Black Garlic Benefits

If you love garlic but haven’t yet tried the aged, black garlic version, you’re in for a treat. As well as offering health benefits, black garlic has a lovely, soft, savoury-sweet flavour with undertones of molasses and balsamic. As a bonus, black garlic does not have a strong odour and is more socially acceptable for long-term users. Black garlic can be added to any savoury dish in place of raw white garlic, but add it towards the end of cooking for maximum effect. Once any garlic is heated for more than 3 minutes, its medicinal benefits are rapidly reduced and, after 10 minutes of heating, the ability of garlic to reduce platelet clotting is completely suppressed.

Black garlic benefits

Black garlic is produced by naturally fermenting fresh garlic bulbs under controlled conditions of high temperature (70 degrees) and high humidity (90%) for at least 21 days. This converts unstable, volatile, smelly sulphurous compounds into stable, odourless substances. Five new amino acids are also generated, along with dark pigments, called melanoidins, which turn the garlic cloves black.

The most exciting change is that the polyphenol content increases by a factor of five as sulfur-based substances, such as allicin, which are responsible for the pungent smell of cut fresh garlic, are converted into other non-smelly substances including flavonoid polyphenols.

Aged black garlic has significantly greater antioxidant activity than non-fermented garlic, offering at least four times more antioxidant activity per gram (and the antioxidant capacity of raw garlic is already high). It therefore has the potential to offer greater health benefits.

The origins of black garlic lie in Korean medicine, centuries ago, and spread to China and Thailand where it was revered as an anti-ageing supplement used to promote longevity. Black garlic is now available in mainstream supermarkets and features on the menu of high-end restaurants.

Black garlic and immunity

Black garlic extracts increase the activity of circulating white blood cells in samples analysed in the laboratory. By increasing the proliferation and activity of these immune cells such as macrophages and natural killer cells, black garlic extracts may improve immune targeting of abnormal body cells.

Cell studies also suggest that aged black garlic extracts can inhibit the growth of stomach cancer, colon cancer and leukaemia cells by triggering their natural self-destruct mechanism (apoptosis). These findings must be treated with caution but may suggest a useful preventative role for black garlic if confirmed in human trials.

Anecdotal evidence suggests that black garlic extracts may reduce symptoms of allergies such as runny nose (rhinitis) and watering eyes. This effect may relate to reduce activity of the B lymphocytes which produce the IgE antibodies linked with allergic reactions.

Black garlic and cholesterol

Black garlic improves cholesterol balance by increasing liver production of the ‘good’ HDL-cholesterol which protects against hardening and furring up of the arteries.

A 12-week study compared the effects of black garlic extracts (6g per day divided into two doses taken before the morning and evening meal) against placebo in 60 volunteers with a mildly raised cholesterol. No significant differences were seen in LDL-cholesterol, total cholesterol or triglycerides but ‘good’ HDL-cholesterol levels increased by an average of 7.45% to significantly lower the projected ten-year risk of heart attack or stroke.

There is also increasing evidence that black garlic helps to reduce the accumulation of fat in liver cells, but this has not yet been confirmed in humans.

Black garlic and diabetes

Raised glucose levels generate free radicals that are associated with a number of diabetes complications. Black garlic helps to quench these through its powerful antioxidant action and may also improve glucose control. If you have diabetes, always monitor glucose levels closely when making any dietary or lifestyle changes, including starting a new supplement.

Black garlic and blood pressure

Black garlic can lower blood pressure in a number of ways, by dilating blood vessels, reducing blood stickiness, by increasing the elasticity of artery walls, and by blocking a hormone called angiotensin II in the same way as some antihypertensive drugs.

A study involving 88 people with uncontrolled high blood pressure found that adding 1.2g aged garlic supplements to their diet every day reduced their blood pressure by 5/1.9 mmHg compared with those taking an inactive placebo. Some responded better than others, and in ‘responders’ blood pressure lowered by 11.5/6.3 mmHg on average.

The only way to know if you are a garlic responder is to take a standardised supplement for up to three months to see if it brings down your current average readings.

Black garlic and blood clotting

Garlic reduces the stickiness of blood to reduce platelet clumping and unwanted blood clots. Studies suggest that eating the equivalent of one clove of fresh garlic per day can reduce blood levels of a substance called thromboxane which is involved in the stimulation of thrombosis.

