Vitamin D deficiency is found in a majority of urban Indians in most studies, which is a curious result for a tropical country. It has also become one of the most over tested and over supplemented conditions in private practice.
Both the deficiency and the overcorrection are worth understanding.
Why Deficiency Is So Common Here
Sunshine alone does not guarantee sufficiency, and several factors explain the paradox.
- Indoor work and study for most daylight hours
- Deliberate sun avoidance, both for comfort in the heat and for skin tone preferences
- Clothing covering most of the skin
- Darker skin pigmentation, which requires considerably longer exposure to produce the same amount
- Air pollution, which reduces the UVB reaching ground level in cities
- Limited dietary sources, particularly in vegetarian diets
- Widespread sunscreen use during peak hours
UVB is only adequate between roughly ten in the morning and three in the afternoon, precisely when most people avoid being outdoors.
What Vitamin D Does
Its principal established role is enabling calcium absorption from the gut and maintaining bone mineralisation.
Severe deficiency causes rickets in children, with bowed legs and delayed development, and osteomalacia in adults, causing bone pain and muscle weakness. Both are still seen in India.
Vitamin D receptors exist in many tissues, and associations have been reported with immunity, mood, cardiovascular health and various diseases. However, supplementation trials for most of these non skeletal outcomes have been largely disappointing. Low vitamin D often accompanies poor health rather than causing it.
The bone and muscle benefits are well established. Claims beyond that should be treated cautiously.
Symptoms of Deficiency
Mild deficiency causes nothing noticeable. More significant deficiency produces symptoms that are easily attributed elsewhere.
- Bone pain, particularly in the lower back, hips, pelvis and ribs
- Muscle weakness, especially in the thighs, causing difficulty rising from a chair or climbing stairs
- Muscle aches and cramps
- Fatigue
- Increased falls in older adults
- Frequent fractures from minor injury
- In children, delayed walking, bowed legs and delayed tooth eruption
Proximal muscle weakness, difficulty getting up from squatting or from the floor, is the most characteristic sign and is frequently attributed to age or deconditioning.
Who Should Actually Be Tested
Routine screening of everybody is not recommended and drives a great deal of unnecessary testing.
- Symptoms suggesting deficiency, particularly bone pain or proximal weakness
- Osteoporosis or a fragility fracture
- Chronic kidney or liver disease
- Malabsorption conditions including coeliac disease and after bariatric surgery
- Long term steroid or anticonvulsant use
- Pregnancy and lactation in at risk women
- Older adults with recurrent falls
- Children with growth or bone abnormalities
The test measures 25 hydroxyvitamin D. Levels below 20 ng/mL indicate deficiency, 20 to 30 is insufficiency, and 30 to 50 is generally considered sufficient. Routine repeat testing after correction is not needed for most people.
Getting Vitamin D From Sunlight
Sun exposure remains the most efficient source, and modest amounts suffice.
- Around twenty to thirty minutes, three to four times weekly
- Between roughly ten and three, when UVB is adequate
- Arms, legs and face exposed, which means enough skin area
- Without sunscreen for that period, then protecting the skin
- Longer for darker skin, up to two or three times as long
- Through open air, since glass blocks UVB entirely, so sitting by a window does nothing
This must be balanced against skin cancer risk and ageing. Brief regular exposure rather than prolonged occasional exposure is the sensible compromise, and prolonged deliberate sunbathing is not recommended.
Dietary Sources
Diet contributes relatively little, particularly for vegetarians, but is worth including.
- Oily fish: sardines, mackerel, salmon, which are the richest natural sources
- Egg yolk
- Fortified milk and some fortified oils and cereals
- Mushrooms exposed to sunlight, one of the few plant sources
- Cod liver oil
A purely vegetarian diet makes adequate dietary intake genuinely difficult, which is one reason deficiency is so widespread in India. Fortified foods help but coverage is inconsistent.
Correcting Deficiency Sensibly
Treatment typically involves a loading phase followed by maintenance, and it should be based on a measured level rather than given indiscriminately.
Common regimens use weekly doses of 60,000 IU for six to eight weeks, followed by monthly maintenance. Daily lower dose regimens work equally well and are gentler.
Calcium intake should be adequate alongside, since vitamin D without sufficient calcium achieves less. Magnesium is also required for vitamin D metabolism.
Note that vitamin D is fat soluble and absorbed better when taken with a meal containing some fat, which is a simple change that improves the response considerably.
The Over Supplementation Problem
Very high dose vitamin D is now widely and casually prescribed, sometimes repeatedly, without measuring levels.
Toxicity is uncommon but real. It causes high blood calcium, producing nausea, vomiting, excessive thirst, frequent urination, confusion, kidney stones and, over time, kidney damage.
It arises from taking high dose supplements repeatedly without monitoring, often from multiple sources at once, or from injections given routinely.
Do not take 60,000 IU weekly indefinitely. Once corrected, move to a maintenance dose. Do not take vitamin D from several preparations simultaneously, and tell your doctor everything you are taking. Our general medicine department reviews supplementation alongside other treatment.
Vitamin D deficiency is genuinely common and worth correcting, particularly where there is bone pain, muscle weakness or fracture risk. Get twenty minutes of midday sun several times a week, take vitamin D with food, and stop the high loading dose once you have corrected rather than continuing it indefinitely.
Our general medicine department at T. Nagar assesses deficiency and supervises correction.
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