Neem in Health Care: An Overview

By: Dr. Gerard Bodekar 1,2* & Gemma Burford, MBiochem 2
1. University of Oxford Medical School
2. Global Initiative for Traditional Systems (GIFTS) of Health, Oxford, OX2 6HG, UK

Introduction

Azadirachta indica A. Juss (Meliaceae) is commonly known as neem, margosa or Indian lilac. It was introduced to Africa by Indian immigrants and the colonial administration (Schmutterer 1995), and has since been naturalized in many African countries and cultivated in several others.

There is a high level of awareness of the medicinal properties of neem in many of the countries to which it was introduced during the last century. In East Africa, its Swahili name, mwarobaini, translates literally as 'of forty' and reflects the popular belief in east Africa that the tree can cure forty diseases. In a postal survey on Azadirachta indica utilization commissioned by the Forestry Research Programme of the UK Department for International Development Protection (Childs, Chamberlain & Harris 1999), 146 responses were received from organizations and individuals working with the species in 38 countries.

In countries where neem is non-native, over 80% of respondents stated that they were aware of its use for human medicine in their area (in comparison to 92% in countries to which it is native). Similarly, during fieldwork in both Ghana and India, 70 - 80% of respondents were found to have used neem for medicinal purposes (Harris, Childs & Chamberlain 2000). This widespread use in Africa is recognised as having potential for both healthcare and micro-enterprise development.

In a survey by the CARE relief organization in Niger to gauge awareness of uses of neem (Van der Burg & Hassane 1990), it was found that 95% of the persons surveyed had heard of using neem leaves for the treatment of diseases. Of those who had heard of a medicinal usage, 98% had used it themselves. The most frequently cited illnesses were digestive disorders, followed by malaria, fever and hemorrhoids.

PARASITIC DISEASES

The efficacy of neem as a broad spectrum pesticide, non-toxic to humans has important implications for its application to parasitic diseases. The bark, seeds (Neem Foundation, n.d.), leaf juice (Health Library, n.d.) and roots (Iwu 1996) are all traditionally used for the treatment of worms. In particular, tender leaves are used in combination with Piper nigrum for intestinal helminthiasis (Chatterjee & Pakrashi 1994). A decoction of leaves is used as a head wash to treat lice and scabies (Cole 2002) and has shown good results in clinical trials among school children with headlice.

There is significant phytochemical evidence for the efficacy of neem leaf and seed extracts, and isolated compounds, in the treatment of malaria, as reviewed by Van der Nat et al., (1991a) and Willcox & Chamberlain (2003).

Some of the major findings are summarized in Table 1. This antimalarial effect has been suggested to be attributable to the imposition of oxidant stress, which inhibits the normal development of Plasmodium (Etkin 1981; Iwu, Obidoa & Anazodo 1986). The use of the gum in treating enlargement of the spleen (Chatterjee & Pakrashi 1994) may also be relevant in the context of malaria.

In addition to treating parasitic diseases, neem has an important role to play in their prevention. Sharma, Ansari & Razdan (1993) have demonstrated that heated cardboard mats impregnated with neem oil are as effective as chemically treated mats in repelling mosquitoes. The cost is estimated at US$ 0.50 per room per year, compared to US$25 per room per year for chemically treated mats. Likewise, neem oil can be mixed with kerosene and burned in lamps (Parmar 1997). It has also been shown that when applied topically at 2% strength in a base of coconut oil, neem oil provides 100% protection against biting by Anopheles culicifacies mosquitoes - the major vector of malaria in rural India - during a 12 hour period (Sharma, Nagpal & Srivastava 1993). Even eating the raw leaves may offer some protection against mosquito bites (Health Library, n.d.)

Table 1. Azadirachta indica as an antimalarial: Phytochemical evidence

MICROBIAL DISEASES

Many of the traditional uses of neem in human medicine - for example, the treatment of septic sores, infected burns, conjunctivitis, oozing from the ear, leprosy and a wide variety of skin diseases, together with the daily chewing of leaves as protection against diarrhoea - suggest the presence of antimicrobial activity. This is borne out by experimental findings. Neem twigs, which have been used as toothbrushes in Africa and India for centuries, have antipyorrhoeal properties (Chatterjee & Pakrashi 1994, UNDP n.d.) and neem-based toothpaste and mouthwashes are now commercially available in India and many industrialized countries (Sittie 1998).

