By Prof. Raphael Nyarkotey OBU
Azadirachta indica, also known as neem, is a tree native to the Indian region (Kharwar et al. 2020). Different parts of this plant have been used in naturopathic practices around the world to treat pain, fever and infection.
Also, it has been used to clean teeth (National Research Council (US) Panel on Neem, 1992; Lakshmi et al. 2015). This has made neem to be sometimes called “the village pharmacy” due to its special medicinal properties from the leaves, flowers, seeds, fruit, roots and bark (Subapriya and Nagini, 2005; Islas et al. 2020). Earlier studies have also confirmed the importance of neem in using flowers to treat bile duct disorders, leaves to treat ulcers and the bark to treat brain illnesses (Kumar et al. 2013).
Due to the uniqueness of this plant, researchers have been able to isolate more than 140 active compounds. These active compounds give neem its antioxidant, antimicrobial, antiparasitic, anti-inflammatory, antidiabetic and wound-healing properties (Subapriya and Nagini, 2005; Lee et al. 2017; Alzohairy, MA, 2016). Researchers are still examining the mechanism of how neem works due to its array of medicinal properties (Islasa et al. 2020; Kumar et al. 2013; Alzohairy, MA, 2016). In this article, I examine the scientific aspects of neem.
Neem, Science
Many studies have been conducted to examine neem extract and the results have been promising. What intrigued me is that most of these studies show promise in diverse areas of health, such as blood sugar management, hair, skin, teeth, liver and kidneys.
Neem, antioxidants
Alzohairy, MA (2016) found that neem is a rich source of antioxidants that can play a role in the prevention and treatment of diseases via the inhibition of bacterial growth and modulation of genetic pathways. Azadirachta indica contains active constituents, including:
- Nimbin
- nimbidin
- nimbolide
- limonoids
- quercetin
Not only do these compounds have anti-fungal and antibacterial activities, but they also exhibit anti-inflammatory, antiarthritic, antitumor activities and more. Neem has been shown to have free radical-scavenging activity and help with the management of cancer through the regulation of cell signaling pathways. It also plays a role as an anti-inflammatory agent via the regulation of pro-inflammatory enzyme activities. Also, Elmarzugi and Eid (2017) found that diverse parts of the neem plant have been used by populations from many countries for the treatment of several diseases, such as:
- leprosy
- eye problems
- elimination of intestinal worms
- skin ulcers and skin diseases
- diabetes
- wounds
- itching
Neem, fertility management
Neem has also been considered as an alternative to a vasectomy due to its anti-fertility effects. A vasectomy is a surgical procedure that sterilises people with testicles by stopping the release of sperm. Three animal studies (National Research Council (US) Panel on Neem, 1992; Subapriya and Nagini, 2005; Upadhyay et al. 1993) found that neem may immobilise and kill sperm with no long-term consequences.
Neem, hair health
One study by (Chaudhary et al. 2017) found that neem seed extract contains azadirachtin, an active compound that could fight parasites that affect hair and skin, such as lice. Azadirachtin works by disrupting parasite growth and interfering with reproduction and other cellular processes.
Two human studies (Abdel-Ghaffar et al. 2012; Mehlhorn et al. 2011) examine the efficacy of a neem-based shampoo for head lice in children. Leaving shampoo in the hair for 10 minutes killed the lice while being gentle on the skin. Other studies (Alzohairy, MA, 2016; Kaur et al. 2004) found that Neem extract and a specific compound nimbidin, found in neem oil, could also treat dandruff due to its anti-inflammatory and antimicrobial properties.
Neem, enhance dental and oral health
It is interesting to know that chewing neem bark to enhance oral hygiene is a normal practice not only in Ghana (Almas et al. 1999). Also, one study by Lakshmi et al. (2015) found that neem’s antiseptic, anti-inflammatory, antioxidant and immune-boosting contents could promote oral health. The study also found that neem could relieve pain and help treat gingivitis, periodontitis and tooth decay.
