Garlic is one of the most popular foods among humans. It was used by ancient civilizations and it still remains a very common food today. Garlic is known to have many health benefits, but there are some side effects which need to be considered when taking garlic supplements or consuming garlic products. There are different types of garlic and they differ in their medicinal properties. Some of these include:
The active compounds found in garlic are called allicin and alliin. Allicin is responsible for its flavor while alliin is responsible for its smell. Both of them are present in high amounts in fresh garlic bulbs (the bulb part) and they are also present in other parts of the plant such as leaves, stems, seeds etc. When consumed orally, both compounds may cause gastrointestinal symptoms if taken at too large a dose. If ingested in sufficient amount, however, they may produce harmful effects.
Gastrointestinal symptoms caused by garlic ingestion include nausea, vomiting and diarrhea. These symptoms occur because of the breakdown of certain amino acids in your body. Amino acids are chemical building blocks that make up proteins within cells. They play various roles in human physiology including muscle contraction and relaxation, nerve transmission and much more. As such, an imbalance of these compounds can have adverse effects on the body.
Both alliin and allicin breakdown to produce a compound called alliinase upon contact with water. Alliinase in turn breaks down to produce a range of compounds which may be beneficial for your health or they may cause negative effects. Allicin is one such compound.
Allicin, as mentioned above, is responsible for garlic’s flavor and its smell. It has antimicrobial and antifungal activity. In lab studies, allicin has been shown to kill or inhibit the growth of bacteria like Staphylococcus aureus and E. coli as well as certain pathogenic fungi. It also has antioxidant activity and can prevent LDL cholesterol (the bad type of cholesterol) from becoming damaged.
Garlic supplements are available in many forms such as tablets, capsules, garlic oil, dried bulbs etc. The common ones are tablets and capsules. The amount of allicin/allicin compounds present in these supplements depend on how the garlic is processed. In general, one tablet of garlic supplement may contain anything between 250-500mg of garlic.
This does not mean that allicin is completely safe. It has some side effects as well. Allicin can irritate the lining of the gastrointestinal tract and can damage the cells which form this layer. This can cause nausea, vomiting and diarrhea. These symptoms are temporary and most people recover from them after some time.
Allicin may also increase the effects of certain drugs. It can decrease blood clots and as such, its effect may be potentiated by blood thinning drugs like warfarin. As such, people who are on medications like warfarin should limit their garlic intake.
Allicin may also increase the risk of bleeding and as such, its effect may be worsened if you are on anti-clotting medications.
In addition, allicin may potentiate the toxic effects of certain heavy metals like lead and mercury. Hence, people with higher exposure to these toxic substances should limit their garlic intake.
Sources & references used in this article:
Garlic: Health benefits and actions by CW Tsai, HW Chen, LY Sheen, CK Lii – BioMedicine, 2012 – Elsevier
Modulation of hydrogen sulfide gasotransmitter limits the proven benefits of garlic by EY Efe, M Dicato, M Diederich – Phytochemistry Reviews, 2019 – Springer
Proven Health Benefits of Garlic-A Review by ZK Labu, MM Rahaman – researchgate.net
Bioactive components of garlic and their physiological role in health maintenance: A review by SG Santhosha, P Jamuna, SN Prabhavathi – Food Bioscience, 2013 – Elsevier
Is garlic a wonder plant by F El-Sabban – Adv. Food Technol. Nutr. Sci. Open J, 2015 – researchgate.net
Garlic shows promise for improving some cardiovascular risk factors by RT Ackermann, CD Mulrow, G Ramirez… – Archives of Internal …, 2001 – jamanetwork.com