Have you been feeling tired all the time lately? Achy bones, low mood, a heavy feeling in your legs when you climb the stairs? Before you blame it on age or a hectic schedule, there is something worth checking. It could be your Vitamin D.
Here is the surprising part. Even in a sunny country like India, Vitamin D deficiency is incredibly common. Researchers estimate that close to 490 million Indians have low Vitamin D levels. That is a staggering number for a nation that enjoys sunshine almost the whole year round.
In plain words, Vitamin D deficiency means your body simply does not have enough Vitamin D to do its job properly. And that job is far bigger than most people realise.
We will look at the signs of Vitamin D deficiency, why it happens, the diseases it is linked to, and what you can do about it.
What Is Vitamin D Deficiency?
Vitamin D is an essential nutrient your body needs for strong bones, healthy muscles, steady immunity and a well-functioning nervous system. When you do not have enough of it, doctors call this Vitamin D deficiency.
Your body makes most of its Vitamin D through sunlight falling on your skin. You also get small amounts from food and from supplements.
But here is the catch. Several everyday things get in the way, sitting indoors all day, darker skin, city pollution, or simply covering up most of your body. So the answer to what is Vitamin D deficiency is not really about the sun being absent. It is about how little of it actually reaches and works on your skin.
About one billion people worldwide are thought to be Vitamin D deficient. So if your report shows low levels, you are far from alone.
Why Is Vitamin D So Important for Your Body?
Think of Vitamin D as the key that unlocks calcium for your body.
You can drink all the milk you like, but without enough Vitamin D, your intestines cannot absorb that calcium properly. When calcium in your blood starts to fall, your body quietly pulls calcium out of your own bones to keep the balance. Over time, this weakens your bones from the inside out.
In adults, this can lead to soft bones, a condition called osteomalacia. In children, the same process causes rickets, where growing bones become soft and bend. Vitamin D also supports your muscles, your mood and your immunity, which is why a shortage can leave you feeling low, weak and run down for no clear reason.
What Are the Common Signs of Vitamin D Deficiency?
This is the tricky bit. Vitamin D deficiency is often called a silent problem, because many people have no obvious symptoms at all. When the Vitamin D deficiency symptoms do appear, they are easily mistaken for ordinary tiredness.
Vitamin D Deficiency Symptoms in Adults
In grown-ups, the common Vitamin D deficiency symptoms tend to creep up slowly. Keep an eye out for these:
- Constant tiredness or fatigue, even after a full night's sleep
- Bone pain, often felt in the lower back, hips or legs
- Muscle weakness, aches or cramps
- Low mood or feelings of depression
- Falling ill often, with frequent coughs and colds
You may also notice you feel more drained during winter. An Indian study found that Vitamin D levels dip noticeably in winter compared with summer, with young adults often the worst affected.
What Are the Signs of Vitamin D Deficiency in Children?
In children, a severe lack of Vitamin D can cause rickets. These are the warning signs of Vitamin D deficiency that parents should never ignore:
- Bowed or bent legs as the child starts walking
- Delayed growth or short height for age
- Weak, sore muscles
- Bone pain or tenderness
- Delay in learning to walk
Indian studies suggest that anywhere between 50 and 90 percent of our children may have low Vitamin D.
What Are the Reasons for Vitamin D Deficiency?
So why does this happen so often, especially in a sunny country? There are usually two big reasons for Vitamin D deficiency. Either you are not getting enough through sunlight and diet, or your body is not absorbing and using it properly.
Let me walk you through the everyday triggers I see most in Indian patients.
Common Vitamin D Deficiency Causes
The most frequent Vitamin D deficiency causes are surprisingly ordinary:
- Limited sun exposure: Long hours in offices, homes and cars mean very little skin meets sunlight
- Pollution: Smog and dust in our cities block the UV-B rays your skin needs to make Vitamin D
- Skin tone: More melanin in darker skin slows down Vitamin D production
- Covering up: Clothing that covers most of the skin, often for cultural reasons, limits sun exposure
- Vegetarian diet: Many Indian meals are naturally low in Vitamin D rich foods like oily fish
- Sunscreen: Wonderful for protecting skin, but it also reduces Vitamin D made by the body
Certain health conditions also play a part. Crohn's disease, celiac disease, kidney disease, liver disease and obesity can all lower your Vitamin D. Some medicines, such as steroids and a few anti-seizure drugs, can do the same. Always tell your doctor about every medicine and supplement you take.
What Diseases Are Linked to Vitamin D Deficiency?
