Neem oil is a natural product derived from the seeds and fruits of the evergreen neem tree. It is used in more than a hundred pesticide products and has important applications in organic farming and medicines. It has been used as a pesticide for hundreds of years and is considered safe (1).

These days, neem oil is touted as a natural alternative to synthetic preservatives.

Neem oil is a mixture of components and not a pure essential oil. Azadirachtin is the active component responsible for repelling and killing pests. The remaining components include fatty acids, essential oils, and other substances. Neem oil components can also be found in other products such as toothpaste, cosmetics, soaps, pet shampoos, supplements, and medications.

Natural preservatives

Most cosmetics include water as an ingredient (to emulsify); therefore, preservatives are needed to prevent spoilage and bacterial growth.

If you’ve ever purchased an all-natural, preservative-free beauty product, such as a face cream, and discovered a ‘strange smell’ before it was completely used up, it means the product has gone bad (i.e., contaminated by yeast, mold, bacteria or fungi). ). Unfortunately, these products produce natural sugars in a humid environment, the perfect breeding ground (complete with food source) for the multiplication of microbes. A product can look and smell good and still be contaminated. If the product is truly all-natural and contains no preservatives, it should be treated as food: made fresh in small batches and refrigerated (and remember, they will expire).

Products made with natural preservatives are slightly better in terms of shelf life if used within 30 days of opening, but you may want to ask the question: how good are natural preservatives vs. synthetic preservatives to control and eliminate any invaders to protect your product (and you)? Therefore, while there are effective naturally-derived preservatives, some can be weakened by exposure to air and water and therefore cannot provide the same broad spectrum protection as synthetic preservatives.

Neem oil as a natural preservative

When neem oil is used as a preservative, it works as an antiseptic, antifungal, antibacterial, antiviral, and antiparasitic. Sounds pretty good, doesn’t it? And it’s used as a pesticide, so it must be effective, right? (Although I doubt that argument works in favor of synthetic preservatives!) Neem oil is effective in keeping oils from going rancid, but it doesn’t protect the product as well from bacteria and yeast because it’s not a preservative for spread spectrum. And he doesn’t seem to like water either. Bad news for technical managers and natural health promoters who want neem oil to be used as a preservative in water-containing cosmetics rather than the much more effective (and therefore safer) synthetic preservatives available for this purpose, like Neolone 950. Strict regulations require such preservatives to kill all common pathogens. (See http://personalcaretruth.com/2010/06/why-cosmetics-need-preservatives/ for a great article on this topic.)

The half-life of neem oil in water is between one hour and four days. “Half-life” means that the concentration decreases by 50% in the measured time period. If we take one day as the half-life of neem oil in water, with a reasonable average of the given limits, we would see that the active concentration drops to 50% in one day, to 25% in two days, to 12.5% ​​in three days, 6% in four days, 3% in five days, and so on. By the time the product reaches the consumer from the day it is manufactured, the neem oil will have essentially completely disintegrated and will not be useful as a preservative; therefore, a water-based product that contains neem oil as the sole preservative is not protected from contamination (posing a greater risk to your health than synthetic preservatives).

Consumers should be more aware of the occasional misleading advice provided by consumer protection groups, particularly Safe Cosmetics and the Environmental Working Group (and their in-depth skin database). We need to question these groups as critically as we question big industry to open a dialogue. I’m not sure why these groups are considered the final authority. Is it because they validate our fears and suspicions of evil corporations? I don’t know, it’s just a guess. While their intentions may be strong, they are often based heavily on Material Safety Data Sheets (MSDS), which are generally available to the public, as one of their sources. MSDSs are helpful, of course; however, people forget or are unaware that MSDS provide safety procedures for workers in an industrial atmosphere to follow in the event of spills / mass exposures – these are “worst case” situations that never apply to consumers of these products.

MSDSs are used to help establish product stewardship and occupational safety and health guidelines for workers and emergency personnel who handle or work with the substance in large quantities. They are not intended for the consumer, but only for those in an occupational setting. It is important to remember when considering the safety issues of the products you are using that: “The dose produces the poison” or, in this case, as preservative expert David Steinberg put it, “Remember, preservatives are safer than bacteria (TM). “

Back to neem oil. An organic chemist, like me, would look at the chemical structure of azadirachtin, the active ingredient in neem oil, and know that it would not be stable in water, as we have discussed above, but that it is easily fragmented by this. reaction with water into smaller, useless pieces. Although most of us are not organic chemists, this is fairly easy to understand.

Neem oil is also hydrophobic, which means that the molecules are repelled by a mass of water. Therefore, to mix water and neem oil (emulsify) for application purposes, certain surfactants must be added. And sure enough, when you review the pesticide / agriculture literature, you find that the diluted product must be used immediately due to its limited shelf life. But not all neem oil products have this disclaimer. It is important to note that some products that contain neem oil remain “stable.” However, the product still loses its neem oil activity; it only continues to provide pesticidal activity by virtue of the other antimicrobials in the formula.

I don’t think anyone (cosmetic manufacturers, natural product suppliers, organic retailers, etc.) is trying to mislead the consumer. It is more likely a matter of conscience (the lack of it). Unfortunately, this type of misinformation puts the health of many customers at risk.