Why Are So Many People Vitamin D Deficient? Warning Signs You Shouldn’t Ignore

August 7, 2026

Vitamin D, also known as the “sunshine vitamin”, is surprisingly deficient in a lot of people despite India being a tropical country where sunshine is plentiful throughout the year. Several studies have consistently shown that a large proportion of adults and children have inadequate vitamin D levels.

A major reason this deficiency often goes unnoticed is that its early symptoms like persistent tiredness, body aches or muscle weakness are vague and usually attributed to stress, ageing or a hectic lifestyle. By the time the deficiency is diagnosed, it may already be affecting bone strength, muscle function or overall health. Understanding why vitamin D deficiency is so common and recognising its warning signs can help you seek medical care before complications develop.

Why does your body need Vitamin D?

Vitamin D is essential for much more than maintaining healthy bones. It helps the body absorb calcium efficiently, ensuring that bones and teeth remain strong throughout life. Researchers have also found that vitamin D contributes to healthy muscle function, supports the immune system, helps regulate nerve function and plays a role in several metabolic processes. Although it is often called a vitamin, it functions more like a hormone, influencing multiple organs throughout the body.

Why is Vitamin D deficiency becoming more common?

Spending More Time Indoors

Today's lifestyle is one of the biggest reasons behind declining vitamin D levels. Office work, online classes, air-conditioned environments and increased screen time mean many people spend most daylight hours indoors. Even people who travel outdoors may do so before sunrise or after sunset, limiting exposure to the ultraviolet B (UVB) rays needed for vitamin D production.

Avoiding Direct Sunlight

Growing awareness about skin damage and tanning has encouraged people to avoid the sun whenever possible. Protective clothing, umbrellas and sunscreen are important for skin health, but they also reduce the skin's ability to synthesise vitamin D.

Urban Living and Air Pollution

In densely populated cities, pollution can reduce the amount of UVB radiation reaching the ground. This means that even on bright days, the skin may produce less vitamin D than expected.

Skin Pigmentation

Melanin, the natural pigment that determines skin colour, also reduces vitamin D production. Individuals with darker skin generally need longer exposure to sunlight to generate adequate amounts.

Increasing Age

The skin gradually becomes less efficient at producing vitamin D as we grow older. Combined with reduced outdoor activity, this places older adults at higher risk of deficiency.

Obesity

Vitamin D is stored in fat tissue. In people with obesity, a greater proportion becomes trapped in body fat, leaving less available for normal physiological functions.

Limited Dietary Sources

Unlike many nutrients, vitamin D occurs naturally in only a small number of foods. Unless the diet includes fortified foods or oily fish, food alone is rarely enough to meet daily requirements.

Certain Medical Conditions

Some chronic illnesses interfere with vitamin D absorption or metabolism. These include disorders affecting the kidneys, liver and intestines, as well as conditions that reduce nutrient absorption.

Symptoms that may indicate Vitamin D deficiency

Vitamin D deficiency rarely announces itself dramatically. Instead, the symptoms usually appear gradually and may worsen over time.

Ongoing fatigue: If you continue to feel exhausted despite sleeping well, low vitamin D may be one of several possible causes worth investigating.

Frequent muscle pain: Muscle soreness without significant physical exertion can sometimes be linked to inadequate vitamin D levels. Some individuals also experience cramps or reduced muscle strength.

Bone & joint discomfort: Persistent aches in the lower back, hips, pelvis or legs may reflect poor bone mineralisation associated with vitamin D deficiency.

Reduced physical strength: Difficulty climbing stairs, carrying groceries or standing from a seated position may indicate weakened muscles, particularly in older adults.

Frequent infections: Vitamin D contributes to normal immune function. Recurrent respiratory infections or prolonged recovery from common illnesses may warrant further evaluation.

Low mood: Although depression has many causes, research suggests that vitamin D deficiency may contribute to low mood in certain individuals.

Slow recovery after injury: Vitamin D supports bone and tissue health. Delayed healing following fractures or surgery may occasionally be associated with inadequate levels.

Hair thinning: Hair loss has multiple causes, but vitamin D deficiency has been linked to certain forms of excessive hair shedding in some people.

Who Should Be More Vigilant?

Certain groups are more likely to develop vitamin D deficiency than others, and if you belong to any of these groups, regular medical evaluation may be advisable.
Those more likely to be deficient are:

Adults above 60 years
Pregnant and breastfeeding women
People with obesity
Individuals who spend most of their day indoors
People with chronic kidney or liver disease
Those with intestinal disorders affecting nutrient absorption
Individuals taking certain long-term medications

How is Vitamin D deficiency diagnosed?

A simple blood test measuring 25-hydroxy vitamin D is the standard way to assess vitamin D status. Depending on your symptoms and medical history, your doctor may also recommend tests to evaluate calcium levels, kidney function or bone health.

Can Vitamin D deficiency be treated?

Most people respond well to treatment when the deficiency is recognised early. However, high-dose vitamin D should never be taken without medical supervision, as excessive intake can lead to serious complications, including elevated calcium levels and kidney damage.
Treatment may include:

Prescription-strength vitamin D supplements
Maintenance supplementation where appropriate
Dietary advice
Safe and sensible exposure to sunlight
Follow-up blood tests to monitor improvement

Foods that help improve Vitamin D intake

Although food alone may not correct a significant deficiency, including vitamin D-rich foods in your diet can support healthy levels. Some foods that are rich in Vitamin D are:

Salmon, sardines and mackerel
Egg yolks
Fortified milk and dairy products
Fortified breakfast cereals
UV-exposed mushrooms

Can Vitamin D deficiency be prevented?

While not every case can be prevented, a few simple habits, like spending time outdoors regularly whenever feasible (following sensible sun safety practices), adding vitamin D-rich and fortified foods in your daily meals, staying physically active, and maintaining a healthy body weight, can significantly reduce your risk.

Have your vitamin D levels checked if you are at increased risk or develop persistent symptoms. Take supplements only if recommended by your healthcare provider.

Don’t ignore persistent symptoms

Fatigue, muscle weakness and body aches are common complaints, but they should not always be dismissed as the result of stress or ageing. In some cases, they may reflect an easily treatable nutritional deficiency.

Seeking medical advice early allows the underlying cause to be identified before more serious complications, such as osteoporosis, recurrent fractures or significant muscle weakness develop.

Expert Opinion

"Vitamin D deficiency has become increasingly common due to limited sun exposure, indoor lifestyles, inadequate dietary intake, and certain medical conditions that affect its absorption. Since Vitamin D plays a vital role in maintaining healthy bones, muscles, and immunity, a deficiency can lead to symptoms such as persistent fatigue, bone or back pain, muscle weakness, frequent infections, and low mood. Individuals at higher risk—including older adults, pregnant women, people with darker skin, and those with chronic illnesses—should consider timely screening and medical consultation. Early diagnosis and appropriate supplementation can help prevent long-term health complications."

-Consultant Internal Medicine
-Desun Hospital, Kolkata

Why choose Desun Hospital?

Desun Hospital offers comprehensive evaluation and treatment for vitamin D deficiency through its experienced team of physicians, endocrinologists, orthopaedic specialists and nutrition experts. Advanced laboratory facilities, preventive health check-up packages and personalised treatment plans ensure accurate diagnosis and holistic management, helping patients maintain stronger bones and better overall health.