Black garlic and weight loss

Black garlic extracts have been found to reduce the accumulation of fat in cultured human fat cells by 15% compared to cultures to which no black garlic was added. Follow up studies suggest that black garlic extracts significantly reduce the formation of white adipose tissue when following a high fat or a high sugar diet. Black garlic also reduce fat accumulation in liver cells, which is a feature of obesity, metabolic syndrome and type 2 diabetes.

Black garlic dose

Black garlic may have additional beneficial biological effects similar to those of raw garlic, but research is in its early days and effects on blood clotting, blood pressure and arterial elasticity have not yet been confirmed. Even so, the growing evidence base may explain why many Eastern cultures revere black garlic as an anti-ageing supplement used, like ginseng and red reishi mushroom, to increase longevity.

A typical dose for black garlic is 200mg concentrated extract, equivalent to 2g whole garlic.

I now take black garlic supplements rather than garlic tablets and have started experimenting with its use in the kitchen. I guess I smell sweeter as a result!

How to add black garlic to your diet

You can simply spread a clove of black garlic onto dark rye bread, or use black garlic in any savoury dish wherever you would normally use raw garlic, such as when making a pasta sauce. Add it towards the end of cooking for maximum effect.

Once garlic is oven-heated (at 200 degrees C) or boiled for more than 3 minutes, its medicinal benefits rapidly reduce so that after more than 10 minutes heating, its ability to reduce platelet clotting is completely suppressed.

Image credits: Isle of Wight Garlic Farm

About Dr Sarah Brewer

QUORA EXPERT - TOP WRITER 2018 Dr Sarah Brewer MSc (Nutr Med), MA (Cantab), MB, BChir, RNutr, MBANT, CNHC qualified from Cambridge University with degrees in Natural Sciences, Medicine and Surgery. After working in general practice, she gained a master's degree in nutritional medicine from the University of Surrey. Sarah is a registered Medical Doctor, a registered Nutritionist and a registered Nutritional Therapist. She is an award winning author of over 60 popular self-help books and a columnist for Prima magazine.

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8 thoughts on “Black Garlic Benefits

  • Lynn

    Hi, if cooking with garlic (at normal cooking temperatures) for more than 3 minutes reduces its benefits, how come fermenting at high temperature and humidity for 21 days doesn’t reduce its benefits? I would be interested to know what is the difference? Many thanks

    • DrSarahBrewer

      Hi Lynn, Excellent question. Once garlic is oven-heated at 200 degrees C, or boiled for more than 3 minutes, its medicinal benefits are reduced. After 10 minutes heating at these temperatures, its ability to reduce platelet clotting is completely suppressed. But when making black garlic, the fermentation occurs under controlled conditions of 70°C and 90% relative humidity. At this temperature chemical reactions can occur that form the black pigments and a new range of antioxidants.

  • Marta

    Hi Sarah,

    every day is a good day to learn something new… It’s the first time I came across black garlic, and had no idea it has so many health benefits. I used to throw it away…. Shame on me.

    Anyway, thanks a lot for this article! It’s an awesome piece of advice.


    • admin

      If garlic in your kitchen turns black then feel free to throw it away as it is contaminated by mould or bacteria. The black garlic with health benefits is produced under strictly controlled conditions of heat and humidity which produces the black melanoidin pigments.

  • KariLee

    I have never even heard of black garlic, but I must say I am thoroughly intrigued!

    I had also not given any thought to the fact that garlic will lose it’s beneficial health properties after heating for more than 10 minutes. That makes sense yet most foods that are cooked with garlic are simmered for a long time, supposedly to blend the flavors.

    I have shared this article with Facebook and Twitter.

    I am sure there are many more like me that have been in the dark about black garlic.

    Thank you for another great article!

      • Teresa

        How many cloves of black garlic should a person consume a day? Someone told me that they eat 3 bulbs a day. Is it harmful to consume 3 or more bulbs a day?
        Thank you for your help!

      • DrSarahBrewer

        Hi Teresa, The usual amount for general well-being is 2g per day, which is 1 to 2 cloves depending on the size. AS it is classed as a food, then higher doses are used for flavouring. 3 bulbs a day does seem high. Excess garlic may cause nausea, body odour, diarrhea and can have a blood thinning effect but there is no robust evidence of serious side effects as a result. Best wishes, Sarah B