The Effects of Probiotics on Depression

by | Aug 22, 2016 | 2016, Depression, Probiotics

Written by Joyce Smith, BS. Eight weeks of probiotic supplementation significantly decreased depression scores, serum insulin levels and hs-CRP while improving insulin resistance and markers of oxidative stress in 20 study participants suffering from major depressive disorder.

shutterstock_310585019Major depressive disorder (MDD), or clinical depression, is a common but serious mood disorder. It causes severe symptoms that can affect how you feel, think, and handle daily activities, such as sleeping, eating, or working. 1 It affects 20 % of the population at some point during their lifetime. 2 Current studies link MDD to lower antioxidant levels, particularly glutathione (GSH) 3 (6) while past studies have shown various health benefits of probiotic supplementation. 4,5 To date, no studies have explored the effects of probiotic use on symptoms of depression, metabolism, high sensitivity C-reactive protein (hs-CRP) and oxidative stress biomarkers in patients with MDD.

The objective of this present study is to determine the effects of probiotic supplementation on depression and metabolic status in patients with MDD.

This study is a randomized, double-blind, placebo-controlled clinical trial involving 40 MDD patients, between 20 and 50 years of age. They were randomly assigned to two groups to receive either probiotic supplements (17 women and 3 men, n=20) or placebo (17 women and 3 men, n=20) for a period of 8 weeks. Probiotic supplements contained Lactobacillus acidophilus (2 × 109 CFU/g), Lactobacillus casei (2 × 109 CFU/g), and Bifidobacterium bifidum (2 × 109 CFU/g). (These probiotic doses were based on a few previous studies in healthy subjects). The placebo group received a placebo that contained starch but no bacteria.

All participants were provided with three dietary records (two weekdays and one weekend) and three physical activity records during the 8 –week period to ensure that they maintained their usual diet and physical activity during this time. Fasting blood samples were taken at the beginning and end of the trial to quantify the relevant variables.

After 8 weeks of supplementation, the probiotic group yielded the following results when compared to the control (placebo).

  • A significant decrease in Beck Depression Inventory (BDI) total scores (−5.7 ± 6.4 vs. −1.5 ± 4.8) (P = 0.001)
  • Significant decreases in serum insulin levels (−2.3 ± 4.1 vs. 2.6 ± 9.3 μIU/mL) (P=0.03)
  • A significant decrease in Homar-IR, a measure of insulin resistance (−0.6 ± 1.2 vs. 0.6 ± 2.1) (P = 0.03)
  • Significant decrease in hs-CRP (−1138.7 ± 2274.9 vs. 188.4 ± 1455.5 ng/mL) (P = 0.03)
  • Significant rise in plasma GSH (1.8 ± 83.1 vs. −106.8 ± 190.7 μmol/L) (P = 0.02)

There were no significant differences between the probiotic and placebo groups with respect to weight, BMI, dietary intake, and physical activity. There was also a trend towards a significant decrease in HOMA-B (P = 0.06) and a significant increase in QUICKI score (P = 0.07) The QUICKI score is a reliable yet simple indirect method for detecting insulin resistance (IR).

This study has several limitations. It did not analyze the impact of probiotic supplementation on more specific biomarkers of inflammation and oxidative stress. Also, long-term studies are necessary to confirm the benefits of probiotic supplementation on cholesterol and triglycerides levels. This study did not mention the specific strains of Lactobacillus acidophilus, Lactobacillus casei, and Bifidobacterium bifidum that were used. Studies involving individual probiotic strains are necessary to determine which probiotic strains positively affected depression and/or metabolic status in MDD patients. Finally large scale trials should be done to confirm the findings of this study.

Source: Akkasheh G, Kashani-Poor Z, Tajabadi-Ebrahimi M, et al. Clinical and metabolic response to probiotic administration in patients with major depressive disorder: A randomized, double-blind, placebo-controlled trial. Nutrition. 2016;32(3):315-320.

Copyright © 2016 Elsevier Inc. All rights reserved.

Posted August 22, 2016.

References:

  1. Yamanishi K, Doe N, Sumida M, et al. Hepatocyte nuclear factor 4 alpha is a key factor related to depression and physiological homeostasis in the mouse brain. PloS one. 2015;10(3):e0119021.
  2. Kessler RC, Berglund P, Demler O, Jin R, Merikangas KR, Walters EE. Lifetime prevalence and age-of-onset distributions of DSM-IV disorders in the National Comorbidity Survey Replication. Archives of general psychiatry. 2005;62(6):593-602.
  3. Lapidus KA, Gabbay V, Mao X, et al. In vivo 1 H MRS study of potential associations between glutathione, oxidative stress and anhedonia in major depressive disorder. Neuroscience letters. 2014;569:74-79.
  4. Broekaert IJ, Walker WA. Probiotics and chronic disease. Journal of clinical gastroenterology. 2006;40(3):270-274.
  5. Asemi Z, Jazayeri S, Najafi M, et al. Effect of daily consumption of probiotic yogurt on oxidative stress in pregnant women: a randomized controlled clinical trial. Annals of Nutrition and Metabolism. 2012;60(1):62-68.