Most of us are low on vitamin D, and most of us think being in the sun for a few minutes is enough to get us the essential vitamin. How important is this vitamin for health? Dr Rakesh Gupta, senior consultant, internal medicine, Indraprastha Apollo Hospitals, says: “Vitamin D is essential for maintaining healthy bones, muscles, and immune function. It helps the body absorb calcium and phosphorus, two minerals needed for strong bones and teeth. Without enough vitamin D, even a calcium-rich diet cannot support optimal bone strength.
Beyond the skeletal system, vitamin D plays a role in regulating immunity, reducing inflammation, supporting nerve and muscle function, and maintaining hormonal balance. Research also links adequate vitamin D levels with better mood, lower risk of infections, and improved metabolic health. This vitamin acts more like a hormone than a nutrient, influencing multiple organs and systems. Because many people get limited sunlight exposure or have dietary gaps, deficiency is common. Ensuring sufficient vitamin D – through safe sun exposure, food sources, and supplements when required-is important for long-term health and disease prevention.”
What are the long-term effects of chronic deficiency?
Long-term vitamin D deficiency can gradually affect multiple parts of the body. The most well-known consequence is weakened bones-leading to osteopenia, osteoporosis, and a higher risk of fractures in adults. Muscles may also become weaker, contributing to fatigue, aches, and a higher risk of falls. Chronic deficiency can weaken the immune system, making frequent infections more likely. Research shows possible links between persistent low levels and higher risk of diabetes, depression, autoimmune conditions, and certain cancers, although these associations vary across studies. In children, severe deficiency may cause rickets, affecting bone development. Over time, poor vitamin D status can also influence heart and metabolic health by contributing to inflammation. Because symptoms often appear slowly, many people remain unaware for years. Correcting deficiency early helps prevent these long-term complications and improves overall wellbeing.
Once levels stabilise, should supplements still be continued?
Whether to continue supplements after vitamin D levels normalise depends on the individual’s lifestyle, sun exposure, diet, medical conditions, and how easily their levels drop. Some people maintain healthy levels with regular sunlight and food sources, needing no long-term supplementation. Others-especially those with limited sun exposure, darker skin tone, obesity, malabsorption issues, or certain medications-may require ongoing low-dose supplements to prevent levels from falling again.
Doctors usually recommend a maintenance dose rather than stopping completely. It is important to avoid unnecessary high-dose supplementation because excessive vitamin D can be harmful. The best approach is to retest levels every six to twelve months and adjust the dose based on medical advice. Supplements are meant to restore and maintain balance, not to be taken indefinitely without monitoring.
People generally use supplements without testing. Is that safe?
Taking vitamin D supplements without testing is not always safe. While deficiency is common, unnecessary supplementation can lead to excessively high levels, which may cause toxicity. Too much vitamin D can raise calcium levels in the blood, leading to nausea, vomiting, constipation, kidney stones, and long-term kidney damage. Because symptoms of deficiency and excess can overlap-fatigue, weakness, or bone pain-testing is the only reliable way to know the actual status. Self-supplementation also leads people to take incorrect doses, such as very high weekly or monthly doses meant only for medical supervision. A simple blood test can guide whether supplementation is needed and what dosage is appropriate. Testing once before starting and once after 3-6 months is usually enough. Using supplements responsibly ensures the benefits of vitamin D without the risks of overuse.
