Saturday, June 28, 2014

Weekend Wonderings: Why is Vitamin E sold in clear bottles if it's light sensitive?

In this post on anti-oxidants, Bridget asks: I've read that many antioxidants are light sensitive. They will quickly become inactivated with exposure to light. I know vitamin C is like this. That's why C serums have to be packaged in opaque or amber bottles. I have read that vitamin E is also light sensitive. So then why is it that I keep seeing vitamin e oil for sale in clear bottles? Was I misinformed about vitamin E being light sensitive? Or are the companies that sell vitamin E oil in clear packaging misleading their customers? Or are there some other factors at work or information I'm not aware of? 

This study found Vitamin E in tablets degraded when exposed to light over a period of time. This study found Vitamin E and Vitamin A in parenteral nutrition packages degraded when exposed to light. And this book confirms Vitamin E is sensitive to heat and light (which is one of the reasons we add it in the cool down phase). So we've established that Vitamin E is sensitive to light. 

Vitamin E degrades because of photo-oxidation. (A double bond interacts with a singlet oxygen (1 oxygen atom), which is produced by the light. It is highly reactive with unsaturated lipids.) 

Interestingly enough, the Handbook of Preservatives doesn't recommend that we store it away from light; it notes that it darkens on exposure to light, but makes no special mention of how we should store tocopherols, but it notes it for other types of tocopherols. In this book, it is noted that a-tocopherol is "quite unstable and light sensitive when used in topical formulations" and so the "active hydroxyl group is, therefore, usually protected by esterification by acetate." (This book says the same thing.) 

Esterification is "an alcohol or (of an alcohol) combined with an acid, to form an ester". (Wikipedia)

It appears there are two answers as to why we get our Vitamin E in clear or frosted bottles. What we get is often tocopherol acetate (see this product at Lotioncrafter), which is more stable that non-acetate versions of Vitamin E. And secondly, Vitamin E isn't so crazy unstable that it can't be in light at all. Much like our carrier oils, it's recommended we keep our Vitamin E in a cool dark place so we reduce the exposure to heat and light, but it isn't going to be ruined if we leave it on our counters for a day or two. Having said this, I think it's a wise idea to keep your Vitamin E where you keep your oils! 

As an aside, in the summer months, I recommend getting your oils into the fridge or freezer. Yes, you can freeze oils! Similar questions and answers can be found in the frequently asked questions section of this blog! 

When it comes to Vitamin C or ascorbic acid, its instability is about more than light sensitivity. It's also sensitive to pH - preferring pH 3 or less - and it's unstable in water. This is why we need to use a different version of Vitamin C, a version that has been esterified to make it more stable. Look for something like ascorbyl palmitate or other, more stable Vitamin C if you want to make products that contain it. 

As an aside, the instability of Vitamin C and expense of the other forms of it are the main reasons you don't see Vitamin C sera on this blog. I'm asked all the time about these products, but I haven't made them because of this instability! It's not as easy as putting a Vitamin C tablet into some water and calling it a serum. You have to find the right kind of Vitamin C and make sure you're formulating it correctly, testing the pH, and so on. If you're interested in making one, here's a recipe from Lotioncrafter using tetrahexyldecyl ascorbate in a water free base. 

Want to know more about what is sensitive to light? Check out this chart! As you can see, Vitamin E and C aren't as sensitive as Vitamins A, D, and K, or riboflavin. 

Interestingly, if you've ever wondered if you could use things like Vitamin E or Panthenol in your alkaline soaps, look at the last line of the chart for your answer. (The short answer is no, they don't like alkaline environments.) But you could use Vitamin E in an acidic environment, like a lotion with loads of AHAs! 

Related posts: 

Join me Monday as we continue formulating with Incroquat BTMS-50 in our One ingredient, ten products series


Anonymous said...

Thanks for answering my question! So do you think I'd be all right getting E oil in a clear bottle at my local supermarket or health food store? Maybe that might not be the ideal option, as those bottles have been sitting there in a well lit store for who-knows how many months? Or maybe I'm just being cautious to the point of anal retentiveness, lol? It seems like they carry at least one brand of E oil at Sprouts that comes in a dark bottle, but for some reason it's way more expensive than the other versions. E oil capsules always seems to come is dark bottles, and given that I mostly make small batches of stuff, maybe that's the way to go for me.

Useful information on vitamin C as well, thanks,


Laura Bisel said...
This comment has been removed by the author.
Laura said...

Hi Susan,
In a blog post on October 4, 2013, you state that vitamin E is heat stable and can be added during the heat phase. This chart says that vitamin E is heat sensitive. I am confused! Can we add vitamin E during the heat phase or should we wait for cool down?

Thank you!

Susan Barclay-Nichols said...

Hi Laura. Heat sensitive is a relative term, and in this case we can add it to the heated phase because it won't make a massive difference...however, I'm suggesting we add it to the cool down phase because I know where that starts. So e people heat their products over 70C or in the microwave, and writing this post I started to worry about that. I'm getting a lot if newbies to the site and I thought adding to the cool down phase was the best suggestion to make.