Attached studies may help to plan and find out dose of garlic oil.

2nd study attached.

Bhupendra Solanke : Thanks so much for your help.

In fact, as I will argue briefly below from a summary of a review I recently undertook, despite several positive trial findings and reviews/analyses, we must examine not isolated individual studies - tempting though this may be - but rather what the WEIGHT/BALANCE of the cumulative and aggregated data, once systematically reviewed and critically appraised, with assessment of methodological quality (I use the Heyland MQS (Methodological Quality Score) metric), and from such review and appraisal, the data on clinically significant benefits of garlic compounds on dyslipidemias, hypertension or diabetes nonetheless remains equivocal, methodologically compromised, and with substantive contradictory findings:

Clinical investigations exploring the effects of garlic and its various preparations in hypercholesterolemia and dyslipidemias have demonstrated contradictory results: the Satitvipawee RCT [1] showed no significant improvement in lipids levels, confirming the same negative findings of several earlier trials [2,3,4]; and a trial [7] of garlic extract therapy in children with hypercholesterolemia found no significant beneficial effect on lipid levels. At a higher level, a meta-analyses [5] of 13 trials including 1056 subjects showed insignificant outcomes, concluding that garlic therapy failed to produce any statistically significant reduction in serum total cholesterol level, LDL-cholesterol level, triglycerides level, or apolipoprotein B level, and there was no difference between garlic and placebo on HDL-cholesterol level. These negative RCT and meta-analytic findings are further supported by the conclusions of a recent (2013) evidence-based critical analysis and review [6] of all systematic reviews to date, concluding that we cannot make a decision whether garlic is effective enough for reducing total cholesterol (TC), triglycerides (TAG), and high-density lipoprotein (HDL), and given that the evidence was very limited and insufficient, relations between garlic intake and reduced risks of all kinds of cancers, antiglycemic/antidiabetic and antithrombotic effects, and effects of garlic on cardiovascular morbidity and mortality remain unclear.

Thus, despite many positive studies, there is nonetheless a large body of contradictory negative RCTs, systematic reviews and meta-analysis that preclude any dispositive conclusions as to efficacy. The divergence of findings may be in large part due to methodological limitations and confounders in the studies: the diverse composition and amount of active sulfur compounds of different garlic preparations; the lack of standardization on active components; differences in type of formulation (garlic essential oil, garlic oil macerate, garlic powder; and garlic extract.); subject recruitment; study duration; dietary control; lifestyle; and the specific (and highly divergent) methods of lipid analyses, among many others.

These limitations, and the presence of unresolved contradictory results is also true of the arguable efficacy of garlic in blood pressure reduction, with very few positive studies available and thus showing only small positive effects that may not be clinically relevant, and so insufficient to draw any conclusions. And as to benefit in the domain of diabetes disease, evidence remains highly provisional, limited to excessively short duration (a mere 4 weeks) RCTs [8], and again with contradictory negative trials [9] that found that AGE (aged garlic extract) did not significantly improve endothelial function, vascular inflammation, oxidative stress or insulin resistance. The failure of the decisive weight of methodological robust data to support a clear benefit to the treatment or management of diabetes therefore again precludes drawing any well-founded conclusions in this domain, as in dyslipidemias and hypertension.

METHODOLOGY OF THE REVIEW

A search of the PUBMED, Cochrane Library / Cochrane Register of Controlled Trials, MEDLINE, EMBASE, AMED (Allied and Complimentary Medicine Database), CINAHL (Cumulative Index to Nursing and Allied Health Literature), PsycINFO, ISI Web of Science (WoS), BIOSIS, LILACS (Latin American and Caribbean Health Sciences Literature), ASSIA (Applied Social Sciences Index and Abstracts), and SCEH (NHS Evidence Specialist Collection for Ethnicity and Health) databases was conducted without language or date restrictions, and updated again current as of date of publication, with systematic reviews and meta-analyses extracted separately. Search was expanded in parallel to include just-in-time (JIT) medical feed sources as returned from Terkko (provided by the National Library of Health Sciences - Terkko at the University of Helsinki). Unpublished studies were located via contextual search, and relevant dissertations were located via NTLTD (Networked Digital Library of Theses and Dissertations) and OpenThesis. Sources in languages foreign to this reviewer were translated by language translation software.

REFERENCES

1. Satitvipawee P, Rawdaree P, Indrabhakti S, Ratanasuwan T, Getn-gern P, and Viwatwongkasem C . No effect of garlic extract supplement on serum lipid levels in hypercholesterolemic subjects. J Med Assoc 2003; 86(8):750–757.

2. Isaacsohn JL, Moser M, Stein EA et al. Garlic powder and plasma lipids and lipoproteins: a multicenter, randomized, placebo-controlled trial. Arch Internal Med 1998; 158(11):1189–1194.

