Basil is an herb in the mint family. It adds flavor to meals, and its nutrients may provide health benefits.

Sweet basil (Ocimum basilicum) plays a role in many Mediterranean, and particularly Italian, cuisines. It forms the basis of pesto and adds a distinctive flavor to salads, pasta, pizza, and other dishes. Indonesian, Thai, and Vietnamese cuisines also feature this herb.

In the diet, sweet basil can provide vitamins, minerals, and a range of antioxidants. Its essential oil may also have medicinal benefits.

Sweet basil is available in many grocery stores, while other varieties have different tastes and fragrances.

Another type of basil is tulsi, or holy basil (Ocimum santum). This plant plays a therapeutic role in Tamil and Ayurvedic medicines, which are predominantly practiced in Southeast Asia. This is different from sweet basil.


basil in a bowel on a table.

Fighting cancer

A review published in 2013 looked at whether tulsi, or holy basil, could prevent cancer.

The authors concluded that the phytochemicals in holy basil may help prevent certain types of skin, liver, oral, and lung cancers.

They appeared to do this by increasing antioxidant activity, changing gene expression, triggering cell death, and slowing cell division.

However, the studies in this review were preclinical or performed in animals. Confirming the effects will require further research.

The essential oil of basil possesses antimicrobial properties (Wannissorn et al. 2005). Moghaddam, Karamoddin, and Ramezani (2009) investigated the effect of basil on Helicobacter pylori and found that methanol, butanol, and n-hexane fractions of basil demonstrated antagonistic activity against the bacteria (MIC = 39-117 μg/disk). While not as potent as amoxicillin, its effectiveness raises possibilities of using individual or multiple spices as potent antimicrobials, especially in areas where commercial antibiotics are in limited supply (Moghaddam, Karamoddin, and Ramezani 2009).

The effects of basil are not limited to its antimicrobial properties because evidence indicates that it also can lower oxidative damage in animal models (Dasgupta, Rao, and Yadava 2004). Feeding mice 200 and 400 mg/kg body weight with a hydroalcoholic extract of basil leaves for 15 days markedly increased GPx (1.22-1.4 fold), glutathione (GSH) reductase (1.16-1.28 fold), catalase (1.56-1.58 fold), and superoxide dismutase (1.1-1.4 fold; Dasgupta, Rao, and Yadava 2004). The change in activity in one or more of these enzymes may explain the decrease in lipid peroxidation caused by basil in studies by Dasgupta, Rao, and Yadava (2004). Drăgan et al. (2007) examined the effects of balsamic vinegar–enriched extracts from several herbs (rosemary, sage, and basil) in soups and salads on oxidative stress and quality of life measures in women with stage IIIB and IV breast cancer. While there was a decrease in oxidative stress, the complexity of the dietary intervention made it impossible to determine the component(s) that led to improvements.

Several studies provide evidence that basil is an antimutagenic spice (Kusamran, Tepsuwan, and Kupradinun 1998; Stajkovic et al. 2007). Stajkovic et al. (2007) studied the antimutagenic effects of basil on mutagenicity in Salmonella typhimurium TA98, TA100, and TA102 cells in the presence or absence of liver microsomal activation. The essential oil of basil, at concentrations ranging from 0.5 μL/plate to 2.0 μL/plate, inhibited mutations from ultraviolet irradiation (dose = 6 J/m2) by 22-76%. Mutations caused by 4-nitroquinoline-N-oxide (0.15 μg/plate) were decreased by 23-52%, and those from 2-nitropropane (14.9 mg/plate) by 8-30%. These findings are consistent with studies by Jeurissen et al. (2008), who demonstrated that 50 μg/mL basil largely blocked DNA adduct formation caused by 1′-hydroxyestragole in the human hepatoma (HepG2) cell line, possibly by promoting phase II enzymes and thereby conjugation and elimination of this carcinogen. These findings likely explain the ability of basil to decrease the mutagenicity of aflatoxin B1 (AFB1) and benzo(a)pyrene (B(a)P) (Stajkovic et al. 2007). The mutagenicity of AFB1 was inhibited by >30% by the presence of 1-2 mg/plate of a hexane-based basil extract and 0.5-1 mg/ plate of chloroform- and methanol-based basil extracts. Because B(a)P mutagenicity was only inhibited by chloroform- and methanol-based basil extracts at doses of 2-5 mg/plate, multiple constituents might be responsible for basil’s antimutagenic activities.

