Could Diet Alter Your Personality?

When we think about personality, we often imagine something deeply ingrained—our tendencies toward extroversion or introversion, our levels of agreeableness or openness to new experiences. Personality seems fixed, an immutable aspect of our core character. But what if this foundation isn't as rigid as we think? What if something as seemingly mundane as the food we eat could alter our personality?

Emerging research in neuroscience and nutrition suggests that diet and personality may be more closely linked than previously imagined. By exploring how nutrients influence brain function, gut health, and hormonal balance, we can begin to understand how the food on our plates might shape who we are, leading to interesting questions and reconsiderations around what makes us…us.

Personality: A Dynamic Trait

Personality is defined as a set of enduring patterns in thoughts, emotions, and behaviors that characterize an individual. Beyond influencing our preferences in partners, friends and more, personality can predict success in life, with certain traits (e.g., higher conscientiousness is associated with longer lifespan). While there are many categorizations of personality, the Big Five (Openness to experience, Conscientiousness, Extraversion, Agreeableness and Neuroticism) are some of the best studied.

It’s important to note that personality traits do change over the years. In early life there may be the most variability in personality, while decreasing levels of change over the course of the decades after age 30. In a recent meta-analysis, it was concluded that some traits (conscientiousness and emotional stability) experience large increases into middle adulthood, with emotional stability increasing throughout our lives. The analysis also suggests that unhelpful traits may be less stable (and therefore more changeable) over our lifespans. Global events may also alter personality traits at scale, as indicated by a 2024 study demonstrating increases in conscientiousness and decreases in extraversion during the COVID-19 pandemic. This work in sum suggests that personality is far from locked into place.

What creates patterns of personality? Genetics certainly play a role, with recent research suggests somewhere between 30-40% heritability. This suggests however, that most of the variables shaping us exist outside our specific codes of DNA, and that environmental factors like upbringing, stress, and life experiences play a more significant role than our genes. An emerging domain of neuroscience suggests that one underappreciated environmental influence on our personality is diet. 

The Gut-Brain Axis in Personality

A growing body of research highlights the role of the gut-brain axis in shaping personality. The gut, often referred to as the "second brain," is home to trillions of microorganisms that collectively make up the gut microbiome. These microbes play a critical role in producing signals like lipopolysaccharide and short-chain fatty acids that influence the brain, as well as regulating inflammation and stress responses.

Studies have shown that a healthy gut microbiome is associated with lower levels of anxiety, depression, and irritability—traits that overlap with personality dimensions such as neuroticism and emotional stability. Conversely, an imbalanced microbiome (dysbiosis) may increase the likelihood of mood disorders, potentially exacerbating traits like anger, impulsivity, or pessimism. A powerful 2018 study found high and low levels of specific gut bacteria were linked to traits like neuroticism and conscientiousness. In a 2020 publication, researchers found that personality traits could even predict the makeup of specific bacteria in the gut.

Diet is a primary determinant of the makeup of the gut microbiome and overall state of gut health. A fiber-rich diet low in ultra-processed food is believed to supports the growth of beneficial bacteria, while diets high in processed foods, sugar, and unhealthy fats promote harmful bacteria. Interestingly, personality traits have also been associated with dietary choices, with some research suggesting neuroticism, for example, is associated with unhealthy diets. 

Neuroplasticity, Personality and Nutrition

One of the most exciting developments in neuroscience is the concept of neuroplasticity—the brain's ability to reorganize itself by forming new neural connections because of life experiences. While neuroplasticity is often discussed in the context of learning or recovery from injury, diet plays a crucial role in maintaining this adaptability.

Certain dietary patterns are believed to enhance healthy neuroplasticity. Omega-3 fatty acids, found in fatty fish like salmon and sardines is believed to help promote the growth of new neurons and synapses. Similarly, antioxidants in fruits and vegetables reduce oxidative stress, protecting brain cells and supporting mental flexibility.

Personality traits such as openness to experience or emotional resilience may benefit from enhanced neuroplasticity. For instance, a diet rich in brain-healthy nutrients could help someone become more adaptable, creative, or emotionally balanced over time. While not a component of most people’s daily diet, certain psychedelic molecules that occur naturally in food are known to influence personality traits, potentially through neuroplasticity. One powerful example is that the psychedelic psilocybin (a neuroplasticity-inducing dietary molecule which found in certain mushrooms) may increase extraversion while decreasing neuroticism in depressed patients, and is linked to increased trait openness for over a year in people having mystical experiences.  

How Metabolism Impacts Personality

Another way diet may influence personality is through its impact on metabolism and specifically blood sugar (glucose) levels. Extreme alterations in blood sugar levels are well known to lead to perturbations in brain state. Issues with blood sugar regulation have become widespread, with 10% of the American population experiencing diabetes and 40% having prediabetes. Of note, an unhealthy diet is a major risk factor for the development of each of these conditions.

Recent research demonstrates that blood sugar issues relate to personality traits. For example, a 2022 publication found higher rates of neuroticism and lower trait openness in people with diabetes compared to those without. Additionally, trait neuroticism at age 16 predicts higher rates of developing metabolic issues like diabetes in adulthood.

How do we know that the interactions between metabolism and personality are a two-way street? In a 2013 study, researchers showed that significant weight gain (a key marker of metabolic health issues) was associated with increases in trait impulsiveness. Additional and fascinating work suggests that personality traits correlate with alterations in brain glucose metabolism. With this said, the research linking metabolism with personality traits remains relatively scarce.  

Inflammation, Diet and Personality

One of the most important signaling pathways influenced by food is what it does to our immune system. Most consider immunity primarily through the lens of a defensive system against microbes. However, we now understand that low grade inflammation, which can result from an unhealthy diet, is a risk factor for a host of brain issues ranging from depression to dementia.  Now, research suggests that chronic inflammatory elevation related to diet may also influence personality.

First, multiple studies show that personality traits and inflammation are related. In a recent review of over 4000 people, it was found that lower levels of inflammation were linked to higher extraversion and higher conscientiousness. Personality traits also seem to predict future levels of inflammation. Very recently, researchers have proposed that the interaction between immunity and personality goes both ways. In a powerful 2022 study, it was found that gene variants related to inflammation were able to predict personality traits.

How Much Can Food Change Personality Traits?

While diet has well-established effects on mood and behavior through pathways including neurotransmitters, neuroplasticity, metabolism and inflammation, the extent to which it can change long-term personality traits remains an area of active research. Most studies focus on correlations rather than causation, which means currently, it’s difficult to prove direct links.

While food is not a magic bullet for transforming personality, it is a powerful tool for shaping the biological and psychological conditions that influence how we think, feel, and behave. By nourishing your body with the right nutrients, you may not only enhance your health but also unlock subtle shifts in the traits that define you.

In the end, the relationship between food and personality underscores an exciting truth: we have more control over who we are—and who we become—than we might have thought. So, the next time you sit down for a meal, consider that you're not just feeding your body; you might also be shaping your mind.