Plants, unlike animals, cannot escape predators. They are literally rooted to one spot. They have overcome this disadvantage by arming themselves with a vast chemical armory as a defense.
Those parts of a plant that are below the ground are particularly vulnerable to attack. Bacteria, fungi, nematodes, larvae, snails, mice — the list of threats is long. Not surprisingly, plants such as onion and garlic, which store food for future growth in underground bulbs, have equipped themselves with defensive chemicals of every conceivable hue and variety.
2,300 chemicals
A recent inventory of the molecular army of garlic, using very sensitive analytical tools of chemistry has shown that there are over 2,300 chemicals in its cloves. Most of them are there for reasons that we do not comprehend yet. Barely 70 of these figure in today’s nutrition charts. These include manganese, selenium and vitamin B6: three human nutrients that garlic is particularly rich in.
Many of the other constituents – thiosulfinates, lectins, saponins and flavonoids, to name a few – can play protective roles in humans too. It is not surprising that humans have a long history of incorporating garlic into their diets. Sumerian clay tablets from 4000 years ago have recipes that use garlic. And beyond nutritive value, garlic has been used for its medicinal properties in many cultures.
In our tradition
In Ayurveda, warm garlic-infused milk, Lasuna Ksheerapaka, is beneficial for respiratory conditions such as asthma, cough and common cold, and for generally improving body strength. Similarly, garlic-infused water (lasuna phata) is used as a tonic, improving digestion by stimulating the secretion of digestive enzymes, and by its carminative properties, which reduce gas formation.
The pungent flavour that is characteristic of garlic and related species comes from a sulphur-containing compound. Allicin is not present in fresh garlic. It is produced when an odour-free precursor called allicin is acted upon by an enzyme. The two are brought together when garlic is chopped, crushed, or even chewed.
Allicin interacts with receptors found on sensory neurons in the trigeminal nerve, which gathers sensations from the mouth and the nose. The pungent taste of garlic is a result of this interaction.
Allicin, and other garlic constituents such as diallyl disulfide have an influence on inflammatory processes. Beneficial effects include the regulation of blood pressure and positive trends in cardiovascular health. Another constituent, the flavonoid luteolin, inhibits the formation and aggregation of amyloid beta plaques, which are major hallmarks of Alzheimer’s disease.
Ongoing research may one day pinpoint the roles played by the many other chemicals in garlic. Some of these, individually or in combinations, may contribute to the betterment of human health. What we know today is that moderation is key to the beneficial use of garlic in our diet, to avoid side effects such as heartburn and diarrhea. Some health practitioners say that four grams every day is about the right amount.
India is the second largest producer of garlic. Impressive varieties of garlic such as the Riya van come from Neemuch and Ratlam in Madhya Pradesh, the largest garlic-producing State. In South India, Karnataka’s Gadag local varieties, with their strong, pungent flavor and aroma sell very well. And then there are the Kashmiri varieties. No matter what your preferences are, a little garlic may add spice to your life and to your health.
(The article was written in collaboration with Sushil Chandani, who works in molecular modelling.)
