Posted on July 20, 2012 by Brant Cebulla
This week in The British Journal of Psychiatry, researchers in Norway have published results from their randomized controlled trial studying the effects of vitamin D on depressive symptoms in otherwise healthy adults.
The study, directed by Dr Marie Kjaergaard and a team of doctors out of the University Tromsø in Norway, found that vitamin D did not beat placebo in improving depressive symptoms in a population of people with low vitamin D levels.
The researchers studied the effects of 40,000 IU of vitamin D₃ per week for 6 months. They randomized 231 participants to either a placebo group or the vitamin D group. The participants had baseline vitamin D levels of 19 ng/ml. They also measured at baseline and 6 months:
The Beck Depression Inventory (BDI) – a self-completed 21-item questionnaire
The Hospital Anxiety and Depression Scale (HADS) – a multiple-choice 14 question survey on depression and anxiety
The Seasonal Pattern Assessment Scale (GSS) – a 6 item questionnaire used to assess symptoms involved in seasonal affective disorder
Montgomery-Asperg Depression Rating Scale (MADRS) – a 10 question survey assessing depressive symptoms
After 6 months, the vitamin D group’s vitamin D levels rose from 19 ng/ml to a mean level of 59 ng/ml. The placebo group’s levels rose three points to 21 ng/ml. Generally, both the placebo and vitamin D groups’ depression scores improved. However, there was no significant difference between placebo and vitamin D in improving these scores.
In a post hoc analysis, the researchers found a statistically significant improvement in HADS score in the vitamin D group over placebo if the patients started with high scores of BDI, HADS and MADRS. On the other hand, placebo performed better than vitamin D in BDI and MADRS scores if the patients started with low BDI, HADS and MADRS scores. Given this discrepancy, the researchers could not ascertain any difference between vitamin D and placebo.
In further post hoc analysis, there was no difference in the effect of vitamin D supplementation in people that were severely deficient in vitamin D versus moderately deficient in vitamin D. Interestingly, 6 patients dropped out of the placebo group during the study due to “adverse events,” while only 1 patient in the vitamin D group dropped out.
Past studies have found mixed results. These results include:
In a study by Sanders et al, a one-time dose of 500,000 IU had no effect on mental well-being in 2258 community-dwelling elderly women.
On the other hand, a Vieth et al study found that vitamin D at 4,000 IU/day performed better than 600 IU/day for general well being in a small pool of 130 participants.
Furthermore, Lansdowne and Provost reported a significant improvement in mood in 44 healthy subjects who were given either 400 IU or 800 IU of vitamin D in conjunction with vitamin A compared to just vitamin A alone.
Lastly, a Jorde et al study administered 20,000 IU or 40,000 IU of vitamin D/week or placebo in 441 overweight women for a year and saw an improvement in the same BDI questionnaire used in this study.
The authors note that the biggest limitation in their study was study length at 6 months in a disorder that may take several years to develop. They call for more research to definitively answer the question if vitamin D plays a role in depression. We also need a better understanding of how vitamin D affects the brain.
Ksaergaard M et al. Effect of vitamin D supplement on depression scores in people with low levels of serum 25-hydroxyvitamin D: nested case-control study and randomised clinical trial. The British Journal of Psychiatry, 2012.
About Brant Cebulla
Brant Cebulla is the Development Director for the Vitamin D Council. He believes Paleo dieting, high intensity fitness and sun exposure are the future in nutrition.