In the food, cosmetics, and pharmaceutical industries, preservatives are key ingredients that ensure product quality and extend shelf life. However, as consumers become more health-conscious, "chemical preservatives" are often linked to safety concerns, while "natural preservatives" have gradually become a market favorite due to their "natural origin" attribute. But why exactly are natural preservatives safer than chemical ones?
1. Origin and Ingredients
The safety of preservatives first comes from differences in their "origin". The essential distinction in source and composition between chemical and natural preservatives determines their inherent gap in safety.
Chemical preservatives are mostly artificially synthesized compounds, such as benzoic acid and its sodium salt, sorbic acid and its potassium salt, and parabens. These substances do not naturally exist in the human body; they are chemical molecules with antibacterial activity produced through chemical processes. To achieve strong antibacterial effects, the molecular structure of some chemical preservatives is designed to be highly stable—which means they may be hard for the human body to break down and thus remain in the body long after working.
Natural preservatives, by contrast, are completely different. Their core ingredients are all extracted or purified from natural plants, animals, or microorganisms: for example, polylysine and natamycin produced by Streptomyces fermentation, and nisin extracted from the fermentation products of Streptococcus lactis. These ingredients are themselves part of the natural ecosystem. Among them, the production strain of nisin is even a beneficial microorganism commonly used in food fermentation. The human body has a natural "recognition" for them, and their safety has been verified through a long history of consumption.
2. Safety Comparison
When talking about "safety", we need to conduct scientific evaluations from four key dimensions: toxicity, metabolic pathway, allergenicity, and environmental compatibility.
Lower Toxicity
The safety of chemical preservatives always faces the issue of "dose dependence". Take common benzoic acid as an example:CAC stipulates its ADI as 0-5mg/kg body weight—which means a 60kg adult should not consume more than 300mg per day. Exceeding this limit may burden the liver. More alarmingly, studies have shown that parabens may interfere with the human endocrine system, and the European Union has now banned their use in children's cosmetics.
Natural preservatives generally have extremely low toxicity, most belonging to the "practically non-toxic" level. For instance, the Joint Expert Committee on Food Additives of the World Health Organization and the Food and Agriculture Organization has determined that the ADI value of nisin is "not specified". It can not only be safely used for food preservation but also be decomposed into amino acids by human digestive enzymes. As an antifungal preservative, natamycin is hardly absorbed by the human body. Even with long-term exposure, it will not damage liver or kidney function, and its safety has been certified by authoritative institutions in more than 100 countries and regions around the world.
More Friendly Metabolism
A major hidden danger of chemical preservatives lies in difficult metabolism. Due to their artificially designed molecular structures, the human body lacks specific enzyme systems to break them down. As a result, some chemical preservatives cannot be effectively metabolized and can only be excreted through the kidneys, which may accumulate in the body with long-term intake. For example, although potassium sorbate is considered a relatively safe chemical preservative, excessive intake may cause intestinal flora disorders, especially for the delicate metabolic systems of infants and young children.
Natural preservatives, however, fully conform to the metabolic laws of the human body. Take polylysine as an example: in the human body, it can be gradually decomposed into lysine monomers by proteases. Lysine is an essential amino acid for the human body, which can directly participate in protein synthesis and be utilized by the human body without any residual burden. The metabolic process of nisin is even simpler: after entering the digestive tract, it is quickly degraded into harmless amino acid fragments by trypsin, without irritating the intestinal mucosa. This metabolic pathway of "coming from nature and returning to nature"fundamentally avoids "accumulative harm".
Weaker Allergenicity
Chemical preservatives are one of the common triggers of allergic reactions. According to data from the China Consumers Association, about 23% of cosmetic adverse reactions are related to chemical preservatives such as parabens and methylisothiazolinone, with symptoms including skin redness, itching, and stinging. Benzoic acid preservatives in food may also induce digestive discomfort in sensitive people, such as nausea and diarrhea.
Natural preservatives have significantly lower allergenicity. On one hand, the molecular structure of ingredients like natamycin makes it difficult for them to penetrate human skin and digestive tract mucosa, hardly triggering allergic reactions of the immune system. On the other hand, the mechanism of action of natural preservatives is gentler. For example, nisin exerts its antibacterial effect by destroying specific receptors on bacterial cell membranes, while human cells do not have such receptors, so it has no toxicity or irritation to human cells. Even people with sensitive constitutions rarely have adverse reactions when using foods or cosmetics containing these ingredients.
Better Environmental Compatibility
The safety of preservatives is not only related to human health but also to environmental safety. After being discharged with sewage, chemical preservatives may remain in water and soil, posing potential hazards to ecosystems. For example, parabens entering the water environment can affect the reproductive capacity of aquatic organisms; methylchloroisothiazolinone may inhibit the activity of beneficial microorganisms in the soil and damage soil fertility.
Natural preservatives, however, have good environmental degradability. Polylysine and nisin are both polypeptide substances. After entering the natural environment, they can be quickly decomposed into amino acids and small molecular peptides by microorganisms in the soil, becoming nutrients for plant growth. Although natamycin has strong stability, it can be gradually degraded into harmless metabolites under sunlight and will not accumulate in water or soil. This "green attribute" not only conforms to the current concept of "sustainable development" but also indirectly confirms its compatibility with the natural ecosystem—which is essentially an extension of "safety".
3. Scientific Application
Some people may ask: if natural preservatives are so safe, does that mean their antibacterial effect is not as good as chemical ones? The answer is no. With the development of extraction technology and compounding technology, natural preservatives have long achieved a balance between "safety" and "efficiency".
For example, after compounding polylysine and natamycin, the former targets bacteria and the latter targets molds and yeasts, forming a "full-spectrum antibacterial" effect. It is widely used in perishable foods such as pastries and meat products, and the shelf life is extended by 30%-50% compared with a single chemical preservative. Nisin can not only effectively inhibit food-borne pathogens but also withstand high-temperature sterilization at 121℃, solving the shortcoming of "poor heat resistance" of traditional natural preservatives. Currently, it has become the preferred preservative for high-temperature processed foods such as canned foods and ham sausages.
4. Conclusion
From ingredient nature to metabolic pathways, from human safety to environmental compatibility, natural preservatives show incomparable advantages over chemical ones due to their "coming from nature and returning to nature" characteristics. Of course, this does not mean all chemical preservatives are "harmful"—using chemical preservatives within national standards is safe, but natural preservatives provide a "better solution": they not only fulfill the preservative function but also increase product added value due to their natural attributes, meeting consumers' demand for "no additives and healthier" products.
In today's era of increasing health awareness, choosing natural preservatives is essentially choosing a lifestyle that is more in line with natural laws and respects human health. With the advancement of science and technology, we have reason to believe that natural preservatives such as polylysine, natamycin, and nisin will gradually replace chemical ones, becoming the mainstream choice in the food, cosmetics, and other industries, and building a "natural defense line" for human health.
