Vitamin D Deficiency: A Major Health Side effect of Human Migration

More than just bones!

pile of human skulls
Photo by Felipe Hueb on

Vitamin D may be our most important ‘vitamin’. Although it has long been known that Vitamin D plays a critical role in the body’s ability to absorb and retain calcium and phosphorus, which are both critical for the formation of bone, recent research has now revealed that Vitamin D plays critical roles in the control of infections, in mental health and in the reduction or perhaps prevention of cancer.

I personally became aware of the probable role of Vitamin D in mental health when I noticed that several of our darker-skinned Indian students were becoming seriously depressed during South Australian winters. When I discovered this, I suggested that they took some Vitamin D rather than the anti-depressive drugs they had been prescribed but I didn’t realize then that Vitamin D deficiency might be associated with major depressive and anxiety disorders.

People migrating

Major increase in worldwide Vitamin D deficiency caused by modern lifestyles and migration

Vitamin D deficiency is present in millions of people throughout the world. Some of this is due to changes in lifestyle where people spend a great deal more time indoors than they ever did before. This overall alteration in behavior has many causes that include loss of traditional types of work, innovation, and mechanization of transport such that walking is less of a necessity, modifications in buildings that encourage more time to be spent indoors and general loss of traditional lifestyles


Under our most natural environments, that is living in the region of the world where our ancestors evolved, our skin color should be adapted to allow it to synthesize adequate amounts of Vitamin D, when it is exposed to sunlight. Those of us whose ancestors lived far away from the equator generally have pale skin with low amounts of the pigment melanin whilst those who evolved to live near the equator have much darker skin, with higher concentrations of melanin.

One apparent exception to this is the Eskimos or Inuits. This race of people initially originated in Asia from where they migrated. In their new home Alaska in the frozen north, they adopted a diet of raw fish and sea animals, the meat of which is exceptionally high in Vitamin D. Their practice of eating the food raw also insured that they had sufficient intake of Vitamin C.

Skin Cancer

White skinned people moving to latitudes with higher amounts of sunshine, can do well in terms of producing Vitamin D in the sun but there is a significant trade-off in the form of sunburn and skin cancer. The good news is that the studies that have been undertaken on sunscreens to date do NOT show that wearing sunscreens prevents our skin from manufacturing Vitamin D. However – be cautious – studies have not yet been undertaken on the sunscreens offering very high levels of protection!

People with black skin can still develop Melanoma but not too surprisingly, white-skinned people are 25 times more likely to suffer from it. But Melanoma is relatively rare compared to other types of Skin Cancer of which there are well in excess of a million diagnoses each year worldwide, mostly in people with lighter skin.

Dark-skinned people living in countries with less sunlight

‘Pre-vitamin D’ or its full name 7-dehydrocholesterol (7-DHC) is a chemical that has been conserved through animal evolution. It is produced as part of the synthesis of cholesterol and with the help of sunlight it is converted to Vitamin D3 (cholecalciferol) in the skin. Vitamin D should probably be regarded as a pro-hormone rather than a ‘vitamin’ because of its diverse biological roles and its evolutionary role in insect metamorphosis.

Vitamin D synthesis is highly influenced by the concentration of melanin in the skin. Melanin actually absorbs and then scatters the Ultra Violet (UV) ‘B’ rays and the this results in far less efficient conversion of pre-vitamin D to D3. Consequently, dark-skinned people synthesize vitamin D far more slowly than lighter-skinned people and need more time in the sun to produce equivalent amounts of this critical vitamin.

Ageing reduces Vitamin D production

Thin aged skin and joint deformity – common signs of aging

Not surprisingly, clothing inhibits the production of Vitamin D in the same way that it protects against sunburn but what is not so well known is that ageing also decreases our ability to produce Vitamin D. Aging affects the production in two ways. It both reduces the synthesis through the skin in sunlight by about half and then there is probably a further decline in the renal production of the active hormone! So, as you age, you either need to spend a lot more time in the sun making your Vitamin D or you need to eat Vitamin D rich foods or take a supplement.

If you have sufficient intake of Vitamin D, you can expect to have stronger bones, heightened immunity, less risk of cancer as well as feeling much happier. But this might not be all the advantages? The fact that almost all cells in our bodies have what are called Vitamin D ‘receptors’. This means that Vitamin D plays at least some role in all our cells!

You might also enjoy watching my YouTube video for some more information about Vitamin D: Vitamin D and 14 health benefits

Published by Dr Judy

I am a PhD Geneticist and have spent many decades working in research related to reproduction and cancer. Both are affected by lifestyle, especially ageing and so I am passionate about teaching people how to change their lifestyles to optimise their health.

I would love to hear your thoughts on this.