Allicin is the active compound which is found in garlic and is produced when the garlic is crushed or sliced. There is not an established Recommended Daily Amount (RDA) for Garlic or Allicin.
Allicin is believed to exert antifungal, antibacterial and antiviral properties and is associated with a number of health benefits relating to cardiovascular disease and cancer, immune support and insulin resistance to name but a few.
Garlic has been used for centuries to treat and eliminate infectious disease, attributed to its allicin content. Allicin has been found to exhibit antibacterial activity against a wide range of bacteria, including multidrug-resistant strains of Escherichia coli. It has also been shown to have antifungal activity, particularly against Candida albicans, antiparasitic activity and antiviral activity (1).
Prevention and treatment of colds- Research has shown garlic is effective in preventing the common cold virus and also helps to speed up the recovery period of the common cold (2). Garlic is thought to also have the ability to restore suppressed antibody response by stimulating immunity cells which help to restore suppressed antibody response. Garlic/allicin is also believed to stimulate the activity of certain immune cells against tumour cells (3). Antiviral properties of garlic have also been reported in studies. Garlic extract was shown to be active against a number of different infections including influenza (4).
Cardiovascular Health- Many clinical studies have shown that garlic/allicin may help prevent cardiovascular disease. Allicin has been shown to lower total cholesterol, LDL, or “bad cholesterol” and triglycerides, and increase HDL (good) cholesterol. (5) (6). This, in turn, may aid in the prevention of heart-related conditions such as heart attack, atherosclerosis, and stroke. In addition, garlic/allicin may support the overall health of the circulatory system, which may help in lowering the risk of heart attack and strokes. (7), (8). In addition, garlic has also been shown to reduce the risk of strokes, heart attacks and various heart diseases. (9) as it is believed to reduce oxidative stress and low-density lipoprotein (LDL) oxidation and have anti-thrombotic (clot forming) effects. Garlic also helps to reduce the risk of cardiovascular attacks due to its blood pressure lowering effect (10).
Cancer- Research into the use of garlic in both the prevention and treatment of cancer has also been shown to be promising (11). Lower cancer rates have been found in cultures with a high garlic intake (12). It has a variety of anti-tumour effects, including tumour cell growth inhibition and chemopreventive effects. In rodents, garlic and its constituents have been reported to inhibit the development of chemically induced tumours in the liver (13), colon (14), prostate (15), bladder (16), mammary gland (17), oesophagus (18), lung (19), skin (20), and stomach (21) in both rodent and human studies.
Diabetes- In studies, there has also shown to be a positive correlation between the consumption of garlic and positive outcomes on blood glucose in the management of Type 2 Diabetic patients (22).
High blood pressure- due to the vasodilator action (widening of the blood vessels) of garlic (allicin), taking a supplement may help to reduce blood pressure and therefore may be of benefit to those suffering from hypertension.
Circulation problems- Due to the anticoagulant action (prevents clotting of blood), garlic (allicin) may be useful for those who have circulatory problems.
Cholesterol- Garlic (allicin) may help to reduce cholesterol making it a useful supplement for those who have high cholesterol or those who suffer from atherosclerosis.
Fungal infections- Due to the anti-fungal action of garlic (allicin), taking a supplement may help to prevent or eliminate candida, thrush and athletes foot.
Immune Support– Garlic (allicin) may help to support a healthy immune system, taking a supplement may, therefore, help to prevent colds, the flu and other common infections.
Sinusitis or Bronchitis– Garlic (allicin) has a decongestant action (relieves congestion in the upper respiratory tract) which may be useful for those with sinusitis or bronchitis or for those with a build-up of catarrh.
Antihistamine– Garlic (allicin) has an antihistamine action, which may provide relief to those suffering from seasonal ailments such as hay fever and other common allergies.
Garlic (allicin) is considered to be safe for most people when taken by mouth appropriately. Side effects may include bad breath, a burning sensation in the mouth or stomach, heartburn, gas, nausea, vomiting, body odour, and diarrhoea. Garlic may also increase the risk of bleeding and so should be used with precaution by those taking blood thinning medications or those with bleeding disorders. No Tolerable Upper Intake Level has been established for Garlic or Allicin.