It was suggested that garlic can lower blood pressure. However, studies testing this assumption have provided conflicting results (Reinhart, 2008).
Garlic has many biologically active agents, especially in the form of a bulb, which was not divided into cloves. Green garlic with long narrow leaves contains a lot of vitamin C. Garlic leaves significantly surpass feathers of green onions in terms of curative properties. Green leaves of garlic are rich with vitamins and sugar. They are used in preparing fresh food. Garlic leaves are especially rich in ascorbic acid. Green leaves of garlic emit phytoncides in the air and create a protective sterile zone, where causative agents of many diseases cannot develop and thus perish. Bulbs of green garlic contain vegetable protein (in particular. amino acid called lysine), polysaccharides, fats, vitamins (ascorbic acid, tiamine, riboflavinum, nicotinic acid), and mineral substances.
Green garlic surpasses all other vegetables in terms of the content of tiamine. Garlic is rich with iodine and calcium and has the same amount of iron as green apples. Sharpness of taste and originality of smell are caused by the presence of the compounds of sulfur and essential oil. Essential oil of green garlic includes phitoncides, which are antibiotics of the highest plants suppressing growth of many microorganisms. Bacterial action of green garlic is so strong that it is often grown together with other cultures for the prevention of their diseases. As claimed by Rahman:
Garlic is also reported to inhibit the pathogenesis of cardiovascular disease and to prevent cancer and other chronic diseases associated with aging. Over the last one-quarter century the role of garlic in treating cardiovascular disease has received much attention (2006).
There is a hypothesis that garlic regulates arterial pressure, improves blood circulation, and reduces risk factors of cardiovascular diseases. Numerous researches were directed at studying the influence of garlic on hyperlipidemia, hypertension, and ability to aggregate platelets. As claimed by Adams
Garlic has achieved a legendary reputation as an antihypertensive medication. It’s been used in China for centuries for that purpose, and the Japanese government officially recognizes garlic as a blood-pressure depressor. American scientists first tried garlic against high blood pressure in 1921. Garlic consistently lowers blood pressure in laboratory animals (2009).
Daily consumption of garlic can have the same impact on the decrease of arterial pressure as usage of medical substances. This conclusion was made by a group of international scientists under the direction of Australian Adelaide University. Patients, who took garlic daily for five months achieved the same results as those who used medical substances. However, scientists do not have reliable information concerning the fact weather garlic has a long-term effect or not. The influence of natural means only amplifies other useful steps such as reduction of meat roducts in a diet, decrease of salt and alcohol consumption, and increase of physical activity.
Garlic reduces arterial pressure and dilutes blood. It is necessary to consult a doctor when using anticoagulants and medicines such as aspirin or warfarin before using garlic as the means for lowering arterial pressure. Fresh garlic contains a large number of minerals, vitamins, and also sulfur, which influences antimicrobic properties of garlic. The impact of garlic on arterial pressure is not fully researched. During one double blind research, which was carried out in Germany, the equivalent of two heads of garlic daily reduced arterial pressure of people from 171/102 mm of mercury to 152/89 mm of mercury for the period of three months.
This blind research conducted by Rahman and Lowe (2006) included eight randomized controlled researches about the influence of garlic on arterial pressure (415 participants), which lasted for 4 weeks. Only three out of eight patients with hypertension took part in research. The dried-up preparation of garlic powder dosed from 600 to 900 mg a day (equivalent 1.8 - 2.7 g of fresh garlic) was used in all researches. There was a report on three of seven researches, which were conducted with the use of placebo. It included statistically reliable information about the decrease in systolic arterial pressure after the use of garlic. Koscielny claims:
A recent study evaluated the influence of garlic on arterial wall thickness and plaque buildup (arterial plaque being an established indicator of atherosclerosis). Patients received garlic supplementation in the form of 900 milligrams of garlic powder daily, or a harmless tablet that contained no garlic powder (2009).
The general average decrease of systolic arterial pressure (7.7 mm of mercury) was higher among patients who used garlic in comparison to those who used placebo. The average general distinction between these two groups was 5.0 mm of mercury. The authors of meta-analysis came to the conclusion that supplements with garlic powder are harmless and can bring some benefit to patients with initial stage of hypertension. However, the information to recommend garlic as a means of clinical therapy for treatment of patients with hypertension is not sufficient.
The cross-sectional research included observation of healthy adults with normal pressure (101 participants), who consumed more than 300 mg of the standardized garlic powder per day during 1 year or more. The observations were also made of a control group (the same age and sex structure, also 101 participants). Arterial pressure, heart rhythm and a level of plasma lipids were identical in both groups. Indicators of aorta rigidity (a speed of a pulse wave distribution and a vascular resistance) were lower in the group receiving garlic.
The double blind research was conducted by Ried, Frank, Fakler, and Sullivan (2008), in which 80 patients with occlusion of a peripheral artery of the II degree randomly received 800 mg of garlic powder or placebo within 12 weeks. The use of other therrapeutic means was not allowed. The usage of garlic led to statistically reliable increase (+31 m) of walking distance in comparison with a group taking placebo. The effect was shown on the fifth week of experiment. The result was a statistically reliable decrease of diastolic arterial pressure, spontaneous aggregation of platelets, and viscosity of plasma and cholesterol level in blood with the application of garlic therapy. The authors of research came to a conclusion that probably garlic is a suitable means, especially when used as a long-term treatment of beginning alternating lameness.
In a double blind research, 60 patients with vascular and cerebral risk factors, including increasing aggregation of platelets, randomly accepted 800 mg of garlic powder or placebo within four weeks. Digestion of garlic led to statistically reliable oppression of the increased relation of aggregation of circulating platelets. Significant changes in a group taking placebo were not observed.
Garlic or placebo were consumed 1 hour after rest in a laboratory situation. It was allowed to consume neither food nor drink during the supervision over the experiment. Haemo dynamic parameters (blood pressure and heart rhythm) and microcirculatory parameters (speed of erythrocytes in skin capillaries on border of a nail roller, capillary blood-groove, counted on diameter; average speed of erythrocytes) were measured before garlic or placebo consumption. The speed of erythrocytes and capillary blood-groove did not change at placebo consumption. Any of these types of treatment did not have any impact on arterial pressure and heart rhythm.
According to Ried:
This systematic review and meta-analysis suggests that garlic preparations are superior to placebo in reducing blood pressure in individuals with hypertension. Future large scale long-term trials are needed to investigate whether standardised garlic preparations could provide a safe alternative or complementary treatment option for hypertension in clinical practice (2008).
The use of garlic and standardized dry additives leads to an insignificant arterial blood pressure. The authors of a blind research made a conclusion that there is no sufficient data to make recommendations regarding garlic consumption was a means to fight hypertension for a prolonged clinic use. However, there are no grounds to think that garlic is harmful. Moreover, recent researches prove that treatment with the help of garlic powder promotes the decrease of lipid level and helps at the initial stages of hypertension, at least, during some time. The use of garlic leads to the decrease of arterial pressure in average 10 mm of mercury.
Besides, there are researches testifying proving the fact that garlic (garlic extract and dry powder) may increase aggregation of thrombocytes and improve microcirculation among patients with arterial disorders. Garlic also improves microcirculation in healthy people. However, additional researches with a bigger amount of participants are necessary for proving this notion.