Could Vitamin D Help Depression?

Q: I would like to know if taking vitamin D could help depression. What test would determine low vitamin D level, what level is considered healthy? And what’s the difference between D2 and D3 supplements? – Laurie

A: Vitamin D is a fat-soluble vitamin that is obtained naturally through foods (although in limited amounts) and sunlight. However, these forms of vitamin D are not active in the body and each must go through 2 conversions in order to become active.

• The liver must first convert the vitamin to 25-hydroxyvitamin D or vitamin D2.

• Next, the kidneys alter the vitamin D2 to the physiologically active form – 1,25-dihydroxyvitamin D, or D3.

Until recently, vitamin D2 and vitamin D3 were used interchangeably to supplement people with low vitamin D levels. However, research has shown that the forms of vitamin D are metabolized much differently in the body. And though findings regarding the relative effectiveness of vitamin D2 vs. D3 supplementation differ,(1) the Vitamin D Council now advocates the use of vitamin D3 orally, so I defer to them about its use.

The bottom line is to get your doctor to check your 25(OH)D levels because this form is the best indicator of vitamin D status. If your levels are below 35 ng/ml, then I would suggest supplementation with vitamin D3 (the amount varies with the level of deficiency).

As for vitamin D’s role in mood

It has been shown that low vitamin D is linked to some cases of depression, specifically when related to seasonal affective disorder.

• Two research studies have shown that supplementing vitamin D in patients who had seasonal affective disorder (SAD) helped improve symptoms. Others show that light therapy helps symptoms. These patients did not have major depression, only SAD related to decreased sunlight.

• Other studies have linked low vitamin D levels to higher incidence of SAD, PMS, non-specified mood disorder, anxiety, and even major depressive disorder.(2)

More research studies need to be done to determine if vitamin D can play a significant role in alleviating major depression.

In addition, there is evidence that vitamin D is linked with brain health, as higher vitamin D levels increase serotonin.(3)

Another consideration is that links have been found between obesity and low vitamin D levels, increasing the importance of testing for those who may be overweight.(4)

[Note: For those without easy access to tests for 25(OH)D – the circulating form of vitamin D (blood calcidiol), used to diagnose deficiency – the Vitamin D Council has partnered with a testing lab to make a mail-in test kit available online.]

Dr. Kristi Wrightson, ND, MS, RD
1. Some studies have found that vitamin D3 is approximately 3 times more effective in raising and maintaining vitamin D levels in the blood. For example, “Vitamin D2 is Much Less Effective than Vitamin D3 in Humans” (Journal of Clinical Endocrinology & Metabolism, Nov 2004). However, another recent study in the JCEM, including some of the same investigators, found that either D2 or D3 could effectively maintain levels of circulating D in the blood. (“Vitamin D2 is as Effective as Vitamin D3 in Maintaining Circulating Concentrations of 25-Hydroxyvitamin D.”) The studies were designed very differently – in terms of time period, dosage, and initial vitamin D status of subjects in the study. So ultimately more research will be needed on the subject to make sure results can be duplicated.

2. “Vitamin D and Mood Disorders Among Women” (Journal of Midwifery & Women’s Health, Sep-Oct 2008); and
“Vitamin D Deficiency is Associated with Anxiety and Depression in Fibromyalgia” (Clinical Rheumatology, April 2007).

3. “Relationship Between Low Vitamin D and Cognitive Impairment Identified for First Time” (Journal of Geriatric Psychology and Neurology, Jan 2009); “Serum 25-Hydroxyvitamin D Concentration and Cognitive Impairment” (JGPN, Dec 2008); and “Vitamin D and Neurocognitive Dysfunction: Preventing ‘D’ecline?” (Molecular Aspects of Medicine, Dec 2008).

4. “Vitamin D Status and Its Relationship to Body Fat, Final Height, and Peak Bone Mass in Young Women” (Journal of Clinical Endocrinology & Metabolism, Jan 2009); and the theory that “Vitamin D Deficiency is the Cause of Common Obesity” (Medical Hypotheses, Mar 2009).

Note: This information has not been evaluated by the FDA. It is generic and is not intended to prevent, diagnose, treat or cure any condition, illness, or disease. It is very important that you make no change in your healthcare plan or health support regimen without researching and discussing it in collaboration with your professional healthcare team.

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