Talk:Garlic
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Previous section on cardiovascular effects was not actually supported by the citations given
There were four studies on blood pressure, their conclusions were:
- This meta-analysis suggests that garlic supplements are superior to controls (placebo in most trials) in reducing BP, especially in hypertensive patients.
- Although... garlic preparations may lower BP in hypertensive individuals, the evidence is not strong.
- The present review suggests that garlic is an effective and safe approach for hypertension. However, more rigorously designed randomized controlled trials focusing on primary endpoints with long-term follow-up are still warranted before garlic can be recommended to treat hypertensive patients.
- Based on data from two randomized controlled trials that compared garlic to placebo in patients with hypertension it appears that garlic may have some blood pressure lowering effect, as compared to placebo but the evidence currently available is insufficient to determine whether garlic provides a therapeutic advantage versus placebo in terms of reducing the risk of cardiovascular morbidity and mortality. Data on the safety of garlic, as a therapeutic entity, in this population is also lacking. More (and large enough) trials comparing several doses of garlic with placebo are needed to detect possible differences in mortality, serious adverse events, and cardiovascular morbidity.
There were two meta-analyses on lipids, one found a clinically relevant effect:
- An 8% reduction in total serum cholesterol is of clinical relevance and is associated with a 38% reduction in risk of coronary events at 50 years of age. High-density lipoprotein cholesterol levels improved only slightly, and triglycerides were not influenced significantly. Garlic preparations were highly tolerable in all trials and were associated with minimal side effects. They might be considered as an alternative option with a higher safety profile than conventional cholesterol-lowering medications in patients with slightly elevated cholesterol.
One found no effect:
- The present meta-analysis did not suggest a significant effect of garlic supplementation on the reduction of Lp(a) levels.
The previous text said simply that the results of the studies were contradictory, which is not really the case, especially when considering only the blood pressure meta-analyses. I've therefore modified the text to more accurately reflect the citation conclusions, and mentioned blood pressure separately from lipids. Merlinme (talk) 17:14, 10 July 2018 (UTC)
Ok, my change has been reverted. Would anybody care to make the case for the text: "but as of 2015, the results were contradictory and it was not known if there are any effects", based on the study conclusions I've given above? Merlinme (talk) 17:17, 10 July 2018 (UTC)
- Bad case of WP:OVERCITE, including Chinese papers on garlic (suspect) and ones too old. Have trimmed and re-summarised to be more nuanced. Alexbrn (talk) 17:23, 10 July 2018 (UTC)
- Fair enough, but I still think it's worth noting that both remaining citations suggest there may be an effect on blood pressure, even if the effect on overall mortality is currently unknown. Merlinme (talk) 17:35, 10 July 2018 (UTC)
- Yeah "may have an effect" wording is just journal-speak straining for significance. It lay terms it's better to be clear this essentially means "unknown", or "unproven". Alexbrn (talk) 17:45, 10 July 2018 (UTC)
- Well, possibly, but when two separate high quality meta analyses (the only citations given, in fact) find some evidence of an effect I think it's at least worth mentioning. Merlinme (talk) 17:48, 10 July 2018 (UTC)
- Ok, I've now been reverted with "Simpler is better". Is that necessarily the case? Which edit gives a more accurate representation of the citations given? The one which mentions that they both find a possible effect in the same direction, or the one which says there's no evidence? Merlinme (talk) 17:50, 10 July 2018 (UTC)
- I'm not seeing the words "no evidence". What are you referring to? Alexbrn (talk) 17:52, 10 July 2018 (UTC)
- Again, let's look at what the two remaining, high quality citations actually say. The first study, American Journal of Hypertension, says:
- Although evidence from this review suggests that garlic preparations may lower BP in hypertensive individuals, the evidence is not strong. A well-conducted and powered trial of longer duration is needed to confirm these findings.
