Neem has anticancer effects. More studies are needed to test its effects in humans.
Neem is an herb that is used as food, in traditional medicine for skin conditions, and for stomach ailments. It is also used as a disinfectant against pests and parasites. Some lab studies show that neem extracts have anticancer activities by inhibiting cancer cell growth. However, there are no human studies showing it to be an effective cancer treatment.
Adverse reactions caused by neem oil have been reported in both children and adults.
A small study found neem bark extract effective in reducing stomach acid secretion without any adverse effects. More studies are needed in humans.
In vitro studies show neem can inhibit cancer cell growth. It has not been studied as a treatment for cancer.
Neem extract has been shown to increase CD4+ cell count and bodyweight in a small number of HIV+ volunteers.
Neem can reduce oral plaque and bacterial count. It is used as mouth rinse in traditional medicine.
Neem oil has been used externally against pests and lice.
Swallowing neem oil can cause severe adverse effects in children.
Vomiting, drowsiness, diarrhea, and seizures associated with coma have been reported.
Allergic contact dermatitis.
Acute contact dermatitis were observed on the scalp and face of a patient following use of neem oil for loss of hair.
Poisoning and neurotoxicity reported in a 35-year-old woman following consumption of a neem-based pesticide, requiring intensive medical care with mechanical ventilation.
Azadirachta indica or neem is a tree prevalent in South Asia. The bark, leaves, flowers, and seeds have been utilized as food and medicine for centuries. In Ayurvedic medicine, neem is used externally for skin conditions, internally for gastrointestinal ailments, and for oral hygiene. Currently, many forms of neem extracts are marketed as dietary supplements.
Neem has antimicrobial activity and is used against a wide range of pests and parasites (1). It is effective against lice (2) and has antiretroviral activity (5). Neem also reduces plaque and decreases oral bacterial counts (3), but data are conflicting (4). A neem bark extract was found to exhibit anti-secretory and anti-ulcer properties (6). Neem may also be effective in the treatment of cholera and diarrhea (7).
A few studies have examined the anticancer potential of neem. An ethanolic extract of neem leaves reduced the incidence of chemical-induced gastric tumors in mice (9), and neem-treated monocytes induced apoptosis in cervical (10) and prostate cancer cells (11). Neem also showed chemopreventive effects in animal models (12). However, human data are lacking.
Mechanism of Action
The ulcer-healing properties of nimbidin from neem seeds are attributed to the stearic and palmitic acid components (14). Anti-ulcer effects are believed to be via the inhibition of the proton pump, H+- K+- ATPase, to control the secretion of hydrochloric acid, inhibition of gastric mucus depletion, and prevention of oxidative mucosal damage (6).
Azadirachta in neem has pestical activity due to its growth-regulating properties, reducing levels of the insect hormone ecdysone (14).
Neem induces cell death in prostate cancer cells by decreasing the levels of Bcl-2, an anti-apoptotic protein. Neem-treated monocytes induce apoptosis in cervical cancer cells by increasing levels of caspases 3, 8 and 9, interferon (IFN-gamma), and by decreasing tumor necrosis factor (TNF-alpha) (10). Neem also acts as an antiretroviral agent via inhibition of viral invasion of host cells (5).
Oral administration of neem oil resulted in severe poisoning in children. Vomiting, drowsiness and diarrhea have also been reported. In most serious cases, seizures associated with coma have occurred (8).
Vomiting, drowsiness, diarrhea, tachypnea with acidotic respiration, polymorphonuclear leukocytosis, encephalopathy, and seizures associated with coma following oral administration of neem (8).
Acute contact dermatitis on the scalp and face of a patient following use of neem oil for alopecia (16).
Poisoning with features of neurotoxicity in a 35-year-old woman following consumption of a neem-based pesticide, requiring intensive medical care with mechanical ventilation (17).
Some studies show that neem extracts have antioxidant activities. Theoretically, antioxidants can decrease the efficacy of certain chemotherapy drugs that rely on the generation of free radicals for their cytotoxic effects.