In case you needed to interrogate the internet for a specific product that could help you magically soothe skin and scalp conditions, look no further than a natural oil with a name as exotic as simple: neem.
Some of the neem oil purchasers on various e-shops find it the panacea to knock down ticks and fleas that tormented their pets. Others claim the neem oil as the quickest and most effective remedy to cure cold sores or relieve symptoms of eczema or psoriasis that not even conventional medicine could address for years.
Overall, nearly everyone who tested this miraculous oil for all sorts of skin disease or parasitic problems was enthusiastic about its broad benefits. Yet, they also agree on one major shortcoming: the smell of the neem oil is so stinky above the most fervid human imagination that, for a few, it turns out impossible to stand—and use.
Determined to discover the wondrous effects of the neem oil to treat the nasty head lice contracted two years ago at a negligent hairstylist’s, I ordered—with a leap of faith, given the notorious odor—a bottle of cold-pressed and organic-certified neem oil.
When the neem oil finally arrived at home, I got eerily impatient to know if I could tolerate that still unfamiliar smell. After screwing off the plastic cap from the bottle, I slowly removed the hygienic seal at the top of the bottleneck, which prevented any odor from being perceived even in the slightest. The excitement went up when I saw the removed seal saturated with neem oil.
Exposing your sense of smell to neem oil for the first time is an almost shocking experience. If the most talented chemist on earth used his fantasy combined with his knowledge, he wouldn’t likely be able to recreate the incredibly acrid and repellent smell of the neem. An intense mixture of smashed garlic and rotten citrus under the appearance of a greenish-yellow wax-looking fat—neem oil is not liquid at room temperature; it needs warmer temperature to liquefy smoothly.
The very first time I exposed myself to the neem oil odor was so revolting that my leap of faith flash-froze at the idea of slathering that freak slime on my head. I, therefore, thought to gradually acclimatize my confidence with the neem oil by adding a dollop to my usual shampoo. Dulled by the shampoo, the neem oil had become olfactory acceptable to finally find the courage to try it for an imminent hair washing. After saturating and massaging my head with the new neem-powered shampoo, any itching got anesthetized in a heartbeat. The sense of relief was not only surprising, but at the time of rinsing, I saw my hair flowing untangled and light as silk under a water jet. Although tested in timid doses, the neem oil had seriously begun to show me what it was capable of: my itches were markedly weaker than at the beginning of the dermatological event!
My leap of faith for not daring more with the neem oil came out when I felt urged to sprinkle my entire head with neem oil before washing my scalp and hair with a specific anti-lice shampoo, powered with neem and other natural tropical extracts, such as cassia amara and tea tree oil. I would then had four-five sessions of fine-toothed iron comb-outs distributed in the successive 20-30 days of treatment. (Head lice may really be tricky to correctly and completely remove because the tiny parasites can lay hundreds of resistant cement-like eggs close to the scalp, growing at different times to be detected by the precision picking of the lice comb.)
Given the mesmerizing benefits of neem oil for my treatment against head lice, I learned to love its smell while continually soothing and nourishing my scalp and hair. The initially unbearable smell of neem oil for the uninitiated gets completely familiar and acceptable with time. From that event on, by the time the head lice entirely disappeared while getting thicker hair and a cleaner scalp, the neem oil became one of my favorite cosmetic oils to keep in my beauty routine. Neem oil is an actual mother-nature arsenal for strengthening hand nails and making a body lotion silkier and quicker to absorb by the skin.
Ultimately, I decided to investigate and research everything about the portentous neem—and why humankind still knows so little about this nearly miraculous plant.
Neem: origin and botany
Native to India and Myanmar, neem (Azadirachta indica) is a botanical cousin of mahogany, belonging to the family of Meliaceae. Its complex foliage resembles that of walnut, and its swollen stone fruits look much like olives. It is evergreen and seldom leafless. Its shade imparted throughout the year is a significant reason why it is prized in the Asian continent.
The neem can adapt to a wide range of climates: it thrives well in hot weather, where the maximum shade temperature is as high as 49 °C and tolerates cold up to 0 °C on altitudes up to 1,500 m. Neem trees can grow up to 30 m tall and 2.5 m in circumference. Their spreading branches form rounded crowns as much as 20 m across. They remain in leaf except during an extreme drought, when the leaves may fall off.
