From mites mating on your skin to midnight feasts causing sunburn, expert reveals surprising facts about our body’s largest organ
IT is the largest and most visible of our body’s organs. But how can we care for our skin if we do not understand it?
Dr Monty Lyman, who specialises in acute general medicine, sheds some light in his new book, The Remarkable Life Of The Skin.
Weighing an average 9kg and covering two square metres, it is a complicated terrain.
Lynsey Clarke and Isabel Deibe pick ten extracts from Dr Lyman’s work.
- The Remarkable Life Of The Skin by Dr Monty Lyman (Bantam Press, £20), is available now.
Ten per cent of men get cellulite
The structure of women’s collagen fibres mean that they get more cellulite than men. While 90 per cent of females have cellulite, only ten per cent of men do.
Cellulite is caused by fat cells in the hypodermis – the third layer of skin – protruding upwards, giving the skin a dimply, orange-peel appearance. The fat cells are kept in place by collagen fibres running from the dermis – the second layer of skin – right down to the muscles below.
In women, these fibres are arranged in parallel, like the columns of a Greek temple, meaning the fat cells can push up through the gaps, forming cellulite.
In men, the collagens fibres are criss-crossed, resembling pointed Gothic arches and keep the fat locked in the hypodermis. The amount of cellulite we have depends on hormones, genetics, age and weight gain.
Mites are mating on your skin
Our skin houses 1000 different species of bacterium, plus fungi, viruses and mites. This community is called the microbiome. When we spend a lot of time with someone we start to share their microbiome.
In a 2017 study scientists picked out cohabiting partners from a group of random individuals in nine out of ten cases. Possibly the most gruesome looking is the Demodex – eight-legged mites which bear resemblance to a spider or crab with a worm’s tail.
The male mites swim around the skin’s oil and sweat at around 16mm an hour, looking for a female to mate with. The females live deep within the sweat glands and hair follicles, popping up very briefly to mate. These mites help to eat away dead skin.
They only live around two weeks but a specific strain of Demodex can remain within a family for generations, as they are potentially transferred via breastfeeding.
No need for four litres of water a day
Water is often said to be the answer to flawless, plump skin – with some people aiming to drink 4 litres a day – but there has been little research into this area. It’s logical as our cells are mostly made up of water and need regular hydration.
However, since our other organs need water too, it is hard to measure whether the extra water gets to our skin. The few existing studies show that the recommended daily intake of water (2.5 litres for men and 2 litres for women) is good for normal skin functions and epidermal hydration.
Dehydration makes skin lose elasticity and shape so a lack of water is bad for skin but that doesn’t mean that drinking above average levels is particularly good for it.
Eating chocolate is not bad for skin
Despite the rumour, most scientific evidence suggests that chocolate DOES NOT have a significant effect on acne. It has a low-glycaemic index due to its high fat content and this actually slows down sugar absorption.
It is the foods with a high-glycaemic index which raise blood-sugar levels and have the strongest evidence for contributing to acne. A recent study of 13 men did find that binge eating 100 per cent cocoa did exacerbate acne but the sample size has to be taken with caution.
Dr Lyman suggests there more likely reason for the chocolate myth, could be confusion between cause and correlation. For instance, women tend to crave sweet treats during the premenstrual part of their cycle, but it is the hormonal changes which are proven to be the most likely cause of spots, not chocolate.
Brain and skin start from same cells
FOOD for thought – the brain and the skin develop from the same layer of cells in the embryo – the ectoderm – and are reunited at points throughout our lives.
Science shows that mental health can affect the physical state of skin, such as psychological stress worsening such conditions as psoriasis.
Living with a skin condition like acne can also have emotional effects such as depression and psychiatric conditions can also manifest themselves in obsessive picking at the skin.
Pre-hol sunbed does not protect skin
Melanin is the skin’s version of sun screen. When the skin is struck by dangerous UVB rays - which hit the epidermis of the skin and slice DNA apart - the cells at the bottom of the epidermis spew out melanin to absorb the ultraviolet light.
This combination of black, brown and red pigment disarms the UV ray’s power and transfers it into harmless heat. Over a period of two or three days after sun exposure we form a tan as a protective response to damage.
However, despite this being the skin’s natural sun screen, it provides an SPF of only 3 and leaves DNA destruction in its wake. Sun exposure is a more significant cause of accelerated skin ageing than all other causes combined. And it is the greatest risk factor for skin cancer.
You smell like what you've eaten
Ever had a particularly potent curry and wondered why you can still smell it days later? While the majority of food waste ends up in faeces, some volatile, aromatic compounds are released in breath, urine and indeed in sweat.
For instance, garlic and onions contain sulphur molecules which come out through the skin in sweat. However, worry not, scientists found that on average, women found the body odour of men who had eaten 12g of garlic more attractive than those who had eaten either 6g or none.
In another study women preferred the aroma of sweat from vegetarian men compared to that of meat-eaters.
Sunburn increases cancer risk years on
Although many people get sunburnt and stay cancer-free, suffering from one instance of severe sunburn as a child increases the risk of melanoma later on in life by 50 per cent.
One study suggests that white women who get five or more severe sunburns in their teens have double the risk of developing melanoma.
This is because once the DNA damage is done, this specific area of skin is left vulnerable for the rest of your life. The DNA can then mutate and develop into a life-threatening cancer.
Collagen skincare does not slow ageing
With ads branding collagen as the elixir to eternal youth, it might shock you that this is not true. Collagen makes up 75 per cent of our skin, giving it structure and plumpness, but levels decrease as we age and smoking and sun damage accelerates this.
This loss contributes to wrinkles and sagging, so treatments offering to replace collagen to reverse this are popular. However, the collagen molecules are too big to penetrate skin from the outside, so any effects are likely to be the short term moisturising qualities of other ingredients rather than the collagen itself.
Even collagen supplements which are said to feed the skin from the inside out have little evidence to show whether they work or not.
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Midnight feasts cause sunburn
Evidence suggests that our skin cells contain complex internal clocks that run on a 24-hour-rhythm which is influenced by the ‘master clock’ which sits in the hypothalamus part of the brain.
Overnight, skin cells which produce protein thrive to prepare the outer barrier of the skin and during the day these cells switch on genes which protect against the sun’s ultraviolet rays.
A 2017 study found that eating late at night means the skin’s clock assumes it must be dinner time and consequently pushes back activation of the UV protection genes – leaving us more exposed and therefore more likely to burn the next day.