Oils

The science of oils

Oils are one of the much-lauded modern defences against the visible effects of ageing. Possessing a simple structure but with multiple uses, oils are appropriate and beneficial for all complexions – especially, perhaps counterintuitively, oilier skins.

Many oils are potent antioxidants, such as argan oil, offering free-radical protection. They can also be dramatically calming and anti-inflammatory, such as borage oil, and as such can help prevent the irritation potentially caused by some active ingredients, either when they accompany them within the same formula or are used alongside these, hence their ability to achieve an improved skin tolerance.

One of the reasons that wrinkles and fine lines suddenly appear deeper by the late thirties is not just the degeneration of collagen and elastin, but because as the skin’s lipids decrease, so too do the skin’s own natural oils and sebum. The moisture barrier breaks down and, as a result, the skin dries out. While many formulas contain some oil, it is not always enough to assist against dehydration or water loss, which is why it is often suggested to use an oil alongside a heavier-weight formula. Oils are naturally lipophilic (fat-loving) and therefore have the considerable advantage of passing through the skin’s lipid layer more rapidly, guarding against loss of water, and enabling the skin to retain hydration far more effectively.

Using oils on oily skin might sound counterintuitive, but working on the principle that an oilier skin produces an excess of sebum, applying further oil achieves the opposite of ‘stripping’ the skin of hydration (which would thereby encourage even further increased production).

An oil can act as a highly efficient vehicle, enhancing delivery and preventing or at least minimising the potential for irritation of the active ingredient it is carrying or accompanying. Here, the ability of oils to possess a smaller molecular size is also important. If you apply an oil before a heavier formula, such as a night cream, the oil molecules can ‘trick’ or encourage the skin into letting active ingredients from the cream – a retinoid or vitamin C, for instance – be delivered deeper into the skin for greater effect and, vitally, closer to the fibroblasts that produce collagen, while still minimising the potential for irritation.

As well as sunscreen, hydration is necessary to sustain collagen production and maintain the integrity of the dermis.

Oils are also emollients, which means that unlike some heavier formulas that have the ability to sink deep into the skin and create long-lasting hydration, or ingredients such as hyaluronic acid, which binds water to the skin cells, the application of oils will remain more superficial, which is in fact one of their key benefits: it is important to know how to optimise their use. Oils also add barrier protection, enhancing the skin’s function. Rather than considering them as synonymous with a moisturiser (they might feel moisturising but are not), they should instead be used to aid and accompany moisturising ingredients such as hyaluronic acid or glycerin.

Given this, it is important to remember that for a product or formula to truly moisturise, it must have both lipophilic and hydrophilic properties – it must deliver both water and oil. The water provides hydration to the cells while oils stay on the outside of the cell, providing a boost in protection. The oil acts as a seal to maintain moisture levels within and help support a strong, healthy barrier function against irritation and inflammation, hence the recommendation to apply oils after serums but before heavier-weight formulas such as a cream. If oils or oil-based formulas are too heavy, they will block pores. Knowing the formula is key: oils with a smaller molecular size (such as squalene, jojoba and argan oil) will absorb into the skin and do not block pores.

Further reading and research

Int. Journal of Fertility and Women’s Med. 1999 Mar-Apr; 44(2):83-95
A lifetime of healthy skin: implications for women
WF Bergfeld

Pharm Dev Technol. 2017 Jul 3:1-12
Design and evaluation of novel topical formulation with olive oil as natural functional active
AH Mota, CO Silva, M Nicolai, A Baby, L Palma, P Rijo, L Ascensao, CP Reis

Pharmaceutical Research, August 2010, Volume 27, Issue 8, pp1746-1749
Application of Nanotechnology in Cosmetics
Li Mu, Robert L. Sprando