The Deficiency Almost Everyone I Know Has
The Test I Nearly Did Not Take
I had been tired for months. Not sleepy — tired. Heavy legs, aching lower back, no enthusiasm for anything, and a general sense of being older than I was.
I put it down to work. Then a routine check-up included a vitamin D test almost as an afterthought.
Mine came back at 11 ng/mL. Anything under 20 is classified as deficient.
What surprised me more was how ordinary this turned out to be. When I mentioned it, three colleagues said they had been told the same thing. My father had been told years earlier and forgotten about it.
Studies across Indian cities have repeatedly found deficiency in a large majority of the urban population — figures of 70-90% appear across many of them. In one of the sunniest countries on the planet. It sounds absurd until you look at how we actually live.
Why It Happens Here, of All Places
Several things stack up, and none of them are individually dramatic.
We are indoors during the hours that matter. Vitamin D synthesis needs UVB, which is only meaningfully present roughly between 10 a.m. and 3 p.m. That is precisely when most of us are inside an office, and I spent years leaving home before the sun mattered and returning after it stopped.
Melanin reduces synthesis. Darker skin is excellent protection against UV damage and it also means you need considerably longer in the sun to produce the same amount of vitamin D — by some estimates three to five times longer than fair skin.
We cover up, for cultural reasons, for sun protection, or simply because of the heat. Synthesis needs skin exposed.
Pollution blocks UVB. In several Indian cities, atmospheric particulate matter measurably reduces the UVB reaching ground level.
Sunscreen blocks it too — which is not an argument against sunscreen, just a factor.
Our diet has almost none of it. Vitamin D occurs naturally in oily fish, egg yolk and liver. A traditional vegetarian Indian diet contains effectively none, and unlike many countries, milk here is generally not fortified.
Air conditioning and glass. UVB does not pass through window glass. Sitting by a sunny window produces nothing at all.
What It Actually Does
I had thought of vitamin D as a bone thing. It is considerably broader than that.
Calcium absorption. Without adequate vitamin D you absorb only a fraction of the calcium you eat. You can drink milk daily and still lose bone density. This is the mechanism behind rickets in children and osteomalacia and osteoporosis in adults.
Muscle function. Deficiency is associated with muscle weakness and aches, particularly in the thighs and upper arms. This explained the heavy legs.
Immune function. Vitamin D receptors are present throughout immune cells, and low levels are associated with more frequent respiratory infections.
Mood. The association with low mood and fatigue is consistent across studies, though the direction of cause and effect is not fully settled.
Insulin sensitivity. Deficiency is associated with insulin resistance, which matters given how common type 2 diabetes is in India.
Common symptoms — persistent fatigue, bone or lower back pain, muscle aches and weakness, frequent illness, low mood, hair thinning, slow wound healing. Every one of these is easy to blame on something else, which is exactly why so many people carry it for years.
Get Tested Rather Than Guess
This is the part I want to be careful about, because vitamin D is a fat-soluble vitamin and you can genuinely overdose on it. Unlike vitamin C, the excess is not simply flushed out.
The test is called 25-hydroxy vitamin D, or 25(OH)D. It is widely available, inexpensive, and does not require fasting.
Interpreting it broadly — deficient below 20 ng/mL, insufficient 20-30, sufficient 30-50, with 50-70 considered optimal by many clinicians. Above 100 is where toxicity concerns begin.
Why you should not simply start taking high-dose supplements based on an internet article: the weekly 60,000 IU sachets sold widely here are a therapeutic dose for a diagnosed deficiency, prescribed for a defined period and then reviewed. Taken indefinitely without testing, they can push you into excess, which causes elevated blood calcium — nausea, kidney stones, and in severe cases kidney damage.
So: test first, treat under medical guidance, retest afterwards. My own correction took about three months of a prescribed regimen followed by a maintenance dose, all decided by a doctor who had my actual numbers. That is the right way round, and it is genuinely the only part of this article I would ask you not to improvise on.
Getting It From the Sun
Free, and more effective than most people assume — provided you do it correctly.
Timing. Between 10 a.m. and 3 p.m., when UVB is actually present. Early morning sun feels pleasant and produces very little vitamin D.
Duration. Roughly 15-20 minutes for lighter skin, and 30-45 minutes or more for darker skin. Enough to be effective, not enough to burn — burning is damage, not progress.
Exposure. Arms and legs, or back. Face and hands alone are too small an area to contribute much.
No sunscreen during that window if you are deliberately synthesising, then cover up or apply it afterwards. Whether to make this trade is a personal call, and if you have a history of skin cancer in the family it is one to discuss with a doctor.
A shadow test that works anywhere: if your shadow is shorter than you are, UVB is strong enough. If your shadow is longer than you, it mostly is not.
What I do now is take a fifteen-minute walk after lunch, outdoors, in short sleeves. It handles vitamin D, the post-meal blood sugar spike and the afternoon slump in one go — which is why it has become the single most useful fifteen minutes in my day.
Food, and the Honest Limits
The best food sources
- Oily fish — salmon, mackerel, sardines, and Indian varieties like bangda and surmai. By far the strongest option
- Egg yolk — modest amounts, and the reason to eat whole eggs rather than only whites
- Fortified foods — some milk, some breakfast cereals. Check the label, because most Indian milk is not fortified
- Mushrooms — the only meaningful vegetarian source, and only if they have been exposed to UV. Sun-drying mushrooms for a few hours before cooking genuinely increases their vitamin D content
The honest limit: if you are vegetarian, food alone will almost certainly not get you there. Sunlight and, where a test shows it is needed, supplementation under medical guidance, are the realistic routes.
One related point worth knowing: vitamin D works alongside magnesium and vitamin K2. Magnesium is required to convert vitamin D into its active form, and deficiency in it is also common. Nuts, seeds, whole grains and leafy greens cover this without any supplement.
The summary of my own experience: correcting this did more for my everyday energy than any diet change I made, and it took a five-hundred-rupee blood test to find. If you have been tired for months and blaming your job, it is worth ruling out.
This is my experience and my reading, not medical advice — dosing and treatment are decisions for your doctor with your test results in front of them.