What is an Humectant?

Tricia Christensen
Tricia Christensen

A humectant is a substance used primarily in foods and cosmetic products to help retain moisture. These substances are called hygroscopic, which means that they are able to absorb ambient water. Some such additives are beneficial when consumed or used. Others, particularly in some foods, are less helpful, may cause abdominal distress, and should probably be avoided.

Sorbitol, a humectant commonly used in food.
Sorbitol, a humectant commonly used in food.

A common humectant in food products is sorbitol. This is a sugar alcohol derived from sugar. It is used in dietetic or sugarless foods and is lower in calories than sugar, so it is a popular choice among those who are dieting. In doses larger than 1.76 ounces (50 g), it has a laxative effect and can cause diarrhea. In the 1990s, consumer advocates successfully lobbied to have product warnings placed on foods containing sorbitol, so people could keep their consumption below harmful levels.

Humectants are used in skin care products to help the skip retain moisture.
Humectants are used in skin care products to help the skip retain moisture.

Polydextrose is another humectant food additive used to replace sugar. It is not only found in sweet foods, but frequently in other foods like salad dressings. This particular substance not only replaces sugar in some foods, but can also be used as a fat or starch replacement. It has a laxative effect as well, so reading the labels of one’s food can inform selection.

Humectants may be used in embalming fluids.
Humectants may be used in embalming fluids.

Glycerol can be found in foods, but is also sometimes specifically prescribed by doctors for constipation, so again cautious consumption is advised. Perhaps the most beneficial aspect of glycerol is not as a humectant but in the manufacture of biodiesel. With current shortages in oil and rising gasoline prices, many have turned to fuel alternatives like biodiesel, and it is predicted that many more will do so.

Mineral oil can build up under the skin and prevent the skin from absorbing essential vitamins and nutrients.
Mineral oil can build up under the skin and prevent the skin from absorbing essential vitamins and nutrients.

Glycerol or glycerin is a frequent addition to moisturizing lotions and skin creams. Some humectants used in skin care products are vegetable oil based. Many work well for moisturizing and smoothing the skin. A substance like mineral oil, however, can actually build up under the skin and prevent the skin from absorbing essential vitamins and nutrients. A number of skin products contain mineral oil, even the more highly priced ones. Consciousness of the deprivation of nutrients to the skin caused by mineral oil has prompted something of a skincare revolution, in which vegetable oils replace the inadvisable mineral oil.

Certain humectant substances can be added to plants at the root level to assist the plant in gathering more ambient moisture. Many gardeners favor this as a way to conserve water. A humectant composed of several oils is also used in embalming fluids. They are said to restore moisture and produce a more life-like appearance for those who will be viewed in open caskets.

Polydextrose is a humectant food additive that is frequently found in salad dressings.
Polydextrose is a humectant food additive that is frequently found in salad dressings.
Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent wiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

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Discussion Comments


Are there ways to preserve things that act as humectants such as mixing avocado, egg white and olive oil without freezing or refrigeration?


The sugar-free hard candies that I suck on to curb my sweet cravings contain sorbitol. I figured out the hard way that if I eat too many of them, I will get diarrhea. I never would have thought that something so small and seemingly harmless could do this to me!


I like using handmade soaps, because they contain the natural humectant glycerin. All glycerin soaps are translucent, though they come in a wide range of colors and scents.

I have noticed that these soaps don't seem to last as long as regular bar soaps do. I can't leave a bar of glycerin soap lying around in a soap dish with any water in it at all, because it will start to dissolve and turn to mush rather quickly.


@Oceana – You are right about it being too moisturizing for someone with oily hair. My hair naturally gets oily by the end of the day, and I wash it every night.

I had tried a humectant shampoo, because I thought maybe my scalp was producing too much oil because it was starved for moisture. I didn't dare use a conditioner, but I thought the shampoo might be okay to use.

It made my hair look as though I hadn't washed it at all. After it dried, I had to wash it again with my regular shampoo.


I have very dry hair that has been damaged by a perm I got a few months ago. Regular conditioners were not doing much to help detangle and moisturize my hair, so I tried a humectant conditioner.

It has made my hair soft and more healthy looking. This kind of conditioner was formulated for people with hair like mine, and the label even says that it is for dry and damaged hair.

I've used conditioners that said this before, but none have worked quite as well as this humectant conditioner. It might be a bit much for someone with oily or even normal hair, but for me, it is perfect.


Glycerin isn't used in producing biodiesel, it's a byproduct of production. Basically, a triglyceride is reacted with an alcohol, stripping off the glycerin backbone and turning the fatty acids into esters that can be used as fuel.


A. Latif from Bangladesh (BD), and I want to make inkjet ink. I want to use humectants as a chemical. Is it possible? If it is possible, what is its business name in Bangladesh? If I cannot get it in Bangladesh, where can I get it?


I think it relieves constipation because by definition a humectant draws moisture within and I can see where the H20 is drawn into the colon and soften the stool. I cheated (I'm a nurse):) But hey, I could be wrong.


Dear anon4073: The reason glycerol helps constipation is precisely because it retains moisture. It's the same reason fiber helps prevent/relieve constipation. The colon's job is to suck excess moisture from the stool before passing it. You need to retain some moisture in your stool, however, in order for your colon to pass it easily. If there is not enough water-retaining undigestable material in your stool, it will dry out and become lumpy and hard to pass regardless of how hydrated you are.


Actually, diarrhea often occurs with dehydration, and dehydration with diarrhea. When a body is experiencing events that cause dehydration, the body will take in water from all available sources to attempt to stay hydrated, this includes taking water out of the bowel and its stool. This may cause an initial constipation affect, but it will shortly be followed by a bout of diarrhea as the body is either re-hydrated or hormones are released into the body.


Since glycerol helps retain moisture, how exactly does it help relieve constipation? Would the constipation not worsen due to decreased moisture?

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