Studies have shown that unprocessed foods, especially fermented foods, help optimize your gut microbiome, thereby supporting optimal mental health, whereas sugar, wheat (gluten) and processed foods have been linked to a greater risk for depression, anxiety and even suicide. The primary information highway between your gut and your brain is your vagus nerve, which connects the two organs.
Your gut also communicates to your brain via the endocrine system in the stress pathway (the hypothalamus, pituitary and adrenal axis), and by producing mood-boosting neurotransmitters like serotonin, dopamine and gamma-aminobutyric acid or GABA. These communication links help explain why your gut health has such a significant impact on your mental health.
The Strong Link Between Sugar and Depression
A number of food ingredients can cause or aggravate depression, but one of the most significant is sugar, particularly refined sugar and processed fructose. For example, in one study, men consuming more than 67 grams of sugar per day were 23 percent more likely to develop anxiety or depression over the course of five years compared to those whose sugar consumption was less than 40 grams per day (which is still far higher than the 25 grams per day recommended for optimal health).
This held true even after accounting for other contributing factors, such as socioeconomic status, exercise, alcohol use, smoking, other eating habits, body weight and general physical health. Lead author Anika Knüppel, a research student in the department of epidemiology and public health at University College London, commented on the findings, saying:
“Sweet food has been found to induce positive feelings in the short-term. People experiencing low mood may eat sugary foods in the hope of alleviating negative feelings. Our study suggests a high intake of sugary foods is more likely to have the opposite effect on mental health in the long-term.”
Research16 published in 2002, which correlated per capita consumption of sugar with prevalence of major depression in six countries, also found “a highly significant correlation between sugar consumption and the annual rate of depression.” A Spanish study published in 2011 linked depression specifically to consumption of baked goods.
Those who ate the most baked goods had a percent higher risk of depression than those who ate the least. This makes sense when you consider baked goods contain both processed grains and added sugars.
How Sugar Wreaks Havoc on Your Mood and Mental Health
Sugar has been shown to trigger depression and other mental health problems through a number of different mechanisms, including the following:
- Feeding pathogens in your gut, allowing them to overtake more beneficial bacteria.
- Suppressing activity of a key growth hormone in your brain called brain-derived neurotrophic factor (BDNF). BDNF levels are critically low in both depression and schizophrenia, and animal models suggest this may actually be a causative factor.
- Triggering a cascade of chemical reactions in your body that promote chronic inflammation, which over the long term disrupts the normal functioning of your immune system and wreaks havoc on your brain.
- Contributing to insulin and leptin resistance, which also plays a significant role in your mental health.
- Affecting dopamine, a neurotransmitter that fuels your brain’s reward system (hence sugar’s addictive potential) and is known to play a role in mood disorders.
- Damaging your mitochondria, which can have bodywide effects. Your mitochondria generate the vast majority of the energy (adenosine triphosphate or ATP) in your body. When sugar is your primary fuel, excessive reactive oxygen species (ROS) and secondary free radicals are created, which damage cellular mitochondrial membranes and DNA. As your mitochondria are damaged, the energy currency in your body declines and your brain will struggle to work properly.
Healthy dietary fats (like coconut oil, olive oil and grass fed butter), on the other hand, create far fewer ROS and free radicals. Fats are also critical for the health of cellular membranes and many other biological functions, including and especially the functioning of your brain.
Among the most important fats for brain function and mental health are the long-chained animal-based omega-3 fats DHA and EPA. Not only are they anti-inflammatory, but DHA is actually a component in every cell of your body, and 90 percent of the omega-3 fat found in brain tissue is DHA.
Eating Real Food Is Key
A paper published in Nutritional Neuroscience last year looked at evidence from laboratory, population research and clinical trials to create “a set of practical dietary recommendations for the prevention of depression, based on the best available current evidence.” According to this paper, the published evidence reveals five key dietary recommendations for the prevention of depression:
- Following a “traditional” dietary pattern such as the Mediterranean, Norwegian or Japanese diet
- Increasing consumption of antioxidant-rich fruits, vegetables, nuts and seeds (note that autoimmune diseases are rampant and whole grains and legumes are loaded with lectins and best avoided.)
- Eating plenty of omega-3-rich foods
- Replacing unhealthy processed foods with real, wholesome nutritious foods
- Avoiding processed foods, fast food, commercial baked goods and sweets
Processed Foods Are Problematic in More Ways Than One
Three brain- and mood-wrecking culprits you’ll automatically avoid when avoiding processed foods are added sugars, artificial sweeteners and processed vegetable oils — harmful fats known to clog your arteries and cause mitochondrial dysfunction. Gluten also appears to be particularly problematic for many. If you’re struggling with depression or anxiety, you’d be well-advised to experiment with a gluten-free diet.
Certain types of lectins, especially wheat germ agglutinin (WGA), are also known for their psychiatric side effects. WGA can cross your blood brain barrier through a process called “adsorptive endocytosis,” pulling other substances with it. WGA may attach to your myelin sheath and is capable of inhibiting nerve growth factor, which is important for the growth, maintenance and survival of certain target neurons.
Processed foods are also a significant source of genetically engineered (GE) ingredients and toxic herbicides like Roundup. In addition to being toxic and potentially carcinogenic, glyphosate, the active ingredient in Roundup, has been shown to preferentially decimate beneficial gut microbes. Many grains need to dry in the field before being harvested, and to speed that process, the fields are doused with glyphosate a couple of weeks before harvest.
As a result of this practice, called desiccation, grain-based products tend to contain rather substantial amounts of glyphosate. This reason alone is enough to warrant a grain-free diet, but if you do choose to eat whole grain products, make sure it’s organic to avoid glyphosate contamination.
Your beverage choices may also need an overhaul, as most people drink very little pure water, relying on sugary beverages like sodas, fruit juices, sports drinks, energy drinks and flavored water for their hydration needs. None of those alternatives will do your mental health any favors.
Anti-Inflammatory Diet Protects and Supports Good Mental Health
As mentioned above, one of the mechanisms by which good nutrition bolsters mental health is by cutting down inflammation in your body, and a high-sugar diet is exceptionally inflammatory. A number of studies have linked depression with chronic inflammation.