Garlic belongs to the onion species and is widely used for seasoning worldwide. Garlic was used for the treatment of cancer way before modern medicine came into existence. In ancient times, garlic was used to treat cancers of the uterus. Garlic and cancer prevention is strongly related.
What is Garlic?
Garlic is a vegetable with scientific name Allium sativum. It belongs to the allium class of plants that also include onions, scallions, chives, and leeks. Garlic consists of sulfur compounds that are the major precursor of its bioactive compounds (substances in food to bring changes in health status), made by crushing, chopping or smashing it.
Supplements of garlic can be classified into four types/groups:
- Garlic powder
- Garlic essential oil
- Garlic extract
- Garlic oil macerate
Effects of garlic on certain cancers:
It is now believed that one of the most promising effects of garlic is seen in relation to certain cancers, and also it improvises the effect of many chemotherapeutic drugs. According to various studies, garlic and cancer prevention shows importance as increased garlic intake leads to low risk of following cancers:
- Gastric cancer
- Colon cancers
- Stomach cancer
- Esophageal cancer
- Breast cancer
- Pancreatic cancer
Effects of garlic on chemotherapeutic drugs:
- Many compounds obtained from garlic extracts seem to have cancer protective roles and seem to enhance the effect of chemotherapeutic agents. A study conducted in 2001 in England claimed that Ajoene (a garlic-derived natural compound) was found to cause significantly cell death of cancer cells in the blast crisis in leukemia (of chronic myelogenous type) patients. The aim of this study was to evaluate the effect of Ajoene on changes in the expression of proteins that cause cancer cells to die, induced by the two principal drugs used in the treatment of AML (acute myeloid leukemia): Cytarabine and Fludarabine. This study concluded that Ajoene significantly enhanced the effect of these two chemotherapeutic agents and suggested the potential role of garlic in combination with fludarabine chemotherapy in patients with refractory or relapsing AML.
- More studies conducted in India in 1990 and 2009 also stated that garlic could reduce the toxicity of Cyclophosphamide, a widely used chemotherapeutic agent, without interfering with its cancer curing abilities. The first study (conducted in mice models) concluded that if an intraperitoneal dose of garlic was given simultaneously with Cyclophosphamide, it reduced the toxicity of the chemotherapeutic drug and also increased the lifespan by more than 70%. Cyclophosphamide, although being a well-known chemotherapeutic drug used to treat many different types of cancers, is also known for its wide array of side effects. One of the main side effects is the drugs ability actually to cause cancerous changes in human cells as well. This effect of the drug to cause deleterious effects on the human genetic makeup is called genotoxicity. The second study conducted in India in 2009 tried to evaluate the effects of garlic in reducing the genotoxic effects of Cyclophosphamide. The results of this study indicated a significant reduction in genotoxicity induced by Cyclophosphamide, and also reported that these effects of garlic extracts were dose dependent.
- Another study also stated that garlic may reduce the side effects of N-Methyl-N-Nitrosourea induced transitional cell (bladder) carcinoma in rats. Favorable results were shown when higher doses were given for longer periods of time.
- Garlic is also documented to be effective in reducing the chromosome damaging effects of Mitomycin C, another chemotherapeutic drug. A study conducted in India in 1993 stated that garlic can reduce the clastogenic (chromosome damaging) effects of 3 substances significantly, which are Mitomycin C, Cyclophosphamide, and sodium arsenate. This study was conducted in mice models, and dietary garlic was given along with these substances. Garlic was shown to reduce the side effects of these drugs efficiently.
- Garlic extracts also influence Adriamycin, another chemotherapeutic drug used to treat breast, bladder, head and neck cancers. Adriamycin is known for cardiotoxic side effects (detrimental effects on the heart muscles). Garlic has been proven to be beneficial in reducing the cardiotoxic effects of Adriamycin(which included heart failure).
- Garlic has also been proven in various studies to reduce the gastric and intestinal side effects caused by Methotrexate that includes gastric ulceration and diarrhea, etc.
- 5 Fluorouracil is another chemotherapeutic drug that is used very commonly in the colon, rectum and head and neck cancers. Some side effects also accompany this drug, and garlic extracts have been proven to ameliorate various 5 Fluorouracil induced damages to the small intestine.
- Cisplatin is another chemotherapeutic agent that is used in a variety of However, it is often associated with limited compliance nephrotoxicity i.e. its ability to damage the human kidney. A study conducted in Mexico in 2008 evaluated the effect of garlic on this particular side effect of Cisplatin.
- Another study conducted in Poland, published in 2011, concluded that some compounds found in garlic help protect the normal (non-cancerous) liver cells that may get damaged during cancer chemotherapy. These particular benefits were obtained from the antioxidant properties (the ability of a substance to reduce the detrimental effects of side products of various ongoing chemical reactions) of garlic.
Garlic has shown anticancer properties in many studies against a number of cancers mentioned in the article. Garlic possesses properties that can help to enhance the effect of chemotherapy drugs. Hence, increased garlic intake leads to a low risk of cancer.
- Garlic and Cancer
- Garlic and cancer prevention
- Effects of garlic
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- Anticancer effects of garlic and garlic-derived compounds for breast cancer control.
- Garlic and cancer: a critical review of the epidemiologic literature
- Garlic consumption and cancer prevention: meta-analyses of colorectal and stomach cancers
- Can garlic reduce the risk of cancers