Many people in the developed world aren’t getting enough vitamin D. This is because this vitamin – unlike many other vitamins – is partly dependent on the amount of exposure to sunlight. Since so many of us now work in offices or factories, under artificial light, vitamin D deficiency is becoming a significant health hazard, especially as people age.
This is doubly true because it is almost impossible to get enough vitamin D simply from food. More important, a lack of this vitamin – a fat-soluble steroid hormone – affects the body’s ability to absorb calcium, iron, magnesium, phosphorus, and zinc.
Foods like fish, eggs, fortified milk, and cod liver oil can supply adequate amounts of vitamin D2. Vitamin D3, however, is only made by human skin, and – while as little as 15 minutes of “swimsuit” exposure can make enough vitamin D for an entire day, many Americans go from the office to home, and then out to eat or for recreation, without ever getting any vitamin D3 from sunlight.
Suspect a vitamin D deficiency if you are dark-skinned; live in the north of the 43rd parallel (Minneapolis, MN; Pierre, S.D.; Augusta, ME); wear pants and long-sleeved shirts (or sunscreen) out-of-doors;, or are breast-feeding a baby, in which case both of you may be vitamin D deficient.
You are also more likely to lack this vitamin if you are over 50, if you often feel down or depressed, if you have a digestive disorder like inflammatory bowel disease, or if your bones ache and your doctor diagnoses fibromyalgia or chronic fatigue syndrome.
Because the body can store this vitamin, overdosing may show up as dry mouth, fatigue, headache, loss of appetite, metallic taste, nausea, sleepiness, vomiting, or generalized weakness. Vitamin D supplementation should only be done under the supervision of a medical professional.
A recent study has shown the benefit of vitamin D in relieving the symptoms of osteoarthritis to be largely inconclusive. People should not take this vitamin if they have kidney disease, atherosclerosis, sarcoidosis, histoplasmosis, or hyperparathyroidism.