3. Berthold HK, Sudhop T, von Bergmann K. Effect of a garlic oil preparation on serum lipoproteins and cholesterol metabolism: a randomized controlled trial. J Amer Med Assoc 1998; 279(23):1900–1902.

4. Luley C, Lehmann-Leo W, Moller B. Lack of efficacy of dried garlic in patients with hyperlipoproteinemia. Arzneimittel-Forschung 1986; 36(4):766–768.

5. Khoo YSK, Aziz Z. Garlic supplementation and serum cholesterol: a meta-analysis. J Clin Pharmacy Therapeut 2009; 34(2):133–145.

6. Li L, Sun T, Tian J, Yang K, Yi K, Zhang P. Garlic in clinical practice: an evidence-based overview. Crit Rev Food Sci Nutr 2013; 53(7):670-81.

7. McCrindle BW, Helden E, Conner WT. Garlic extract therapy in children with hypercholesterolemia. Archiv Pediatrics Adolesc Med 1998; 152(11):1089–1094.

8. Sobenin IA, Nedosugova LV, Filatova LV, Balabolkin MI, Gorchakova TV, Orekhov AN. Metabolic effects of time-released garlic powder tablets in type 2 diabetes mellitus: the results of double-blinded placebo-controlled study. Acta Diabetol 2008; 45(1):1-6.

9. Atkin, M. The effects of garlic upon endothelial function, vascular inflammation, oxidative stress and insulin resistance in patients with type 2 diabetes at high cardiovascular risk: a double blind randomised placebo controlled trial. DPharm thesis, University of Portsmouth 2011.

Dear Dr. Constantine Kaniklidis:

Your answer is very comprehensive and clear about t the arguable efficacy of garlic in blood pressure reduction, blood cholesterol reduction and dislipidemia. This may be due to the lack of standardization of the garlic supplements formula and other involving factors. In our research plan, we have to control such limiting factors and methodology. My question: what is Heyland MQS (Methodological Quality Score) metric?

Thank you very much .

Maitree

Maitree:

The Heyland MQS metric was developed by Daren Heyland at Queen's University in Kingston, Ontario, and is a tool for assessing the methodological quality of studies/trials/RCTs, like rival tools such as the well-known Jadad scale, or the PEDro scale or the Chalmers score, the COSMIN Checklist, among many others. I favor the Heyland MQS metric as a far more refined and sophisticated, but easy to use, quality assessment tool (it uses 9 methodological criteria, not just 5 as in the rather crude Jadad scale which misses some critical quality factors). And the MQS stands above the others in being based on a core spectrum of well-selected highly evaluative validated criteria. The "art" of using it is to see, after some carefully study, that as the MQS threshold defines it, high methodological quality requires a score of 8 or greater; failure to achieve this threshold (below 8) is correctly judged as low quality (if one "does the numbers" one can see a low score must necessarily compromise key requirements of trial quality).

The major problem for potential users is finding a clear description and actual instance of the tool itself, which is often deployed but not actually shown in studies using it, or at best relegated to materials supplemental to the article (which almost no one ever notices, or reads). So below are some relevant references for the "live" use of the Heyland MQS metric. See especially reference #2, and particularly its Supplementary Table S1.

However, I have put together an annotated version of the metric which I think enhances and clarifies it more for the potential user. That is now accessible as a supplementary resource to my article:

Diabetes Prevention - Promise and Limitations: A Review,

available on my ResearchGate profile.

References

1. Heyland DK, Novak F, Drover JW, Jain M, Su X, Suchner U. Should immunonutrition become routine in critically ill patients? A systematic review of the evidence. JAMA 2001 Aug 22-29; 286(8):944-53. [References #2 and #3 are the same; the correct

2. Kellow NJ, Savige GS. Dietary advanced glycation end-product restriction for the attenuation of insulin resistance, oxidative stress and endothelial dysfunction: a systematic review. Eur J Clin Nutr 2013; 67(3):239-48. At: http://www.nature.com/ejcn/journal/v67/n3/full/ejcn2012220a.html

One stop for all clinical trials: http://clinicaltrials.gov/.

Hi Tiny Wang: Thanks a lot for your message!

Dear Dr. Maitree Suttajit Sir,

Please also have a look at these useful RG links and PDF attachment.

Article Pharmacology and Cardioprotective effects of Garlic: A Review

Article Garlic for Treating Hypercholesterolemia A Meta-Analysis of ...

Article Pharmacological Effects of Garlic (Allium sativum L.)

Article Garlic: A review of potential therapeutic effects

Article Potential of garlic (Allium sativum) in lowering high blood ...

Article A randomized trial of the effects of garlic oil upon coronar...

Regards