Not just a sweet leaf: Stevia extracts may help tackle obesity
Publishing their findings in the peer-reviewed Journal of Medicinal Food, the Mexican researchers reviewed both in vitro and in vivo studies which looked at the beneficial effects reported for steviol compounds – aqueous and alcoholic stevia extracts – derived from the leaves, flowers and roots of the stevia plant.
These studies analysed the plant's anti-obesity, anti-hyperglycemic, anti-hypertensive and anti-hyperlipidemic effects, all of which make it interesting to tackle the symptoms of metabolic syndrome. This is characterised by factors such as abdominal obesity, inflammation and diabetes, that are associated with an increased risk of cardiovascular diseases.
While there are several chemically synthesized pharmaceuticals for treating these diseases, many of them have secondary undesirable effects such as lactic acidosis, metallic taste, and vitamin B12 deficiency, according to the reviewers from the from the Autonomous University of Yucatan.
“Therefore, there is a demand for new natural-based medicinal compounds [and] Stevia rebaudiana Bertoni [is] a potential source for these compounds,” they write, particularly due to its absence of toxicity and reputation as an edible plant worldwide.
Cardiovascular risk factors are on the rise. According to the World Health Organisation (WHO) the number of people suffering diabetes alone rose from 30 million globally in 1995 to 347 million in 2014. By 2030 it predicts this number will rise to 366 million.
It also estimates that worldwide obesity has more than doubled since 1980.
Currently, stevia is commercially cultivated to extract its sweeteners but it also contains other compounds, such as phytochemicals, that provide beneficial properties to health.
Theses include: diterpenes, labdabos, triterpenes, stigmasterol, tannins, ascorbic acid, alkaloids, steroids, saponins, flavonoids, b-carotene, chromium, cobalt, magnesium, iron, potassium, phosphorus, riboflavin, thiamine, tin, zinc, apigenin, austroinilina, avicularin, b-sitosterol, caffeic acid, campesterol, caryophyllene, centaureidin, chlorogenic acid, chlorophyll, kaempferol, luteolin and quercetin.
The authors identify three separates rat or mice studies in which orally administered stevia for a period of between three and nine weeks led to a weight reduction.
One 2015 study looking for sucrose replacement in beverages found that that satiety levels of SR, aspartame, and saccharose were similar among each other but stevia reduced the glucose and postprandial insulin levels, write the authors.
Other human and animal studies identified stevia as beneficial in lowering blood pressure. For instance, one study, hypertensive patients were given 250 mg of steviosides for one year. “Results indicate that their systolic and diastolic APs decreased after 3 months of starting the treatment without any negative effect on the biochemical parameters.”
The authors conclude that more research is needed to determine the diverse mechanisms of action of stevia-based treatments.
Source: Journal of Medicinal Food
“Stevia rebaudiana Bertoni: A Natural Alternative for Treating Diseases Associated with Metabolic Syndrome”
Published online ahead of print, 9 August 2017
Authors: Areli Carrera-Lanestosa and Maira Segura-Campos
