Liver is a good source of retinol, the animal form of vitamin A. (Photo by ulterior epicure)
Since the CE ferulic acid experiment will take quite a while to finish, I'm going to try using a topical vitamin A product as well. I will only be using it on the left side of my face, so that if there are positive results, I'm able to attribute them to the correct product.
I've chosen a retinol-A cream from Young Again, since it was quite cheap compared to the alternatives and is supposed to be less irritating than tretinoin, which is the acid and most effective form of vitamin A. If retinol proves ineffective, I'm going to try the real deal.
The 2 oz (about 57 grams) jar contains 600,000 IU of retinol. Considering that 1 International Unit is equivalent to 0.3 micrograms of retinol, one jar should contain 600,000 * 0.3 mcg = 180,000 mcg = 180 mg of retinol. This would mean that 180 mg / 57,000 mg = 0,3 % of the cream is retinol, making it a 0,3 % retinol cream. I'm not sure whether this is enough to be effective, but the strongest creams I could find all had 600,000 IU per 2 oz.
At least one study suggests that topical retinol improves fine wrinkles and increases collagen production without the irritating effect of tretinoin.