Introduction

The postprandial state (from Latin post-prandium) is defined as the period following the consumption of food; therefore, glycaemia and postprandial dyslipidemia refer to the variation in plasma glucose and lipid concentrations, respectively. Scientific evidence shows that there is a correlation between the abnormal postprandial state and the development of atherosclerosis^1,2. During the postprandial metabolism of food fats, lipoproteins abundant in triglycerides of intestinal origin are generated that can interact with circulating leukocytes, with macrophages and with cells of the smooth muscle of the vascular wall. This can cause localized accumulation of lipids, as well as variations in the expression of genes related to atherosclerosis. Similarly, it has been observed that lipid deposits in the arteries are not only a consequence of the high concentration of low-density lipoproteins (LDL) in the plasma but are also the result of a normal process of absorption, transport, and deposition. serum lipids. On the other hand, experimental studies indicate that the size of the particle is a key point and determinant of atherogenicity. The size of the LDL particles (18-25 nm) and the HDL high-density lipoprotein (10-25 nm) allow them to cross the endothelium, however, their effect is opposite since LDL is atherogenic and HDL is antiatherogenic. This is due to the participation of HDL in the so-called reverse cholesterol transport³.

Atherosclerosis is a systemic inflammatory disease with a high predisposition to trigger cardiovascular diseases, it develops gradually, its pathogenesis is multifactorial, genetic and environmental factors intercede, that is, unhealthy habits (no physical activity, non-beneficial diet rich in fat , sugars, alcohol consumption and smoking)⁴, it is a process in which the arteries of medium and large caliber enlarge and become rigid, there is a distensibility of the vessel, accumulation of atheroma plaques, response of inflammatory mediators , damage to the endothelium and formation of thrombi, excess cholesterol can precipitate in the form of crystals within the macrophage (cells specialized in the localization and phagocytosis of bacteria and other organisms), that activates inflammasomes, cytoplasmic complexes with rich proteins that play a primary role in the inflammatory process (cytokine 1L1β), there is recent evidence that the NLRP3 inflammasome is a key point in the progression of atherosclerosis^5,6, without a doubt the ight inflammation is the fundamental part of many chronic diseases, it has been observed that this process is related to age, at older age there is an exponential increase in the risk of inflammation, becoming a factor in the development of cardiovascular disease (CVD), related with affections to the heart or blood vessels, the most frequent are coronary artery disease, stroke, venous thrombosis, cardiomyopathy, hypertensive heart disease, thromboembolic disease and arrhythmia⁷.

Currently there are studies focused on evaluating and characterizing dietary fiber in various sources of residues of different plant species^8,9,10 considering the role and its beneficial chemical and biological attributes of its consumption in health, which is why there is interest in the food industry to use it in the manufacture of high consumption products such as bakery and pastries.

Dietary fiber is an entity made up of different compounds, in relation to its chemical structure, its physical and biological properties, it is a heterogeneous mixture of different compounds, which is why it has been the subject of controversy to define it, dietary fiber comes from various sources , like vegetables, it is considered with prebiotic effects with functional activity, this depending on the type of fiber and the microbiota of the individual, its function in health goes beyond the nutritional aspect, it is not absorbed or digested in the intestinal tract superior, reach the colon intact where they are attacked by the intestinal microbiota¹¹.

Dietary fiber exerts an action in the protective control against cardiovascular diseases, as well as in the decrease of the postprandial serum concentration of glucose and insulin, both in healthy individuals and in those suffering from Diabetes mellitus (DM); the mechanism is explained by the increase in the viscosity of the nutrient content in the small intestine, which delays the diffusion of glucose towards the ciliated border of the intestinal mucosa; the binding of glucose to dietary fiber (DF) and a decrease in its availability for absorption; and the inhibition of the action of α-amylase on starch¹².

There is scientific evidence on the medicinal and nutritional properties, among others, of Stevia leaves¹³; facilitates digestion, gastrointestinal functions and maintains the feeling of vitality and well-being, due to the presence of water (80% to 85%), glycosides, β-carotene, chromium, riboflavin, cobalt, magnesium, potassium, iron, phosphorus, thiamine, zinc, etc. Through various investigations it has been shown that the extracts of stevia leaves are safe for use in food and beverages for the entire population in general, without any side effects, through various investigations it has been shown that the extracts of the Stevia leaves are safe for use in food and beverages for the entire population In general, without any side effect¹⁴, however there is little scientific literature on the physicochemical and biological properties of stevia (Stevia rebaudiana Bertoni ) stems, these tissues are generally considered as waste, so they are little used, some reports of the literature mention about the attributes of these tissues, they constitute a good source of bioactive compounds with different mechanisms of action¹⁵, among these compounds is dietary fiber¹⁶ which could be used to develop functional foods for the regulation of energy intake and reduction of intestinal absorption of nutrients, improving yes the energy available, according to the above, the intention of this study was to evaluate the effect of consumption of a fibrous extract of Stevia rebaudiana Bertoni on postprandial glycemia levels in healthy subjects.

