lower blood pressure By Garlic

Garlic can lower blood pressure by 10%... but only if you take it in tablet form
Those with hypertension, or high blood pressure, could control their condition better by adding garlic to conventional medication
Eating the real thing would not have the same effect - allicin is produced when raw garlic is crushed but much is destroyed during cooking
     
Garlic: Pill work better than cloves

Garlic could help cut blood pressure by 10 per cent – but only if you take it in the form of tablets, claim scientists.
Twelve weeks of treatment with garlic tablets led to a ‘significant’ cut in blood pressure, slashing the risk of a heart attack or stroke, according to a review of evidence.
Researchers claim those with hypertension, or high blood pressure, could control their condition better by adding garlic to conventional medication.
The review of 21 studies on humans found supplements of dried garlic containing a guaranteed dose of the active ingredient allicin consistently led to reductions in blood pressure.
But eating the real thing would not have the same effect, says the review. Although allicin is produced when raw garlic is crushed or chewed, much of it is destroyed during cooking.
The tablets also have the significant advantage of not producing the bad breath associated with eating fresh garlic.
The review looked at supplements with a guaranteed allicin yield of 1.8mg per dose.
The earliest authoritative clinical trial to be published in 1990 found taking Kwai brand garlic tablets led to a significant fall in blood pressure of 10 per cent within 12 weeks.
More studies conducted since 1990 have demonstrated significant blood pressure lowering effects from dried garlic releasing allicin at 1.8mg per dose.
Not all garlic preparations release allicin in significant, standardised amounts, says the review by nutritionist Dr Pamela Mason in the journal Complete Nutrition.

Garlic is thought to counter high blood pressure because it stimulates production of the chemicals nitric oxide and hydrogen sulphide, which helps relax blood vessels.
Dr Catherine Hood, an independent expert in nutrition and dietetics, said: ‘This review found evidence that garlic, in particular Kwai, can reduce the stickiness of the blood, results in dilatation of the arteries and has antioxidant activity.’
Dr Hood said there was some evidence garlic may also use the same mechanism as drugs called ACE inhibitors to lower blood pressure. 
The drugs stop the body creating a hormone known as angiotensin II. This has a variety of effects but essentially relaxes blood vessels.
Nutritionist Sarah West said other research suggests allicin helps lower ‘bad’ LDL cholesterol and triglycerides – a common form of fat.
She added: ‘It would be very difficult to get a therapeutic dose from eating raw garlic, it would need 30 cloves at one sitting – and we don’t actually have the evidence that it would work.
‘The allicin content of raw garlic varies enormously and a significant drawback is the odour on the breath – a problem you don’t get with tablets.


Garlic for Hypertension

Garlic is widely used by patients for its blood pressure lowering effects. In this analysis, we reviewed the currently available evidence to determine the impact of garlic on cardiovascular events and mortality in patients with hypertension. 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.

Abstract

Background: 
Garlic is widely used by patients for its blood pressure lowering effects. A meta‐analysis published in 2008 concluded that garlic consumption lowers blood pressure in hypertensive and normotensive patients. Therefore, it is important to review the currently available evidence to determine whether garlic may also have a beneficial role in the reduction of cardiovascular events and mortality rates in patients with hypertension.

Objectives: 
To determine whether the use of garlic as monotherapy, in hypertensive patients, lowers the risk of cardiovascular morbidity and mortality compared to placebo.

Search methods: 
A systematic search for trials was conducted in the Cochrane Hypertension Group Specialised Register, CENTRAL, MEDLINE, EMBASE, AGRICOLA, AMED, and CINAHL up to November 2011. A hand search of reference lists of identified reviews was conducted. Experts in the area were also contacted to identify trials not found in the electronic search. Clinicaltrials.gov was searched for ongoing trials.

Selection criteria: 
Randomized, placebo‐controlled trials of any garlic preparation versus placebo for the treatment of hypertension were included.

Data collection and analysis: 
Two reviewers independently extracted data and assessed trial quality using the risk of bias tool. Data synthesis and analysis was performed using RevMan 5.

Main results: 
The search identified two randomized controlled trials for inclusion. One trial included 47 hypertensive patients and showed that garlic significantly reduces mean supine systolic blood pressure by 12 mmHg (95% CI 0.56 to 23.44 mmHg, p=0.04) and mean supine diastolic blood pressure by 9 mmHg (95% CI 2.49 to 15.51 mmHg, p=0.007) versus placebo. The authors state that garlic was "free from side effects" and that no serious side effects were reported. There were 3 cases "where a slight smell of garlic was noted."

The second trial could not be meta‐analysed as they did not report the number of people randomized to each treatment group. They did report that 200 mg of garlic powder given three times daily, in addition to hydrochlorothiazide‐triamterene baseline therapy, produced a mean reduction of systolic blood pressure by 10‐11 mmHg and of diastolic blood pressure by 6‐8 mmHg versus placebo.

Neither trial reported clinical outcomes and insufficient data was provided on adverse events.

Authors' conclusions: There is insufficient evidence to determine if garlic provides a therapeutic advantage versus placebo in terms of reducing the risk of mortality and cardiovascular morbidity in patients diagnosed with hypertension. There is also insufficient evidence to determine the difference in withdrawals due to adverse events between patients treated with garlic or placebo.

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.

How Much Garlic Should You Eat to Lower Blood Pressure?

A woman slices garlic on a cutting board. Photo Credit angelsimon/iStock/Getty Images
The use of garlic dates back to ancient times -- it has been used for many purposes, including as a means to treat heart disease. Garlic is still used by many to lower blood pressure, but the preparation and amount affects its blood pressure-lowering potential.

Allicin for High Blood Pressure

Although several studies show that garlic lowers blood pressure, the exact mechanism of how it does so warrants more study, according to researchers of a study published in Nutrition Research in 2014. Allicin is a highly unstable and reactive compound in garlic. It is an active ingredient associated with garlic's blood pressure-lowering effect, especially in those who have high blood pressure or hypertension. Researchers of a review study published in 2008 in BMC Cardiovascular Disorders concluded that the higher the starting blood pressure, the greater the reduction in the blood pressure after treatment with garlic.

Raw Fresh or Dried Garlic
According to the Linus Pauling Institute, when you crush, chop or chew raw fresh garlic, an enzyme called alliinase is released, which starts a series of reactions resulting in the formation of allicin. Raw fresh or dried garlic may provide you with the most allicin. The allicin potential decreases with age or heat-treatment of the garlic. Researchers say that due to the instability of allicin, forms of garlic other than fresh raw or dried garlic, such as aged or cooked garlic, may have less allicin-forming potential. The instability of allicin is also the reason pure allicin is not available as a supplement.

Are Garlic Pills Good to Lower Blood Pressure? 

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Dose Dependent
Researchers of a study published in 2013 in Pakistan Journal of Pharmaceutical Sciences divided individuals diagnosed with hypertension into groups, each with a different dosage of garlic -- 300, 600, 900, 1200 or 1500 milligrams of garlic per day -- or a placebo or blood pressure medication. They found that all the garlic dosages decreased blood pressure comparatively as much as the blood pressure medicine did, and that there was a greater reduction in blood pressure with the higher doses of garlic and with a longer duration of treatment. In the review in BMC Cardiovascular Disorders, the authors found that most of the studies that showed garlic’s blood pressure-lowering effect used a dosage of 600 to 900 milligrams of garlic per day.