The great ‘hair wash’ debate

Myth and argument have long surrounded how frequently we should wash our hair:

• Regularly to maintain a clean healthy scalp and hair, or not at all to ‘preserve’ the scalp’s natural oils?
• Should we use shampoos and conditioners (and which ones are better), or just rinse the hair in water to effect a ‘chemical-free’ cleansing?

Recent surveys and case studies (1) have determined that 5-6 times per week is the optimal frequency to minimise internal and external ‘pollutants’ and maintain a healthy hair and scalp; only 15% of surveyed participants indicated this hair cleansing frequency was their standard routine.

What are internal and external pollutants?

Our scalp is a specialised extension of our body’s skin covering; hair follicle ‘dense’ (2) where 60% of body heat is dispersed from the head. Scalp hair serves as both a thermal insulator and protective sun cover.

The natural functions of perspiring from sweat glands, oil (sebum) from sebaceous glands (3), and a continuous shedding (exfoliation) of the skin’s outer layer combine with external pollutants to build up on the scalp. This in turn may generate proliferation of micro-organisms – yeasts and bacteria – which can irritate and inflame the scalp.

External factors are UV (A+ B) radiation from the sun, hot, dry winds, swimming in chlorinated pools and/or sea water, seasonal pollens, as well as the many harmful particles and heavy metals carried in environmental pollution – now an everyday part of urban, hi-density living.

Cigarette smokers and ‘vapers’ have the added burden that smoking adversely effects scalp microbiome, as well as hair quality and hair growth by vasoconstricting and progressively obliterating the micro-capillary network to the hair bulb. It’s also believed toxic chemicals contained in cigarette smoke interfere with matrix cell DNA synthesis of the developing hair.

Punyani et al (2021) found that cleansing the hair 5-6 times per week led to the highest overall satisfaction with hair and scalp conditions. These included hair loss, hair shaft fragility (brittleness), softness and lustre. Results were supported by both objective (technical) and subjective (self-perception) participant surveys – irrespective of age or gender. 

Daily shampooing did not reduce or deprive the scalp milieu of moisturising sebum as scalp lipid concentrations were essentially the same as those only shampooing once per week.

Who should adopt this daily wash frequency?

Whist it’s likely not practical for everyone to shampoo their hair daily (4), those within the following categories should consider doing so:

• Hi-intensity daily training routines that promotes increased sweating, sebum production (i.e.: HIT training, distance running or sprint training etc.).
• Swimming in chlorinated pools (particularly) and ocean sea water. Both will tend to result in scalp oxidative stress, irritation and inflammation. A ‘double shampooing’ is recommended for those regularly swimming in chlorinated pools.
• Individuals with a history of very oily scalps (termed: seborrhoeic Oleosa). Supplements such as zinc or Omega-3 are often helpful in controlling excessive scalp oiliness.
• Occupations where the working environment is unclean, dirty, dusty or in an enclosed polluted air situation (i.e.: concreters, brick + tile layers, motor mechanics, and foundry workers etc.).
• People who are concerned with ongoing scalp irritation, scaling or inflammation. They should also seek a professional diagnosis of the condition and the appropriate treatment.
• Inhabitants of tropical, hi-humidity climates – particularly during the hottest months.

There is a plethora of quality shampoos available to the consumer now. Many have aromatherapy or ayurvedic derived ingredients – or at least are chemical-minimised formulations.

Ideally shampoos which are sodium lauryl/laureth sulphate-free (SLS, SLES), are free of silicones, chemical surfactants, and paraben preservatives would be better for hair follicle health and the scalp microbiome environment.

Copyright Anthony Pearce 2023

1. The Impact of Shampoo Wash Frequency on Scalp and Hair Conditions (Punyani et al -2021
2. Depending on ethnicity, the adult human head contains 100-120K hair follicles at birth.
3. Sebaceous gland lipids (oils) tend to oxidise, i.e.: become rancid when not regularly cleansed from the scalp.
4. Those with very long hair or a thick hair density which takes hours to dry and style, or those with tight, curly hair.