Materials and Methods

Results

The evaluation was carried out in a sample of 16 young and healthy female volunteers. The population median was 22 years old, and the mean BMI was 21.6 kg / m² ± 1.69 (Table 1). The foregoing reveals that the study population presented a normal weight, since according to the BMI criteria proposed by the World Health Organization (WHO) ²¹ it is categorized within the “normal” range.

Considering that time 0 (T 0’) of the postprandial test corresponds to fasting glycemia, it was observed that no participant showed altered glucose levels, according to the diagnostic criteria of the American Diabetes Association²². In this same sense, no statistical differences were observed between the means of the T 0’ glycemia of the test with the fibrous extract and the control test with glucose (86.50 ± 6.40 mg / dL and 84.62 ± 7.42, respectively; p = 0.225) (Figure 1).

Figure 1 Glycemic response to treatments. * p <0.05, ** p <0.001. Paired T-Student test Source: elaboration from own data 

When comparing between the different times, it was observed that there were statistical differences in the times T 15’, T30’, T 45’, T 60’ T 90’ and T 120’, between the glycemia of the test with the fibrous extract and of the control test with glucose (p <0.05). At these same times, significantly lower glycemic values were observed in the test with the fibrous extract (p<0.05)(Figure1).

Another relevant aspect is that when comparing T 0’ and T 120’ in the control test with glucose, it was observed that the glycemia at the end time (91 ± 12.89 mg / dL) was significantly higher than the baseline glycemia (84.62 ±7.42 mg / dL) (p = 0.029). This shows that, in the study population, 120 minutes after ingesting a glucose load is not enough to recover baseline blood glucose levels. This was a contrary condition to that observed in the treatment with the fibrous extract, since after 120 minutes of ingestion of this, the glycemia was significantly lower than the basal glycemia (80.4 ± 9.69 and 86.5 ± 6.4, respectively; p =0.006). Statistical differences were even observed between the glycemia in T 120’ of the control group and the fibrous extract (p = 0.001). No statistical differences were observed between the glycemia at T 0’ of the control group and the treatment group (p = 0.225) (Figure 2).

Figure 2 Glycemic response to treatments at times 0’ and 120’. *p <0.05. Paired T-student test. Source: elaboration from own data 

The average value of the area under the curve (AUC) of glucose was 709.18 ± 23.60, while that of the fibrous extract of stevia stems was 556.59 ± 50.47 (figure3).Statistical analysis revealed that the AUC of glucose was statistically higher than that of fiber extract (p = 0.0001). Based on these data, it was estimated that the glycemic index of the fibrous extract was 79.2%, which makes it similar to foods such as whole wheat bread²³.

Figure 3 Area under the curve of treatments. Source: elaboration from own data. 

Discussion

According to analyzed data in this study, the glycemic response with the fibrous extract was significantly lower than with the glucose control; It can be seen that before consumption the mean of the reference food was 89mg / DL at minute 15; with the fibrous extract it was reduced (84.62 mg / DL), and at 120 minutes it was 129mg / DL (reference food), and 97mg / DL (fibrous extract); the results shown were similar to the trial reported in another study²⁴ .

