Is garlic good for you?

Garlic has long been associated with health benefits – from curing a cold to lowering blood pressure and cholesterol levels. But will eating more garlic really improve your heart health?

Is garlic a vegetable?

Garlic is technically a vegetable from the allium family, which includes onions and leeks.

However, a clove of garlic is only around 3 to 6g so does not count as 1 of your 5-a-day.

You need to eat around 80g of any vegetable for 1 portion, which is equivalent to 13 to 26 cloves of garlic.

Instead, most people use smaller amounts of raw, fresh garlic to add flavour when cooking.

What's the nutritional content of garlic?

An average clove of garlic contains 3 to 4 calories and provides small amounts of potassium, manganese, phosphorus, B vitamins, vitamin C and polyphenols (protective plant chemicals).

What is allicin in garlic?

Chopping or crushing fresh garlic produces a chemical called allicin – a compound which gives fresh garlic its distinctive smell and pungency.

Allicin is a type of antioxidant – a group of natural compounds found in fruits and vegetables that may reduce inflammation and have been linked with a lower risk of cardiovascular disease.

Some studies suggest that allicin levels in fresh garlic are at their highest about 10 mins after crushing or chopping when the enzymes in the garlic have had time to react with the air.

Dried and ready-chopped garlic may contain lower levels of allicin compared to fresh garlic.

What is black garlic?

You can now buy black garlic which is made by heating garlic bulbs gently at a high humidity for several weeks. This process, often described as ‘fermentation’, makes the cloves soft, black, sweet, sticky and mildly flavoured.

Although black and other forms of ‘aged’ garlic contain less allicin, studies suggest they contain higher levels of more powerful antioxidants and polyphenols.

For this reason, black and aged garlic are typically used to make garlic supplements and products such as capsules, powder and garlic extract.

What are the benefits of garlic?

Although raw white garlic has a long history of medicinal use, particularly for heart health, strong evidence for specific health claims is limited.

Most studies look at the effects of aged or black garlic supplements/extracts which contain much higher amounts of some of garlic’s active compounds compared to those found in the 1 or 2 cloves of garlic you would cook with.

Does garlic lower blood pressure?

Some research suggests that garlic, mostly in supplement form, may modestly reduce blood pressure, particularly in people with high blood pressure.

A recent analysis of 10 studies looked at the effect of taking garlic products (e.g. garlic powders and garlic extract) on people with pre-existing high blood pressure.

Although a small drop in blood pressure was observed in some groups of people, the authors concluded that overall garlic supplements had a minimal impact on blood pressure.

However, using fresh garlic as a flavouring instead of salt can help lower your salt intake which will help lower blood pressure.

Does garlic lower cholesterol?

A recent analysis of multiple studies suggests that taking garlic supplements can result in small improvements in total cholesterol, lowering bad cholesterol (LDL) slightly and sometimes raising good cholesterol (HDL).

However, the evidence is mixed, inconsistent and too weak to make any firm conclusions or recommendations.

Other foods may help to lower cholesterol as part of a balanced diet.

Is it worth taking garlic tablets and supplements?

At the moment, evidence for garlic supplements is too limited and inconsistent to recommend taking them for health benefits.

It’s much better to include fresh garlic as part of a healthy diet, rather than relying on supplements.

To reduce risk of cardiovascular disease, it’s important to think about your whole diet rather than focusing on one food, like garlic.

For example, reducing salt intake by cutting back on processed foods, checking food labels and eating plenty of fruit and vegetables will have an impact on blood pressure.

Similarly, reducing saturated fat and eating more plant‑based foods such as peas, beans, lentils and wholegrains is likely to improve your cholesterol levels more than taking supplements.

Garlic supplements can interact with certain medicines such as blood thinners (anticoagulants) like warfarin, so always check with your GP before taking any nutritional supplements.

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