No, I don’t mean that “boring, bland, diet food” (although healthy food is not boring, but more on that later). What I’m talking about is your standard food intake. You know, the “wholegrain” sandwich and pasta, the takeaway pizza, the “healthy” rice bowl or potato mash – those kind of things.
How can they make you depressed – they taste like happiness right?! Well, despite the short-term boost in mood, a high-carbohydrate, high-sugar diet can lead to something called insulin resistance.
Insulin resistance (IR)
What is it? IR happens when the cells in your body are not responding to the hormone insulin. Insulin, a hormone produced by the pancreas, takes excess glucose from our blood stream into many cells throughout the body.
When your cells refuse to open their ‘doors’ to insulin, the excess glucose remains in the blood wreaking all sort of trouble. Here’s just a few of the issues caused by IR:
- The cells run out of fuel. Yes, our cells need glucose to produce energy and function properly.
- The cells become malnourished. When our cells open their ‘doors’ to glucose, they also let in vital nutrients such as amino acids and vitamins. These nutrients are also needed for proper cellular function.
- Burnout of pancreatic cells. The beta-cells of the pancreas are responsible for producing insulin. These cells are stimulated by excess glucose in the blood. Constantly high blood glucose levels will force these cells to work overtime, pumping out as much insulin as they can until they start to burn out and die. The result: reduced capacity of the body to produce insulin. This is the beginning of diabetes.
IR and brain chemistry
OK, we now know that both insulin and glucose are needed to take nutrients into our cells. But how does that relate to our mood, brain chemistry and depression specifically?
You may have heard that our moods are regulated by our brain chemistry. What that means is that certain chemical molecules can affect how our brain cells function. Such molecules are called neurotransmitters – they transmit ‘information’ from a nerve cell to another nerve cell or a muscle cell or any other cell in our body.
Neurotransmitters are made inside the brain from amino acids (the building blocks of protein) and other compounds. To get inside the brain, the amino acids have to pass a protective barrier called the blood-brain barrier (BBB). This process requires sufficient amounts of insulin and the cells to be sensitive to insulin’s actions.
The important neurotransmitters for regulating our moods are serotonin, dopamine, adrenalin, acetylcholine and GABA. Here’s how two of them are made:
Audio from Dr. Oscar Coetzee, Masters in Human Nutrition lecturer and clinical nutritionist.
So when the cells in our body, including the brain, are not responding properly to insulin fewer amino acids can cross the BBB leading to a drop in the amount of neurotransmitters in the brain. This alters our brain chemistry and can lead to many emotional and psychological symptoms including the below:
So here you are – what you eat can make you depressed by altering your brain chemistry! Of course there are more factors including stress, addictive and toxic foods as well as vitamin and mineral deficiencies. These will be covered in future posts, so keep an eye out if you’re interested!