Lower levels of certain probiotics in the gut might be linked to a higher risk for depression, according to a study from the National Institute of Neuroscience in Tokyo. Counts of bifidobacterium and Lactobacillus in fecal samples were estimated in 43 patients with depression and 57 controls. Results showed that the patients with depression had significantly lower levels of Bifidobacterium and tended to have lower Lactobacillus counts compared to healthy controls. Individuals with bacterial counts below an optimal cut-off point were much more likely to be depressed. There also was a higher risk in these patients for irritable bowel syndrome (IBS). How often an individual consumed fermented milk products was directly related to the Bifidobacterium count. The researchers conclude that this is the first study to find a direct link between lower probiotic levels in the gut and major depressive disorder.

Reducing trans fatty acid intake improves mood, according to researchers at Loma Linda University School of Public Health.

People who eat healthful diets are less prone to anxiety and depression, according to a study from Isfahan University of Medical Sciences in Iran.

In Perspective: Maintaining a healthy gut environment appears to affect the circulatory, hormonal, immune, and even appetite systems, possibly lowering the risk for everything from heart disease, allergies, colds, and diabetes to food cravings and obesity.  The Tokyo study suggests we can add mood to that list.

Aizawa E, Tsuji H, Asahara T, et al: Possible association of Bifidobacterium and Lactobacillus in the gut microbiota of patients with major depressive disorder. Journal of Affective Disorders 2016;202:254-257.

Ford P, Jaceldo-Siegl K, Lee J, et al: Trans fatty acid intake is related to emotional affect in the Adventist Health Study -2. Nutrition Research 2016;36:509-517.   

Saneei P, Hajishafiee M, Keshteli A, et al: Adherence to Alternative Healthy Eating Index I relation to depression and anxiety in Iranian adults. British Journal of Nutrition 2016;116:335-342.