Garlic belongs to the genus Allium and is closely related to the onion, rakkyo (an onion found in Asia), scallion, chive, leek, and shallot. It has been used by humans for thousands of years and was used in Ancient Egypt for both culinary purposes and its health and therapeutic benefits.
This article will look at the potential health benefits of garlic and cover any research that supports the claims.
- In many countries, garlic has been used medicinally for centuries.
- Garlic may have a range of health benefits, both raw and cooked.
- It may have significant antibiotic properties.
Garlic has been used all over the world for thousands of years. Records indicate that garlic was in use when the Giza pyramids were built, about 5,000 years ago.
Richard S. Rivlin wrote in the Journal of Nutrition that the ancient Greek physician Hippocrates (circa. 460-370 BC), known today as “the father of Western medicine,” prescribed garlic for a wide range of conditions and illnesses. Hippocrates promoted the use of garlic for treating respiratory problems, parasites, poor digestion, and fatigue.
The original Olympic athletes in Ancient Greece were given garlic – possibly the earliest example of “performance enhancing” agents used in sports.
From Ancient Egypt, garlic spread to the advanced ancient civilizations of the Indus Valley (Pakistan and western India today). From there, it made its way to China.
Throughout history in the Middle East, East Asia, and Nepal, garlic has been used to treat bronchitis, hypertension (high blood pressure), TB (tuberculosis), liver disorders, dysentery, flatulence, colic, intestinal worms, rheumatism, diabetes, and fevers.
Currently, garlic is widely used for several conditions linked to the blood system and heart, including atherosclerosis (hardening of the arteries), high cholesterol, heart attack, coronary heart disease, and hypertension.
Garlic is also used today by some people for the prevention of lung cancer, prostate cancer, breast cancer, stomach cancer, rectal cancer, and colon cancer.
It is important to add that only some of these uses are backed by research.
A study published in the journal Food and Chemical Toxicology warned that short-term heating reduces the anti-inflammatory effects of fresh raw garlic extracts. This may be a problem for some people who do not like or cannot tolerate the taste and/or odour of fresh garlic.
Below are examples of some scientific studies published in peer-reviewed academic journals about the therapeutic benefits (or not) of garlic.
Lung cancer risk
People who ate raw garlic at least twice a week during the 7 year study period had a 44 per cent lower risk of developing lung cancer, according to a study conducted at the Jiangsu Provincial Center for Disease Control and Prevention in China.
The researchers, who published their study in the journal Cancer Prevention Research, carried out face-to-face interviews with 1,424 lung cancer patients and 4,543 healthy individuals. They were asked about their diet and lifestyle, including questions on smoking and how often they ate garlic.
The study authors wrote: “Protective association between intake of raw garlic and lung cancer has been observed with a dose-response pattern, suggesting that garlic may potentially serve as a chemopreventive agent for lung cancer.”
Organo-sulfur compounds found in garlic have been identified as effective in destroying the cells in glioblastomas, a type of deadly brain tumour.
Scientists at the Medical University of South Carolina reported in the journal Cancer that three pure organo-sulfur compounds from garlic – DAS, DADS, and DATS – “demonstrated efficacy in eradicating brain cancer cells, but DATS proved to be the most effective.”
Co-author, Ray Swapan, Ph.D., said “This research highlights the great promise of plant-originated compounds as a natural medicine for controlling the malignant growth of human brain tumour cells. More studies are needed in animal models of brain tumours before application of this therapeutic strategy to brain tumour patients.”
Women whose diets were rich in allium vegetables had lower levels of osteoarthritis, a team at King’s College London and the University of East Anglia, both in England, reported in the journal BMC Musculoskeletal Disorders. Examples of allium vegetables include garlic, leeks, shallots, onions, and rakkyo.
The study authors said their findings not only highlighted the possible impact of diet on osteoarthritis outcomes but also demonstrated the potential for using compounds that exist in garlic to develop treatments for the condition.
The long-term study, involving more than 1,000 healthy female twins, found that those whose dietary habits included plenty of fruit and vegetables, “particularly alliums such as garlic,” had fewer signs of early osteoarthritis in the hip joint.
Potentially a powerful antibiotic
Diallyl sulfide, a compound in garlic, was 100 times more effective than two popular antibiotics in fighting the Campylobacter bacterium, according to a study published in the Journal of Antimicrobial Chemotherapy.
The Campylobacter bacterium is one of the most common causes of intestinal infections.
Senior author, Dr Xiaonan Lu, from Washington State University, said, “This work is very exciting to me because it shows that this compound has the potential to reduce disease-causing bacteria in the environment and in our food supply.”
Diallyl trisulfide, a component of garlic oil, helps protect the heart during cardiac surgery and after a heart attack, researchers at Emory University School of Medicine found. They also believe diallyl trisulfide could be used as a treatment for heart failure.
Hydrogen sulfide gas has been shown to protect the heart from damage.
However, it is a volatile compound and difficult to deliver as therapy.
Because of this, the scientists decided to focus on diallyl trisulfide, a garlic oil component, as a safer way to deliver the benefits of hydrogen sulfide to the heart.
In experiments using laboratory mice, the team found that, after a heart attack, the mice that had received diallyl sulfide had 61 per cent less heart damage in the area at risk, compared with the untreated mice.
In another study, published in the Journal of Agricultural and Food Chemistry, scientists found that garlic oil may help protect diabetes patients from cardiomyopathy.
Cardiomyopathy is the leading cause of death among diabetes patients. It is a chronic disease of the myocardium (heart muscle), which is abnormally thickened, enlarged, and/or stiffened.
The team fed diabetic laboratory rats either garlic oil or corn oil. Those fed garlic oils experienced significantly more changes associated with protection against heart damage, compared with the animals that were fed corn oil.
The study authors wrote, “In conclusion, garlic oil possesses significant potential for protecting hearts from diabetes-induced cardiomyopathy.”
Human studies will need to be performed to confirm the results of this study.
High cholesterol and high blood pressure
Researchers at Ankara University investigated the effects of garlic extract supplementation on the blood lipid (fat) profile of patients with high blood cholesterol. Their study was published in the Journal of Nutritional Biochemistry.
The study involved 23 volunteers, all with high cholesterol; 13 of them also had high blood pressure. They were divided into two groups:
- The high-cholesterol normotensive group (normal blood pressure).
- The high-cholesterol hypertensive group (high blood pressure).
They took garlic extract supplements for 4 months and were regularly checked for blood lipid parameters, as well as kidney and liver function.
At the end of the 4 months, the researchers concluded “…garlic extract supplementation improves blood lipid profile, strengthens blood antioxidant potential, and causes significant reductions in systolic and diastolic blood pressures. It also leads to a decrease in the level of oxidation product (MDA) in the blood samples, which demonstrates reduced oxidation reactions in the body.”
In other words, the garlic extract supplements reduced high cholesterol levels, and also blood pressure in the patients with hypertension. The scientists added that theirs was a small study – more work needs to be carried out.