A neem tree typically begins bearing fruit after 3‒5 years, becomes fully productive in 10 years, and from then on, can produce up to 50 kg of fruits annually. It may live for more than two centuries. The fruit is an olive-like drupe, up to almost 2 cm long. When ripe, it is yellow or greenish-yellow and comprises a sweet pulp enclosing a seed. The seed is composed of a shell and a kernel (sometimes two or three kernels), each about half of the seed’s weight. It is the kernel that is used most in pest control. The leaves also contain pesticidal ingredients, but they are much less effective than those of the seed.
Of all the neem products, oil is perhaps the most commercially important. To obtain neem oil, the seeds are first broken open, and the kernels separated. The nuts are then pressed in industrial expellers or in hand- or bullock-operated wooden presses. The oil yield is sometimes as high as 50% of the weight of the kernel.
Unlike most vegetable oils, the cold-pressed neem oil contains sulfur compounds, whose pungent odor is reminiscent of garlic. Neem cake, the residue left after the oil has been removed, has unique promise as a fertilizer containing more nitrogen, phosphorus, potassium, calcium, and magnesium than farmyard manure or sewage sludge.
Neem: why it is omnipresent in the Ayuverdic tradition and called “The Wonder Tree” by the UN
For over 5,000 years of empirical evidence, Ayurvedic practitioners have long revered neem, since the healing tree has relieved so many different pains, fevers, infections, and other complaints that it has been called “the village pharmacy.”
Neem medicinal properties are documented in the Vedas, ancient Sanskrit texts, which refer to Neem as Sarva Roga Nivarini—”the curer of all ailments”—for being present in about three-quarter of all Ayurvedic formulations.
Neem preparations are reportedly effective against a variety of skin diseases. The oil is especially beneficial to treat different dermal microbial infections and parasitic infestations. Also, extracts from neem bark are highly effective at both preventing and healing gingival inflammations and periodontal disease.
The Persian-origin name of the neem Azad-Darakth stands for “free tree”, as to symbolize the freedom of humanity to exchange knowledge and relief. Not by chance, the neem has been named by the United Nations “The Wonder Tree“—interchangeably, “Cornucopia Tree” or “Miracle Tree”—of the 21st Century, for its virtually endless multipurpose applications in organic agriculture besides topical medicine.
In the 20th century, the neem cultivation was spread outside of India in tropical and subtropical Africa, the Americas, Australia, and the South-Pacific islands, where the tree not only thrives successfully but even helps reforest areas by providing dense shade and oxygen streams all year round.
Today, the neem is well established in at least 30 countries worldwide. Some small-scale plantations are also reportedly prosperous in the United States of America (Arizona, Florida, and California).
Among its countless benefits, the neem tree is also highly effective at controlling farm and household pests, so that entomologists that discovered the neem properties to control insects predict that this tree may usher in a new era of nontoxic and organic pesticides.
Indian scientists took up neem research as far back as the 1920s. Still, their work was little appreciated elsewhere until 1959, when the German entomologist Heinrich Schmutterer witnessed a locust plague in Sudan. During this onslaught of billions of winged marauders, Schmutterer noticed that neem trees were the only green plants left standing. On closer investigation, he saw that although the locusts settled on the trees in swarms, they always left without feeding. To find out why, he and his students have studied the components of neem ever since.
Schmutterer’s work spawned a growing amount of lively research from the 1960s onward, encouraging several hundred researchers in at least a dozen countries studying various aspects of the neem compounds.
Both the oil and extract obtained from the neem seeds and leaves respectively constitute, in fact, a massive arsenal of insecticidal and antimicrobial compounds, being effective against over 200 insect species as well as most nematodes, mites, fungi, bacteria, and viruses.
The naturally-occurring neem chemicals can disrupt an incredibly long list of pestiferous species through subtle and sophisticated mechanisms, while leaving humans, warm-blooded animals, and non-leaf-eating insects unharmed. Furthermore, the extracts obtained for various parts of the plant are all biodegradable and, unlike synthetic pesticides, they are unlikely to induce genetic resistance and, therefore, lose efficacy against the pests targeted.
The neem active ingredients bear no resemblance to today’s synthetic insecticides, as they are composed only of carbon, hydrogen, and oxygen, but no atoms of chlorine, phosphorus, sulfur, or nitrogen. This characteristic makes the neem active molecules unique in that they are not outright killers in one stand, but rather mess up the target insect behavior or life process in a more subtle and sophisticated way. The pest, in fact, will no longer feed, breed, or metamorphose, since even a microscopic trace of the neem substances is so unbearably repellant and dazzling to alter the pest’s existence.
