3 Foods Psychologists Avoid Eating At All Costs

Nutritional psychiatry is a relatively new yet intriguing field in the study of health. You may have heard that you should avoid eating a particular dessert if you have an upset stomach or that there are foods to both avoid and eat for your cholesterol. But researchers are also studying how what you consume can affect your brain and mental health. 

There are a few reasons for this, but a big one is the connection between your gut and brain. As explained by registered dietitian Christine Byrne in Outside, "Ninety-five percent of our body's serotonin (the neurotransmitter that helps regulate mood) is produced by probiotics in the gut." So it makes sense that what you put in your gastrointestinal system, how it's digested, and what bacteria it feeds can all have a bearing on your mood. With this in mind, there are usually recommendations to include whole foods, lots of fruits and vegetables, and healthy fats (as observed in regimens like the Mediterranean diet). 

What foods should you avoid eating, though? If you were to google the question, you'd face lots of different recommendations. However, most experts would largely group the foods into three broad varieties — refined or added sugars, highly processed foods, and alcohol. While this is by no means an exhaustive list, it's a fairly widely-discussed one. Refined sugars, for example, have been linked with increasing your risk of depression and impairing memory. Let's take a closer look. 

Refined and added sugars could increase your risk of depression

In a 2017 study published in Scientific Reports, a cross-sectional analysis of 23,245 people found that consuming added sugars through sweet treats and beverages was linked with increased risk of common mental disorder (CMD) and depression. Elsewhere, a 2019 meta-analysis of observational studies published in the Journal of Affective Disorders found that drinking sugar-sweetened beverages could lead to depression. In 2024, a cross-sectional study spanning the years 2011–2018 published in BMC Psychiatry found that an increase of 100 grams a day of dietary sugar intake was associated with 28% higher prevalence of depression. The researchers looked at 18,439 adults aged 20 years or older. 

Refined or added sugars have inflammatory effects on your body, which could be one of the reasons for these mental health concerns. Additionally, drastic spikes and drops in blood glucose levels can have negative consequences on your mental wellbeing. Notably, the sugar "high" that you feel after consuming the food (thanks to the dopamine system reward) also results in a crash — leading to mood fluctuations. It also doesn't help that sugar can be highly addictive for some people. It perpetuates a vicious cycle that doesn't benefit your body or your brain long-term. 

In a piece for Aviv Clinics, dietician Kathryn Parker said when it comes to memory, overconsumption of refined sugars is thought to hamper the production of a chemical connected to learning, memory, and complex thinking called brain-derived neurotrophic factor, or BDNF. High-fructose corn syrup, table sugar, and coconut sugar are some examples of refined sugars. Candy, cakes, cookies, and soft drinks typically contain added sugars.

Avoid eating highly processed foods

It might feel like it's hard to avoid processed foods, especially when you walk down the aisles of a supermarket and all you see are labels that are long and confusing to read. But experts put highly processed foods on the list of foods you should avoid. We're talking sugary beverages, processed meats, fast food, frozen meals, etc. 

According to a 2023 study published in JAMA Network Open, increased consumption of ultra-processed foods was associated with increased risk of depression. A 2022 systematic review and meta-analysis in Nutrients linked this type of diet with increased risk of depressive and anxiety symptoms. Yet another 2022 study published in JAMA Neurology connected highly processed foods with cognitive decline in middle-aged and older adults. 

Again, experts point to the gut to mind connection. Not consuming enough fiber, as a result of overconsuming ultra-processed foods, could be one factor. As explained by Wolfgang Marx, president of the International Society for Nutritional Psychiatry Research, fiber (apart from being food for good bacteria) helps with the production of short-chain fatty acids in your gut, which in turn impacts your brain. "We know that people with depression and other mental disorders have a less diverse composition of gut bacteria and fewer short-chain fatty acids," he told (The New York Times). The chemical additives don't help, he added, as they can mess with your gut health too. Plus, highly processed foods can shorten telomere length (the DNA marker for cellular aging). "Shortening our telomeres may mean that we are at risk of degenerative disease earlier in life," nutritional psychiatrist Dr. Uma Naidoo wrote in a CNBC piece.

Alcohol is the third addition to the list

Excessive alcohol consumption was linked with poor academic performance and mental health outcomes among 2,518 undergraduate students aged 18 to 24, per a 2017 study published in PLOS One. Elsewhere, a 2017 cross-sectional study of the Finnish general population published in the European Journal of Public Health found that binge drinking is tied to psychological distress, a lack of life satisfaction, and poor mental health.

If you enjoy a drink or two every now and again, you're probably already aware of how alcohol lowers your inhibitions and makes you feel carefree and happy. But the other side of the coin is that emotions like sadness, anger, or frustration might also become more pronounced. Alcohol is a depressant, which means that it decreases central nervous system activity and slows down brain functioning, leading to slurred speech, impaired movement, etc. Long-term consumption can decrease the neurotransmitters in your brain resulting in increased feelings of anxiety and depression. This is why alcohol is on the list of foods you should avoid when dealing with depression.  

Low self-esteem, impaired learning and learning capacity, induced panic, poor judgment, and diminished executive function are some of other brain-related long-term and short-term effects of alcohol consumption. Now that you know about three foods psychologists steer clear of, you may want to check out three popular foods cardiologists avoid eating at all costs.

If you or someone you know needs help with mental health, please contact the Crisis Text Line by texting HOME to 741741, call the National Alliance on Mental Illness helpline at 1-800-950-NAMI (6264), or visit the National Institute of Mental Health website.