Updated

Updated · HuffPost · Aug 21

Vitamin D Deficiency Affects 60% Globally as Doctors Urge 1,000-2,000 IU Supplements

Updated

Updated · HuffPost · Aug 21

Vitamin D Deficiency Affects 60% Globally as Doctors Urge 1,000-2,000 IU Supplements

Q: What hidden condition makes Vitamin D useless for some, leaving bones fragile despite taking daily high-dose supplements?

The hidden condition is often **chronic kidney disease or another disorder that prevents vitamin D from being activated**, and in rarer cases **vitamin D–resistant rickets/osteomalacia** or other phosphate-wasting disorders. Vitamin D from supplements is not fully active when swallowed. The body must convert it in the **liver** and then, crucially, in the **kidneys** into calcitriol, the hormone-like form that helps absorb calcium and mineralize bone. If the kidneys are damaged, a person can take large daily doses and still have **soft, fragile bones, bone pain, weakness, or fractures** because the vitamin is not being properly activated. The broader medical literature also points to **malabsorption disorders** such as celiac disease, Crohn’s disease, bowel disease, or after gastric bypass surgery, where the problem is that vitamin D is not absorbed well enough. In those cases, standard supplements may appear “useless” because blood levels do not rise adequately. Doctors say a poor response to vitamin D should trigger testing, not more unsupervised high-dose use. The key lab is **25-hydroxyvitamin D**, but clinicians may also check **calcium, phosphate, parathyroid hormone, kidney function**, and sometimes the active form, **1,25-dihydroxyvitamin D**, depending on the case. That is why experts warn that persistent bone fragility despite supplements may signal an **underlying kidney, gut, liver, or inherited metabolic disorder**, not simply a lack of sunlight or low intake.

3 articles · Updated · HuffPost · Aug 21

About 60% of people worldwide do not get enough vitamin D, doctors said, despite summer sun and the nutrient’s central role in bone strength, muscle function and broader health.
100 to 400 IU a day from a healthy diet usually falls short, and sun exposure often does too because UVB is weaker early, late, in winter, through pollution, sunscreen and indoor lifestyles.
Older adults can make far less vitamin D from the same sunlight—a 20-year-old may produce two to three times more than a 70-year-old—while darker skin, kidney or liver disease, bowel disorders and some seizure drugs also raise deficiency risk.
Doctors said vitamin D3 is generally preferred when supplementation is needed, with many adults requiring about 1,000 to 2,000 IU daily, though dosing should be individualized and monitored.
Too much vitamin D can also be harmful, causing high calcium, kidney problems, brain fog and fatigue, underscoring advice to consult a physician rather than self-dose.