Adams: Let's move on to discuss some of the other disorders or diseases that are correlated with vitamin D deficiency. Let's talk about mental health and Seasonal Affective Disorder.

Dr. Holick: Principally, Seasonal Affective Disorder is due to the fact that people who live in northern climates can't easily regulate the production of melatonin by the pineal gland. And melatonin is a hormone that causes you to fall asleep basically, or to hibernate. And so for many people that live in northern latitudes, the sun's rays are not intense enough and long enough in exposure time to regulate melatonin levels. So people will wake up in the morning in winter time, their melatonin levels are not suppressed as they should be if you're exposed to some bright sunlight, and as a result they feel tired and they want to hibernate throughout the winter. They get depressed.

There is one study, however, that looked at patients with seasonal affective disorder and looked at exposing them to a tanning bed, and looking at their vitamin D levels, and they could show a direct benefit from increasing blood levels of 25-hydroxy vitamin D and relief of symptoms of seasonal affective disorder. We also know that people during the winter time have aches and pains in their bones and muscles, and it also makes them depressed. And we now recognize that vitamin D is very important for muscle function, and that people who are vitamin D deficient are prone to have muscle weakness, they're more likely to fall and they're more likely to have bone fractures. We also know that if you're vitamin D deficient, not only does it precipitate and exacerbate osteoporosis in older men and women, but it causes a very subtle and quite devastating bone disease known as osteomalatia. Long story short, osteomalatia is like adult rickets. And what it does is it causes severe bone discomfort, achiness in the bones and also in the muscles. And these patients are often misdiagnosed as having fibromyalgia.

Adams: Yes, that makes sense.

Dr. Holick: There was a study done in Minnesota by Dr Plotnikoff and what he showed was that, he looked at over 150 individuals. And we're talking about children ages 10+ and adults up to the age of 65, presenting at a Minnesota hospital in the wintertime, complaining of muscle aches and pains and bone pain. Many of these, especially young women in their 20s, were given Motrin or some type of over the counter drug, or even a prescription strength anti-inflammatory drug (NSAIDs) because the doctors couldn't figure out what was going on. 93% of that entire group of children and adults complaining of bone pain or muscle pain were vitamin D deficient.

Adams: Wow.

Dr. Holick: And none of the doctors at the time recognized the signs and symptoms or worked these people up for vitamin D deficiency, or treated them appropriately.

Adams: What a tragic failure of diagnosis and treatment.

Dr. Holick: I see this all the time in my clinic. I see women as well as men coming in complaining of severe achiness in their bones and muscles. A complete work up, sometimes thousands of dollars are spent, to do all kinds of tests, not to find the cause, only to be seen by me, only to find that they're vitamin D deficient. As I explained, it takes months, it takes years to become vitamin D deficient, and to have such problems with your bones and muscles, and it takes months at least if not up to a year of intensive vitamin D treatment and sunlight exposure in order to reverse that effect.

Adams: That's an important bit of information: you're saying months to years to reverse the deficiency?

Dr. Holick: Right, but what I also tell my patients is that they'll begin to feel better after a month or two, but it's not something that's going to happen overnight. And I have one particular case of a woman who was hospitalized, totally immobile and was just complaining of global bone pain and muscle aches and weakness ... she couldn't even get out of bed! And her doctors didn't know what to do with her. She basically was admitted to the hospital to die. And I happened to see her because I was on call for that weekend, and I instantly recognized it -- she was African American, she was not outside at all. I was convinced based on my physical exam. Typically what I like to do is if you take your forefinger and press on the breastbone a little bit, if the patient winces in pain, it's consistent with osteomalatia. And that's exactly what she did. She was excruciatingly uncomfortable with minimum touching of her sternum. I was convinced that she had osteomalatia. And I told her, I want you out of the hospital. I'm giving you vitamin D, and I'm telling you to go out and be exposed to some sunlight, and you're going to start feeling better in a month or two. Hopefully you'll get in your wheelchair, and then eventually you'll be able to walk within six months. And then sure enough, I just saw her in clinic this past Monday, and she now is up and walking around, using a walker. Really almost for the first time in half a dozen years.

Adams: Fascinating. How many other people are in nursing homes and hospitals right now suffering from nothing more complicated than this deficiency?

Dr. Holick: I saw another case in my clinic on Monday, which was absolutely shocking, which again shows how pervasive this concept is that the American Academy of Dermatology has provided to the media. I saw a 45 year old woman who brought in her 7 year old son, and her son had severe rickets. She's Caucasian, as is her son and the father. And she was told, because she was older when she had her first pregnancy that she was at very high risk of having a potential problem, that she should never be exposed to any sunlight.

Adams: Unbelievable!

Dr. Holick: And so she followed her physician's advice. And then she was told that when she gives birth, that she should solely breastfeed her infant, and that the infant should not receive any extra outside nutrition or supplements. And she followed the physician's advice.

Adams: And passed on the vitamin D deficiency.

Dr. Holick: By this age, the child had severe bowing of the legs, and that's severe rickets.

Adams: Fascinating. And it seems like, well, what do you estimate -- how many people are in nursing homes and hospitals right now with this condition, and those buildings are typically windowless...

Dr. Holick: Doesn't matter actually, because vitamin D rays are absorbed by the glass, so even if you're exposed to sunlight through glass, you can't make any vitamin D.

Adams: And that's all glass?

Dr. Holick: All glass. And so if you're driving in the car all the time, it's not going to do you any good. But the bottom line is this -- a study was done in Mass General Hospital. They found over 50% of inpatients - these are young adults, and middle aged, and older adults - were vitamin D deficient. Typically, on average, probably 50-80% of nursing home residents, 50-60% of inpatient hospital patients, and on average I would estimate, 40% of the population in the United States at large, if they're not getting some sensible sun exposure, are probably deficient in vitamin D.