What is the difference between a 20 yuan shampoo and a 200 yuan shampoo?

People often complain: Why do I spend money on a lonely shampoo when I buy a big-name shampoo that is popular all over the Internet? What is the difference between a big-name shampoo that costs hundreds of yuan a bottle and an affordable shampoo that costs dozens of yuan? Let's have a good chat today~

Too long to read

If we look at the ingredients, there is absolutely no difference of 10 times between a 20 yuan shampoo and a 200 yuan shampoo. In fact, the water content of both is 80% to 90%, and the main ingredient of the remaining part is surfactant, and the difference between different shampoos is not much.

What is "Surfactant"

First of all, we need to explain what surfactants are.

The main purpose of shampoo is to remove dirt, mainly grease, and surfactants are the effective ingredients for removing grease. Not only shampoo, but almost all cleaning products in daily home use surfactants to work.

From the perspective of chemical structure, surfactants are generally amphiphilic molecules, that is, one end of the molecule is hydrophilic and the other end is hydrophilic. Therefore, when surfactants are placed between water and oil, they act like peacemakers, bringing together the water and oil that originally disliked each other. Intuitively, it is a state of perfect harmony, and the interface between water and oil disappears.

Image source: pexels

This phenomenon has a deeper explanation in physics. Simply put, it changes the surface tension of the liquid, making it "active", hence the name of surfactant.

It is precisely because of this function of surfactant that it can be the main ingredient in shampoo. When it comes into contact with hair, the oil on the hair can be smoothly integrated into the water, and rubbing can further accelerate the process, so that the dirt on the hair and even the scalp can be washed away.

There are many types of surfactants, and there are no less than a thousand products that have been commercialized. Naturally, there are differences between different surfactants.

The most traditional artificial surfactant is stearate, which has been around for thousands of years. When animal fats and alkali are mixed together, a saponification reaction can occur, resulting in a surfactant mainly composed of stearate. For a long time, it was also the main detergent used by humans to wash their hair. Nowadays, generally only soap is made of stearate. If you use it to wash your hair, it will damage your hair due to its strong alkalinity, which is indeed very inappropriate.

Modern surfactants have eliminated some of the shortcomings of traditional surfactants and are also very different in composition.

The ingredient list on shampoo packaging is usually arranged according to the amount of content. If you look carefully at the ingredient list, you can generally find terms such as "polyether", "polyoxyethylene" and "sodium sulfate" in the first few types. They are the new generation of surfactant ingredients. Their characteristics are that they can be stable under neutral conditions and have strong detergency.

If it is a high-end shampoo, some more special surfactants will be added, especially some natural plant-derived ingredients. Indeed, some plant ingredients in nature have cleaning ability, such as extracts from soapberry trees. However, these extracts are often not used directly, and need to be processed by extraction, refining, modification and other means. Their specific ingredients are also varied. In addition to fatty acid salts, there are also some amino acid-type surfactants.

Image source: pexels

Although these special surfactants make shampoos more high-end, the actual cleaning effect is not that significant. Therefore, if you really want to compare different shampoos, you have to look at other functional ingredients.

What are the functional ingredients in shampoo?

If entry-level shampoos are used to wash hair clean, then advanced shampoos mainly have some additional hair care effects, including removing dandruff, nourishing the scalp, darkening hair, removing oil and even preventing baldness.

The structure of hair is not as simple as it seems. It is closely connected to the hair follicles inside the scalp. If we regard the growth of hair as the growth of a tree, it is not difficult to understand that whether a tree grows well or not, it is important to take care of the tree itself, but it is more important to fertilize and water the soil.

Therefore, it is easy to understand why high-end shampoos pay more attention to the research and development of various nutrients. There are many types of these nutrients, and you also need to consider your actual needs when choosing.

Image source: pexels

For example, the ingredients that nourish the scalp are mainly some small molecule nutrients, such as amino acids, vitamins, etc., which can play a supplementary role to a certain extent. However, it should be noted that these ingredients must be mainly ingested through food. Especially vitamins, B vitamins and vitamin E are related to hair growth, but if the body itself is deficient, shampoo cannot make it up. This is like planting trees in a desert area, watering alone will not work. Some high-end shampoos use plant extracts as nutrients, which may be more comprehensive in terms of function.

For example, many shampoos add some ingredients to prevent hair loss, and the most representative one is minoxidil. In clinical practice, there is indeed a lot of evidence that minoxidil is effective for seborrheic alopecia, but in shampoo, the actual effect is still different from that of drugs. Therefore, for this need, you should choose under the guidance of a doctor.

For the demand of hair color, the actual role that shampoo can play is very limited. On the one hand, the inability of hair follicles to synthesize melanin is affected by many factors, including the lack of nutrients mentioned above. On the other hand, modern people have high pressure in life and irregular sleep, which can also cause premature graying of hair. Therefore, if you need to use shampoo to make your hair darker, it is not easy.

As far as shampoo is concerned, some of the functions that can be directly experienced are oil control, antibacterial and anti-allergic.

