There has been a lot written about retinoids, by professionals, by bloggers, by quacks, even by me. So, how are there still questions? I believe that the answer to this question lies in the skin itself—everyone’s skin is different, so what works for your skin, might not work for my own. I bring this up because I will be doing a series of posts about retinoids this month, and I really want to preface it by saying the information contained in this series is based on my own personal experience and research. I am not a physician. I am not a licensed esthetician. I have worked in the skincare and beauty industries for over 10 years, but I am NOT LOOKING AT YOUR SKIN. So read, glean what you can, hopefully even enjoy, and then ask a professional who can give you a proper skincare diagnosis.
Now that all of that nasty stuff is out of the way, let’s get down to the science! This introductory post is just to give a little background on what retinoids actually are. Chemically, retinoids are related to vitamin A. I find there is a good deal of confusion regarding the difference between the terms retinol, retinoid, Retin-A, and vitamin A, and so I will define them briefly below. Basically, these terms relate to different forms of vitamin A derivatives–there are several types, most of which function similarly when use on the skin.
Sidebar: I know most of you won’t find anything of interest in this post, but stay with me here. If you absolutely have to check out, see the bottom of the post for a roadmap of where this series will be heading. I promise those of you just looking for a quick guide will get it. Eventually. Keep in mind, I am not above writing posts for my own edification and amusement. Until then, you can’t say I didn’t warn you what I’m about (see below).
Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, retinoid acid, carotenoids, and several others. Vitamin A is a fat-soluble vitamin that serves several important functions in the body. Vitamin A can be synthetically manufactured or naturally derived. Vitamin A can be naturally derived from two sources—animals or plants. Plant-derived vitamin A falls into the group called carotenoids. Vitamin A derived from animals falls into the group retinoids.
As to the chemical structure of vitamin A, for anyone who actually cares, all forms of vitamin A have a beta-ionone ring attached to a isoprenoid. A beta-ionone ring, seen below, is part of a group called ionones which are aroma compounds found in many essential oils. Ionones are actually derived from the degradation of carotenoids–found in, you guessed it, carrots (among other things).
An isoprenoid (which the little structure you see above is attached to), is a class of organic compounds composed of two or more units of hydrocarbons. Each unit consists of 5 carbon atoms arranged in a specific pattern. Isoprenoids are mostly classified according to the number of isoprene units they contain, and as there are several forms, I won’t both posting a visual of the chemical structures.
The term retinoid refers to the group of vitamin A derivatives into which retinol, along with several other forms, falls. As previously mentioned, retinoids are either animal-derived or synthetically made. Retinoids aren’t only just good for your skin, but also play a role in vision, regulation of cell differentiation and proliferation, growth of bone tissue, immune function, and activation of tumor suppressor genes! Clearly these things pack a real punch.
There are three generations of retinoids, with some researchers designating a fourth generation. We will discuss the different generations and types further in our next post.
The retinoid molecule is hydrophobic, meaning it does not mix well with water–this will come into play when we discuss formulation and delivery systems. The basic structure of the molecule contains a cyclic end group, a polyene side chain, and a polar end group.
Retinol is just one type of retinoid. It is a form of Vitamin A that occurs naturally in the skin and is commonly found in over-the-counter products.
In the body, retinol is converted to retinoid acid or retinal. Retinoid acid is the form that is beneficial to the skin.
Retin-A is an isomer of the vitamin A molecule, and was developed in the 1970s. The original use was as an acne treatment, but today it has many applications.
We will revisit these distinctions in upcoming posts.
Speaking of upcoming posts, I just wanted to take a minute to outline what I will be posting over the coming weeks (as part of this series), so you know what you’re in for!
- Retinoids pt. 2a: The Mechanism
- Retinoids, pt. 2: The Types (Including a Handy Chart)
- Retinoids, pt. 3: The Benefits
- Retinoids, pt. 4: How To Choose One
- Retinoids, pt. 5: The Retinol Face, and How to Conquer It
- Retinoids, pt. 6: Retinoids and Everything Else you Use
- Retinoids, pt. 7: Contraindications
- Retinoids, pt. 8: Everything You Need to Know (Infographic)
Also, as this will be a series of retinoid posts, if you have any questions you’d like answered, feel free to leave them in the comments!