A hearty dose of garlic?

Scientists in the US have discovered why eating garlic is good for the heart: it boosts your natural supply of hydrogen sulphide (H₂S), relaxing blood vessels and increasing blood flow around the body. The team found that red blood cells in the body break down sulphur-containing compounds in garlic and convert them into H₂S.¹ 

Garlic is one of the oldest natural remedies, having been recommended by physicians for more than 5000 years. It is a natural antibiotic and has a range of potential uses, from reducing cholesterol to fighting cancer. But despite a wealth of historical evidence, medical trials with garlic supplements have had mixed results. 

One reason for this is that garlic can have different effects depending on how it is prepared. Intact garlic bulbs contain no strong smelling compounds and have almost no physiological activity. This is why garlic should be crushed to release its beneficial effects, rather than simply cut up or cooked whole. Crushing garlic allows plant enzymes to react and produce a variety of sulphur compounds, including organic polysulphides such as diallyl disulphide and diallyl trisulphide. These compounds are responsible for ’garlic breath’ but also for the bulb’s healing properties. 

The team, based at the University of Alabama, added small amounts of freshly-crushed garlic to human red blood cells and found they began releasing H₂S. ’Key to our work was the use of a novel measuring method - we invented a sulphide sensor capable of measuring sulphide levels in solution in real time,’ David Kraus, who worked on the project, told Chemistry World. 

Although toxic in high levels, H₂S is an important signalling molecule in the body and acts as a vasodilator, opening blood vessels. ’Very recently, H₂S has also been shown to help prevent the severe damage that occurs in heart attacks,’ Kraus added.²

The researchers hope the work will lead to a way of standardising garlic supplements by measuring the amount of H₂S they produce. Understanding the mechanisms behind this process could also lead to new treatments for heart conditions, they say. 

Commenting on the findings, Harold Seifried, a nutritional chemist at the National Institute of Health, Maryland, told Chemistry World: ’Garlic certainly may have some usefulness for future drug discovery as more is known about the molecular targets and mechanisms of action.’ 

Lewis Brindley