Is garlic an everyday superfood?

Aphrodisiac, money, food, medicine, vampire repellent – garlic has had many uses throughout the ages.

More recent evidence-based research suggests garlic may be effective against high blood pressure, cardiovascular disease, cholesterol, colds and some cancers.

We've teamed up with the British Dietetic Association (BDA) to see if the health claims about garlic stand up to closer scrutiny.

Garlic contains vitamins C, B6, manganese, selenium and other antioxidants (notably allicin)


The evidence

High blood pressure
An authoritative review from 2012 of the best available evidence on the use of garlic to treat high blood pressure identified one good quality study that suggested that 200mg of garlic powder three times daily reduced blood pressure. However, the review concluded that there was insufficient evidence to say if garlic was an effective means for treating high blood pressure and reducing death rates.

Cholesterol
A well-conducted review from 2009 of 29 good quality studies (involving a combined total of 1,794 participants) concluded that garlic (mainly garlic powder) produced "modest reductions" in total cholesterol levels.

Common cold
good quality review from 2012 of the best available evidence concluded there was insufficient evidence regarding the effects of garlic supplements in treating or preventing colds. Most studies that claimed this were of poor quality. The review said one reasonably good study suggested that garlic may prevent colds, but that more research was needed to back up the finding.

Cancer
The evidence is mixed. A 2007 World Cancer Research Fund review concluded that garlic "probably protects against" bowel and stomach cancers. A more recent review from 2009 of the best available research on humans concluded that there was "no credible evidence" with stomach, breast, lung and womb cancers, but that there was "very limited evidence" that eating garlic may lower the risk of colon, prostate, oral, ovary or renal cell cancers.


The dietitian's verdict

Alison Hornby, a dietitian and BDA spokesperson, says: "Garlic is a delicious flavour used widely in Mediterranean and Asian cooking.

"Studies using high concentrations of garlic extracts have been associated with improved blood circulation, healthier cholesterol levels and lower blood pressure, all of which reduce the risk of cardiovascular disease. However, current evidence does not support the use of garlic supplements to improve health. 

"Garlic is particularly useful in cooking as it provides an alternative to salt in adding flavour to meals, along with lemon juice, chilli, herbs and spices. Eating less salt is important for avoiding high blood pressure."


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Page last reviewed: 02/06/2013

Next review due: 02/06/2015

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The 2 comments posted are personal views. Any information they give has not been checked and may not be accurate.

alexrossy said on 14 September 2013

What about today's (14/09/2013) Daily Mail article that argues that tablets are better than raw as they have a guaranteed allicin content of 1.8mg per dose?
They claim that as the amount of allicin produced is variable and due to allicins unstable nature, you would need to eat 30 cloves in one sitting to be guaranteed an allicin dose of 1.8mg. Also, the tablets wont make your breathe stink!

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tosh12 said on 22 August 2013

We are told (telegraph 7/8/13) that garlic contains allicin, an antibiotic and anti-fungal compound that protects it against pests and is believed to be the source of the health benefits. It is released when a garlic clove – or, indeed, entire head – is crushed or chopped. The allicin is more or less destroyed when cooked or pickled in vinegar.

More likely then, if this true, garlic is a superfood in its natural state, less so as a processed powder that the review conclusions here were based on.

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Superfoods: the evidence

We examine the evidence behind the health claims of the most popular superfoods