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Synthetic non-calorie sweeteners v/s Natural stevia
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Tuesday, 01 September, 2015, 08 : 00 AM [IST]
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Ramesh Kumar Sharma
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fiogf49gjkf0d ‘Sweet on Stevia: Sugar Substitute Gains Fans’ a news story published in the March 23, 2008, issue of Columbia Daily Tribune, obviously had been in limelight; when case histories database of a number of symptoms believed to be caused by synthetic non-sugar sweeteners ingestion became too voluminous to be overlooked.
Case Histories: Aspartame and Saccharin
The most advertised synthetic sugar substitute aspartame (aspartyl-phenylalanine-1 methyl ester) was observed to be responsible for headaches and dizziness to consumers suffering from phenylketonuria (a disease due to incapability of patient to metabolise phenylalanine). These observations supported the research work ‘Aspartame a Susceptibility to Headache’ carried out by Schiffman SS, et al published in N Engl J Med in 1987.
The question further gained momentum with the logic that aspartame perhaps can also turn a healthy consumer prone to phenylketonuria. The oldest synthetic sugar substitute saccharin (o-benzosulfimide or anhydride of o-sulfimide benzoic acid) had been in the list of carcinogens (cancer causing chemicals) since 1972 when USDA banned the use of this non-nutritive sweetener following researches proving its role in increasing bladder cancer in rats. Although, in 2000, it was removed from the list of carcinogens, still it is normally sold for direct use in the form of mixtures containing 90 per cent dextrose (example Sweet’N Low) providing 3.6 kilocalories per gram (while pure sugar provides 4.0 kilocalories per gram) to human body.
Other Synthetic Sugar Substitutes
Trials on acesulfame potassium (potassium salt of 6-methyl- 1,2,3 oxathiazine-4(3H)-one 2,2 dioxide) hinted that it may increase the occurrence of breast tumours in laboratory animals. The Cylamate (calcium salt of cyclamic acid or cyclohexanesulfamic acid) was banned in 1970 in the United States on account of carcinogenic property leading to blood cancer if consumed in large doses. The synthetic non-nutritive sweetener sucralose (partially chlorinated sugar or sucrose; 3-OH groups substituted by chlorines) is considered as an organochlorine compound. That is why 10 gram of splenda is composed of only I gram of sucralose. Its 80 per cent content is dextrose and 10 per cent is maltodextrin. Therefore in 2000s the natural sugar substitute Stevia truly gained fans; there was no exaggeration in Columbia Daily Tribune news.
‘Natural’ - not Necessarily Safe
A natural product is not always a safe product. The aforementioned news, on one hand, described the increasing popularity of natural sugar substitute stevia among demand- raisers of suitable low-calorie or non-nutritive sweetener. On the other hand, it revealed the fact concerned with safety concerns of stevia. Canada and European Community scientific panels did not approve it and declared that stevia was unacceptable for use in food. Prior to this the US FDA, in the early 1990s, had rejected stevia for use as a food ingredient on account of a research work which showed that high dosages of stevia sweetener fed to rats reduced sperm production and increased cell proliferation in their testicles causing infertility or other problems. Later on it was also stated that steviol (13-hydroxykaur-16-en-18-oic acid) the active ingredient of stevia non-nutritive sweetener, can be converted in laboratory into a mutagenic compound, which may promote cancer by causing mutations in the cells’ DNA. However it does not mean that steviol certainly goes in the same way in the body. In 1995, FDA allowed stevia to be used as a dietary supplement.
Stevia: Botany, Chemistry, Safety Concerns
Stevia is a bush (stevia rebaudiana bertoni); leaves being used to produce extracts having sweetness up to 300 times that of sugar. Stevia leaves are sweet due to steviol glycosides, mainly composed of stevioside and rebaudioside. Stevioside has three beta-D-glucose replacing three hydrogen atoms of steviol molecule. Experiments on rats and hamsters have shown that high doses of stevioside decrease the production of sperm in males and in the same situation females had fewer and smaller offspring. Despite this in December 2008, the FDA approved the use of purified rebaudioside A from stevia rebaudiana Bertoni, and classified it as Generally Recognised as Safe (GRAS). Rebaudioside A, also called Reb-A and rebiana, has one beta-D-glucose molecule replacing a hydrogen atom and a chain of three beta-D-glucose molecules replacing one more hydrogen site of steviol.
Stevia Market Products
Stevia products are marketed under the popular brand names Truvia and PureVia, but the packets are not just Reb A or rebiana. Both Truvia and PureVia contain erythritol, a low-calorie sugar alcohol sweetener. One packet of Truvia (3.5 gram) contains 3 gram of erythritol, 65% as sweet as table sugar with caloric value 0.2 calories per gram, and only 0.5 gram Reb-A.
