From A to K - Vitamin dictionary focussing on skin ...

In company with enzymes that are endogenously produced, the vitamins control biochemical reactions in the body. While enzymes work as catalysts and can regularly be substituted by new formation, the vitamins use up and cannot be synthesised although they usually are incorporated into endogenous cycles in which they are recycled to a certain extent. Just to mention an example: after their antioxidative effects, most but not all of the abreacted vitamin E molecules are regenerated with the help of vitamin C. After a certain time, however, there is need for exogenous replenishment.
On the skin surface and depending from the applied dose, the vitamins have completely different effects than in the intra-physiological context. Vitamin C can be mentioned here as a significant example which in its form as free ascorbic acid in high concentration has keratolytic effects outside the body analogous to an alpha hydroxy acid.
Vitamin B12 cannot be topically absorbed and only has a slight antioxidant effect on the skin surface due to its high molecular mass.
Besides its genuine functions, provitamin B₅ has additional effects on the skin that are not allowed for in physiological respect - such as for instance the increased skin hydration or the penetration-enhancing effects for exogenous active agents.

In their campaigns for cosmetic skin care products sales promotion departments freely use information on the effects of vitamins as known from technical literature for vitamin deficiency. However, these effects will never materialise with a balanced way of life. In the following survey only the cosmetic effects and the resulting applications are compiled.

¹⁾ The numerical gaps in the enumeration of vitamins are due to the fact that the formerly assumed vitamin properties of the vitamins B₄, B₈, B₁₀ and B₁₁ have not been proved.
²⁾ The typical vitamin deficiencies as described in literature have neither been listed in the table nor in the section cosmetic purpose since they will never materialise in the context of a normal European diet. Functions and occurrence have been specified in H. Lautenschläger, Vitamine in der Kosmetik, medical Beauty Forum 2011 (1), 14-16 und (2), 16-18.
³⁾ The carrier function of liposomes and nanodispersions is based on their content in native phosphatidylcholine that fluidises the skin barrier and so improves its permeability for active agents.
⁴⁾ Derivatives are chemical modifications of the vitamins; they are enzymatically transformed into free vitamins in the skin. By-products of this process are further physiological substances such as acidic acid, propionic acid, palmitic acid, stearic acid, linoleic acid, phosphoric acid or alcohol.
⁵⁾ Provitamins are naturally occurring physiological compounds that are enzymatically transformed into vitamins in the skin.
⁶⁾ Substitutes are active agents without structural resemblance to vitamins but with (partially) analogous cosmetic effects.
⁷⁾ BfR: Bundesinstitut für Risikobewertung (Federal Institute for Risk Assessment in Germany)

Dr Hans Lautenschläger

From A to K - Vitamin dictionary focussing on skin care

Besides minerals and omega-3- and omega-6-fatty acids, the vitamins are a group of vital substances for the human metabolism that can only be orally ingested or topically absorbed. Dr Lautenschläger, chemist, has compiled a list of the most important vitamins for the skin care.