Journal of Diabetes and Endocrinology
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Article Number - F177E3242280


Vol.5(1), pp. 1-2 , January 2014
DOI: 10.5897/JDE2013.0071
ISSN: 2141-2685



Letters

Could the antiglycemic role of vinegar be investigated in a double-blind trial?



Amin Zarghami
  • Amin Zarghami
  • Student Research Committee, Babol University of Medical Sciences, Babol, Iran
  • Google Scholar
Afshin Khani
  • Afshin Khani
  • Student Research Committee, Babol University of Medical Sciences, Babol, Iran
  • Google Scholar







 Accepted: 19 November 2013  Published: 31 January 2014

Copyright © 2014 Author(s) retain the copyright of this article.
This article is published under the terms of the Creative Commons Attribution License 4.0


We read with great interest the Mahmoodi et al.'s (2013) article published in the January issue of the Journal of Diabetes and Endocrinology. The authors investigated some hematological and blood biochemical factors in type 2 diabetic patients in a double blind randomized controlled trial (RCT).

One of the queries about this study is the random allocation. According to the standard criteria for RCT study design protocols (Schulz and Grimes, 2002), the authors did not mention any details about the vital sections of the protocol in their study. Though matching cases between two groups in an endocrinological trial is critical, the authors matched groups based on sex and body mass index (BMI) while for example the duration of morbidity could play an essential role.

It is well-known that vinegar contains about 3 to 9% acetic acid. The authors did not determine the dosage of the product they used. Besides, why did the authors try a single volume for vinegar? On the other hand, using 15 ml as a single volume is unknown. For example in the study of Ostman et al. (2005), different amounts of vinegar; 18, 23 and 28 g (6% acetic acid) were used in their investigation. In another crossover trial, individuals with either insulin resistance (n = 11) or type 2 diabetes (n = 10) consumed a vinegar processed drink (20 g apple cider vinegar, 40 g water, 1 tsp saccharine) or placebo drink before the consumption of a mixed meal (Johnston, Kim et al. 2004).

Another controversial aspect of the study is the placebo use. It is obvious that the unique taste of vinegar cannot be blinded by single water. According to ethical considerations, all the subjects must be informed about the study’s intervention at the beginning of the study, however the introduction of vinegar/water (placebo) for the subjects definitely failed the blinding objective. The only way to eliminate this issue is designing a cross-over RCT. According to the review of Johnston et al. (2010) on four randomized crossover trials, they evidently indicated that two teaspoons of vinegar (10 g) effectively reduced postprandial glycemia. It seemed that the only way for achieving intellectual data is cross-over design. Otherwise, pharmacologists should produce a placebo with the same taste and without any side effects.

Besides, in the statistical analysis the authors declare that they performed analysis of variance (ANOVA) test. However, according to the presented data the study was designed based on analyzing different parameters between 2 groups (intervention vs. placebo), thus the ANOVA test is not indicated.

Altogether, RCT studies are known for producing one the highest level of evidences among research studies and thus require extra attention in its study design. It seems that authors failed to achieve this goal.

Johnston CS, Kim CM, Buller AJ (2004). "Vinegar improves insulin sensitivity to a high-carbohydrate meal in subjects with insulin resistance or type 2 diabetes." Diabetes Care 27(1): 281-282.
Crossref
 
Johnston CS, Steplewska I, Long CA, Harris LN, Ryals RH (2010). "Examination of the antiglycemic properties of vinegar in healthy adults." Ann. Nutr. Metab. 56(1):74-79.
Crossref
 

Mahmoodi M, Hosseini-zijoud SM, Hassanshahi G, Nabati S, Modarresi M, Mehrabian M, Sayyadi A, Hajizadeh A (2013). "The effect of white vinegar on some blood biochemical factors in type 2 diabetic patients " J. Diabetes Endocrinol. 4(1):1-5. 

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E Ostman, Granfeldt Y, Persson L, Bjorck I (2005). "Vinegar supplementation lowers glucose and insulin responses and increases satiety after a bread meal in healthy subjects." Eur. J. Clin. Nutr. 59(9):983-988.
Crossref
 
Schulz KF, Grimes DA (2002). "Generation of allocation sequences in randomised trials: chance, not choice." Lancet 359(9305):515-519.
Crossref
 
 

 


APA Zarghami, A., & Khani, A. (2014). Could the antiglycemic role of vinegar be investigated in a double-blind trial?. Journal of Diabetes and Endocrinology, 5(1), 1-2.
Chicago Amin Zarghami and Afshin Khani. "Could the antiglycemic role of vinegar be investigated in a double-blind trial?." Journal of Diabetes and Endocrinology 5, no. 1 (2014): 1-2.
MLA Amin Zarghami and Afshin Khani. "Could the antiglycemic role of vinegar be investigated in a double-blind trial?." Journal of Diabetes and Endocrinology 5.1 (2014): 1-2.
   
DOI 10.5897/JDE2013.0071
URL http://academicjournals.org/journal/JDE/article-abstract/F177E3242280

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