Osteomalacia is most commonly caused by a lack of vitamin D. Vitamin D is an important nutrient that helps you absorb calcium in your stomach. Vitamin D also helps maintain calcium and phosphate levels for proper bone formation. It’s made within the skin from exposure to ultraviolet (UV) rays in sunlight. It can also be absorbed from foods like dairy products and fish.

Low levels of vitamin D mean that your body cannot process the calcium your bones need for structural strength. This can result from a problem with diet, lack of sun exposure, or a problem with your intestines. If you’ve had surgery to remove parts of your stomach or small intestine, you may also have a problem absorbing vitamin D or breaking down food to release it. Certain conditions can interfere with the absorption of vitamin D:

-- Kidney and liver disorders can affect the metabolism of vitamin D.
-- A diet that doesn’t include phosphates can cause phosphate depletion, which can also lead to osteomalacia.
-- Phenytoin and phenobarbital are drugs used to treat seizures. They can also cause osteomalacia.
-- Celiac disease can damage the lining of your intestines and prevent the absorption of key nutrients like vitamin D.
-- Certain types of cancer can interfere with vitamin D processing.