In a report with extracts from Stevia leaves²⁵ the results were optimal at minute 20 after stevia overload; In a different trial to measure and compare the postprandial effect of dietary fiber with other digestible carbohydrates²⁶ it was observed that at minute 30 the postprandial effect was lower with dietary fiber than in the samples of digestible carbohydrates, the evidence shows that there is a notable decrease of glucose; Scientific evidence about dietary fiber demonstrates its favorable effects on health, such as the benefit in the absorption and regulation of blood sugar levels, promote the health of the intestinal microbiome, help control healthy weight, inducing satiety, promote digestive health, stimulate the reduction of total cholesterol in the blood, decrease the risk of developing cancer, among others²⁷. In the different studies, there are positive results that indicate that stevia extract can be used as an additive into food. In the aforementioned study²⁴ 3 different formulations were used: 25%, 50% and 75% of the stevia extract, in our study 5 grams of extract were used and similar results were obtained, reducing blood glucose in the study subjects. However, for Antón²⁵ study, the formulation of stevia used to make his product is not shown. Specific studies by administering 6 g of partially hydrolyzed gum agar (soluble fiber) at each meal for twelve months, it was observed that postprandial plasma glucose levels and triglycerides were significantly reduced; the American Diabetes Association recommends the consumption of 20 to 25 g / day in healthy people and up to 50g / day in people with Diabetes; However, the amounts present limitations in palatability and secondary gastrointestinal problems²⁸ in Mexico there are not complete tables of fiber content in foods, The tables recording the fiber content refer to tables from other (foreign) countries, which do not refer to the type of chemical analysis to calculate it²⁹, considering that each food has different types of fiber, so it can be over or underestimated in For each food, it is admitted that the population living in the field consumes a greater amount of fiber, this population ingests significant amounts of fruits, vegetables, greens, cereals and legumes where fiber is present, a report from ^{ENSANUT 2012} shows the lack in fiber consumption from an early age³⁰, and the results of the mid-way survey of ^{ENSANUT 2016} show data of lack of fiber consumption in children with food insecurity from 24 to 59 months, in adolescents (men:23.7 g, and women 21.2 g), observing lower consumption in older adults (men: 20.2, and women: 17.9g)³¹, according to this report, rural localities in Mexico are going through a change in their eating habits, they are substituting natural to processed foods, due to the accessibility of this type of food. products, observing a preference for foods and beverages sweetened with refined sugars and high in saturated fats, and a significant decrease in the consumption of natural foods, a source of vitamins, minerals, and fibers, this is influencing the increase in overweight and obesity, diseases related to chronic degenerative diseases such as diabetes mellitus (DM), hypertension, among others.

Advances in food and nutrition technology have contributed to the design and development of an extensive range of foods rich in dietary fiber based on their technological properties that have been accepted by consumers interested in maintaining healthy diets, with respect to this type. food. products, in Mexico there are a series of complementary laws and official standards (NOM) that must comply with the labels of all industrialized products to guide the consumer³², among these is the Official Mexican Standard NOM-043-SSA2-200533³³, Basic services of health. Promotion and education for health in alimentary matters. Criteria for providing guidance; NOM-051-SCFI / SSA1-2010³⁴, among the general labeling specifications for prepackaged foods and non-alcoholic beverages -Commercial and health information, establishes that in the declaration of the nutritional properties of an industrialized food it is necessary to provide information to the consumer about the amount and type of dietary fiber (polymers of natural carbohydrates, those obtained from food raw materials by physical, enzymatic or chemical and synthetic means with beneficial effects on health) of the product in question in the nutritional tables, in the modification of this standard (NOM-051-SCFI/ SSA1-201034)³⁵ the front labeling system of products is established, to guide the consumer in the nutritional criteria on the content of excess energy, critical nutrients and ingredients that represent excessively a health risk.

Considering the chemical characteristics of Stevia rebaudiana, classified as a 100% natural non-toxic³⁶ species, supported by various scientific studies that have been carried out on leaves and stems, have shown its safety, most of these studies have focused on its sweetening power , especially from the leaves, without caloric intake when metabolized, is antacid, cardiotonic, does not cause tooth decay when fermented by oral bacteria, with microbiological activity, improves hypertension, among others, so through this study they are provided interesting data regarding the impact of the beneficial effects of Stevia rebaudiana fibers on health.

Conclusions

The fibrous extract of Stevia rebaudiana stems has a high fiber content; The results obtained in this study provide and contribute with scientific information about the physiological effect and health benefit in the consumption of dietary fiber in the diet, considering the amount, its ingestion favors the glycemic response in healthy patients, compared to reference foods. In summary, Stevia rebaudiana stems, due to their dietary fiber content, can be an alternative for the use and revaluation of waste sustained in the circular economy for the development of functional products, giving it an added value that contributes in some way to reducing overweight and obesity, with a hypoglycemic effect in patients with type 2 diabetes mellitus (DM), because it benefits the decrease in postprandial glycemia, improving the insulin resistance of these patients, in addition to that this fiber would grant qualities by improving the texture an+d palatability of foods allowing to partially replace sugars and fats, reducing the calorie content of the products in which they are incorporated.