- The second study, Cochrane Database, says:
- Based on 2 trials in 87 hypertensive patients, it appears that garlic reduces mean supine systolic and diastolic blood pressure by approximately 10-12 mmHg and 6-9 mmHg, respectively, over and above the effect of placebo but the confidence intervals for these effect estimates are not precise and this difference in blood pressure reduction falls within the known variability in blood pressure measurements. This makes it difficult to determine the true impact of garlic on lowering blood pressure.
- This is currently summarised in the article as: "clinical research to determine the possible effects of consuming garlic on cardiovascular diseases and various cardiovascular biomarkers has shown no clear evidence of effect." Now I personally think that completing failing to mention that both of the high quality citations find a possible effect on blood pressure, even if they think the evidence is "not strong", even if they draw no conclusions on any effect on mortality or therapeutic outcomes, is misrepresenting the citations. In this, case if "simpler" means "completely ignoring their tentative findings and calls for more research" then I don't think simpler is better.
- That is why I thought "while there is limited evidence of a reduction in blood pressure versus placebo the overall effect on mortality is currently unknown" was a better summary of those two citations. I'm happy to consider alternative forms of wording, but I'd consider any wording which does not mention that both studies find a possible effect on blood pressure to be misrepresenting the current state of research. Merlinme (talk) 22:16, 10 July 2018 (UTC)
- Cochrane reports that there are problems with the completeness, applicability and quality of the evidence so a fairer summary would not just be "a possible effect", but a possible non-effect. Or we could just simplify it and say it is unclear, which is neater. For practice, Cochrane concludes "This makes it difficult, if not impossible, to determine the true impact of garlic on reducing blood pressure" so we are well aligned. I can't currently access the AJH source - what does it say about caveats applying to the evidence? Alexbrn (talk) 05:15, 11 July 2018 (UTC)
- I agree with Merlinme and have adjusted the wording of the section to reflect that there is evidence of an effect on blood pressure but not on cardiovascular morbidity and mortality. We have three recent meta-analyses all saying that there is a statistically significant effect. Yes, the Cochrane source hedges its bets, but they only looked at 2 trials, as that study was mainly interested in the effect on cardiovascular morbidity and mortality. The two meta-analyses that were specifically looking at the effects on blood pressure had fewer caveats about the results. Kaldari (talk) 06:36, 31 March 2020 (UTC)
- Cochrane reports that there are problems with the completeness, applicability and quality of the evidence so a fairer summary would not just be "a possible effect", but a possible non-effect. Or we could just simplify it and say it is unclear, which is neater. For practice, Cochrane concludes "This makes it difficult, if not impossible, to determine the true impact of garlic on reducing blood pressure" so we are well aligned. I can't currently access the AJH source - what does it say about caveats applying to the evidence? Alexbrn (talk) 05:15, 11 July 2018 (UTC)
- Again, let's look at what the two remaining, high quality citations actually say. The first study, American Journal of Hypertension, says:
- I'm not seeing the words "no evidence". What are you referring to? Alexbrn (talk) 17:52, 10 July 2018 (UTC)
- Ok, I've now been reverted with "Simpler is better". Is that necessarily the case? Which edit gives a more accurate representation of the citations given? The one which mentions that they both find a possible effect in the same direction, or the one which says there's no evidence? Merlinme (talk) 17:50, 10 July 2018 (UTC)
- Well, possibly, but when two separate high quality meta analyses (the only citations given, in fact) find some evidence of an effect I think it's at least worth mentioning. Merlinme (talk) 17:48, 10 July 2018 (UTC)
- Yeah "may have an effect" wording is just journal-speak straining for significance. It lay terms it's better to be clear this essentially means "unknown", or "unproven". Alexbrn (talk) 17:45, 10 July 2018 (UTC)
- Fair enough, but I still think it's worth noting that both remaining citations suggest there may be an effect on blood pressure, even if the effect on overall mortality is currently unknown. Merlinme (talk) 17:35, 10 July 2018 (UTC)
The effect of eating garlic on blood pressure is barely worth mentioning, 4 mmHg. I rewrote the sentence, but this is marginally encyclopedic (WP:UNDUE), even with the reviews supporting the statement.--Zefr (talk) 16:31, 31 March 2020 (UTC)
