Study under review: Vitamin D Supplementation Affects the Beck Depression Inventory, Insulin Resistance, and Biomarkers of Oxidative Stress in Patients with Major Depressive Disorder: A Randomized, Controlled Clinical Trial
Everyone feels sad sometimes. For some people, however, sadness can grow into a debilitating medical condition known as depression, or major depressive disorder (MDD). MDD is quite prevalent, affecting approximately 20% of people at some point in their lifetime, and has been linked to other physiological complications, such as increased risk of cardiovascular disease, dyslipidemia, diabetes and hypertension. Increase in oxidative stress in MDD patients has also been reported. Overall, MDD patients have been shown to have decreased lifespan and quality of life.
Vitamin D is a fat-soluble secosteroid (a steroid with an “open” ring) that enhances absorption of essential elements, such as magnesium, iron, calcium, phosphate, and zinc. Traditionally, the majority of vitamin D has been obtained from exposure to sunlight. It is also available through dietary consumption, mostly through fortified foods like milk and cereal. Vitamin D obtained from sunlight or diet requires hydroxylation (addition of a hydroxyl “–OH” group) in the liver to become biologically active.
There are two major forms of vitamin D: D2 (ergocalciferol, obtained from foods) and D3 (cholecalciferol, synthesized following exposure to sunlight). Collectively, both isoforms are termed calciferol. Calciferol is converted into calcidiol, a parahormone, in the liver, and subsequently converted into the biologically active form calcitriol in the kidneys. Calcitriol binds the nuclear vitamin D receptor, which is ubiquitously expressed, inducing transcription of various target genes. Vitamin D plays an important role in proper bone formation and maintenance of bone density, along with a possible role in the immune system. Vitamin D deficiency has been associated with a variety of diseases, including osteoporosis, neurodegenerative diseases, cardiovascular disease, and complications during pregnancy.
Serum vitamin D levels have also been negatively correlated with depressive symptoms. Recent meta-analyses have shown a connection between higher serum vitamin D levels and improved depressive symptoms in people with MDD. There are also a number of studies on the effects of various levels of vitamin D supplementation in MDD patients. Some studies suggest no benefits of vitamin D to mood symptoms of MDD; however, a meta-analysis of existing studies concluded that vitamin D supplementation of 800IU per day or more in vitamin D deficient patients has a positive impact on MDD mood symptoms.
In addition to a positive effect on mood, vitamin D supplementation has been shown to have a positive effect on glucose and cholesterol levels in pregnant women with gestational diabetes (high blood sugar during pregnancy). Recent meta-analyses have indicated that type 2 diabetes is significantly more common in MDD patients, and markers of oxidative stress are elevated in MDD patients. Since the researchers behind the current study have recently shown that high-dose vitamin D supplementation improves glucose levels, oxidative stress and inflammation in type 2 diabetes patients, in this study they wanted to investigate the effect of vitamin D supplementation on oxidative stress and blood glucose in MDD patients, as well as the effect on mood change.
Vitamin D supplementation has been shown to be beneficial in studies on depression and metabolic disorders; however, no studies have investigated effects of vitamin D supplementation on both mood and metabolic markers in a population of MDD patients. This study was designed to investigate the benefits of high-dose 8-week vitamin D supplementation in MDD patients.
Other Articles in Issue #17 (March 2016)
Kneed relief? Try collagen
Glucosamine has gotten the bulk of public attention concerning joint health, and most of the studies, but small amounts of undenatured collagen may be as or more effective for arthritis symptoms.
Chromium has long been viewed as a potential anti-diabetic supplement. But the form of chromium in supplements may not always be the final form your cells get. This study looked at a potential connection to cancer, through testing extremely high dose chromium exposure.
Fish oil and football: an unlikely pair
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- Interview: Marie Spano, MS, RD
Protein: sleep fuel?
Protein is typically thought of as a muscle-building supplement, but its uses go beyond that. This study looked at the potential for protein supplementation to improve sleep during a weight-loss diet.
Creatine, depression, and brain energetics
The human brain is a powerhouse, consuming tons of fuel to keep all those intricate neural connections going. Brain energetics may play a role in major depression, which makes creatine a potential adjunct to antidepressants and therapy.
The taurine-blood pressure connection
With well over half of Americans having either hypertension or prehypertension, effective supplements are a highly researched area. The amino-acid like compound taurine may be a safe and easy-to-obtain treatment option.
Is organic meat healthier?
Part of the allure of organic food is the potential for improved nutrition. But studies in the past have tended to focus on organic plant foods. This broadranging meta-analysis of 67 studies puts organic meat to the test
- Interview: Matt Smith MD