How Your Skin Colour is Linked to Your Mental Health
Things are often not as they appear. The world appears flat and still; it is round and spinning. Matter appears solid; it is vibrating energy. Humans appear to belong to different races. Fooled again: race is an illusion.
Our common ancestry
Non-African people today are all the sons and daughters of migrants. It’s a story that began a long, long time ago. About 200,000–300,000 years ago.
In his book Out of Eden, geneticist Stephen Oppenheimer explains how every non-African person can trace their ancestry back to Africa. Equatorial East Africa, to be precise. We all go back to black. Every person on this planet is related to everyone else, having a female and male ancestor in common and originating from a single population.
Those were the days! We ran about, mostly naked, enjoying year-round, wall-to-wall sunshine. We didn’t know it, but we had vitamin D on tap and our dark skins offered protection from the excesses of the sun’s rays.
Then, around 70,000 years ago (the experts are still debating the exact date, and the exact reason) large numbers of Homo sapiens packed up and set off to explore the wider world, travelling north and south of the equator.
Travelling polewards meant the wearing of more than just a strategically-positioned fig leaf, if they were to survive. Our ancestors made some baffling choices about where to settle and ended up in some rather inhospitable places.
Take Cheddar Man. When it comes to England’s green and pleasant land, the first modern man to arrive and settle here was black. Very black. He also had curly black hair and striking blue eyes. (See for yourselves.) That’s what scientists discovered in 2017, when Britain’s oldest complete human skeleton, dated to about 10,000 years ago, underwent DNA analysis and facial reconstruction.
Despite the shock headlines, Cheddar Man was nothing unusual. He was just a regular Brit, his features characteristic of the Western European population at the time. Indeed, British people today share approximately 10% of their genetic ancestry with the same population that gave us Cheddar Man.
DNA analysis revealed that after leaving Africa, Cheddar Man’s ancestors moved into the Middle East, before migrating to Europe. From there, getting to Britain was easy. The island was once joined to mainland Europe via a strip of land called Doggerland (no kidding), so was accessible to anyone prepared to walk.
Which was all well and good, but that left Cheddar Man and all other long-distance migrants with a large, vitamin D-shaped hole. That hole has continued to expand rapidly as a result of modern diets and lifestyles, and is affecting our mental health.
You, me and vitamin D
Vitamin D is made in the skin in the presence of sunlight. Or more specifically, on exposure to solar ultraviolet B (UVB). Sunlight has two ultraviolet rays: UVA and UVB. UVB is the one needed to make vitamin D, but it can also cause your skin to burn.
Exposure to sunlight was obviously much reduced for these early settlers. As part of a biological response to this threat to their survival, people living in colder climes began to lose skin pigmentation, in order to absorb more UVB to make vitamin D.
“Our colour may have more to say about where our ancestors lived over the past 10,000–20,000 years than about their genetic divergence over the previous 60,000 years.” (Stephen Oppenheimer, Out of Eden)
We didn’t know it at the time, but lack of sunlight put us at serious risk of declining health. It still does, and we still fail to grasp the seriousness of the situation. The association between mental ill-health and vitamin D deficiency is well documented.
Vitamin D and the brain
You probably associate vitamin D with bone health, but that’s just a fraction of the picture. There are receptor sites for this vitamin throughout the brain and deficiency is associated with a range of neurological disorders, including depression, schizophrenia, dementia (including Alzheimer’s) and Parkinson’s disease.
Vitamin D is a key brain nutrient and deficiency can be detrimental even in the womb. Research has found that low vitamin D, in pregnancy or early childhood, may be a trigger for autism spectrum disorder in people genetically predisposed to the condition. There is also a link with attention deficit hyperactive disorder — higher maternal circulating vitamin D levels in pregnancy are associated with reduced risk of developing ADHD-type symptoms in childhood.
The risk to children can extend into later life.
“The likelihood of having depression in vitamin D deficient persons is significantly higher compared to those with adequate vitamin D status.” (Ganji et al).
There also appears to be a strong association with schizophrenia. A systematic review of 19 studies that measured serum vitamin D levels in patients with the condition found that 65.3% of those patients were D-deficient.
Schizophrenia is more common in colder climates on higher latitudes, and more common in black people than in white people. These two factors suggest a possible role of vitamin D in the development of the disorder. Clinical trials are surely a matter of urgency.
How bad is it?
There are one billion people across the globe estimated to be vitamin D deficient. Over two-thirds of people in the US and Canada have ‘suboptimal’ vitamin D. Figures for people living in the UK are similar.
