Introduction

In humans the skin is our largest organ and provides a physical and chemical barrier between the outside environment and the inside tissues and organs. Structurally the skin is comprised of two main layers, the epidermis, and the dermis (see figure 1). The upper layer, the epidermis, is responsible for many of the barrier functions. The dermis, the innermost layer, is the structural and nutritive support network for the epidermis. 

Linoleic acid (LA, Omega 6) is the most abundant PUFA in the skin. It is most prevalent in the epidermis. The role of LA as an essential fatty acid (EFA) was originally determined by Burr & Burr (1929). In a study conducted on laboratory rats they induced a PUFA deficiency syndrome by rigorous exclusion of fat from their diet. The deficient rats showed abnormal growth, dandruff, loss of hair, lesions on their tail, abnormal appearance, and degenerative changes in the kidneys. Reproduction was also affected. When small amounts of lard were added to their diet their deficiency syndrome was cured. (Burr & Burr 1929)

In 1930 they isolated which fats could alleviate the deficiency symptoms and found by adding omega 6 to their diet this was achieved. It was noted that omega 3 could restore normal growth but not relieve the skin disorder. In the skin LA has an essential barrier function and as such is a water repellent, is important in conserving our water balance and providing a barrier against the environment. (Burr & Burr 1930)

Arachidonic acid (AA, Omega 6) is the second most abundant PUFA in the skin. Found within the cell membrane of the epidermis keratinocytes, it is the starting point for local eicosanoids, short lived potent chemical messengers involved in the inflammatory response. When the skin is damaged, it is these local eicosanoids that are mobilised to initiate the healing response. 

Deficiency & Diseases

One of the first organs to show an EFA deficiency is the skin. It is characterised by increased transepidermal water loss (TEWL). TEWL is linked to the integrity of the barrier function of the skin and is directly related to EFA composition in the epidermis. Dry, scaly skin is a symptom. Reversal of EFA deficiency can be achieved by either topical application of EFA’s to the skin, such as hemp seed oil or a body lotion made from it and/or the ingestion of oils rich in LA such as hemp seed oil. 

A common disease of the skin is atopic eczema and psoriasis. A 20-week Finish study compared the effects of dietary hemp seed oil and olive oil in patients suffering from atopic dermatitis. The 20 participants, split into two groups of ten, consumed 30ml (2 tbsp) of the assigned oil for a total of 16 weeks. Each group consumed the assigned oil for eight weeks, then a break of four weeks with no oil, then the groups swapped oils and consumed the assigned oil for eight weeks. Patients in the study reported statistically significant decreases in skin dryness, itchiness and use of dermal medication after consumption of hemp seed oil. (Callaway, 2005) 

Conclusion

Omega 6 (n-6) and omega 3 (n-3) EFA’s are crucial to the healthy functioning and appearance of the skin. Both dietary and topical supplementation with EFA’s can have profound effects on the structure and function of the skin. This is evident in the attenuation of skin sensitivity and inflammatory skin disorders with either the topical application or dietary consumption of omega 6.

In individuals who have used hemp seed oils for longer periods of time improvements have been seen in the skin within weeks, stronger finger nails (months) and thicker hair (years).

References

Burr, G. O., & Burr, M. M. (1929). A new deficiency disease produced by rigid exclusion of fat from the diet. J Biol Chem, 82: 345-367.

Callaway, J., & Schwab, U. (2005). Efficacy of dietary hempseed oil in patients with atopic dermatitis. Journal of Dermatological Treatment, 16: 87–94.