![[Adobe Stock]](https://sp-ao.shortpixel.ai/client/to_webp,q_glossy,ret_img,w_750,h_375/https://www.psypost.org/wp-content/uploads/2025/07/sad-depressed-man-750x375.jpg)
Increased intake of dietary selenium is associated with a lower likelihood of reporting suicidal thoughts among American adults. A recent analysis of population health data indicates that as consumption of this trace mineral rises, the odds of experiencing suicidal ideation decrease. These findings were published in the Journal of Affective Disorders.
Suicide remains a persistent public health challenge around the world. Public health officials and medical professionals prioritize identifying early warning signs to prevent tragic outcomes. Suicidal ideation, characterized by thinking about self-harm or ending one’s life, is a primary indicator of future suicide attempts.
Most prevention strategies currently focus on psychological and social risk factors. Mental health professionals typically look for signs of depression, anxiety, or social isolation. However, researchers are increasingly investigating how physical health and nutrition influence psychiatric well-being.
Trace minerals play specific roles in brain function and mood regulation. Selenium is one such essential element. It is found naturally in soil and appears in foods such as nuts, seafood, meats, and whole grains.
The body utilizes selenium to create selenoproteins. These proteins help manage oxidative stress and regulate the immune system. Previous research has hinted at a link between low selenium levels and mood disorders like depression.
Haobiao Liu of Xi’an Jiaotong University and Zhuohang Chen of Fudan University sought to explore this connection specifically regarding suicidal ideation. They noted that prior studies on trace elements and suicide yielded inconsistent results. Some earlier investigations were limited by small participant numbers or specific demographic focuses.
Liu and Chen designed their study to analyze a much larger and more representative group of people. They utilized data from the National Health and Nutrition Examination Survey (NHANES). This program collects health and nutritional information from a cross-section of the United States population.
The researchers aggregated data from survey cycles spanning from 2005 to 2016. They applied strict exclusion criteria to ensure the reliability of their dataset. For example, they removed individuals with implausible daily calorie counts to avoid data errors.
The final analysis included 23,942 participants. To assess what these individuals ate, the survey employed a dietary recall interview. Participants described all food and beverages consumed over the preceding 24 hours.
Interviewers conducted two separate recalls for each participant to improve accuracy. The first took place in person, and the second occurred via telephone days later. The researchers calculated average daily selenium intake from these reports.
To measure mental health outcomes, the study relied on the Patient Health Questionnaire (PHQ-9). This is a standard screening tool used by doctors to identify depression. The researchers focused specifically on the ninth item of this questionnaire.
This specific question asks participants if they have been bothered by thoughts that they would be “better off dead” or of hurting themselves. Respondents answered based on their experience over the previous two weeks. Those who reported having these thoughts for several days or more were classified as having suicidal ideation.
The researchers used statistical models to look for associations between selenium levels and these reported thoughts. They accounted for various confounding factors that could skew the results. These included age, gender, income, body mass index, and overall diet quality.
The analysis showed an inverse relationship. Participants with higher levels of dietary selenium were less likely to report suicidal ideation. This association persisted even after the researchers adjusted for the other demographic and health variables.
The researchers calculated the change in risk based on units of selenium intake. In their fully adjusted model, they found that a specific unit increase in intake corresponded to a 41 percent decrease in the odds of suicidal ideation. This suggests a strong statistical link between the nutrient and mental health status.
To understand the trend better, the researchers divided participants into four groups based on intake levels. These groups are known as quartiles. The first quartile had the lowest selenium intake, while the fourth had the highest.
Comparing these groups revealed a consistent pattern. Individuals in the top three groups all had a lower risk of suicidal thoughts compared to the bottom group. The risk reduction was most pronounced in the group with the highest consumption.
The study also tested for a “dose-response” relationship. The analysis indicated a linear negative association. As the amount of selenium in the diet went up, the reports of suicidal thinking went down.
The authors propose several biological reasons why this might happen. One theory involves oxidative stress. The brain is sensitive to damage from free radicals, and selenium-based enzymes help neutralize these threats.
Another potential mechanism involves inflammation. High levels of inflammation in the body are often found in people with depression and suicidal behaviors. Selenium has anti-inflammatory properties that might help protect the brain from these effects.
Neurotransmitters may also play a role. These are the chemical messengers that allow nerve cells to communicate. The study authors note that selenium might influence the regulation of serotonin and dopamine, which are critical for mood stability.
Despite these promising findings, the study has several limitations. The research was cross-sectional in design. This means it captured a snapshot of data at a single point in time rather than following people over years.
Because of this design, the study cannot prove that low selenium causes suicidal thoughts. It only shows that the two things are related mathematically. It is possible that people who are depressed simply eat fewer nutrient-rich foods.
Another limitation is the reliance on memory for dietary data. It is difficult for people to remember exactly what they ate in the last 24 hours. This can lead to inaccuracies in the estimated nutrient intake.
The assessment of suicidal ideation also had constraints. Using a single question from a depression screener provides a limited view of a complex behavior. It does not capture the severity or duration of the thoughts in detail.
The researchers also acknowledged that individual biology varies. People absorb nutrients differently based on their genetics and gut health. The study could not account for how well each participant’s body utilized the selenium they consumed.
Future research is necessary to confirm these results. The authors suggest that prospective studies are needed. These would follow large groups of people over time to see if baseline selenium levels predict future mental health issues.
Clinical trials could also provide stronger evidence. In such studies, researchers would provide selenium supplements to some participants and placebos to others. This would help determine if increasing intake directly improves mental well-being.
Investigating the biological pathways is another priority. Scientists need to understand exactly how selenium interacts with brain chemistry. This could lead to new treatments or dietary recommendations for people at risk of suicide.
Until then, the findings add to a growing body of evidence linking diet to mental health. They highlight the potential importance of proper nutrition in maintaining psychological resilience. Public health strategies might one day include dietary optimization as part of suicide prevention efforts.
The study, “Does dietary selenium protect against suicidal ideation? Findings from a U.S. population study,” was authored by Haobiao Liu and Zhuohang Chen.
