What are the benefits of niacinamide for the face?

Moisture loss can lead to dry, flaky, and dehydrated skin due to an increase in the permeability of the epidermal barrier. However, research shows that the niacinamide can help maintain a healthy skin barrier, demonstrating a reduction in transepidermal water loss, an increase in skin resistance to allergens and other impurities, and an improvement in the moisture content of the stratum corneum. The proposed mechanisms that explain this property include:

• an increase in the biosynthesis of ceramides as well as the level of other nonpolar lipids in the intercellular space of the stratum corneum (cholesterol, free fatty acids, etc.), known to play a central role in homeostasis and the structural and functional integrity of the epidermal barrier function, based on the activation of mRNA expression of serine palmitoyltransferase, the key enzyme in the synthesis of sphingolipids;

• an enhanced and faster differentiation of keratinocytes through an influence on keratin K1, specifically expressed in the spinous and granular layers of the epidermis, which results in an increase in epidermal renewal.

By enhancing the structure of the skin's protective barrier, it helps to retain moisture and prevent pollutants or other potential irritants from entering, making the skin more hydrated and less sensitive.

Several studies have demonstrated that niacinamide can help to soothe redness caused by inflammatory skin conditions such as acne, rosacea, and eczema. The mechanism by which redness is improved may be related to the enhancement of the skin barrier function. Indeed, an increase in barrier function can lead to less irritation when the skin is exposed to environmental aggressors, and therefore less redness.

Beyond improving the hydration of the stratum corneum, niacinamide has also demonstrated anti-inflammatory and immunomodulatory properties at the skin level. It modulates the production of cytokines by immune cells, such as IL-1β, IL-6, IL-8 and TNF-α, in a dose-dependent manner, linked to the inhibition of the activity of the enzyme PARP-1. This impacts the activation of NF-kB and MAPK signalling pathways, thus reducing inflammation and improving clinical signs. Niacinamide also decreases the degranulation of mast cells and the production of prostaglandin E2 (PGE2) induced by UVB by keratinocytes.

It has been demonstrated that topical niacinamide has the ability to increase the levels of intracellular NAD and NADP cofactors, which decrease with age, and whose reduced forms (NADH and NADPH) possess antioxidant properties. It thus helps to limit the action of free radicals by trapping the oxidising radical and protecting the skin from damage directly to DNA, lipids and proteins caused by factors such as natural ageing, UV rays from the sun, pollution or stress. Some research has also shown that topical niacinamide reduces the appearance of wrinkles and fine lines. It is believed to have the ability to stimulate the production of collagen in the dermal matrix and proteins in the epidermis, such as keratin, filaggrin and involucrin.

Several reports suggest that skincare formulas containing 5% niacinamide may also impact pigmentation and aid in fading hyperpigmented spots. The benefits were observed after twelve weeks of use. It has demonstrated reversibly blocking the transfer of melanosomes from melanocytes to surrounding keratinocytes by inhibiting keratinocyte factors, distinguishing it from other brightening actives that directly affect tyrosinase activity. Indeed, an in vitro study showed that daily use of a moisturising cream with 5% niacinamide inhibits 35 to 68% of the transfer of melanosomes from melanocytes to keratinocytes. By preventing the transfer of melanin into the skin, niacinamide thus helps to eliminate hyperpigmentation and even out skin tone.

The glycation of proteins (collagen, elastin) with sugar leads to the formation of cross-linked products of a yellowish-brown colour (Amadori products), which accumulate in the components of the skin matrix. These oxidation products are responsible for the dull complexion observed in damaged skin. Thanks to its antioxidant capabilities as a precursor of the coenzymes NADP and NAD, niacinamide inhibits these oxidative processes. It can thus help to improve the appearance of photo-damaged and photo-aged skin.

Although sebum can fulfil important functions (providing antioxidants, regulating transepidermal water loss, etc.), the presence of this sebum layer that covers the surface of facial skin is considered unsightly and undesirable. It contributes to facial shine, and gives the skin a greasy appearance. However, the niacinamide applied topically has proven effective in reducing sebum production by the sebaceous glands, which can prevent skin breakouts and clogged pores. Its mechanism of action has not yet been fully elucidated.

Topical niacinamide is also believed to have bacteriostatic effects on Propionibacterium acnes, which could be explained by its action on the Sir2 enzyme. In addition to its anti-inflammatory and sebostatic role, topical nicotinamide could thus have an anti-acne effect. Indeed, clinical trials on patients suffering from moderate acne have reported that the topical use of niacinamide has led to a regression of inflammatory lesions after eight weeks of treatment.

The over-activation of PARP-1, an enzyme, by UV rays involved in cellular senescence, ageing and cancer, leads to a depletion of cellular NAD, which causes a slowdown in the DNA repair process. However, nicotinamide replenishes cellular energy, as it is a precursor of NAD and NADP. Moreover, it has an inhibitory effect on PARP-1 through negative feedback, thus preventing cellular senescence. Finally, nicotinamide also protects against UVA and UVB induced immunosuppression. Therefore, nicotinamide could protect and mitigate the mutagenic and immunosuppressive effects of UV light on the skin, beneficial in the prevention of skin cancer.

Nothing has been proven to reduce pore size, but niacinamide can help to minimise their appearance. It's important to note that sebum is associated with the enlargement of pores. Interestingly, niacinamide appears to have the ability to normalise sebum secretion and this effect plays a role in preventing pore congestion and therefore its dilation.

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