The truth about Stevia

There are many advocates of Stevia who make claims about its wonderful health benefits. On the other side there are plenty of people who are suspicious of this new superfood. But... what does the science say? Keep reading to discover the truth and myths of stevia.

Stevia is a plant, native to Brazil and Paraguay, whose steviol glycosides are about 250-300 times sweeter than sugar. The stevia leaves contain some vitamins, including A, B, and C; minerals, such as iron, zinc, calcium, magnesium, sodium and potassium, proteins, fiber and other elements.

The sweet molecules are obtained by soaking the ground, dried leaves in water and then separating the  best-tasting compounds to later purify them. The final product is molecularly identical to the steviol glycosides of the stevia leaves, but its taste is more similar to sugar. There are many steviol glycosides, including rebaudioside C, dulcoside A, rebaudioside B and steviolbioside, which only differ in the number and ordering of sugar molecules attached to the same steviol backbone. However, the main ones are stevioside and rebaudioside A.

There are a number of diseases affected by stevia:

DIABETES

This plant might help in the treatment of diabetics given the fact that several have found that some steviol glycosides lower glucose production in the nephrons (kidney tubules) and decrease blood glucose in type 2 diabetics. Nevertheless, an 8-week rebaudioside A treatment did not show these effects in the type 2 diabetic rats.

A 2000 study concluded that rebaudioside A can stimulate insulin production, and thus be useful in the treatment of type 2 diabetes mellitus.

A 2008 study of 122 humans revealed that long-term use of rebaudioside A does not affect blood glucose levels or blood pressure in type 2 diabetics. That same year, another study reached the same conclusion when 72 people, healthy or with type 1 or 2 diabetes, consumed 250 mg of steviol glycosides 3 times per day for 3 months without altering blood glucose levels. 

Aqueous stevia extracts, not the commercial kind, have been shown to increase glucose tolerance and decrease blood glucose in healthy individuals. Likewise, 91 mg of orally taken stevioside with a meal lowered blood glucose and glucagon in type 2 diabetics. 

Moreover, stevioside and steviol stimulate pancreatic β-cells to secrete insulin and, therefore, may be beneficial to counteract high levels of blood glucose in the treatment of type 2 diabetics.

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The fact that it has no calories and does not increase blood glucose or trigger an insulin response may be due to the fact that steviol glycosides pass through most of the gastrointestinal tract unchanged. It is not until they reach the colon when the gut flora break down steviol glycosides into steviol and glucose units. The former is metabolized by the liver and excreted through the urine, leaving no accumulation of any byproduct of stevia.

BLOOD PRESSURE

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Several studies have found that stevia lowers blood pressure while increasing urine and sodium secretion in rats. Another study showed that it also dilates blood vessels of animals with normal and high blood pressure. While stevioside in dogs had hypotensive effects, another study indicated that rebaudioside A had no effect on blood pressure in rats.

Of outmost importance is a 2006 study that suggested that isosteviol inhibits angiotensin-II and endothelin-1. The former is a substance your body naturally creates that narrows your blood vessels, leading to hypertension. The latter is a gen whose expression creates a vasoconstrictor and can even be a carcinogen. Therefore, isosteviol may have beneficial effects on the cardiovascular system and prevent tumorigenesis.

In humans, the effects of stevioside on blood pressure are controversial. Several studies showed that rebaudioside A has no effect on blood pressure in patients with normal and high blood pressure. 

However, another study showed that patients with hypertension could decrease both their systolic and diastolic blood pressure by consuming 250 mg of stevioside 3 times daily for 1 year. Yet another study found no effect on blood pressure when administering a high dose of stevioside for 6 weeks.

ANTIBACTERIAL, ANTIFUNGAL AND ANTIVIRAL

It is a strong antibacterial that fights against a plethora of pathogenic bacteria, including some Escherichia coli strains. One study reported its beneficial effects on reducing dental plaque. It might be effective against Candida albicans and has been shown to posses some antirotavirus activity.

IMMUNOMODULATOR

Stevioside has been shown to enhance the immune system response and to decrease inflammation both in cells and mice, treated and not treated with an immunosuppressive drug.

ANTICANCER AND ANTIOXIDANT PROPERTIES

A 2002 mice study indicated that stevioside, rebaudiosides A and C, and dulcoside A  significantly inhibit inflammation, contain anti-tumor effects, pose no risk to diabetics and did not produce any abnormality. There are other studies which showed the same anticancer effect.

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A few months ago, steviolbioside was found to effectively suppress human hepatic, breast and pancreatic cancer cells. The study concluded that the remarkable inhibition of breast carcinogenesis ''makes steviolbioside a potential remedy for human breast cancer''.

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Stevia contains a substantial number of triterpenes, polyphenols, flavonoids, and tannins, all antioxidant compounds. Some of its flavonoids include kaempferol, quercetin, apigenin, chlorogenic acid, caffeic acid, luteolin, isoquercitrin, and isosteviol, which are even commercialized as health supplements. 

Moreover, kaempferol has been shown to reduce pancreatic cancer by 23%. 

Given its considerable antioxidant potential, stevia protects against DNA damage, free radicals and all the issues caused by them.

PREGNANCY

Rebaudioside A has been tested in rats for 2 generations and had no effects on gestation lengths or growth.

BUT... IS IT TOXIC?

In 1991, stevia was banned due to concerns that it might cause cancer. Four years later you could buy it as a food supplement and, in 2008, it was “Generally Recognized as Safe” (GRAS) and the Acceptable Daily Intake (ADI) was set at 4 mg of steviol per kg of body weight, thanks to corporate sponsoring. Now you can buy Coca Cola’s Truvia, Pepsi’s PureVia, or Wisdom Natural Brand’s SweetLeaf everywhere.

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As a result, many people have worried about its toxicity for decades. These concerns are well-grounded if we take into consideration the background of the brands that sell us Stevia. Nevertheless, this might be one of the few exceptions were these big corporations are not marketing a downright harmful product.

In 1996, a Japanese study found that stevioside was transformed by gut bacteria into a toxic compound, steviol, which is highly mutagenic. However, a 2010 study indicated that PROVIDED you stay within the ADI, this will not have any effect on your health.

On the other hand, there are plenty of studies which show that it is not genotoxic or mutagenic, neither in vitro or in vivo, in acute or chronic administration, in males or females, in low or extremely high doses.

CONCLUSION

As a general rule of thumb, the more whole plant foods you eat, the better. If sometimes you feel like adding an extra sweetness to your meal, I would opt for Stevia as it is calorie free, natural, nontoxic and even provides some health benefits.

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I highlight the need for eating WHOLE PLANTS and developing a taste for them. Our society has become too accustomed to sugar and I believe we need to ''detoxify'' our taste receptors from so much sweetness.

With that being said, there is a food you can eat everyday to satisfy your sweet tooth: FRUITS! They are the most tasty, nutritious, health-promoting, hydrating food you could ever eat!

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