The anticancer properties of basil in preclinical studies are mixed. In studies with Sprague-Dawley rats fed with an AIN-76 diet with or without high concentrations of basil (6.25% and 12.5%), there was no clear indication of a decrease in 9,10-dimethyl-1,2-benzathracene (DMBA)-induced mammary cancer. It is unclear whether the quantity of the procarcinogen examined, the simultaneous induction of both phase I and II enzymes, or some other factors accounted for the lack of protection by adding basil to the animals’ diet (Kusamran, Tepsuwan, and Kupradinun 1998). Nevertheless, there is evidence that basil can decrease DMBA-induced carcinogenesis. Providing Swiss mice with a diet containing 150 or 300 mg/kg body weight of basil extract decreased DMBA-induced skin tumors (12.5% reduction and 18.75% reduction for lower and higher doses, respectively), and lowered the tumor burden per mouse. Compared to the average number of tumors per mouse in the controls, the tumor burden was approximately 2.4 times lower (p < .01) in the low-dose basil group and 4.6 times lower (p < .001) in the high-dose basil group (Dasgupta, Rao, and Yadava 2004). It is unclear whether differences in the response between mice and rats reflect the species, the cancer site, or the dietary or procarcinogen exposures.

DNA methyltransferase (MGMT) is a critical repair protein in the cellular defense against alkylation damage. MGMT is highly expressed in human cancers and in tumors resistant to many anticancer alkylating agents. Niture, Rao, and Srivenugopal (2006) examined the ability of several medicinal plants to upregulate O6-methylguanine adducts. Both ethanol and aqueous extracts of basil increased MGMT protein levels in HT29 human colon carcinoma cell lines 1.25-fold compared to controls after 72-hours incubation. Compared to the control, basil increased glutathione-S-transferase (GST) protein activity 1.33-fold after 12 hours of incubation; after 24 hours, GST activity increased 1.68-fold compared to the control, which declined to 1.47-fold after 72 hours incubation. Because MGMT is one of the body’s first lines of defense against alkylation DNA damage, a small increase (two- to threefold) in this enzyme may protect against mutagenic lesions (Niture, Rao, and Srivenugopal 2006).

The anticancer properties of basil may also relate to its ability to influence viral infections. Individuals with hepatitis B are recognized to be at increased risk for hepatocellular carcinoma (Fung, Lai, and Yuen 2009; Ishikawa 2010). Chiang et al. (2005) evaluated the antiviral activities of basil extract and selected basil constituents in a human skin basal cell carcinoma cell line (BCC-1/ KMC) and a cell line derived from hepatoblastoma HepG2 cells (2.2.15) against several viruses, including hepatitis B. Impressively, Chiang et al. (2005) found that the aqueous extract of basil, along with apigenin and ursolic acid, displayed greater anti-hepatitis B activity than two commercially available drugs, glycyrrhizin and lamivudine (3TC). Overall, these studies raise intriguing questions about the merits of using commercially available spices to retard viruses and potentially cancer. Undeniably, much more information is needed to clarify the amounts and durations needed to bring about a desired viral response and the mechanism by which a response occurs.

It should be noted that there are concerns about excess basil exposure. Estragole, a suspect procarcinogen/mutagenic found in basil, raises questions about the balance between benefits and risks with the use of this and other spices (Muller et al. 1994). Now, the majority of evidence points to the antimutagenic effects of basil outweighing the potential adverse effects associated with estragole-induced cell damage (Jeurissen et al. 2008).


Some people should take care when eating basil.

Blood clotting

Just 1 tablespoon of basil provides 10.8 mcg of vitamin K, which plays a role in blood clotting. This amount is between 9% and 12% of an adult’s daily requirement.

High levels of vitamin K can affect the action of some drugs, including warfarin (Coumadin). Anyone who uses blood thinners should speak to a doctor before increasing their intake of basil.


Some people have allergic reactions if they consume or otherwise come into contact with herbs in the mint family.

Anyone with this type of allergy should avoid basil and check premade foods to ensure that it is not an ingredient.

If an individual experiences hives, swelling, or difficulty breathing after eating basil, they should receive urgent medical attention.

A severe allergic reaction can become anaphylaxis, a life threatening emergency.


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