You may already know that the skin is the human body’s largest organ. It is responsible for a number of important processes within the body, including regulating temperature, preventing disease from entering the body, controlling our natural UV protection, and preventing water loss through the skin.
The skin is made up of two main parts: the dermis and the epidermis. These sit on top of the subcutaneous tissue (also known as the hypodermis), which is made up of fat and connective tissue.
The dermis is the inner part of the skin and is with you for life (which is how tattoos stay permanent - the ink goes right down to this part). The dermis contains the fibroblasts (where collagen and elastin are produced), as well as water and hyaluronic acid, to give our skin structure and hydration.
The epidermis is the outer part which controls water loss and produces the NMF (natural moisturising factor) to ensure our skin is kept hydrated and protected from changes in our environment. This part continually renews, on around a 28 day cycle (which is why you should trial any regime for 4 weeks before reviewing its effects).
New skin cells are produced in the basal layer and are gradually moved up through the layers of the epidermis as more cells are generated below, until after around 28 days they sit at the very top part of the epidermis, known as the stratum corneum. This is effectively made up of dead skin cells, which then shed naturally as the keratin binding them dissolves, and newer cells are pushed up from below.
How does this affect your skincare regime? In short, any product that claims to affect collagen and elastin production (the majority of anti-ageing products) needs to penetrate down into the dermis to make contact with the fibroblasts. Anything that is designed to affect pigmentation needs to penetrate down to the basal layer of the epidermis (where the melanocytes are positioned) to have its affect. Understanding how far a product needs to penetrate into the skin to have an effect helps us to choose which type of product to choose.
The structure of a product will determine how far into the skin it can penetrate. Most serums are silicone in water emulsions. Silicones can enhance the delivery of active ingredients, allowing them to then penetrate deeper into the skin to have an effect on the lower layers of the epidermis, and even the dermis. Moisturisers (usually oil in water formulas) will not penetrate as far and are really designed to affect the outer part of the epidermis only, protecting the skins natural barrier function, and plumping the outermost layers through hydration. In conclusion – different product types work for different skin concerns, and usually it’s best to use a combination of these for best overall results.