Moreover, Elavarasu et al. (2012) test-tube studies found that neem could lessen bacteria’s ability to colonise the surface of our teeth, which reduces plaque formation. Another human 21-day study compared neem to pharmaceutical chlorhexidine mouthwash (Chatterjee et al. 2011) in 45 people with gingivitis. The study found neem mouthwash to be as effective as chlorhexidine mouthwash — at reducing gum bleeding and plaque.
Neem, liver and kidney health
Another important study I found was the impact of neem extracts in improving liver and kidney health due to their numerous antioxidant properties. One study in rats by Bhanwra et al. (2000) found that neem leaf extract decreased liver damage induced by high-dose acetaminophen.
Fast forward, another study in rat by Moneim et al.(2014) found the same result and recommended that neem extract enhanced kidney tissue damage caused by chemotherapy medication. This means that those battling kidney diseases as a result of conventional treatment could incorporate it in their treatment.
Neem, skin health
One study by Lin et al. (2018) found that neem seed oil is rich in fatty acids, such as oleic, stearic, palmitic and linoleic acids. Together, these fatty acids have been found to have anti-inflammatory, antioxidant and antimicrobial properties that enhance skin health. An earlier study found that Ayurveda practitioners used this plant to treat psoriasis and eczema, though few scientific studies support this claim (Thas, JJ, 2008).
Other studies found that neem is also used to improve skin elasticity and acne. For instance, one test-tube study by Vijayan et al. (2013) found that neem oil could enhance long-term acne treatment when added to solid lipid nanoparticles (SLNs), a new type of drug formulation that offers a stable release of active ingredients. However, more human studies are needed.
Neem, wound and ulcer healing
Two animal studies (Alzohairy MA, 2016; Gautam et al. 2015) found that neem leaf extract quickens wound healing via an increased inflammatory response and the formation of new blood vessels. For instance, one review by Koriem, KM (2013) found a 34-day case study, where 100 mg of neem oil was applied topically twice daily to heal chronic skin ulcers.
In another human study (Bandyopadhyay et al. 2004), 6 people with intestinal ulcers took 30mg of neem extract orally twice daily. After 10 days, acid secretion had reduced drastically; and after 10 weeks, the ulcers were almost completely healed.
Neem, anti-malaria
Results have been mixed in this area. However, two studies (National Research Council (US) Panel on Neem, 1992; Nathan et al. 2005) confirmed that neem contains active compounds called limonoids. A study in mice found that limonoids may be as effective at targeting malaria-infected cells as conventional treatments using chloroquine. However, one test-tube study by Farahna et al. (2010) demonstrates no positive effect of neem extract on malaria outcomes.
Also, a previous study by Sharma et al.( 1993) examined the impact of neem oil as mosquito repellent and found that when 2 percent neem oil was mixed with coconut oil and then applied to the exposed body parts of human volunteers, it provided complete protection for approximately 12 hours from the bites of all anopheline species. The study concludes that the application of neem oil can even offer protection from malaria in endemic countries.
This means that Neem oil could act as a great natural mosquito repellent that is safe to use against parasites transmitted by the bite of infected mosquitoes, which can cause malaria.
Neem, diabetes management
Three animal studies (Subapriya and Nagini, 2005; Islas et al. 2020; Alzohairy, MA et al. 2016) found that neem leaf extract could be a contender for new diabetes medications. This is because neem extract could help revive cells that produce insulin — the hormone that helps control blood sugar — and lower blood sugar levels (Bhat et al. 2011).
Neem, natural insecticides
One study by Kudom et al. (2011) investigates how a low-tech mosquito control method can be used by local people, particularly in Africa. The study notes: There are serious environmental concerns regarding the large-scale application of most conventional insecticides. There is a need for alternative methods that are more effective, less expensive and environmentally friendly.
