Niacinamide (vitamin B3)

What is niacinamide?

Niacinamide is the amide form of vitamin B3, a small molecule of about 122 daltons that penetrates skin readily — the opposite problem to NAD+, to which it is a precursor. It has one of the deepest evidence bases of any cosmetic active.

How does niacinamide work?

Several mechanisms operate at once, which is unusual. It supports synthesis of ceramides and other barrier lipids, improving measured transepidermal water loss. It interferes with the transfer of melanosomes from melanocytes to keratinocytes, which is the basis of its pigmentation effect — it does not bleach, it interrupts delivery. It has anti-inflammatory activity relevant to blemish-prone skin, and it feeds the NAD+ pool that DNA repair enzymes draw on.

Concentration matters, and so does tolerance

Most published work sits between 2% and 5%. Barrier and sebum effects appear at the lower end; pigmentation effects generally need the higher end and sustained use. Above roughly 5% the returns flatten while the likelihood of flushing, tingling and irritation rises.

Worth naming plainly: the DIA Toning Serum in the Youlief range carries niacinamide at 15%. That is at or above the usual tolerability ceiling. It is not unsafe, but a meaningful proportion of users will find it uncomfortable, and there is little evidence that 15% outperforms 5% for most endpoints. Anyone with reactive skin should introduce it gradually.

The vitamin C myth

The claim that niacinamide cannot be combined with vitamin C traces to old work in which the two were heated together and converted to nicotinic acid, causing flushing. Those conditions are not typical of formulated products or of normal use. In practice the combination is used widely without issue. It is a real chemical reaction under the wrong conditions, not a rule for your bathroom shelf.

What does niacinamide not do?

It does not remove existing pigment, only slows new deposition — so results are gradual and require sun protection to be visible at all. It does not resurface. And it will not repair a barrier that is being actively damaged by over-exfoliation.

Levels in the range

Vegalab uses niacinamide in Brightening (2 to 5%), Clarifying, and across several skincare products. Youlief uses it in nine of twelve products, from 0.2% in a cleanser up to 15% in DIA Toning.