The oil is antibacterial against Salmonella typhosa which cause typhoid and blood poisoning (Patel & Trivedi 1962) and Staphylococcus aureus, responsible for food poisoning, abscesses and wound infections (Schneider 1986), as well as several other pathogenic bacteria (Rao et al 1986), both gram-positive and gram-negative.

Khan and Wassilew (1987) have shown that neem oil is toxic to cultures of 14 common fungi. These include members of the genera Trichophyton (athlete's foot fungus), Epidermophyton and Microsporum (ringworm), Trichosporon (fungus affecting the intestinal tract), Geotrichum (a yeast-like fungus causing infections of the lungs and mucous membranes) and Candida, responsible for thrush. In a clinical evaluation, patients with severe chronic ringworm (who had tried other treatments without success) were treated with a neem leaf extract, which cleared the infection within two to three days. The patients remained free of infection one year later (Cole 2002). Neem bark also has anti-fungal properties (UNDP n.d.)

Certain viruses are also targets for inhibition. Neem leaf extract has been shown to reduce the entry of smallpox, fowl pox and herpes viruses to non-infected cells (Rao et al 1969; Rai & Sethi 1972) and there are preliminary reports of low to moderate inhibition of hepatitis B virus (National Research Council 1992).

Another important aspect of the control of microbial diseases is stimulation of the immune system, for which there is strong evidence that neem can be helpful. Upadhyay et al (1992, 1993) have demonstrated that leaf, bark and seed extracts all enhance the production of interleukin-1 (IL-1), interferon, tumour necrosis factor (TNF) and GM-CSF by human peripheral blood leukocytes in culture, while neem oil stimulates the production of cytokines,IL-1 and interferon in vivo in mice.

Njiro and Kofi-Tsepo (1999) and Ray, Banerjee & Sen (1996), respectively, have illustrated the modulation of cell-mediated immune system, such as mice by extracts of neem bark. Conversely, other aspects of the immune system, such as complement pathways, may be inhibited by neem (Van der Nat et al, 1989, 1991b).

INFLAMMATORY CONDITIONS

In the context of skin diseases, not only the antimicrobial effects of neem but also its anti-inflammatory effects are of interest. Okpako (1977) has demonstrated the inhibition of prostaglandin synthase by neem leaf and bark extract. Okpanyi and Ezeukwu (1981) have shown that a 75% methanolic extract of neem leaf and bark inhibits carrageenin-induced rat paw oedema.

The same extract also exhibits antipyretic effects in hyperpyretic rabbits (ibid). Van der Nat et al. (1991a) have reviewed the anti-inflammatory properties of both limonoids and polysaccharides isolated from neem, and conclude that both acute phase inflammation (carrageenin-induced oedema model) and subacute or chronic inflammation (formaldehyde-induced arthritis model) are susceptible to inhibition by limonoids.

In the treatment of eczema and psoriasis - for which neem is traditionally used - the component nimbin has been shown to be four times as effective as the steroid hydrocortisone, but without side effects such as thinning of the skin. Another component, nimbidin, is at least as effective as the non-steroidal drug phenylbutazone, used in hospitals (Cole, 2002). As a topical treatment for skin complaints, neem is non-mutagenic and non-irritant (National Research Council 1992).

The traditional use of neem seed oil against ulcers is well supported by in vivo laboratory evidence, both for the protection of gastric and duodenal mucosa against stress-induced or chemically induced lesions, and for the enhancement of the healing process in chronic gastric lesions induced by acetic acid (Pillai & Santhakumari 1984). Blockade of histamine receptors is suggested as a possible mechanism for this effect.

DIABETES

Neem is widely prescribed by contemporary Ayurvedic physicians for the treatment of diabetes mellitus. Van der Nat etal. (1991a) give an extensive review of in vivo studies and a limited clinical trial supporting the hypothesis that leaf extracts, seed oil and nimbidin exert hypoglycaemic/antihyperglycaemic effects.


IMMUNOMODULATORY PROPERTIES

Willcox & Chamberlain (2003) note that the effects of neem on the immune system are complex with some evidence pointing to an immunostimulant effect, while other evidence suggests that neem can act as an anti-inflammatory agent. In the case of humoral immunity, malaria infection leads to the production of specific anti-malarial IgM, IgG and IgD antibodies and it has been shown that passive transfer of IgG across the placenta protects newborns against malaria (March, 1993).

