Cosmeceutical Vitamins: Vitamin B

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Chapter 9 Cosmeceutical Vitamins: Vitamin B

Donald L. Bissett, John E. Oblong

INTRODUCTION

The nutritional value of B vitamins has long been known, and in recent years the utility of topical vitamin B₃ (niacinamide) and provitamin B₅ (panthenol) is being increasingly recognized. There are several reports of topical niacinamide and panthenol providing therapeutic dermatologic effects. More recently, both of these B vitamins have been utilized in topical cosmetic products to provide beneficial effects for a wide array of more common skin problems such as those associated with aging. In those applications, these B vitamins have been found to be well tolerated by the skin and can thus be used broadly across skin types.

The likely mechanisms involved in these effects have not been completely elucidated. However, since both of these B vitamins are precursors to important cofactors in metabolism, a general mechanism involving this precursor function can be invoked.

This chapter overviews the topical effects and mechanisms of these B vitamins. Since there is a considerable literature on both materials, this review can by necessity only briefly describe the array of published work.

NIACINAMIDE

• Material

Vitamin B₃ encompasses a family of structurally similar compounds. The focus here is on niacinamide, also known as nicotinamide and in older literature as vitamin PP (for pellagra preventing). Niacinamide is a water-soluble, stable, low molecular weight substance that readily pene-trates the stratum corneum.

• Topical therapeutic effects

Niacinamide has been used topically in prevention of photodamage, reduction in acne, improvement in bullous pemphigoid, and treatment of rosacea and atopy. The specific mechanisms for these effects have not been defined, although there are considerable effects of niacinamide that may contribute. Additionally, niacinamide is a precursor to NAD(P) and their reduced forms NAD(P)H, cofactors which are important in many cellular metabolic enzyme reactions, so it has potential to impact many tissue functions. Also, since the reduced forms of these cofactors are potent antioxidants, a redox regulation mechanism is a strong possibility.

• Topical cosmeceutical effects

Topical niacinamide is extremely well tolerated by the skin. That mildness and the broad use potential noted above have triggered several recent controlled cosmeceutical clinical studies, which have revealed many beneficial effects of chronic topical niacinamide in aging skin.

BARRIER AND IRRITATION

Topical niacinamide reduced transepidermal water loss (TEWL), indicating improved barrier function. The treated skin was found to be significantly more resistant to damage by barrier-destructive agents such as the surfactant sodium lauryl sulfate (SLS) and trans-retinoic acid. This translates into less irritation and facial red blotchiness (Fig. 9.1).

Fig. 9.1 Red blotchiness improvement by topical 5% niacinamide in Caucasian facial skin: (A) baseline; (B) 8 weeks

The mechanism for barrier improvement is likely due to niacinamide-induced increases in skin barrier layer lipids such as ceramides and barrier layer proteins such as keratin, involucrin, and filaggrin. Increases in these primary structural components would be expected to have a significant effect on building the barrier.

HYPERPIGMENTED SPOTS

Chronic topical niacinamide also reduces the appearance of hyperpigmented spots in both Caucasian and Asian facial skin. The mechanism for this was found to involve inhibition of melanosome transfer from the melanocytes to the keratinocytes. With transfer inhibited, the melanocytes stop producing melanin. As anticipated, the melanin reduction effect is reversible with cessation of niacinamide treatment both in culture and clinically.

YELLOWING (SALLOWNESS)

With topical niacinamide, yellowing was significantly prevented (Figs 9.2 and 9.3). The mechanism for this may involve antioxidancy via NAD(P)H, specifically prevention of protein glycation (Maillard reaction), the end products of which are cross-linked yellow-brown proteins (Amedori products) that accumulate in skin. Niacinamide has been reported to have antiglycation properties.

Fig. 9.2 Anti-yellowing effect in Chinese facial skin by topical 3.5% niacinamide: (A) baseline; (B) 4 weeks

Fig. 9.3 Topical 5% niacinamide prevents skin yellowing (‘b’ value analysis from images)

TEXTURE AND SEBUM

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