Vitamin D. What a roller coaster. There's the Vitamin D Council telling you to aim for a level of 60-80 ng/ml, and then the Institutes of Medicine rather grumpily suggest 20 is sufficient with a monstrous report no one has time to read except Chris Masterjohn. Vitamin D Council says no risk of toxicity below 150 - Chris Kresser, Paul Jaminet, and Kurt Harris talk about lack of randomized controlled trials and suggest somewhere between 20-50 as a good range (depending on the expert and depending on your skin color), and there is risk of kidney stones, calcification, and premature aging at higher levels. As I am a (very) pale woman, and I have looked at a bit of the pregnancy and cancer literature, I tend to think, hey, pale pregnant women might do better a bit above 50, Caucasian women should aim for 40-50, and everyone else, 30-40 is probably a good range. But Kurt makes a good point in his podcast with Chris Kresser - the 25 (OH) Vitamin D3 level we al measure is still indirect. 1,25 OH Vitamin D is the active hormone, but its metabolism is tightly regulated and levels are rarely out of a narrow range no matter how deficient we are - so who knows what a low serum level of 25 (OH) Vitamin D3 actually means in local areas, such as the brain, or in scanning for cancer cells in other sequestered areas of the body.
I don't know if I really have much of a horse in this race, though, as the data for mental health is scanty, to say the least. But the theory is sound for vitamin D to play a prominent role in mental health, as it interacts with stress hormones and nerve growth and repair, and seems especially active in those areas of the brain associated with mood, appetite, and sleep (the hippocampus and hypothalamus).
Australian researchers have been valiantly paving the way in single megadoses in seniors for years now. In the Vital D Study, 2317 women over 70 living in the community were recruited from voting rolls (which is compulsory in Australia). Women were included in the study if they had a high risk of hip fracture or previous hip fracture, osteoporosis, or high risk of low vitamin D levels. For several years, they were given a single dose of 500,000 IU Vit D3 or placebo (in 10 easy to swallow capsules) once each year in the autumn or winter, and several measures were followed along the way.
One of the measures, more fractures, proved that standing on the sun once yearly is not a terrific way to prevent them. The active group getting the vitamin D had significantly more fractures and falls.
And then there is depression. It was a lot of people, so the typical short scales were used (the GHQ-12 questionnaire). I already blew the punch line in the title. The active group had no significant difference from the placebo group in the amount of depression or change of depression with the huge bolus of vitamin D3.
Let's look more closely. The average vitamin D level for all the women at the beginning of the study was about 50 nmol/L (1 ng/ml = about 2.5 nmol/l, so the more typical 25 OH vit D3 level measurement I'm used to seeing is 20 ng/ml.) For the most part, the women in the active arm had vitamin D levels 40% higher than the placebo arm, with a level of 120 nmol/l (48 ng/ml) after dosing, and 90 nmol/l (36 ng/ml) after 3 months.
And the discussion, which is (typically) the most interesting part. The association between vitamin D and mental health is inconsistent. Epidemiology shows a correlation between low levels of vitamin D and depression. In a small fibromyalgia study, mood and fibromyalgia symptoms were not related to vitamin D levels before or after supplementation, even in those with vitamin D deficiency. In another 6 month study of older women receiving 800 IU Vit D3 and 1000 mg calcium daily, depression scores did not improve compared to placebo. In another group of folks receiving 100,000 IU Vit D3 vs phototherapy for seasonal affective disorder, Vit D3 was a clear winner. In another study of obese individuals, 20,000-40,000 vit D3 per week for a year showed a beneficial effect on depressive symptoms, though those with a baseline level > 40 nmol/L (16 ng/ml) had no benefit.
How to pull it all together? Well, 1,25 OH Vitamin D, the active form, definitely has a role in the central nervous system in neurogeneration and repair. However, the CNS may have a separate conversion system from 25 OH Vit D3 than the rest of the body. Evidence from a study I blogged about earlier suggests maybe a u-shaped curve is applicable - neonates with the lowest and highest amounts of vitamin D had the highest risk of schizophrenia later in life.
It is probably safe to say that giving 70 year old women massive doses of vitamin D3 once a year is a bad idea - bones and mental state accounted for. "Clinical studies of vitamin D in clinical populations with documented insufficiency remain warranted." And, indeed, at no time in history would we ever have been exposed to 500,000 IU vitamin D3 in a single day.
My personal clinical experience? A LOT (I'd say 1/2 to 2/3) of people who come to see me have horrible vitamin D levels. I live in the far north of the US, but it is not uncommon for levels of 12-14 ng/ml to show up on my initial tests, with the lowest I have seen being 4. I would have to say, sunshine and/or vitamin D supplementation (depending upon the season) has perked up my clinical population over a timeframe of, say, 6 months. At the same time we have implemented other interventions (nutrition, therapy, medication), so who knows what made the difference.
Is Vitamin D the end-all, be-all missing link to the question of crappy modern health and modern disease? No. Does it play a role? Most likely. But you can't overdose on vitamin D via sunshine, and you sure can via megasupplements. Vitamin D is a hormone that sticks around for a while, not something to muck around with willy-nilly. I supplemented this winter, as I was low. I'll make every effort to soak up the rays all summer. Will I supplement next winter? Probably not.