Blood pressure news
Can garlic lower blood pressure?
A recent journal article has claimed that taking garlic supplements can significantly reduce blood pressure in people who have high blood pressure.
The article did not publish new research, but was a “meta-analysis” of previous research. That is, it compiled and analysed previous studies to see if an overall conclusion could be drawn from their individual results.
The analysis identified 11 previous studies of garlic supplements and blood pressure. In most of this studies, participants took the garlic in powdered form, in doses ranging from 600 mg to 900 mg daily.
The length of the studies ranged from 12 to 23 weeks.
Taken together, the various studies showed that garlic reduced systolic blood pressure by an average of 4.6 mmHg. In people with high blood pressure, the average reduction in blood pressure was 8.4 mmHg systolic and 7.3 mmHg diastolic. The higher the person’s blood pressure at the beginning of the study, the more their blood pressure was reduced.
A 600mg dose of garlic powder contains 3.6 mg of allicin, garlic’s active ingredient. 900 mg contains 5.4 mg of allicin, whereas
a fresh clove of garlic can contain anything from 5 mg to 9 mg of allicin.
This analysis makes interesting reading, as it certainly indicates that garlic can have an effect on blood pressure, even in people who have high blood pressure. The value of a meta-analysis is that it pulls together the results of different smaller studies to give an overall picture of what research is saying about a particular topic.
However, there is a lot more research that needs to be done before garlic could be recommended as a treatment for high blood pressure. Firstly,
although the various studies lasted over periods of up to 23 weeks, there is no evidence to show that the effects of the garlic powder would last over the long-term.
Blood pressure medicines continue to have an effect for years, but at the moment, we do not know if daily garlic would have the same effect over a longer period.
Secondly, although this study shows that garlic can reduce blood pressure, it does not show whether this reduction in blood pressure leads to a reduction in heart attacks and strokes. Again, research has shown blood pressure medicines to be very effective in reducing risk of heart attacks and strokes. As the authors of this paper state, more research needs to be done to find out if garlic has the same effect.
Finally, the study looked at daily supplements of garlic powder, but the authors also show that garlic supplements contain less of the active ingredient, allicin, than a fresh clove of garlic. There is therefore a question about whether powdered garlic is the best option.
Fresh garlic is an excellent flavouring for meals like pasta sauces, for example. If you are trying to reduce the amount of salt you eat, garlic can really help to boost the flavour of your food. So adding fresh garlic to meals may have be a cheaper, and possibly more effective way of getting the effects of allicin than paying for garlic supplements.
Source: Ried K et al., Effect of garlic on blood pressure: A systematic review and meta-analysis, BMC Cardiovascular Disorders 2008, 8: 13 (www.biomedcentral.com)
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