What These Ingredients Do
If you're asking this question, you're probably already aware that Vitamin C and Niacinamide (which is Vitamin B3) are both good for the skin.
Vitamin C and Niacinamide deliver their benefits via different angles and mechanisms — so when used together, they're more effective than using just one.
Why Topical Application Matters
You might ask yourself: I take a multi-vitamin that has Vitamin C and Vitamin B3 in it. Why do I also need to apply these ingredients on my skin?
For Vitamin C, as we age, the levels of Vitamin C naturally decline in the skin even if we maintain a healthy and well-balanced diet. The exact mechanism is unknown, but it may be related to decreased blood flow to your skin because of aging-related changes in microvasculature. One study published in 1993 by Tsuchida showed that blood flow to your skin at 70 years old decreases to less than half — about 40% that of a 20-year-old — which in turn can reduce nutrient flow to the skin.
In healthy skin, levels of Vitamin C are 425% higher in the epidermis than the dermis (which is the layer that receives blood flow), so your epidermis needs to pull Vitamin C up from your dermis. You want that Vitamin C in the outer layer of skin because it protects everything inside from UV damage. In aging, you have decreased Vitamin C in both layers — a vicious cycle where you not only accumulate more damage, but are also more vulnerable to it without that protective antioxidant shield.
Antioxidants like Vitamin C get depleted as they fight free radicals. To maintain that protection, you have to replenish Vitamin C levels regularly. Topical supplementation directly onto the skin offers an efficient route to restoring those levels.
The Science of Skin Aging — A Fascinating Study
Before we get into the study on Niacinamide, there's a term we need to introduce: cofactors. Cofactors are helper molecules that play critical roles in keeping our cells functioning. Without them, enzymes can't do their job. Our body takes niacinamide and converts it into very important cofactors.
In 2001, Oblong and colleagues took skin cells (specifically fibroblasts — the dermal cells that make collagen) and cultured them in dishes. One cell line was derived from the skin of a 7-year-old; the other from a 72-year-old.
When the cells received the exact same nutrients, the skin cells from the older person had only about half the NADPH levels compared to those from the younger person. NADPH is one of the key cofactors derived from Niacinamide. Further, the older skin cells produced much less collagen — and loss of collagen is why our skin looks more saggy as we age. This gradual cellular deterioration with age is called senescence in biology.
When Niacinamide was added to the nutrient medium for the older cell line, intracellular NADPH levels increased and the cells began to produce more collagen — meaning niacinamide supplementation could partially compensate for senescence and restore older skin cells to behave more like younger ones.
This is why direct, topical supplementation of vitamins can have a meaningful effect on skin health — as we combat the effects of the environment and general aging to maintain firm, youthful, and healthy skin.
Why They Belong in Separate Products
Not only can you use both Vitamin C and Niacinamide in your skincare routine — we think you should. But when making a skincare formulation, there is a good reason not to combine them into a single product.
In most cases, the Vitamin C used in skincare is ascorbic acid (or L-ascorbic acid, though on ingredient labels you'll see just "ascorbic acid" per INCI standards). If a product says it contains Vitamin C, probably 95 out of 100 times it's ascorbic acid — the most researched and proven form. It's water soluble, which is why you usually find it in a serum, but it has to be formulated very specifically to actually penetrate the skin barrier.
If you've experienced irritation from a niacinamide product in the past, it may be because the product was not appropriately formulated and the niacinamide converted into niacin. Always check the pH and concentration of your niacinamide products.
If you see ascorbic acid and Niacinamide formulated together in the same product, one or the other may not be working as well as it should — because these two ingredients are optimal and stable in different pH ranges. Keep them in separate products and you get the best of both worlds.
How to Use Both in Your Routine
Apply them separately in steps. The general rule of thumb is to wait a minute or two between products to allow each to absorb before layering the next.
Want to go even deeper? Check out Maelove's Deep Guide to Vitamin C and the Deep Guide to Niacinamide.
- Lin FH, Lin JY, Gupta RD, Tournas JA, Burch JA, Selim MA, Monteiro-Riviere NA, Grichik JM, Zielinski J, Pinnell SR (2005). "Ferulic Acid Stabilizes a Solution of Vitamins C and E and Doubles its Photoprotection of Skin." J Invest Dermatol 125: 826–832.
- Oblong JE, Bissett DL, Ritter JL, Kurtz KK, and Schnicker MS. "Niacinamide stimulates collagen synthesis from human dermal fibroblasts and differentiation marker in normal human epidermal keratinocytes: Potential of niacinamide to normalize aged skin cells to correct homeostatic balance." 59th Annual Meeting American Academy of Dermatology, Washington, 2001.
- Tsuchida Y (1993). "The effect of aging and arteriosclerosis on human skin blood flow." J Dermatol Sci 5(3): 175–181.