Willcox & Chamberlain (2003) report that Ray et al (1996) showed that the mice fed on A. indica leaf extracts (in peanut oil) produced more IgM and IgG than controls in response to challenge with ovalbumin, and this effect was dose-related. And in rats and mice, production of antibodies in response to challenge with sheep red blood cells is increased after intraperitoneal injection of 100 mg / kg of aqueous neem bark or leaf extract, and immunosuppression due to stress was reduced (Sen et al, 1992; Njiro & Kofi Tsekpo, 1999, reported in Willcox & Chamberlain 2003).

In the case of cell-mediated immunity, Upadhyay and co-workers (1992) have found that neem seed oil injected intraperitoneally in mice induces the production of IFN by spleen cells. Upadhyay et al also report that neem seed oil increases peritoneal leucocyte counts, enhances the phagocytic activity of macrophages, enhances the lymphocyte proliferative response to in vitro mitogen challenge, and enhances the cellular immune response to tetanus toxoid.

Yet, in vitro research has found that a neem bark decoction reduced the phagocytic activity of neutrophils, but stimulated the production of Migration Inhibition Factor (MIF) by human lymphocytes (Van der Nat et al, 1987).

FUTURE RESEARCH PRIORITIES

It is clear that further research into the toxicity of these species is required before crude preparations of A. indica leaves can be recommended as medication, for example in the treatment of chloroquine resistant malaria or od HIV-related illness. Nonetheles, in practical terms, they remain a first-line treatment for many rural inhabitants of developing countries. International investment could, perhaps, be better directed towards maximising the efficacy and safety of widely used preparations - such as teas - than towards attempts to isolate and characterise active ingredients.

OTHER USES

There is some evidence for hypotensive, antitumour and mild central nervous system suppressive effects of neem (Van der Nat et al. 1991a). Other traditional uses of the tree, not yet subjected to phytochemical investigation, are listed in Table 2.


(1) Iwu 1996 (4) Health Library, n.d.
(2) Chatterjee & Pakrashi 1994 (5) Varier, n.d.
(3) Neem Foundation, n.d.

Table 2. Other common medicinal uses of neem

CONCLUSIONS

It is evident that Azadirachta indica has the potential to contribute significantly to local health care and bioenterprise development in India, Africa and elsewhere. As there are many existing cultivation programmes, additional research into propagation and optimum agronomic practices is not warranted. What is called for is a greater appreciation of the tree's medicinal value, and how it can be optimized while minimizing side effects. Raised awareness of low-cost processing techniques using locally available technology, and of effective strategies for packaging and marketing medicinal products, are also essential. A multidisciplinary approach is required, with the involvement of foresters, ethnobotanists development specialists, pharmacologists, traditional health practitioners, local farmers, and other relevant stakeholders.


TRADITIONAL NEEM REMEDIES FOR GOOD HEALTH

AILMENT PRESCRIPTION

Joint pains, rheumatism, ringworm, :Regular massaging of body with neem oil.
Scabies, itch

Fever :Neem leaf decoction taken with pepper powder.

Dandruff, falling hair, lice, infection in :A handful of leaves boiled in 4 teacups water
scalp for 10 minutes. After cooling and filtering, the decoction is used for rinsing hair.

Headache :Make hot infusion of neem bark. Drink one cup
every morning and evening for 3 days.

Sore eyes :Boil 10 freshly cleaned neem leaves along with
cotton in a litre of water for approx. 10 minutes. Cool. Use immediately as an eyewash.

Throat pain and infection :Crush neem leaves in water, remove fibre. Warm it up.Strain. Add a little honey and gargle

Itch, skin infections, cracks in the sole :Grind equal quantities of neem leaves and turmeric and apply on affected areas.

Lesions, open wounds, etc :Neem bark, boiled thoroughly in water, cooled and used to wash the affected parts.

Acne, pimples and skin infections :Apply pure neem leaf powder mixed with water to the affected area.

Scar due to burns :Boil 1 teacup neem bark in 4 teacups water.Remove from fire and shake liquid. Apply the emerging froth on the affected area. Repeat several times and for several days.

Stomach ache :Crush about 3" x 3" piece of neem bark and immerse the pieces in one cup of hot water for 15 minutes. Strain. Take 1 cup of the infusion morning and evening for 2 days.

Worms :Make a decoction of neem bark. Take 6 teaspoons of the decoction twice daily for 7days.