It’s terrible what hospitals can do to you. We all know someone who checked into the hospital with his or her mind completely intact, but then quickly (especially if there was surgery) became confused and disoriented in a most disturbing way.

It’s called hospital-acquired delirium. And, yeah, it’s scary.

Delirium in the hospital is more common—and more dangerous—than you may think. It’s a severe condition that mostly affects older patients (although not only older patients) and is often missed by hospital staff, especially in emergency rooms. If it’s not treated promptly, it can lead to longer hospital stays and poor health outcomes, including permanent cognitive problems and even a higher risk for mortality. It’s more common if there’s already some cognitive impairment, but research shows that between 3% and 29% of “low risk” patients without any existing cognitive problems succumb to delirium after a hospital stay. A combination of surgery, infection, social isolation, dehydration, poor nutrition and mind-affecting pharmaceuticals such as painkillers, sedatives and sleeping pills can bring it on…quickly.

You can’t control all of these factors, especially in the heat of the moment during emergency treatment. But researchers have discovered a nutritional factor that may protect against hospital-induced delirium…vitamin D.


Researchers examined records of about 4,500 men and women (average age 59) who were admitted to one of two large teaching hospitals in Boston from 1993 to 2006. They included patients who had been tested before their hospitalization for blood levels of vitamin D and excluded those who had a history of delirium or dementia. Of all the patients, 198 (4%) were ultimately diagnosed with hospital-acquired new-onset delirium.

Their vitamin D levels told a story. Even after adjusting for age, sex, race, other illnesses and reason for hospitalization (medical or surgical), low preadmission vitamin D status was strongly associated with risk for hospital-acquired delirium.

Among all the patients studied, the average blood level of vitamin D was 22 nanograms per milliliter (ng/mL), which is on the low end of normal (20 ng/mL to 40 ng/mL). (A blood level of 35 ng/mL to 40 ng/mL is probably ideal, experts believe.) But those with the lowest vitamin D levels were most prone to delirium. Compared with patients who had blood levels 30 ng/mL and over, patients with levels from 10 ng/mL to 20 ng/mL were 50% more likely to develop delirium—and those with levels under 10 ng/mL faced double the risk. And that wasn’t just a handful—about one in six (16%) of all the patients studied had levels under 10 ng/mL. Adjusting for other possible factors, including history of depression, calcium level and season of vitamin D testing, didn’t change the results.


It’s an observational study, which means it can’t prove (or disprove) that a lack of vitamin D caused delirium, so it’s possible that whatever caused delirium in these patients also made their vitamin D levels plummet. Nor does this study show that bringing vitamin D levels up to speed proactively prevents delirium. More studies will be needed to explore that hypothesis.

But it’s a reasonable hypothesis, and there is good reason to believe that vitamin D may play a specific role in protecting the brain and the mind. The brain has vitamin D receptors throughout, and there is evidence that the active form of vitamin D may remove plaque, a hallmark of Alzheimer’s, from brain cells, scientists have recently discovered. Research has shown that low blood levels of vitamin D are linked with dementia, Alzheimer’s disease and depression.

In a way, though, the exact question is beside the point. Medicine is about balancing benefit and harm, and in this case, if you’re vitamin D–deficient, there’s no harm, and potentially much benefit, in bringing your body’s vitamin D level up to normal! According to the National Institutes of Health, 77% of Americans are deficient in vitamin D, with blood levels under 30 ng/mL, and 6% have levels under 10 ng/mL. Even if you don’t know your level, taking a daily supplement that contains up to 2,000 IU or 3,000 IU is considered safe.

An even better idea: Get a blood test. It’s simple, quick, and inexpensive. If your level is low, your health-care provider may prescribe a higher dosage for a while or even recommend vitamin D injections to get your level up to normal quickly.

If you are going into the hospital or know someone who is, the idea of getting tested for vitamin D beforehand…and reaching a normal level with a supplement if need be…is a no brainer. It may prevent a scary form of delirium that can take hold in the hospital and lead to a downward health spiral. Even if it doesn’t, it’s a healthy thing to do.


Ensuring you get enough vitamin D is something you can do before hospitalization. Once there, there are additional steps you can take to avoid delirium…or arrest it before it gets too bad. Whether it’s you or a loved one, make sure that items such as eyeglasses or hearing aids are readily available, books and other familiar objects are nearby, and that the patient walks around if possible, stays hydrated, and gets as much sleep as possible in the sleep-depriving hospital environment. Regular visits from friends and family are key, since being (and feeling) isolated can lead to loneliness and fear that in turn can be a factor in delirium. Monitor medications carefully, especially pain and sleep drugs, which can contribute to confusion and push a patient toward delirium. If you’re caring for a loved one who does become agitated, confused or disoriented while in the hospital—even if it comes and goes, a common feature of hospital-induced delirium—alert the staff and ask specifically for a delirium evaluation from a mental health care provider. Basic treatment, including making sure the patient is well hydrated and nourished…stops taking dangerous medications if possible…gets daily exercise…is surrounded by familiar objects…and stays connected to family and friends, can often turn incipient delirium around before it gets too bad. For more prevention tips, see Bottom Line’s Delirium Danger and Bottom Line’s Protect Your Mind in The ICU.