Acceptable Daily Intake (ADI)
As per a report with title ‘Sugar Substitutes: Health Controversy over Perceived Benefits’ published in 2011 in Journal of Pharmacology & Pharmacotherapeutics (Medknow Publications) the acceptable daily intake of stevia (Reb A) might be up to the limit 4 mg/kg body weight of consumer. The report presents simultaneously a remark while expressing the established value for stevia ADI limit. This remark goes on in this way -
“Stevia is derived from stevia rebaudiana, a South American plant, and it has been used for centuries to sweeten beverages and make tea in the plant’s native Paraguay. Rebuadioside A is one compound within the stevia plant that provides sweetness. The steviol glycosides meet purity criteria established by the JECFA (WHO). The clinical studies show that they have no effect on either blood pressure or blood glucose response, indicating stevia sweeteners are safe for use by individuals with diabetes. Recent studies including human studies on intake, metabolism and toxicity, support the safety of stevia sweetener. Based on the published research, independent scientific experts in both the US and globally have concluded that stevia sweeteners are safe for people of all ages and an ADI of 4 mg/kg body weight (expressed as steviol) has been established (Bentley EM Mackie IC; Health Educ. Res. 1993; 8:519-24). Stevia has a very low acute toxicity, and no allergic reactions to it seem to exist (Genus JM, Stevioside, Phytochemistry, 2007, 64:913-21; PubMed). Just because a substance is natural, does not mean that it is safe. Many natural plant components are toxic. And while a long history of use does indicate that a substance is free from severe, immediate toxic effects, it does not guarantee that the substance is entirely safe. Rare adverse effects, delayed effects, or effects that occur only with long-term use may not be identified initially.”
Out of this statement, the message clearly goes that stevia sweetener should be taken by diabetes patients only. Particularly if diabetes patient is a growing child, this sweetener should be given to him or her as per body weight within the upper limit 4 mg/kg body weight.
Dieticians Suggest minimally Processed Stevia
Contrary to medicos’ opinion that Reb A (and not the raw stevia leaves) should be taken by consumers; the dieticians normally suggest minimally processed stevia for human consumption because stevia processing involves various steps and lots of non-nutritive chemicals. One important comment by Conner Middlemann Whitney, “Just say “No” to Artificial Sweeteners; and “only a Little” to Natural Ones,” in this context, is worth mentioning -
“Stevia, a non-caloric sweetener derived from the stevia rebaudiana plant, is a useful sugar alternative, if you don’t mind its slightly metallic, licorice-like taste. Choose minimally processed stevia (green-leaf liquid and powder) rather than the heavily processed white powder. (Stevia processing involves dozens of steps and lots of non-nutritive chemicals to convert it from green leaf to white powder). Beware, too, of added flavours and dextrose (a sweetener derived from genetically engineered corn) in many commercial stevia products. And finally, don’t forget that stevia, which is 200 times sweeter than table sugar, will keep your sweet tooth alive and kickin’! Moreover, I wouldn’t be at all surprised if stevia had metabolic effects similar to those described in the new sucralose study.”
In the context of this remark, it is worth mentioning that new sucralose study has been carried out by Pepino My, Tiemann CD et al. This study with title ‘Sucralose affects glycemic and hormonal responses to an oral glucose load’ was published in September 2013 issue of Diabetes Care. A clinical trial with the above mentioned hypothetical comment on 17 obese subjects (BMI 42.3±1.6 kg/m) confirmed the hypothesis.
Whitney does not give a clear-cut opinion on whether or how to consume stevia sweetener. According to him, minimally processed stevia should be consumed which is quite contrary to that FDA approves (approval of Reb-A, single isolated sweetener from stevia leaves). He also suspects that stevia might have adverse metabolic effects similar to those exerted by sucralose and other synthetic sugar substitutes. That means research work on stevia metabolism is in preliminary stage and lot of clinical trials and experiments with laboratory animals, in this context, are required.
Update in Leading Daily
Patterson Clark, on March 2, 2015, summarising Susan Swithers (anti-sugar substitutes) - JO Mill (pro-sugar substitutes) debate, reported to Washington Post – “Our paleolithic ancestors happened upon ripe autumn fruits, ingestion of the simple sugar fructose stimulated their appetites, encouraging them to eat more and more. But take that metabolism and plug it into a modern, relatively sedentary culture with constant access to heavily advertised sweeteners, and all sorts of troubles emerge: tooth decay, diabetes, obesity, gout, fatty liver disease and damage to the kidneys and the circulatory system. Clever chemists have attempted to circumvent those problems by formulating artificial sweeteners, which promise pleasure without peril.”
Conclusion
It can be safely said in the context of above description that Indian food industry should not go with any sugar substitute for sweetening purpose, whether it be a synthetic or natural like stevia, unless the research work scenario regarding sugar substitute metabolism is clear.
(The author is a Bikaner-based food consultant)
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