There are many substances that can reduce the secretion of oil on the scalp, among which selenium disulfide and salicylic acid are relatively common ingredients. Although they are indeed effective, they are inevitably irritating. Therefore, when actually using them, you should choose according to your own feelings after washing.

If you live in a hotter area and are more prone to sweating, then antibacterial is also necessary. The selenium disulfide and salicylic acid mentioned above each have certain antibacterial properties, but if it is really a hard requirement, they alone are not enough, but some hard-core antibacterial agents should be added. For example, quaternary ammonium salt is a broad-spectrum antibacterial agent that is not only effective against bacteria, but also against many fungi, and it is also a surfactant itself. Some people often have itchy scalps or even ringworms due to fungal infections. In the treatment, you may also choose this type of shampoo.

Image source: pexels

Allergies are also a common phenomenon when using shampoo, but since everyone's allergens are very different, it is impossible to directly judge from the ingredients. Through continuous research and development, high-end shampoo manufacturers will have some advantages in anti-allergic issues, such as acidity and alkalinity control, and the selection of other additives such as thickeners and defoamers, which may be more meticulous. Therefore, if you have allergies, it is worth spending more time on the selection of shampoo.

In general, high-end shampoos generally pay more attention to the functions of shampoos, but whether it is worth it depends on the consumers' own judgment.

Two "pitfalls" of shampoo

By looking at the skeleton of shampoo, we can also know what ingredients can meet our needs. The core function of shampoo is cleaning.

Everyone has different hair quality, and smart people know that it is more practical to choose the one that suits them rather than pursuing brands. There are also many IQ taxes that are easy to fall into in shampoo products, which affect the price.

1

The more foam, the better the cleaning effect?

Many people will notice that the more shampoo is used, the more foam is produced. If there is no foam, it means that the hair is not clean. This design idea can be traced back to the era of "liquid soap" a hundred years ago. At that time, people first came into contact with this novel detergent and were not sure whether it was good or not. So the merchants added foaming agents to make users feel that there were a lot of foams when using it. Naturally, they accepted a setting: the more foam, the better the cleaning effect.

Image source: pexels

In fact, there is no direct correlation between foam and cleanliness, just like the sewage discharged by many factories can also have a lot of foam. Therefore, judging the quality of shampoo based on the amount of foam is not scientifically based, and consumers should pay attention to this. However, because people can intuitively feel this, shampoo manufacturers still pay attention to the problem of foam, and through the blending of foaming agents and defoaming agents, the relationship between residual oil in hair and foam is achieved. Consumers also form a fixed mindset and think that if there is no foam on the hair, it is still not clean.

2

No silicone oil, no irritation?

Another common marketing point is "silicone oil". Silicone oil is mainly composed of some organic silicon additives, which have extremely low surface energy. In other words, silicone oil can make hair very smooth and soft. According to current research, there is no evidence that silicone oil is harmful to hair (you can review the previous article "Is "Silicone-free Shampoo" worth buying? You will understand after reading it!"), but shampoo manufacturers will still launch more expensive silicone-free products.

Summarize

There are definitely differences between 20 yuan shampoo and 200 yuan shampoo, mainly in some personalized functions, such as anti-hair loss and antibacterial. But whether these differences are worth spending so much money on depends on the actual needs of consumers. After all, for some people with allergies, the feeling of having an itchy scalp all night after washing once is really not as good as spending more money.

References

[1] Shi Benyun. More than 70% of consumers are dissatisfied with the hygienic conditions of centralized tableware disinfection[N]. China Consumer News, 2021-12-21(004). DOI:10.28867/n.cnki.nxfzb.2021.002589.

[2] Sun Changhao. Nutrition and Food Hygiene. 8th edition. People's Medical Publishing House. 2018

[3] Wang Xueshuo, Cui Shenghui, Xing Shuxia, Ding Hong. Hazard analysis, contamination investigation and prevention of Salmonella in catering food[J]. Chinese Pharmaceutical Affairs, 2013, 27(09): 974-979. DOI: 10.16153/j.1002-7777.2013.09.006.

[4]http://wzmsa.wenzhou.gov.cn/art/2022/12/7/art_1370840_58922297.html

[5] GB14934-2016 National Food Safety Standard for Disinfection of Tableware and Drinkware

[6] GB31654-2021 National Food Safety Standard General Hygiene Specification for Catering Services

[7]https://315.sh.cn/html/bjsy/2020/10/26/0952fdd4-4d2d-42d8-a253-90f5639d376a.shtml

[8] Chen Dijun, Jiang Yao, Guan Yuwei, et al. Comparison of cleaning effects of different cleaning methods on cutting boards made of three materials after Escherichia coli contamination[J]. Shanxi Chemical Industry, 2023, 43(04): 19-21. DOI: 10.16525/j.cnki.cn14-1109/tq.2023.04.006.

Author: Sun Yafei, Ph.D. in Chemistry from Tsinghua University, Yuan Zhiqin, Associate Professor of Beijing University of Chemical Technology

Reviewer: Tang Qin, Director and Researcher of the Medical Science Department of the Chinese Medical Association