Per the Cosmetic Cop Ingredient Dictionary:
Topically applied niacinamide has been shown to increase ceramide and free fatty acid levels in skin, prevent skin from losing water content, and stimulate microcirculation in the dermis. It also has a growing reputation for being able to treat an uneven skin tone and to mitigate acne and the red marks it leaves behind (known as post-inflammatory hyperpigmentation). It is an excellent ingredient for those struggling with wrinkles and breakouts. Niacinamide is stable in the presence of heat and light.And in clinical studies:
Topical niacinamide reduces yellowing, wrinkling, red blotchiness, and hyperpigmented spots in aging facial skin. http://www.ncbi.nlm.nih.gov/pubmed/18492135
I will still mix my own to save money and avoid unnecessary chemicals. (Studies show a 5% solution works.) Below are some options all with good reviews. Probably because Niacinimide works. I'd show a picture of my mixture in my pretty vintage cut glass bottle, but I add turmeric and I accidentally added a ton. It's a scary yellow. Termuric is also beneficial for acne or other irritation prone skin, but it can stain. It hasn't stained my skin yet though. And I think a bit of a 'golden glow' would be a good thing on my white skin.