By now you may have heard some of the buzz. Scientists first started experimenting in rats and are now doing human studies which seem to show that by introducing certain strains of bacteria into the gut symptoms like depression and anxiety can be altered. Very exciting indeed! I am imagining in 20 years instead of taking Prozac or Xanax we will be eating carefully cultivated symptom-specific yoghurts or kefirs. A much more elegant solution to mood disorders with little to no side effects.
I recently read a study (Steenbergen, Sellaro, van Hemert, Bosh & Colzato, 2015) in which the researchers gave a combination of Bifidobacterium bifidum, Bifidobacterium lactis, Lactobacillus acidophilus, Lactobacillus brevis, Lactobacillus casei, Lactobacillus salivarius and Lactococcus lactis to a group of depressed patients. The participants took the supplement for 4 weeks and showed a significant decrease in symptoms of negative thinking, including negative thoughts directed towards the self. Anyone who has experienced a depressive episode can attest to the painful cycle of rumination on negative thoughts and events as well as the painful self-recrimination and self-attack that occur so often in depressions.
While all of us experience a sad mood from time to time some of us begin to slide down the slippery slope, ending up in a clinical depression. Much of the time mental health providers attribute this vulnerability to genetics, and it very well may be just that. However our ability to influence our genetics at this point is extremely limited. Better to impact the sad mood before it gains momentum and turns into an insidious depressive episode that can span months and debilitate a person.
So how is the magic happening? The mechanisms are still being worked out but our gut actually produces an abundance of chemicals that interact with the brain. Some, like tryptophan, reach the brain through the endocrine system. Others impact the immune system which in turn impacts the brain in areas linked to mood. Research so far seem to indicate that gut microbiota communicates with the nervous system via neural, endocrine and immune pathways. Microbiota also seem to be involved in the regulation of the stress response (e.g. hypothalamic-pituitary-adrenal axis). So having the optimal gut bacteria may actually help us shut down the stress response or even avoid engaging it. The gut is also involved in the inflammatory response and inflammation has been shown to be related to depression (as well as other problems like cardiovascular disease).
So far human studies are limited (I have reviewed 4 to date) but ALL have shown improvement in symptoms of depression and anxiety. Unfortunately the studies don't all use the same bacterium so it's not yet clear which ones are the most powerful. This most recent study utilized a combination of 7 and that seems to be a good way to "hedge your bets". Lactobacillus casei has been used in 3 of the 4 studies I have reviewed so that might be one to look for. As always consult your medical professional if you are going to make changes to your diet including any supplementation. And keep a lookout for more studies to be rolling in. The way to improve your head may just be through your gut!
Wishing you health and happiness,