Controversy: Are hydrogenated oils bad for your skin? Part one – hydrogenation

Yesterday, I mentioned there’s this thing going around now that hydrogenated butters are bad for your skin, so I thought I’d take a look at the claims that are being made about this…

I needed to know exactly what’s being said about them, so I did a search, and found this page – Maty’s Are hydrogenated oils bad for your skin? – which I’ll use as the basis for this post along with other references. (I found a ton of pages like this, but this one was the most concise.)

“Used throughout the food industry to prolong shelf life and save money, hydrogenated oil is a man-made ingredient produced by adding hydrogen atoms to vegetable oil. It may sound harmless, but this process increases the saturated fat content and can turn the oil into a trans fat.  Trans fats promote inflammation and have been linked to both weight gain and heart disease. Research also shows that the molecular structure of hydrogenated oils is closer to plastic than oil. We think that’s crazy!”


First, click here to learn more about hydrogenation if you want a really detailed description. Quick summary: Oils with double bonds, like oleic acid or linoleic acid, which are unsaturated, are hydrogenated by breaking those bonds, then adding an hydrogen atoms, which makes them lie straighter so they can pack in more and be more solid, and increase the shelf life by reducing the potential for rancidity. Oils without double bonds are called saturated, so it is correct to say that this would be considered a saturated fat.

Are oils hydrogenated to prolong shelf life? Definitely!


What’s a cis fat? What’s a trans fat? These are fatty acid chains consisting of carbons (C) and hydrogen (H).

In the cis configuration – the first chain – the missing hydrogen atoms are on the same side of the double bond (cis means “same”). The molecules bend at the site of the double bond, giving us a kinky molecule that won’t pack in nice straight, dense lines like the saturated fatty acids. Put a bunch of these together and you have a liquid oil! You can see in the first diagram above, erucic, ararchidonic, oleic, linoleic, and linolenic fatty acids have these kinks, so you can predict that oils that contain a lot of these will be liquid.

In the trans configuration – the second chain – the missing hydrogen atoms are on the opposite sides of the double bonds. (“Trans” means across.) The chain doesn’t bend much, so they have a straighter shape. Meaning they can pack in more densely, resulting in an oil that behaves as a solid saturated oil instead of a liquid oil. It has a higher melting point, doesn’t need refrigeration, and is cheaper than saturated oils like coconut or palm oil.

If an oil is hydrogenated, this means all the double bonds are broken and it becomes saturated, meaning there are no double bonds. No double bonds – no cis or trans configurations.

If an oil is only partially hydrogenated, this can result in the production of trans fats.

Can hydrogenation “turn the oil into a trans fat”? Yes, if it’s not fully hydrogenated. We see in food ingredient lists all the time, “partially hydrogenated (something) oil”, but the ones we’re using are hydrogenated. Fully hydrogenation = saturated fatty acid = no double bonds = no cis or trans configurations.

So the answer to this bit is yes, partial hydrogenation can result in the production of trans fats, HOWEVER full hydrogenation will not result in trans fats. 

Before we leave this question, I wanted to share this quote with you and a few links…

“If all the double bonds are hydrogenated, the unsaturated fat becomes saturated. However, if only some of the double bonds are hydrogenated, the fat is described as “partially hydrogenated.” But another important thing happens to the double bonds in the partial hydrogenation process: The double bonds that are NOT hydrogenated are converted from cis to trans. Overall, the fat is still unsaturated, but now the double bonds are trans rather than cis. And that’s how a trans fat is born!” (Reference)

If you want to learn more, this is a great article on this topic from the American Chemical Society! And I can’t suggest enough that you check out this link to the ChemLibre text for Chemistry, Hydrogenation of Unsaturated Fats and Trans Fat! And this is another good resource

Before we leave this topic, I encourage you to check out this link to learn about impact of the shape of the fatty acid as I thought it was interesting.


Not all trans fats are created by partial hydrogenation. You can find naturally occurring trans fats in conjugated linoleic acid (CLA), and eladic acid, like those in dairy products.Yep, milk produced by ruminants – cows, sheep, goats – contains naturally occurring trans fatty acids. (Reference) But we see people using goat’s milk in all kinds of products from soaps to lotions without concern, so…


We use hydrogenated things all the time, not just hydrogenated oils in the form of something like a thickened oil to act as a butter. (Hence my use of the word “thingie” instead of oil.)

You’re using hydrogenated ingredients – some approved by COSMOS or ECOcert – in all kinds of ingredients that are hydrogenated or use hydrogenation as part of the process of creating them.

Even squalane, an emollient I think we can all agree that squalane is pretty darned awesome stuff when we include it in our products as it can help dry and chapped skin and so much moreI found this on Chemists’ Corner, “The presence of double bonds leads to oxidative stability problems with squalene. That lead to the hydrogenation of squalene to create squalane.”

My short answer is no, based on just the hydrogenated ingredients I’ve shared in this list, they’re not bad for our skin. (Although what “bad for our skin” means is another million word essay…)

Join me tomorrow as we work through this topic by taking a look at the molecular structure of hydrogenated oils.