They found that a low crude extract of neem can inhibit the growth and development of mosquitoes, while a crude powder can kill off mosquitoes (most likely by suffocating the insects). Azadirachtin is the component of neem that appears to be responsible for about 90 percent of its anti-pest effects. Neem products do not necessarily provide absolute insect control. However, frequent applications can reduce pest populations dramatically by repelling them and inhibiting their larval development, growth, fertility, mating and egg laying as well as deterring feeding.
Neem supports plant
Neem can help boost plant health by discouraging unwanted pests as well as fungi. The EPA points out that “cold-pressed neem oil has been used for hundreds of years to control plant insects and diseases”. One article by Susan Jones, published by The American Orchid Society, reports that you can use neem seed oil as a safe leaf polish, though some plants may be sensitive. A neem spray solution for plants (more on that later in this article) should completely cover all plant surfaces for maximum effectiveness.
One important precaution with plant use is never to use neem solutions on plants during hot weather (85 degrees Fahrenheit or warmer) or in direct sunlight. In addition, avoid damage to plant tissues by placing plants in the shade until the neem application is dry.
Warning
Neem is generally considered safe in adults for topical use on the skin for up to two weeks, when taken by mouth for up to 10 weeks, or when applied inside the mouth for up to six weeks. Neem can be unsafe for adults when used in large amounts or for extended periods. The main concern with overuse is it may harm the liver or kidneys.
For instance, one study by Mishra and Dave(2013) found that Neem seed extracts are made of various fatty acids and about 2 percent bitters, which are considered toxic. Levels of these bitters differ between products and may be influenced by extraction and storage methods.
According to the EPA, “no risk to human health is expected from the use of cold-pressed neem seed oil because of its low toxicity via all routes of exposure”. Azadirachtin and other active ingredients in the neem seed have been shown to have insecticide properties that are effective against a broad spectrum of insects, many mites and nematodes, and even snails and fungi, but they are unlikely to cause harmful effects. According to the EPA, “when used as directed on product labels, neither clarified hydrophobic extract of neem oil nor azadirachtin are expected to harm non-target organisms.”
Oral intake
Two studies by (Sinniah, and Baskaran, 1981; Dhongade et al. 2008) have found that infants have experienced severe poisoning after being given neem oil at doses of 0.18–1.06 ounces (5–30 ml). Another study by Koriem, KM (2013) also found one man experienced neurological and psychotic symptoms after consuming 2.1 ounces (60 ml) of neem oil.
These studies were in humans, though none was found in animals (National Research Council (US) Panel on Neem. Neem, 1992; Alzohairy, MA, 2016). These animal studies showed no evidence of toxicity at levels as high as 2.27 grams of neem per pound (5 grams per kg) of body weight. Note that these results could not have the same effect on humans. Finally, anecdotal evidence links excessive neem leaf tea intake to kidney failure (National Research Council (US) Panel on Neem. Neem, 1992).
Islas et al. (2020) also found that oral neem use could lower blood sugar; hence, people taking diabetes medications should consult their doctor. Groot et al.(2017) found that though topical use appears to be safe if diluted with other ingredients, direct application to the skin is not recommended as is likely to irritate.
For those looking for babies, it is advisable to stay away from neem consumption as one old study (Upadhyay et al. 1993) found that neem has long-term contraceptive effects in men after a single dose. Due to its ability to halt sperm development and the limited research into its safety, you should avoid neem if you’re trying to have children.
Take home
Evidence suggests that neem may treat dandruff, lice, gingivitis and dental plaque as well as promote wound healing.
NB: Prof. Nyarkotey has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions and medical associations to justify his write-ups. My articles are for educational purposes and do not serve as medical advice for treatment. I aim to educate the public about evidence-based scientific naturopathic therapies.
The writer is a Professor of Naturopathic Healthcare, a Medical Journalist, and a science writer. President, Nyarkotey College of Holistic Medicine & Technology (NUCHMT)/African Naturopathic Foundation, Ashaiman, Ghana. Currently BL Candidate at the Gambia Law School, Banjul. E. mail: [email protected].
