Did you ever wonder why people hailing from certain regions have light-coloured skin and people indigenous from other geographies have dark skin? Or why we are fairer as babies than we are as adults? Or even why the palms of our hands and the soles of our feet lack pigment?

The answer to all of these questions is this: because of the sun and its effect on the human body. Through a process of natural selection, people of the right colour (or melanin richness, so to speak) have been the last ones left standing according to their suitability to the latitude that they have found themselves in. The further away from the equator you go (where there is less sun all year round) the more lacking in melanin the skin is. Closer to the equator, the melanin starts kicking in. (However much the desi aunty may hate this, it is true!)

Skin that is nearly pigment free (white) will allow up to 70% of ultraviolet light in, whereas black skin can allow in as little as 3%.

Why is that?

Basically, white people are built like big solar panels so that even with small amounts of sunshine, they manage to charge up on their vitamin D during the sparse sunshine hours that they get year round. The body creates vitamin D when it is exposed to ultraviolet rays and its production is crucial for the body’s ability to absorb calcium.

Now for us brownies, it is the opposite story. Those of us who have our boundary walls right next door to the sun need protection from overloading on it, otherwise precious stores of folate get depleted. Folate is vital to sperm production as well as spinal and brain development.

However in today’s world, we have taken things a little too far it seems. We avoid the sun like the plague. With brown skin, we need up to 45 minutes of direct sunlight on our arms or legs everyday. However, we do our damnedest to avoid even three. The result is that we have an ‘epidemic’: vitamin D deficiencies are now almost the norm. I myself have one!

The obvious question here is what about sun damage? For decades we have been told to use sunblock (with a high SPF) to keep out those mean ultraviolet rays, yet now we find out avoiding them can harm us too? Yes, this is one of those crazy moments where both things are harmful. But if you follow some good advice from a doctor, you may find your way around this.

Dr Najia Ashraf (Msc in Dermatology from King’s College, London) suggests exposing yourself to the sun only after 4pm. This ensures that you have your ultraviolet cake and get to eat it too. She also suggests getting yourself tested for a deficiency before self-medicating with supplements (as many people are now doing). Overdosing on vitamin D is dangerous and can cause calcium deposits in places you don’t want: like your heart! It can also cause kidney damage.

Too little vitamin D can result in chronic acne, lethargy, bone pain and even bone deformities. Since I have been diagnosed and have been put on a heavy dose of vitamin D my skin has cleared up. As an adult acne sufferer, I can’t even begin to tell you the joy that brings. So if any of you are acne sufferers out there, get thee to the Aga Khan Lab for a vitamin D test. If you are deficient, then run along to the doctor for your prescription and your miracle cure! Chronically tired people report newfound energy. Either way, the next time you get your blood panel, check on your vitamin D levels. Chances are, you probably have a deficiency.

So now you know: white people are white so that their bodies can make vitamin D with even a teeny bit of sunshine, while black people are black so that the melanin in their skin can protect them from too much folate-killing ultraviolet light. Babies are fairer so that they can make loads of vitamin D, so that they can grow all those bones and teeth. Our palms and soles are pigment free because they are barely exposed to the sun, and so they do not need protection.

So the next time some nosy Aunty makes a comment about how fair or dark you are, just tell her this: “Yes I know, my body’s melanin levels have protected my ancestors and myself from calcium depletion / folate depletion for generations.”

Let her chew on that.