It’s all about the right latitude
Some vitamin D is stored in the liver, which is just as well. Even so, we can only store so much. We can only make it during the summer months and supplies are probably non-existent by the end of October. And even in the southern hemisphere, specifically Australia, deficiency affects a third of the population.
The further north you are, the worse the situation becomes. Once you travel above 37º latitude in winter, you stop making vitamin D, even with prolonged exposure to sunlight. Residents of Edmonton, Canada, are on 52 degrees north latitude. They cannot make sufficient levels of vitamin D for 5 months of the year. London is on 51.3 north latitude, so Londoners can expect much the same ability. In Britain overall, deficiency rises to 90% during spring and winter.
Who’s affected? The most vulnerable groups are:
Dark skinned people
Black people need about five times more time in the sun to produce vitamin D than the fair skinned, thanks to the blocking effect of the pigment melanin.
People with little exposure
If you cover up when you go out, or spend little time outdoors, you can forget making any vitamin D. Sunscreens don’t help either. Factor 8 blocks vitamin D3 synthesis by 95%, factor 15 by 98%.
That’s because oily fish, such as salmon, is one of the few dietary sources of this vitamin. If, like me, you were forced to chug cod liver oil as a child, get over it. It is an exceptionally rich, albeit disgusting source of vitamin D. Other natural food sources are liver and eggs.
Vitamin D deficiency affects nearly 50% of older adults, though the real figure may be as high as 90%. People over 60 require three to four times more sun exposure than people under 20. That’s because they have decreased presence of 7-dehydrocholesterol, a substance required to make vitamin D in the presence of sunlight.
One possible outcome for older people is reduced cognitive function — there is an established association between cognitive impairment and vitamin D deficiency.
Studies reveal that a high level of body fat inhibits the release of vitamin D stored in the liver. The higher the BMI of an individual, the lower the level of vitamin D in the blood.
Wherever you currently reside, and whatever your ethnicity, we all share the same genetic inheritance and the same requirement for vitamin D.
“Researchers suggest that human populations over the past 50,000 years have changed from dark-skinned to light-skinned and vice versa as they migrated to different UV zones,and that such major changes in pigmentation may have happened in as little as 100 generations (≈2,500 years)” (Jablonski 2011)
Genetic changes are normally slow to occur, and indeed we are little changed since the end of the Paleolithic era. Our ancient genome has an average mutation rate of 0.5% per million years, meaning it “still resides for the greater part in the Paleolithic era.”
However, non-genetic adaptations do occur fairly quickly, by comparison. Environmental factors such as sun exposure affect our characteristics, including skin colour, without altering our DNA sequence. Even so, it can still take several thousand years for these variations to occur. So, thousands of years from now, white people living in places such as Australia and South Africa will become darker. Black people living in cold climes will become paler. Plenty of scope there for more hate crime, if we survive that long.
We Homo sapiens are the last remaining species belonging to the Homo genus. So far, over 20 species of extinct humans have been identified. Sometimes, they even co-existed.
If we sapiens struggle to get along, and frequently fight over our perceived differences, how on earth did those different species of human manage to rub along together? It’s impossible to tell, but it’s probably a good job that they had limited weapons capacity and hadn’t discovered nuclear fission. If you think someone with a different skin colour poses a threat, you should have met Homo erectus, a species of human that existed for the best part of two million years. These strong, large people could have knocked ten bells out of all of us, just with their bare hands.
As the title of an article in Newsweek proclaimed, in August 2014, “There is no such thing as race”. Written by Robert Wald Sussman, author of the book The Myth of Race: The Troubling Persistence of an Unscientific Idea, this article describes how, in 1950, an international panel of experts at UNESCO issued a statement confirming that “race” is not a biological reality; it is a myth.
When they looked for the differences separating us, all they found were similarities.
Race is an illusion, one of many myths that humans have created out of their big, foolish noggins. Vitamin D deficiency and the global mental health crisis are a tragic reality, one that unites us yet is generally overlooked.
According to the World Health Organization,
“Depression is a leading cause of disability worldwide.”
Obviously, there are many causes of mental ill-health, because nothing in life is ever that simple, but it is clear that vitamin D deficiency is a much-overlooked significant factor.
It is often said that we should celebrate our differences. Perhaps that’s true, but more importantly I think we should celebrate our similarities.
And make sure we all get enough vitamin D.
For more information on how to get that vitamin D, see my article How to fight depression with vitamin D.