Digestion: the root of depression and anxiety?

As someone who has suffered from depression and anxiety in some form for basically as long as I can remember, I’ve been told over and over again that depression and anxiety are caused by a chemical imbalance in the brain. And for a while I believed this. I tried a variety of antidepressants and other pharmaceuticals, some of which even worked—for the short-term. But I was always left with lingering symptoms. What I finally discovered was that a chemical imbalance isn’t the whole story, and may not even be an accurate way to think about mental health at all (1)! Instead we need to start at the beginning, to how our bodies get all of the raw materials needed for mood regulation (including for building the neurotransmitters that traditional medical practitioners place so much focus on): Digestion.

In this article I’ll first describe the ways that digestion of particular macronutrients—in particular, protein and fat—significantly impact our mental health status, and then provide some concrete steps you can take to start improving your digestion.

Let’s first take a look at proteins. Neurotransmitters (for example serotonin, dopamine, GABA, norepinephrine, and acetylcholine—neurotransmitters directly linked to mood) are primarily synthesized from amino acids which the body obtains by properly digesting proteins. A diet lacking in protein or poor digestion of proteins (for example due to inadequate hydrochloric acid production in the stomach—we’ll talk about this later, don’t worry) can lead to low quality neurotransmitter production. Neurotransmitter issues can manifest as mood disorders including depression, anxiety, impulse control issues, and irritability, amongst others. Importantly, although a variety of neurotransmitters have been linked to mood, recent research argues against the deficiency/imbalance model commonly touted in the medical community (more on this in another post) (1). Good quality sources of protein include grass-fed beef, pasture raised chickens and eggs, and wild-caught fish.

Fat digestion is also fundamental to healthy brain function which, in turn, is crucial to promoting mental wellness. The brain is composed of approximately 60 percent fat and so proper fat digestion provides the essential building blocks for brain health (2). The fatty acids that we get from properly digesting fats are also a key component of cell membranes (including brain cells), which play a huge role in cell communication and subsequently our mood and cognition. High quality fats you can incorporate in your diet include butter or ghee from grass-fed cows, cold-pressed olive and avocado oils, organic coconut oil, and a variety of nuts and seeds.

So how do you know if you are digesting your food well? If you have symptoms like acid reflux, bloating, gas, diarrhea, constipation, greasy stools (or stools that float), it’s possible that you are not digesting your food as well as you could be. One of the most common digestive issues many people face is a lack of hydrochloric acid production in their stomachs (3). When this happens, our bodies are unable to break down proteins appropriately (which is so necessary for building neurotransmitters). Similarly, greasy or floating stools is a good indicator that fats are not being digested properly. Working with a functional nutritionist can help pinpoint specific digestive issues you might be facing, but here are four tips to improve digestion that you can start doing right now!

1) Before you start eating, take at least 2-3 deep breaths. This relaxes your body, switching your brain from sympathetic mode (fight or flight) to parasympathetic mode (rest and digest).

2) Try to eat slowly and chew each bite sufficiently. Try for at 20-30 chews per bite.

3) Make sure to consume water away from meals, at least 10 minutes before or after eating. Drinking water during meals dilutes the hydrochloric acid in our stomachs which can significantly impact our digestion (for more on this see a great blog post.

4) If you are experiencing any of the digestive issues listed here try adding apple cider vinegar (about 1-2 tablespoons) or lemon juice to a small amount of water and drinking immediately before eating. This will help increase the acidity of your stomach for support in digestion (3).



(1) Lacasse, J.R., and J. Leo. (2005). Serotonin and Depression: A Disconnect between the Advertisements and the Scientific Literature. PLoS Medicine 2(12): 1211-1216.

(2) Chang, C.Y., Ke, D.S., and J.Y. Chen. (2009). Essential fatty acids and the human brain. Acta Neurologica Taiwanica 18(4): 231-241.

(3) Wright, J.V., and Lenard, L. (2001). Why Stomach Acid is Good for You: Natural Relief from Heartburn, Indigestion, Reflux, and GERD. New York: M. Evans.