Author: Matt Whitaker, Digital Health Lead/12 July 2018
Aging is an inescapable progression that comes with the inevitability of time. It is a complex process involving: genetic, hormonal and environmental mechanisms which impact individuals psychologically, physiologically and cosmetically. Greying hair is an example of a cosmetic change for most people as they age. It is a perfectly natural process that many dread; begging the question – can you minimise the likelihood or extent in which hair greying can occur?
The average age in which hair greying becomes apparent is mid 30’s for whites, late 30’s for Asians and mid 40’s for Africans. By the age of 50, around 50% of the population have grey (or at least obviously greying) hair.
What causes hair to go grey?
To understand why hair turns grey, and what might speed it up, it is important to first understand the basic anatomy of hair and what gives it colour. Hair is a complex and highly variable biomaterial found on our body. Each hair has its own hair follicle, small sacks that line the cells on our skin. Within these follicles there are pigment cells, also referred to as melanin. It is the melanin that dictates the colour of that particular hair. Melanocytes are cells that produce melanin. The reason why hair can turn grey is because over a period of time these follicles lose pigmentation and thus colour. There are a number of things that can affect this:
An accurate predictor of when and whether you are likely to get grey hair is to look at your parents and grandparents and what age it became apparent for them. Our genetics are a huge contributor to the likelihood and extent of hair greying, and are of course (unfortunately for some) non-modifiable.
As we age we naturally lose pigmentation in our hair follicles, this is unfortunately inevitable for most.
Additionally age increases free radical production (see below) and decreases the body’s ability to defend against them. This imbalance leads to the progressive damage of cell structures.
Hair greying may be associated with a vitamin B12 deficiency, as B12 can act as a defensive mechanism for the prevention of grey hair. Other dietary deficiencies associated with hair greying include: ferratin, calcium, vitamins D3, zinc, iron and copper (copper helps to add pigments to your hair follicles).
Omega 3 and zinc are imperative for hair strength and may help in the restoration of colour.
Smoking is linked to hair greying. The mechanism behind this is because smoking leads to the generation of large amounts of reactive oxygen species, leading to oxidative stress (see below).
Stress and Oxidative stress
Oxidative stress is fundamentally an imbalance between free radicals and the body’s ability to fight them.
Free radicals are highly reactive oxygen species (ROS) that can directly damage cellular structures such as membranes, lipids, proteins and DNA. They are created when cells metabolise glucose as energy, when the immune system is fighting off an infection and when the body is detoxifying pollutants and pesticides. The body has a number of defensive mechanism against free radicals, such as antioxidants, but this is a topic in itself for a future blog.
There is a theory of aging called ‘the free radical theory’. This theory suggests that reactive oxygen species damage DNA (both nuclear and mitochondrial), leading to mutations, inducing oxidative stress and ultimately inhibiting the melanin and the pigmentation of the hair. This can affect both the melanocyte (producer of melanin) and the hair bulb epithelium (the base of the hair itself). This basically means the oxidative stress can inhibit colour in the hair – making it grey.
The reactive oxygen species can make the melanocyte dysfunctional and make them undergo a process called apoptosis- a programmed self-destruction of the cell. Apoptosis can be linked to an increased risk of cancer, so therefore greying of the hair might be a defence mechanism against this and why grey hairs are more apparent in the elderly population.
So stress DOES make hair go grey?
Not necessarily… oxidative stress – which I was referring to above, is not the same as “stress” in the way we might commonly think of it from day to day. Stress is a response to times of anxiousness, overwork, concern or perceived threat. There doesn’t actually seem to be any evidence supporting a mechanism in which stress in this manner can directly cause hair greying in humans.
Despite this, many media stories have alluded to the fact that hair greyness is associated with stress. This is also something that many people assume to be true. But any research findings supporting this seem to be exaggerated from animal studies (mostly in mice). One could absolutely make the argument that findings from mice studies are not applicable to humans. In mice, shortly after birth the melanocytes in the skin disappear but remain in the hair follicle (potentially because the mice have a coat of hair). In humans the melanocytes remain on the skin cells. Practically speaking this means we have very different hair to mice. Who would have thought it?! Other research supporting this claim has been done in petri dishes on cells of a human scalp, which even then only shows weak correlations with hair greying when the cells were exposed to the stress hormone cortisol. Again, this isn’t really applicable to a living human.
Saying this, cortisol, when measured in hair, can be used as a marker to predict chronic stress levels in an individual, although this claim is from observational evidence which does not consider a number of other lifestyle factors that are likely related.
The most plausible mechanism linking stress to hair greying is the fact that chronic stress can potentially increase oxidative stress which, is more firmly associated with hair greying (as discussed above).
The prevention of hair greying depends on cause. If it is occurring as a result of a medical condition then it is advisable you seek medical attention from a GP.
There is no scientific evidence that supports the use of any supplement, herbal treatment, product or particular diet for the prevention of human hair greying.
Some lifestyle factors such as not smoking, ensuring adequate micronutrient (vitamins and minerals) intake and minimising the production of reactive oxygen species may play a preventative role.
Alas, arguably the factors that contribute the most, genetics and aging cannot be modified.
Overall there is little evidence that supports the perception that stress increases the likelihood of hair greying, and none of the evidence there is in living humans. Stress is of course associated with a number of other outcomes that negatively influence health, including, but not limited to: anxiety, depression, compromised sleep quality, impaired glycaemic control, increased insulin secretion and weight gain. This has previously been discussed here.
The process of hair greying is not fully understood and thus is far from conclusive. Oxidative stress is only one piece of the puzzle and more research is needed to better understand the underlying mechanisms behind the greying process.
Any questions, feedback and/or suggestions would be most welcomed, as is any request for the research supporting this blog. Please email me at Matthew.Whitaker@xperthealth.org.uk