STEVIA REBAUDIANA
Our modern life style and diet habits are reflected in today’s growing phenomenon of overweight and obesity.
The accumulation of body fat and its consequent weight increase are followed by an imbalance between calorie intake and energy consumption, but also by modifications in hormonal profile, concerning above all sugar metabolism (insulin in this case is the most involved hormone).
The increase of adipose tissue seems to be associated with persistent low intensity inflammation which is the consequence of an excessive ingestion of fats and/or simple sugars. This determines insulin resistance and facilitates fat mass accumulation.
Obesity is a risk factor for cardiovascular pathologies, hypertension, type 2 diabetes, ictus, certain types of cancer, muscular-skeleton disorders and chronic respiratory diseases which worsen the quality of life.
On the contrary, the efficacy of a healthy diet in the reduction of risk factors and the prevention of pathologies associated to diets or the ability to reduce the possibility of recurring in particular of cardiovascular diseases have been widely demonstrated.
A 5-10% body weight loss in obese subjects can reduce many health risks, as it improves lipid and lipoprotein profile, hypertension, diabetes and insulin resistance, it reduces osteoarthritis risks and relative symptoms, certain types of cancer and other risk factors involved in the development of chronic diseases.
Weight loss can be fostered by the adoption of certain measures such as for instance substituting (in coffee, tea, drinks etc.) sugar with low calorie sweeteners (better if of natural origin): this is a simple but effective habit.
Also the introduction or the increase of physical exercise is necessary to improve one’s life style.
Recently, as a result of the positive European evaluation concerning the safety of steviol glycosides, extracted from the leaves of Stevia Rebaudiana Bertoni, and its subsequent authorization to be used as a sweetener in EU, a new sweetener which is an effective natural alternative to sugar and other sweeteners is available in Italy.
Stevia was first discovered by the indigenous populations who used its leaves to sweeten their drinks. The consumption of Stevia spread throughout South America, including Argentina and Brazil in the 19th century.
Its utilization besides South America started when the botanist M.S. Bretoni “discovered” it in 1887. In 1931 two French chemists M. Brideled and R. Lavielle, isolated the main components that give Stevia its agreeable flavour: steviol glycosides.
Already utilized for their medical as well as sweetening properties, many of the components of Stevia were gradually studied in the following years both to eliminate any doubts concerning their safety and to study all their possible positive applications.
Since 1970 Japanese researchers have carried out studies on Stevia underlining the absolute safety of its utilization.
Also international food safety institutions such as the joint FAO and OMS Commission of international experts (respectively the UN Food and Agricultural Organization and World Health Organization) on food additives (JEFCA), the European Food Safety Authority (EFSA) and also national food safety agencies have created a “panel” on the safety of the consumption of Stevia and its components.
Recently, EFSA has elaborated a “Scientific Opinion on the safety of steviolglycosides for the proposed uses as a food additive” in which the daily intake of 4mg/kg of steviol glycosides (expressed in stevioliequivalent) is considered safe.
Steviol glycosides are intense sweeteners extracted from the leaves of the plant called Stevia (Stevia
Rebaudiana Bertoni). The sweetening power of substances such as steviosides and rebaudiosides is from 40 to 300 times greater than sucrose. Toxicological tests have underlined that these substances are neither genotoxic nor cancerogenic nor have harmful effects on the human reproductive system or of developing children.
Owing to the high sweetening power of the most commonly used glycosides, an almost impalpable quantity is necessary to sweeten compared with sucrose.
Effects of Stevia on blood glucose levels in subjects with diabetes
Purified Stevia in doses up to 1000mg has no immediate effect on blood glucose or on insulin levels in subjects with diabetes.
A study concerning this matter showed that there was no difference in the undesired effects between subjects taking Stevia and subjects taking a placebo.
Effects of the sweetener in subjects with type 2 diabetes
A blind randomized study underlined that the regular use of the extract of the leaves of Stevia has no effect on blood glucose, on insulin on glycated haemoglobin (HbA1c), on blood lipids (cholesterol and triglycerides) of subjects affected by type 2 diabetes.
By following 122 subjects who were taking a daily dose of 1000 mg of extract from Stevia leaves or a placebo for 4 months, the researchers did not find any difference in the undesired effects in the two groups of subjects.
Effects of Stevia in non diabetic adult subjects.
A study carried out on 100 healthy adult subjects who were taking a daily dose of 1000 mg of Stevia leaves extract or a placebo for 4 weeks underlined that a regular use of purified extract from Stevia leaves does not have any effect on blood pressure or on the health of healthy adult subjects. No difference was in fact found between the side effects of both groups of subjects.
A study with the aim of evaluating the tolerability of 1500 mg of stevioside (three daily 500 mg doses) found that the utilization of stevioside for 2 months was associated with a respectively 6.7% systolic and a 6.4% diastolic pressure decrease without besides tolerability side effects.
Moreover, this study showed that the Stevia group presented a reduced amount of left ventricular hypertrophy with a value of 11.5% for the Stevia group compared with the 34.0% of the placebo group.
In hypertension subjects, the intake of 250mg of stevioside three times a day (total 750 mg) determined a blood pressure decrease (8.1% systolic and 13.8% diastolic) compared with the placebo group after three months and it was maintained for the following nine months.
Interestingly the subjects with regular blood pressure did not show pressure variations.
Effects of stevia on reproduction health and development
Many studies on reproduction toxicity and on the development of newborns of various animal species have shown there are no reproductive health problems also for the following generations of these animals even when taking large doses. Moreover, there was evidence that pure steviol glycosides (both stevioside and rebaudioside A) have a metabolic profile and a pharmacokinetics which is similar in humans and rats therefore a report submitted to FDA underlines that the utilization of stevia does not present health risks to human reproduction and therefore it can be taken also during pregnancy.
Allergizing/toxic effects of Stevia extracts
According to a report submitted to FDA no doubts appeared on the possible allergizing or toxic effects of the products of degradation or of the glycosides contained in the product. According to all the available data it was concluded that there was no scientific evidence of possible toxic or allergizing effects of steviol glycosides.
L’Accademia del Fitness – Wellness – Antiaging