24 October 2024
How grape seed could keep your hair colour bright
Could grape seeds rescued from wine-making be the sustainable secret to protecting coloured hair?
Possibly the oldest farmed fruit in the world, grape vines (Vitis vinifera) have been a vital crop for thousands of years.
Not only are they used to produce countless flavours of wine the world over, they’re also useful food crops, giving us grapes, raisins and even edible leaves.
In 2022, the global production of grapes clocked in at just under 75 million tonnes. They’re so widely grown, Antarctica is the only continent you won’t find grapevines growing on.
But grapes aren’t just grown for their flavour. Grape seed extract has been considered a health supplement, although there are limited clinical studies to understand its effects.
But recent research from Kew scientists has revealed that these extracts could be a sustainable way of protecting coloured hair.
What is hair made of?
To understand how grape seed can protect dyed hair, first let’s take a deep dive into how hair works.
Hair is made of protein called keratin, the same material that makes up our nails and the top layer of our skin. It also makes up the feathers, horns and claws of various animal species.
There are three major parts to a strand of hair. The centre of the hair, the medulla, is made of mostly fat molecules. The middle layer is known as the cortex and is made up of rod-shaped bundles of keratin. Finally, the outer layer, the cuticle, is made up of thin dead cells that overlap like tiles.
When it comes to hair colour, the cortex is the key. This is chock-full of the pigment melanin, which gives hair its colour. Different amounts of the pigment decide our natural hair colour.
It’s also the reason that hair goes grey with age, as the cells responsible for producing melanin begin to die.
How does hair dye work?
But what about when we want to change the colour of our hair from its natural shade?
When hair is bleached, using chemicals like hydrogen peroxide, it breaks down the melanin. This causes the hair colour to become paler and whiter, the natural colour of keratin.
This is where we can then add a dye. Different dyes will work slightly differently, but the majority add to colour by loading the cortex of our hair fibres with chromophores. These are molecules that absorb light and reflect it at a specific wavelength, just like melanin.
By adjusting which chromophores we have in our dyes, we can alter what shade of colour our hair becomes.
Unfortunately, this isn’t permanent. Every time hair gets wet, some of these chromophores will be washed away. As hair grows, more of the natural hair colour will be revealed on the younger hair. And then there’s the sun.
The light of day
We think a lot about protecting our skin from the effects of sunlight, but we might not always think about protecting our hair.
Sunlight, along with the visible light we can see, also contains ultraviolet radiation that can cause damage to both skin and hair. Even in uncoloured hair, UV light can cause damage to the proteins, making it brittle and faded.
When coloured hair is exposed to sunlight, the UV causes proteins in the hair to become oxidised, which creates free radicals. These highly reactive molecules can cause damage to the dyes, resulting in colour fade.
So how can we stop the sunlight from dulling our shade?
Grape seed extract and antioxidants
Over the last decade, antioxidants have become well-known as one of many secrets to a healthy diet.
While the best ways to incorporate these into your daily lunch are still up for debate, it’s known that the health benefits from plant-based diets come in part from their high levels of antioxidants.
But antioxidants aren’t just for eating. They’re potentially the solution to UV-driven colour fade in hair.
Antioxidants can interfere with the production of free radicals in hair, in turn reducing the damage they can wreak on hair colour.
So where do we get our antioxidants from? It’s been known for a long time that botanical extracts are rich in antioxidants, including extracts from pomegranates and rice.
Another potential candidate is grape seed extract. While it’s long been used as a health supplement, scientists from Kew and Procter & Gamble were interested to see if it could help protect dyed hair from the effects of UV radiation.
Investigating grape seed protection
To learn more, the researchers exposed dyed hair samples to artificial sunlight, to investigate exactly how the UV radiation affected the dye. They also used various samples of grape seed extract on the hair to discover which parts of the extract could provide some protection.
The study found that UV did cause the production of free radicals in hair, resulting in colour fade. The chemical tryptophan was found to be a key part in this process.
Fortunately, the researchers also discovered that grape seed extract is an effective way to reduce the production of freed radicals and protect hair colour for longer.
The secret to the protection seemed to come from chemicals in the grape seed extract known as flavonoids. Extracts that contained procyanidin and catechin provided protection against the production of free radicals.
You might be more familiar with these two as tannins, the molecules that give red wine its characteristic dry mouthfeel.
The source of the seed
One of the benefits of using grape seed extract in colour protecting hair products is that there’s already a readily available source: winemaking.
The first step in winemaking, after harvesting, is to press the grapes and collect the juices. But what about what’s left behind?
The mix of squashed seeds, skins and stem is called pomace, which can be used for a variety of things. This includes as feed for livestock, food colouring, fertilizer and even to make brandy. And now we can add another use to the list.
Since grape seeds are particularly tough, they don’t get crushed in the pressing step. It means they can be separated and mixed with solvents to create grape seed extract.
Kew’s work with Procter and Gamble
We’ve teamed up with Procter & Gamble (P&G) to use our world-class scientific knowledge and expertise to identify and authenticate key botanical ingredients in the Herbal Essences bio:renew range.
