products slightly affect blood glucose levels, but significantly stimulate pancreatic beta cells to produce insulin (due to the BCAAs they contain - branched chain amino acids) .

In general, it is advisable to give preference to fresh vegetables and greens - these are excellent sources of fiber, which not only activates the motility of the large intestine, thereby contributing to the evacuation of feces, but also slows down the absorption of monosaccharides.

It is advisable to limit foods containing lectins:

• nuts;

• tomatoes;

• potato;

• Bell pepper;

• eggplant;

• grain crops.

This is relevant, first of all, with an already existing violation of the permeability of the intestinal wall, or if it is damaged, which can lead not only to a perversion of absorption processes, but also to suppression of enzymatic cleavage, since some of the enzymes are located precisely on the epithelial villi, and not only in the intestinal lumen. This, by the way, causes a certain percentage of complaints about lactase deficiency in those patients who do not have genetically determined fermentopathy.

Cereals containing gluten, as well as its hidden sources, also fall under the category of the ban:

• Wheat flour;

• rye;

• barley;

• oats (not labeled “gluten free”);

• pasta and pastries using the above grains;

• canned food;

• semi-finished products;

• purchased sauces;

• confectionery;

• sausages;

• yogurts;

• granola and breakfast cereals;

• couscous;

• soy sauce;

• semolina;

• bulgur;

• beer.

Lack of carbohydrates in food

Glucose homeostasis, as we previously demonstrated with the example of the insulin-glucagon relationship, is clearly regulated and under the relentless control of the endocrine system. With a decrease in its concentration below 2.8 mmol/l, hypoglycemia occurs, which is usually noted not only in the context of a particular disease (for example, with an overdose of insulin by a patient with diabetes mellitus), but also during starvation.

With insufficient intake of this monosaccharide, first of all, those cells suffer that, being deprived of mitochondria, are not able to metabolize other classes of organic compounds. The most striking and, perhaps, explainable example is erythrocytes: their structure in terms of ultrastructures is maximally simplified (they are devoid of even a nucleus) with the sole goal of giving the entire possible area to the hemoglobin contained inside, capable of binding carbon dioxide and oxygen.

Glycolysis occurring in the cytoplasm, one of the easiest ways to utilize this sugar, provides them, albeit in a very modest amount, with energy, allowing them to perform their vital function.

In addition, glucose deficiency also affects the functioning of the nervous tissue: the brain, being limited from circulating blood by such an obstacle as the blood-brain barrier (BBB), is not able to utilize fatty acids as an energy substrate: they circulate in the serum not in a free state, but in complexes associated with plasma proteins - the molecules of the latter are simply not able to overcome passport control in the form of the BBB.

The symptoms that usually arise (when you, say, being carried away by work, missed one or two meals), appear, at least initially, from the side of the autonomic nervous system - for example, they are noted:

• fatigue;

• dizziness;

• "fog in the head";

• confusion.

Of course, over time, the nervous system is restructured to a slightly different type of nutrition: it begins to utilize the ketone bodies synthesized by the liver.

In general, given that such a condition as hypoglycemia is a frequent companion of some serious pathologies (for example, insulinomas - tumors of insulin-producing cells; as well as liver and kidney damage, which causes disturbances in the gluconeogenesis reactions occurring in these organs - endogenous glucose synthesis), a clear differential diagnosis by a doctor is necessary.

In general, even in the absence of concomitant diseases, which can lead to a sharp decrease in the concentration of glucose in the serum, with its insufficient intake, a high degree of load falls on the adrenal glands: as already mentioned, the cortisol produced by the cells of the cortical layer of this endocrine organ causes the synthesis of the necessary for the flow gluconeogenesis enzymes. In a way, this is a paradox: after all, the less glucose is supplied with food, the more actively it is produced in the cellular factories of the liver.

Constant stimulation of the adrenal glands eventually leads to their natural depletion. However, the stress experienced by the body in conditions of a decrease or complete absence of carbohydrate intake, meanwhile, will also affect the menstrual cycle: there is a so-called stealing effect of pregnenolone, the mother of all steroid hormones. It is natural that his metabolism will be directed not towards the production of sex hormones, but towards the formation of cortisol to maintain a bursting siren of alarm.

The rate of carbohydrates for weight loss

Both in order to lose weight, and in the context of the treatment and prevention of insulin resistance, many go to extremes, completely eliminating the intake of this class of organic compounds with food components or minimizing it.

At the moment, doctors agree that it is not worth reducing the amount of carbohydrates below 100 grams - given the essential functions that they perform in our body, and the needs of many organs for them - in particular, "beyond the barrier".

Undoubtedly, it is necessary to give preference to complex sugars, the digestion and breakdown of which takes much more time compared to simple sugars. Add legumes, long-cooked cereals, vegetables and greens to your diet.

In the treatment of insulin resistance and overweight, it is advisable to exclude fruits from your diet - at least sweet ones:

• grape;

• bananas;

• mango;

• papaya

• pears;

• apples;

• persimmon;

• melons;

• watermelon.

Given the significant contribution that fructose makes (which, recall, cells cannot use as an energy source without first converting it into glucose) to the development of fatty liver, you should still focus on berries: having a relatively low glycemic index, they are, in addition, sources of many vitamins, antioxidants and dietary fiber.

In addition, I would like to emphasize once again the need to check product labels for the presence of hidden sugars (we have given some of their names below). You also need to understand that the “healthy product” that is not always labeled and advertised with certainty is actually such: take dates, which are widely added to raw food “healthy” desserts: their glycemic index, by the way, is much higher than that that of glucose (165 compared to 100).