I was recently asked by a customer if hydrogenated vegetable oils were 'bad' for our skin.  She was looking at my ingredient list for the Hydrating Beauty Balm which had listed hydrogenated vegetable oil; part of the olive wax I use.  

I mentioned that using a substance on the skin could have different physical effects than using them in food and that I understood that when ingested partially hydrogenated fats or trans-fats  can be a physiological disaster insomuch as they are linked with cardiovascular disease.

I assured her that hydrogenated vegetable oil is totally safe and beneficial to use in skincare; they act to add lipids to the top layers of the stratum corneum but they can not penetrate further than that into the blood stream.

Why use them?

There are a number of reasons why you might want to use hydrogenated vegetable oil above other types of oil thickeners.  Firstly, Hydrogenated oils are known for having a very long shelf life.  Longer than the original oil.  That means they do not go rancid quickly; and oxidised oils are not good for the skin.  

Secondly, because they are generally standardised, the product will always be the same.  Using a natural butter or wax may vary considerably in texture, viscosity and behaviour from batch to batch which means the quality of the product will change for the better or worse. It is always good to have your key ingredients standardised as much as possible so that you can guarantee the same quality each time the product is made.

Thirdly, fully hydrogenated vegetable oils have the ability to thicken oil without changing the sensory feel of the end product. You can make a balm with light oils and the end product still feel light on the skin despite using a butter.

Forth, they also add extra occlusive benefits in that they help prevent transepidermal water loss.

Processing

Some people feel that hydrogenated vegetable oils are not good because for the skin because ‘chemicals’ are used in the processing. Normally oils or fats have different levels of saturated and unsaturated fats naturally present naturally. Saturated fats are hard at room temperature and unsaturated fats are liquid at room temperature.

Hydrogenation is a way to turn all or some of the unsaturated fats into  the saturated form using a chemical process which involves hydrogen (that stuff in water) and a catalyst, normally nickel (a metal).

So what is the process of hydrogenation?

Let’s take Jojoba oil as an example.   This involves heating the oil with steam to about 160c in a pressurised  container. A nickel catalyst is introduced as it  is released into a converter.  When 'charging' is complete hydrogen gas is added whilst the catalyst and the oil are mixing which creates a uniform slurry.  The reaction of the oil, catalyst and hydrogen creates heat.  Once the temperature has reached about 205-230 c the reaction is complete and cold water is added to cool it down. After this there are a series of processes which remove the hydrogen gas and nickel; this happens with filtration, using citric acid as a chealant (binds to metals) and further filtration so that there is no residue of nickel left in the wax.  (1) After processing there are no reactants left in the finished fat.

How to Identify a Hydrogenated or Partially Hydrogenated Oil

If you see a wax that you would normally see as an oil such as Apricot, Hemp or Almond wax , the likelihood is that it has been hydrogenated. Either it will be fully hydrogenated and have the prefix 'hydrogenated' before the botanical name in the international nomenclature (INCI).

• Olive Wax has the INCI of hydrogenated vegetable oil, Olea europaea (the one I use)

• Almond wax has the INCI of hydrogenated vegetable oil, Prunus amygdalus dulcis

• Apricot wax has the INCI of hydrogenated vegetable oil, Prunus Armeniaca Kernel Oil

There are also vegetable butters like avocado butter and almond butter which contain the hydrogenated variety of the vegetable oil and the oil itself - these are a result of partial hydrogenation.  The INCI will also look similar to the above. Hydrogenated oils are normally used to thicken a product. They will thicken the oils in lotions and creams.  They are also a great alternative to using beeswax if you are going for the vegan market.

But are they safe to use in skincare?

Whether a hydrogenated vegetable oil is considered safe depends on the starting oil as hydrogenation is only about changing some of the double bonds into single bonds or making something that is unsaturated, saturated.   There are also a great deal of natural butters such as shea and cocoa butter that are naturally saturated.

All the oils used in skincare in the West are considered safe according to the Cosmetic Ingredient Review but there are other things to consider.  You may want to avoid using one synthesised from Peanuts or Soya bean if you are worried about adverse reactions from allergens.

Some people are also uncomfortable with the process: the fact that hydrogen and a metal are used in hydrogenation, but when all vegetable oils are processed they often use similar processes to extract the oil from the raw material, and this doesn’t mean they are dangerous to use.

Of course there are some oils that are cold processed but often this is half the story, a great many cold processed oils also go through some kind of chemical extraction. With both oil extraction and hydrogenation, there are steps to ensure there are no solvents or catalysts left in the final product.

Can Hydrogenated Oils Be Absorbed into the Blood stream?

The main function of the skin is to protect internal organs from outside assault. The saturated fat molecule is considered too large to penetrate the dermis and enter the bloodstream. In fact hydrogenated oils are used as an occlusive layer; this means that their purpose is to sit on the top of the skin and stop any moisture from the skin from escaping. We use them precisely because they do not get absorbed.

Final Word

We all make choices and have our limits with how far we want to push 'natural' so if you don't want to use hydrogenated wax or butter there are other options.  

Waxes like Carnauba and Candelilla wax come straight from the leaves of the tree.  They are harder waxes that melt at a much higher temperature than most hydrogenated waxes or beeswax. You also have the aromatic Bayberry wax which is scraped off the fruit of the Bayberry shrub. There are also various butters on the market that vary in consistency, texture and melting point. It is just a matter of testing them to see if they have the effect you want in your natural, botanical formulations.

References: (1) Seventh International Conference on Jojoba and Its Uses: Proceedings, edited by A. R. Baldwin