Garlic – witchcraft or real cure?

Hippocrates was an early supporter of the healing effects of garlic.

Hippocrates was an early supporter of the healing effects of garlic.

Garlic is widely used around the world for its pungent flavour as a seasoning or condiment. It is an important component in many dishes of various regions, including Asia, the Middle East, northern Africa, southern Europe and parts of South and Central America. Garlic has also been used as a medicine in many cultures for thousands of years. This blog entry will focus on its potential healing properties.

Early ‘medicos’ like Hippocrates, Galen, Pliny the Elder, and Dioscorides, the personal physician to the Roman Emperor Nero, all mention the use of garlic for many conditions, including parasite invasion, respiratory problems, poor digestion, and low energy. The question is should healing of such a range of ailments be seen as witchcraft or can it actually be true effects?

Proof of effectiveness

Witchcraft it might be, but there is clear evidence that consuming garlic can be effective in influencing a wide range of diseases and conditions. Animal studies, and some early research studies in humans, showed possible cardiovascular benefits of garlic. Garlic supplementation reduced accumulation of cholesterol on the vascular walls of animals and humans and inhibited vascular calcification. It also lowered blood pressure. A 2012 meta-analysis of randomised, double-blind, placebo-controlled trials looking at the effects of garlic on serum lipid profiles, found garlic was superior to placebo in reducing serum total cholesterol and triglyceride levels.

So far so good, but there is more. In 1924, garlic was found to be an effective way to prevent scurvy, because of its high vitamin C content. It has also been found to enhance thiamin absorption, and therefore reduces the likelihood of developing the thiamin deficiency beriberi. Garlic can be used as a disinfectant because of its bacteriostatic and bactericidal properties. It was used as an antiseptic to prevent gangrene during World War I and World War II. More recently, it has been found from a clinical trial that a mouthwash containing 2.5% fresh garlic showed good antimicrobial activity.

It has been proposed that garlic might prevent or fight the common cold with backing of a long tradition in herbal medicine using garlic for hoarseness and coughs. However, a systematic review of published scientific reports concluded that there was insufficient clinical trial evidence regarding the effects of garlic in preventing or treating the common cold. Claims of effectiveness appeared to rely largely on poor-quality evidence, but it might be too early to give up. More research will be needed to resolve this issue so keep trying if you’re a believer.

What is the magic compound?

Allicin in garlic has healing effects (Photo : David Goering)

Allicin in garlic has healing effects (Photo : David Goehring)

Garlic produces a chemical called allicin, an organosulfur compound. This compound is only present in garlic after the tissue has been damaged. Allicin is released by crushing or chewing raw garlic and cannot be formed from cooked garlic. When fresh garlic is chopped or crushed, the enzyme alliinase converts alliin in the garlic into allicin. Allicin exhibits antibacterial, antifungal, antiviral, and antiprotozoal activity. It is actually garlic’s defence mechanism against attacks by pests. It is what seems to make garlic work for certain conditions. However, the allicin formed is very unstable and quickly changes into a series of other beneficial sulfur containing compounds such as diallyl disulfide and others.

Allicin also makes garlic smell and causes bad breath (halitosis), as well as giving sweat a pungent “garlicky” smell. This is due to the formation of allyl methyl sulfide, a volatile liquid which is absorbed into the blood during the metabolism of garlic-derived sulfur compounds. From the blood it travels to the lungs and further to the mouth, causing the bad breath, and to the skin, where it is exuded through skin pores. Some products are made “odorless” by aging the garlic, but this process can also make the garlic less effective. A better way is to sip milk at the same time as consuming garlic to neutralise the bad breath. Plain water, mushrooms and basil may also reduce the odour.

So what to believe?

A detailed scientific review of garlic’s potential therapeutic effects was published in 2014. Scientific findings have shown that garlic has the potential to lower high blood pressure by as much as 7% or 8%, reduce hardening of arteries (atherosclerosis) as people age, reduce the risk of developing colon, rectal and stomach cancer, reduce the number of tick bites at high doses, and treat fungal infections of the skin. That’s the good news.

Unfortunately, garlic seems to have little effect on blood sugar, either in people with diabetes or those without it, a claim proposed by some early studies. Taking garlic by mouth for stomach ulcers caused by Helicobacter pylori infection initially looked promising, but has since been dismissed as being ineffectual for treating people infected with this bug. Some doubts have also been raised in relation to the claimed effects on lowering cholesterol and triglyceride levels, although there are conflicting results. Garlic has no positive influence on breast or lung cancer.

Bad as that might be there are still some hope for a few other claimed healing effects. There is some preliminary evidence that garlic might be helpful for improving urinary flow in people affected by benign prostatic hyperplasia. Going one step further it has been shown that men in China who eat about a clove of garlic daily seem to have a 50% lower risk of developing prostate cancer, but it is uncertain if this effect is universally applicable. Preliminary research also suggests that garlic might reduce the frequency of colds when taken for prevention, but once affected by a cold it still had to run its course.


Belief can be a strong healer.

That leaves the witchcraft

Although there are some indications that preventive use of garlic might stop a common cold in its tracks, it is a common belief that taking garlic during a cold reduces either symptom severity or the number of days of illness. There is no information from randomised controlled trials to confirm this, but plenty of websites vouching for the beneficial effects of garlic in limiting cold symptoms. One website recommending to pop a whole garlic clove in your mouth and chop away got 85 comments testifying to the effectiveness of garlic in relieving symptoms and shortening common cold recovery time.

Belief can be a strong healer or is it just the garlic breath that keeps everyone far out of sneezing range?

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