Neem main chemical broadside is a mixture of natural compounds called tetranortriterpenoids or limonoids. At least nine neem limonoids—among which azadirachtin, salannin, meliantriol, nimbin, and nimbidin are the most significant—have a demonstrated ability to treat infestations and diseases in plants and mammals.
Azadirachtin, the most outstanding neem component, is considered as the most potent growth regulator and feeding deterrent existing in nature. By inhibiting molting, it keeps the larvae from developing into pupae, which die without producing a new generation. Azadirachtin acts by mimicking the host’s growth hormone structure, competing for the actual hormones necessary to the correct development of the parasitic organism. Azadirachtin is also so repugnant to insects that they will no longer be able to swallow and starve to death rather than feed on materials contaminated even with the tiniest hint of the neem component.
Azadirachta excelsa—a species of neem variously known as “marrango”, “sentang”, or “Filipino neem”—is equipped with an additional limonoid called marrangin, which shows the same mode of action as azadirachtin but is two to three times more active.
20 sulfurous compounds give the neem its notorious smell, making the neem oil cake the highest in sulfur content (1‒1.5%) of all the natural oil cakes. The strong garlicky odor of neem materials has been proven effective to repel insects and discourage oviposition in grain storage environments. In a study in Ghana, dry cacao beans mixed with alternate layers of dried neem leaves remained free from the attack of Ephestia cautella up to 9 months in the warehouse.
Neem: potentialities and barriers as an organic pesticide
As consistent research has been conducted to test the safety and efficacy of neem for use as an insecticide, neem insecticides are being manufactured and exported to various countries. Neem is the most important among all bioinsecticides for controlling pests.
In a 2006 research in Nigeria, neem insecticidal preparations prove their efficacy against the cocoa mirid Sahlbergella singularis. A high mortality rate of 88%, 97%, and 99% were recorded against the mirids with a neem seed aqueous crude extracts at 10%, 20%, and 30% respectively at 96 h after treatment.
All this potential is of vital importance for the world’s most economically disadvantaged countries, which encounter severe problems with various agricultural pests and a widespread lack of even primary medicine. The neem tree could, in fact, bring good health and better crop yields within reach of farmers too poor to buy pharmaceuticals or farm chemicals. Extracting the seeds requires no special skills or sophisticated machinery, and the resulting products can be applied using low-technology methods.
On top of all that, neem by-products (the seedcake and leaves, in particular) can also be used to naturally fertilize the local soils and help foster sustainable crop production. The neem leaves, which are slightly alkaline (pH = 8.2), are suitable for neutralizing acidity in the land. Additionally, the neem trees work as physical windbreakers in agroforestry systems by cutting wind velocity near the ground by 45‒80%, resulting in less erosion and more soil moisture.
In spite of all its promises, the development of neem products has not yet received massive support in 2020. Shelf-life, photosensitivity, and volatilization are critical limitations hindering the large-scale application of neem as a reliable biopesticide.
One of the main problems facing the commercial development of neem is a lack of industrial interest, mainly due to the difficulty of patenting natural products. As a result, there is still low awareness of the potential of neem products, which do not get widely publicized in the farming community and elsewhere.
The main disadvantages of neem include its low stability under field conditions, due mainly to a high rate of photodegradation, as well as short residence time and slow killing rates, compared to conventional pesticides. In layman’s terms, neem preparations need to be reapplied on the treated crop as their beneficial effect is not as immediate as that of the most resistant but polluting pesticides.
Furthermore, genetic factors, environmental factors, and type of extraction method influence the chemical composition of neem extracts, which implies no standardization of their efficacy and, consequently, application in the control of agricultural pests.
In the last years, however, there is a resurgence of research on neem for integrated biological control techniques that can protect beneficial insects and work in tandem to keep harmful pests at bay from farm crops.
For sustainable agriculture, nanotechnology can help develop environmentally-friendly agricultural inputs like neem, improve the safety and stability of active agents like azadirachtin, and enhance their pest control activity. Through this approach, the number of necessary applications of neem oil can be reduced and made more precise and efficient, bringing substantial economic benefits, especially for the farmers who usually have limited access to technical inputs in economically penalized areas of the world.
Have you ever heard about the neem and its benefits for human and plant health? If you have successfully been using neem, feel free to tell your experience in the comment section. Thanks!