It supports heart health, has antimicrobial and anti-fungal properties, and contains antioxidants – natural chemicals that protect the body against damage from free radicals that can cause diseases such as heart disease and Alzheimer’s.
Garlic’s health benefits have been known about for centuries. It was reputedly used to give the pyramid builders in Ancient Egypt stamina, and in 18th century France, grave diggers drank wine containing crushed garlic to ward off the plague.
Dr Sarah Brewer says: ‘Garlic is an important ingredient in the Mediterranean diet which also includes vegetables, pulses, fruits, fish, red wine and nuts, and is used to help protect against heart disease. It’s thought to lower high blood pressure – a really common condition which can raise your risk of heart attack or stroke.’
What does garlic do?
Garlic dilates blood vessels and in some studies, it has been found to reduce blood pressure. It also stops blood platelets clumping together, potentially preventing damage to arteries.
Allin and allicin the active ingredients found in garlic (allicin is produced from allin) – which are destroyed by cooking – also have antimicrobial properties, which may help fight off infections and be beneficial for immunity.
Garlic is believed to support heart health by lowering blood pressure, slowing down hardening of the arteries and acting as an anticoagulant (stopping blood from clotting and damaging the arteries).
High blood pressure affects an estimated 16 million people in the UK; 31 per cent of men and 28 per cent of women, and yet around a third of people don’t even realise they have it. A 2013 review confirmed allicin had cardio-protective effects and concluded it should be developed as a health product for heart health.
Some studies have shown taking a garlic supplement can reduce blood pressure in people who have the condition. However, another review of evidence concluded it was unclear if reducing blood pressure by taking garlic necessarily reduced heart disease and deaths from heart attacks and strokes.
A study carried out in 2001 found that people taking daily garlic supplements had fewer colds than those taking a placebo, and if they did catch a cold they recovered quicker. A more recent review of garlic and common colds, admitted the 2001 study, did show garlic may prevent colds but said other evidence was limited and that more studies were needed to confirm this.
Getting garlic from your diet
Garlic is related to the allium genus of bulbs which also includes onions and is commonly added to curries, pasta sauces and casseroles to add flavour. It’s easy to grow in the garden, too. But you’d have to eat an awful lot of it to get the sort of therapeutic quantities tested in scientific studies. This is because the ingredients in garlic – including alliin and allicin – are destroyed by cooking. For these reasons, many people find it more convenient to take a garlic supplement instead, rather than eat raw garlic which can cause breath odour.
There isn’t an upper safety limit for how much garlic you should consume. Minor side effects from high doses can include indigestion, gas and diarrhoea.
The main safety concerns centre on the fact that garlic thins the blood so you should always check with your doctor first if you are taking blood-thinning medication, such as warfarin, aspirin or non-steroidal anti-inflammatory drugs (NSAIDs) including ibuprofen.
There is no set recommended daily allowance for garlic. Dosage range is: 2 to5g fresh garlic daily; 0.4 to 1.2g dried powder daily; 2 to 5mg garlic oil daily. A typical daily supplement dose is two 800mg capsules a day.