Human migration over the last 500 years from sunny places to colder, darker more northerly homes has led to a surge in the number of people suffering from vitamin D deficiencies, a new study reveals.
Academics created a computer model to calculate the difference in exposure to UV rays from the sun in both a person’s ancestral and current location.
They found going to places with lower levels of sunlight can result in vitamin D deficiency, which is directly associated with higher risk of mortality from illnesses including cardiovascular disease, diabetes, hypertension, and certain cancers.
Recent research even finds that vitamin D affects the severity of COVID-19.
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Human migration over the last 500 years from sunny places to colder, darker more northerly homes has led to a surge in the amount of people suffering from vitamin D deficiency, a new study reveals (stock image)
‘Our results suggest that low UV regions that have received substantial immigration from high UV-R regions experience lower life expectancy than would have been the case in the absence of such migration flows,’ the researchers write in their study, published in Oxford Economics Papers.
‘If current movements of people continue, which to a large extent represent movements from “South to North”, much more variation [in life expectancy] is likely to become visible during the 21st century,’ the researchers from the University of Southern Denmark and the University of Copenhagen say.
The study focused on groups of people that migrated from sunlit regions to low-sun areas in the last 500 years.
One such example is the Great Migration In the US at the start of the 20th century as African-American people flocked from the segregated southern States northwards to the north-east US to avoid racial persecution and poverty.
‘Research finds that the Great Migration within the USA reduced the health of African Americans significantly,’ study author Dr Thomas Barnebeck Anderson told MailOnline.
‘While this research suggests that some of the impact may be linked to changes in the intake of alcohol and cigarette smoking, it is worth noting that migrants also experienced changes in the environment.
‘For example, moving from Georgia to New York would imply a reduction in ambient UV-R (sunlight) of roughly 43 per cent, implying in turn a considerable increase in the risk of vitamin D deficiency for an African American.
‘Whether a vitamin D mechanism could be contributing to the decline in health outcomes in the aftermath of the Great Migration seems to be an interesting topic for future research. ‘
The researchers created an algorithm that compared sunlight intensity in the ancestral place of residence of the population with the actual level of sunlight at their current home.
Risk of vitamin D deficiency was defined as the difference between the two, and the researchers used this to investigate how a larger figure affected life expectancy.
They found that greater risk of vitamin D deficiency is negatively correlated with life expectancy when accounting for all other factors.
Vitamin D is naturally produced in the body when skin is exposed to sunlight, but given the long winter months, people are not spending enough time outdoors.
As well as sunshine, vitamin D is also naturally found in oily fish such as salmon, egg yolks, mushrooms and red meat. The NHS says adults should have around 10 micrograms of vitamin D every day.
Officials estimate one in five Britons are deficient in vitamin D — the equivalent of 13million Britons.
The vitamin has recently been linked to Covid-19, with several studies finding it offers protection against the virus.
One such study recently revealed diet supplementation with vitamin D pills reduces the risk of catching infections.
In October, Matt Hancock urged people to take vitamin D to help boost their overall health and said the Government would be ramping up public health messaging to encourage uptake of the supplement.
But in December UK health officials found there is ‘not enough evidence’ that taking vitamin D can prevent or treat Covid-19.
An analysis from Swiss researchers of 2,157 healthy men and women aged 70 and older found omega-3 users were 11 per cent less likely to suffer infections.
One study found that 72 per cent of NHS workers in Birmingham who were lacking in the ‘sunshine vitamin’ (left column) tested positive for coronavirus antibodies in the blood — a sign of previous infection. This compared to just 51 per cent for those who had a healthy amount of the vitamin (right column)
The study took place between 2012 and 2014, long before the coronavirus pandemic exploded in November 2019.
While these findings therefore do not provide direct proof the the supplements can protect the elderly against coronavirus, they are applicable, the experts say.
People with dark skin are particularly vulnerable to vitamin D deficiency due to high melanin levels which inhibits production.
This is due to an evolutionary trade-off, the Danish researchers write in their study.
Human skin turns sunlight into the vitamin but high levels of melanin evolved to protect skin from being damaged by the high-energy UV rays of the sun, which can cause cancer.
As a result, people with high levels of melanin, which confers darker skin, are more at risk of vitamin deficiency but less exposed to skin cancer.
However, when people migrate away from areas of high UV rays to places with lower sunlight levels, such as further north, this trade-off becomes disadvantageous.
As a result, vitamin D deficiency is more prevalent in people with darker skin.
Previous research has found that in the US, 97 per cent of all black people had vitamin D deficiency. This figure drops substantially to 70 per cent for white people.
Another study has found black people in the US have vitamin D levels half of what i seen in white people.
The long-term impact of vitamin D deficiency is an increased the risk of heart disease, high blood pressure, diabetes and some types of cancer.
‘Vitamin D deficiency may become an increasing public health issue in the years to come, at least in the absence of preventive public health measures,’ the researchers add.