In today’s world, if you visit a doctor, you’ll often find something on your test list that wasn’t common before: “Check your vitamin D level.” Strange, isn’t it? It has become so routine now that many people take vitamin D supplements without thinking twice. But have you ever wondered why?
Now let’s consider something else. Bangladesh is a tropical country. We get a lot of sunlight—sometimes too much of it. So how is it possible that various studies have shown 60 to even 100 per cent of our population has low levels of vitamin D? It’s confusing. We have sunlight, yet we’re still deficient. Why?
To unravel this mystery, scientists across the world are working tirelessly. It used to be believed that vitamin D was only important for bone health, helping prevent conditions like rickets in children or brittle bones in adults. But that’s just the beginning of the story. We now know vitamin D may be linked to a wide range of serious health issues including depression, anxiety, certain cancers, heart disease, and autoimmune disorders. That’s why understanding this “sunshine vitamin” has become more important than ever.
But here’s the bigger puzzle: If people in Bangladesh are getting enough sun, why are their vitamin D levels still so low?
We looked at a few obvious reasons. First, the best time for your body to make vitamin D from sunlight is between 11:00 a.m. and 2:00 p.m.—which is also office time. Most people are indoors behind walls, curtains, or desks. Then, there’s our cultural habit of avoiding direct sunlight. Whether it’s umbrellas, long sleeves, or simply staying in the shade, we unknowingly block the very thing we need. So is that the whole story?
Actually, no. The real clue lay somewhere deeper—inside us, written in our DNA.
I’m Dr Kazi Lutfar Rahman, currently pursuing my PhD at Ulster University. This mystery pushed me to dig deeper into what might be stopping our bodies from using sunlight to make vitamin D. I focused on people who should, in theory, have good vitamin D levels—traffic police working all day in the sun, health workers moving through slums and alleys, and young athletes playing outdoors. Still, many of them had low levels. Why?
That’s where genetics came in.
Back when I was doing my MPhil under Professor Qazi Shamim Akhter at Dhaka Medical College, I took on this challenge. But scientific research in Bangladesh is never easy—especially when it involves genetics, one of the most delicate and complex areas of human biology.
Our work began during the peak of the COVID-19 pandemic. Labs were closing down, movement was restricted, and equipment was often unavailable. I had no prior advanced training in gene analysis—I had to learn everything from scratch. Some tests failed multiple times. Days turned into nights as we repeated protocols again and again. But we didn’t give up.
After months of effort, we finally identified a specific piece of the puzzle: a tiny region in a gene called CYP2R1. This gene plays a critical role in activating vitamin D in the human body.
Here’s what we discovered: a group of people had a variation in this gene that made it harder for their bodies to process vitamin D—even when they were getting enough sunlight. This variation had never been reported before in Bangladeshi adults. It was the first discovery of its kind.
When I compared our data with global databases, I found something fascinating: People from colder, darker countries often have a different variation in the same gene that helps them produce vitamin D more efficiently. In contrast, we—people living in a sun-rich country—carry a variation that actually reduces our ability to make it.
Nature works in strange ways. Maybe it’s a balancing act: if you live in a sunny region, your body naturally tones down production. If you live in a dark, cold place, your body becomes more efficient. But when our lifestyle changes—like working indoors or avoiding the sun—this natural balance is disrupted.
Finally, our findings were accepted into GenBank USA, GenBank Japan, and the European Nucleotide Archive—official repositories for global genetic data. We also published our research in the international journal PLOS One, so now the world knows about this hidden genetic trait in Bangladeshi people.
So, what can you do?
Catch some sun: Aim for at least 15 minutes of sunlight, three times a week, between 11:00 a.m. and 2:00 p.m., without sunscreen and with your arms and face exposed.
Don’t fear the sun: Moderate sun exposure is healthy and essential.
Stay active outdoors: A walk in the sun lifts your mood and boosts vitamin D.
Eat right: Include vitamin D-rich foods like fish, eggs, and fortified milk when possible.
Get tested if needed: If you feel tired, weak, or low for no reason, check your vitamin D level.
And here’s one more thing—my research shows that not everyone’s body works the same way. Because of genetic differences, some people might need more sun or even supplements to maintain a healthy level.
A final thought
I began this journey with a simple question: Why are we deficient in vitamin D in a land full of sunlight? That question took me into the depths of human genetics, international databases, sleepless nights, failed experiments—and finally—to discovery.
My goal now is to expand this research, reach more people, and help shape public health guidelines tailored for our country—not just copy-pasted from elsewhere. Because every body is different. And every country deserves its own answers.
The author, Dr Kazi Lutfar Rahman, is a PhD researcher at the University of Ulster, Coleraine, UK.