All about Vitamin K

Vitamin K is a fat-soluble vitamin stored in fats. It was discovered accidentally in 1929 during experiments on sterol metabolism and was immediately associated with blood clotting. The quinone family includes a variety of forms of Vitamin K. The nature of the carbon chain attached to the quinone differentiates them.

• Vitamin K1 (C31H46O2). It is naturally synthesised by plants during photosynthesis. Also known as phylloquinone, phytomenadione or phytonadione, it is found in photosynthetic organisms such as algae. This form is the one used in cosmetics.

  In the industry, the vitamin K1 is currently produced synthetically.

• Vitamin K2 (C31H40O2). Also known as menaquinone, it is found in the bacteria of the intestinal flora as well as in the consumed plants. This form is generally used in oral anticoagulant treatments or as a dietary supplement.

• Vitamin K3 (C11H8O2). This is one of the synthetic forms of vitamin K, also known as menadione. In reality, it is an intermediate in the synthesis reaction of vitamin K. Due to its side effects on the liver, it is not used in human nutrition.

The vitamin K, particularly vitamin K1, offers numerous benefits for the skin. It is found in many cosmetic products, ranging from healing creams to eye contour serums. The concentrations of vitamin K in skincare products vary from 0.1% to 1% approximately. It is also consumed orally, in dietary supplements.

• Vitamin K protects against photoaging.

  Vitamin K could potentially counteract photoaging through the elimination of reactive oxygen species (ROS), which when unstable can transform into free radicals, responsible for the oxidative degradation caused by UV rays.

  Indeed, a study has shown that the cycle of Vitamin K can have antioxidant effects, particularly through Vitamin K-hydroquinone, a product of Vitamin K reduction. This could prevent lipid peroxidation (oxidative degradation of lipids) by breaking the chain of responsible free radicals.

  Indeed, biological lipid membranes are vulnerable to peroxidation. This can disrupt the integrity of the membranes, such as those of skin cells. It is therefore conceivable that vitamin K could have an antioxidant effect on the skin and protect it from the cutaneous impact of photoaging.

• Vitamin K optimises the healing process.

  Due to its ability to increase the formation of fibroblasts, collagen, blood vessels, and hydroxyproline (an amino acid involved in collagen synthesis), vitamin K applied topically has the potential to promote wound healing. It has also been demonstrated that blood coagulation can stimulate healing.

  Given that Vitamin K strengthens blood clotting, this could contribute to its mode of action. Reactive Oxygen Species (ROS) also play a significant role in the pathogenesis of skin wounds: their overproduction during oxidative stress delays healing. Taking into account its antioxidant capacity, Vitamin K could enhance wound healing.

• Vitamin K possesses anti-inflammatory properties when taken orally.

  Vitamin K1 could reduce the inflammatory response triggered by lipopolysaccharide (LPS) and decrease the expression of IL-6, a pro-inflammatory cytokine involved in chronic skin inflammatory diseases. Thus, the regulation of inflammatory cytokine expression could contribute to the suppression of inflammation by Vitamin K.

• Vitamin K reduces vascular imperfections.

  The topical application of Vitamin K could potentially improve bruising and other blood circulation disorders, an effect observed in studies on contusions. There is no clearly defined mechanism of action, but this effect could be due to blood clotting by strengthening the vascular walls. These results offer great hope in the treatment of bluish dark circles (vascular) or conditions related to microcirculation blood disorders such as rosacea.

• The vitamin K could reduce hair whitening due to ageing.

  It is important to note that no studies have been conducted on the use of vitamin K for hair, and there are currently no hair products containing vitamin K on the market. However, assumptions about potential effects can be made, particularly due to the antioxidant action of vitamin K.

  Let us recall that the vitamin K cycle could block lipid peroxidation. During photo-aggravated hair ageing, lipid oxidation damages the hair fibre. Hair pigments absorb and filter solar rays to protect hair proteins.

  However, when pigments act to protect these proteins, they can be damaged, resulting in grey or white hair. Vitamin K could then protect the hair pigments and reduce the effects of oxidative stress on them.

Generally, the vitamin K does not cause any particular danger for the majority of consumers. However, some clarifications need to be made.

The vitamin K1 in its pure form is prohibited in cosmetics, according to the European Commission Directive 2009/6/EC of 4th February 2009.

Indeed, several cases of allergic skin reactions have been recorded following the topical application of Vitamin K1. Its use also carries risks of sensitisation to Vitamin K. Therefore, individuals taking oral medication treatments based on Vitamin K may encounter problems. Finally, it is said to be light unstable, degrading rapidly. This makes it difficult to use in cosmetic formulations and can make the skin photo-sensitive.

Today, cosmetic brands tend to use vitamin K1 oxide, an oxidised form of vitamin K1, which causes less irritation and is more stable in sunlight.

It should be noted that the effectiveness of Vitamin K oxide has been studied in the context of post-operative redness treatments, and it appears to have the same effectiveness as pure Vitamin K1 in this regard. However, when it comes to its antioxidant or anti-inflammatory power, no studies have been conducted using Vitamin K oxide. Therefore, more scientific evidence is needed to substantiate the claims about it.

Very few studies have been conducted on children and pregnant women. If you find yourself in either of these situations, it would be wise to consult your doctor before applying vitamin K to your skin, even though the risk of observing a reaction is reduced. Furthermore, sensitisation to vitamin K is the main risk. If you are taking vitamin K medications, discuss this with your doctor before proceeding.

It is advised to keep cosmetics containing vitamin K protected from UV rays and to carefully consult the usage precautions indicated on the instructions for use of the treatments due to the instability of vitamin K in the face of UV rays. And if you have any doubts, to observe potential skin reactions, you can perform a skin tolerance test of the product containing vitamin K in the crook of the elbow, the inner side of the wrist or behind the ear.

For further information, please refer to a health professional.

• THIJSSEN H. H. W. & al. The potent antioxidant activity of the vitamin K cycle in microsomal lipid peroxidation. Biochemical Pharmacology (1997).

• LEE W. S. Photoaggravation of hair aging. International Journal of Trichology (2009).

• DIRECTIVE 2009/6/CE DE LA COMMISSION du 4 Février 2009. Journal officiel de l’Union européenne (2009).

• Opinion on vitamin K1 (phytonadione). Scientific Committee on Consumer Safety (2010).

• NOVÁKOVÁ L. & al. Vitamin K – sources, physiological role, kinetics, deficiency, detection, therapeutic use, and toxicity. Nutrition Reviews (2022).