This is where things turn serious. Left untreated for long, low Vitamin D is connected to several Vitamin D deficiency diseases. The bones bear the brunt of it:
- Rickets in children, where soft bones bow and bend
- Osteomalacia in adults, meaning soft and painful bones
- Osteoporosis, where bones turn brittle and fracture easily
- Hypocalcaemia, or dangerously low blood calcium
- A higher overall risk of bone fractures
Research is also exploring links between low Vitamin D and poor muscle strength, mood disorders and even reduced cognitive function in older adults. The science on some of these Vitamin D deficiency diseases is still settling, but the effect on bones is beyond doubt.
Who Is Most at Risk of Vitamin D Deficiency?
Some people run far more easily than others. You should be extra watchful if you are over 65, since ageing skin makes less Vitamin D. The same goes for infants who are only breastfed, people with darker skin, those who spend most of the day indoors, pregnant or breastfeeding women, and anyone living with obesity or a digestive condition.
The recommended daily intake of Vitamin D varies by age and life stage:
- Infants up to 12 months: 10 mcg (400 IU) per day
- Children, teenagers, and adults aged 1 to 70 years: 15 mcg (600 IU) per day
- Adults aged 71 years and older: 20 mcg (800 IU) per day
- Pregnant and breastfeeding women: 15 mcg (600 IU) per day
How Is Vitamin D Deficiency Diagnosed?
The good news is that diagnosing this is refreshingly simple. A single blood test, called the 25-hydroxyVitamin D test or 25(OH)D for short, measures the level of Vitamin D in your blood.
Doctors do not test everyone routinely. But if you have risk factors or troubling symptoms, your doctor will likely suggest this test. It is a small step for some big peace of mind.
What Is the Right Vitamin D Deficiency Treatment?
Here is the reassuring bit. Vitamin D deficiency treatment is usually straightforward and very effective. The goal is simple: to bring your levels back up and then keep them steady.
Most Vitamin D deficiency treatment plans combine three things: the right dose of Vitamin D supplements, sensible sun exposure, and a diet richer in Vitamin D. Vitamin D comes in two forms, D2 and D3. Your body absorbs D3, known as cholecalciferol, more easily, and it is available over the counter. Please do not start high doses on your own, though. Too much Vitamin D can do harm, which we will come to shortly.
Which Foods Are Rich in Vitamin D?
You can top up your levels naturally with everyday foods:
- Fatty fish such as salmon, sardines and mackerel
- Egg yolks
- Mushrooms
- Cod liver oil
- Fortified milk, curd, breakfast cereals and orange juice
For our many vegetarian readers, fortified milk, curd, mushrooms and a doctor-advised supplement are your best friends.
How Can You Prevent Vitamin D Deficiency?
Prevention is wonderfully simple. Try to get 15 to 20 minutes of gentle morning sunlight on your arms and face a few times a week. Many of my patients find that an early morning walk does the job nicely.
Pair that with a balanced diet and, if your doctor advises, a supplement. Just do not overdo time in the harsh midday sun without sunscreen, because too much sun raises your risk of skin cancer. It is all about balance.
When Should You See a Doctor?
If you have been feeling unusually tired, achy or low for a few weeks, please do not brush it off. Talk to your doctor, especially if you have any of the risk factors we discussed.
A simple blood test can tell you exactly where you stand.
Your bones carry you through your whole life. They are worth keeping strong.
Can You Have Too Much Vitamin D?
Yes, you can. While you cannot overdose from sunlight, taking too many supplements can cause Vitamin D toxicity. This can push your blood calcium to harmful levels, leading to nausea, increased thirst, poor appetite, constipation, weakness and confusion. This is exactly why self-medicating with high doses is risky. When in doubt, check with your doctor first.
Get tested at Unipath. Our diagnostic team can check your Vitamin D levels with a simple, reliable Vitamin D Test. If you have been ignoring those nagging signs, now is the time to get clarity. Book your test with Unipath today and give your bones the attention they deserve.
References & Citations:
1. Cleveland Clinic. Vitamin D Deficiency: Causes, Symptoms & Treatment. 2022.
2. Sahay M, et al. Vitamin D status and determinants in Indian children and adolescents: a multicentre study. Scientific Reports. 2022.
3. Prevalence and Correlates of Vitamin D Deficiency among Adult Population in Urban and Rural Areas of the National Capital Region of Delhi, India. Indian Journal of Community Medicine. 2023.
4. Prevalence of Vitamin D Deficiency Among Infants in Northern India: A Hospital Based Prospective Study. 2020.
5. Prevalence and patterns of Vitamin D deficiency and its role in cognitive functioning in a cohort from South India. Scientific Reports. 2024.
6. National Institutes of Health, Office of Dietary Supplements. Vitamin D Fact Sheet for Consumers.
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