Can Eating More Dietary Fiber Reduce Suicidal Thoughts?

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  • An analysis of data from the National Health and Nutrition Examination Survey published in the Frontiers in Nutrition found that individuals who eat very little fiber in their diet are more likely to think about suicide.
  • For every additional daily 1 gram of fiber per 1000 kcal of food, the risk that a person will be thinking about suicide decreased by 5%.
  • After dietary fiber intake reached 7.8 grams per 1000 kilocalories of food per day, further increase in fiber consumption was not associated with the risk of thinking about suicide

Editor’s Note: This article presents the results of a scientific study published in a scientific journal. It does not constitute medical advice. The presented results are correlational in nature, and they should not be interpreted as cause-and-consequence relations. The origin of the reported association is unclear. It is possible that intentionally eating more dietary fiber would not affect suicidal ideation. Dietary fiber intake or diet in general is not a replacement for appropriate medical treatment.

The desire to survive and preserve one’s own life is one of every individual’s most powerful instincts. It is deeply rooted in both biological and psychological processes developing in our bodies. This instinct, called self-preservation instinct, is what makes us prioritize the pursuit of basic needs such as food, water, shelter, or safety. It operates through our body’s stress response, the response that prepares us to flee, fight, or freeze in response to threats (Corr, 2004; Russell & Lightman, 2019), but also through our desire to avoid pain and reactions to situations that cause fear.

The self-preservation instinct makes us prioritize basic needs such as food, water, shelter, or safety and operates through our body’s stress response.

Suicide

In spite of this, more than 700,000 people worldwide intentionally end their own lives every year (Huang et al., 2024). They commit suicide. Many do it due to overwhelming emotional pain, feelings of hopelessness, or because they believe that their situation cannot improve. These feelings become so strong in these individuals that they overwhelm the self-preservation instinct.

Mental health conditions contribute significantly to the risk of suicide. Estimates state that the risk of suicide is 5-8% for individuals suffering from depression, alcoholism, or schizophrenia (Brådvik, 2018). Social factors, like isolation, financial stress, or abuse, can amplify the feelings leading to suicide. In some cases, impulsive decisions during a moment of intense distress lead to suicide.

Suicidal ideation – thinking about suicide

Committing suicide is generally not easy. Aside from the self-preservation instinct, humans design their environments and societies to preserve human well-being and prevent harm. Before committing suicide, individuals first start thinking intensely about it. This is called suicidal ideation.

It usually starts with an occasional thought of death or an imagination of life ending without any plans to act on it. As distress deepens, a person might actively start contemplating the idea of suicide. Further down the line, one might start forming a plan, deciding on the method, time, and place. In the final stage, the person will start gathering the means to commit suicide and take preparatory steps, ultimately leading to making an attempt on one’s own life. This process is described by what is now called a three-step theory of suicide (Klonsky & May, 2015).

The current study

Study author Huaying Huang and her colleagues noted that dietary interventions have shown great potential for preventing and treating affective disorders (Huang et al., 2024). This includes regulating dietary fiber intake. A recent meta-analysis showed that an increase of 1 gram in dietary fiber intake (per day) reduces the risk of depression by 24% (Fatahi et al., 2021). These authors hypothesized that dietary fiber intake might also be associated with suicidal ideation (thinking about suicide). They analyzed data from the National Health and Nutrition Examination Survey to explore this.

What is dietary fiber?

Dietary fiber is a type of carbohydrate found in plant-based foods that the body cannot digest. Although the body cannot digest it, dietary fiber serves as a food source for beneficial bacteria living in our guts. The availability of fiber helps these bacteria grow and maintain activity levels. In turn, the activity of these bacteria produces substances that interact with our body, reducing inflammation, strengthening the gut wall lining, and providing other health benefits (Takiishi et al., 2017) (see Figure 1).

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Figure 1: Role of Dietary Fiber in Gut Health

Dietary fiber serves as a food source for beneficial bacteria living in our guts. These bacteria produce substances that interact with our body, reducing inflammation, strengthening the gut wall lining, and providing other health benefits.

 

The National Health and Nutrition Examination Survey

The National Health and Nutrition Examination Survey is a complex study program aiming to evaluate the health and nutritional condition of non-institutionalized residents of the United States. The program selects a nationally representative sample of 5000 individuals every year.

Participants of this study program complete health interviews and undergo physiological examinations. The program collects data on their demographics, socioeconomic situation, dietary habits, health, physical characteristics, and laboratory tests.

This analysis used data from 21,865 participants about dietary fiber intake, obtained through two dietary interviews asking participants to list foods and beverages they consumed in the previous 24 hours. Dietary fiber intake data used in the analysis was the average of quantities participants reported in the two interviews. Data about suicidal ideation came from answers to item nine of the Patient Health Questionnaire (PHQ-9) “Over the last two weeks, how often have you felt that you would be better off dead or hurting yourself in some way?”. Participants’ average age was 47 years. 51% of them were females (see Figure 2).

 

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Figure 2. Study Procedure (Huang et al., 2024).

Higher dietary fiber intake was associated with lower suicidal ideation

Results showed that 781 participants, or 3.6%, thought about suicide (i.e., had suicidal ideation). Individuals with suicidal ideation were more likely to be Hispanics, living alone, and smokers. They tended to have lower education, came from poorer families, and had lower dietary intake of unsaturated fatty acids and sodium.

The average dietary fiber intake was 7.8 grams per 1000 kilocalories of food. Individuals with higher dietary fiber intake were less likely to be thinking about suicide. However, this relationship was more complex. With each additional 1 gram of fiber per 1000 kilocalories of food (per day), the risk that a person will have suicidal ideation dropped by 5%. However, the association between higher dietary fiber intake and decreased risk of suicidal ideation was only present among individuals consuming less than 7.8 grams of fiber per 1000 kilocalories of food. Among individuals consuming more than 7.8 grams of fiber per 1000 kilocalories of food per day, fiber intake was not associated with suicidal ideation (see Figure 3).

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Figure 3. Study Findings  (Huang et al., 2024)

 

Conclusion

The study found that individuals consuming little dietary fiber were at an increased risk of suicidal ideation. Among those consuming average or above-average quantities of fiber, this association was not present. While the cause of this association remains unknown, these findings open a possibility that the risk of suicide in the general population could potentially be reduced through dietary interventions and policies.

The paper “Association between dietary fiber intake and suicidal ideation: a cross-sectional survey” was authored by Huaying Huang, Jianjiong Fu, Keyu Lu, Yaming Fu, Pan Zhuge, and Yu Yao.

 

References

Brådvik, L. (2018). Suicide Risk and Mental Disorders. International Journal of Environmental Research and Public Health, 15(9), 2028. https://doi.org/10.3390/ijerph15092028

Corr, P. J. (2004). Reinforcement sensitivity theory and personality. Neuroscience & Biobehavioral Reviews, 28(3), 317–332. https://doi.org/10.1016/j.neubiorev.2004.01.005

Fatahi, S., Matin, S. S., Sohouli, M. H., Găman, M.-A., Raee, P., Olang, B., Kathirgamathamby, V., Santos, H. O., Guimarães, N. S., & Shidfar, F. (2021). Association of dietary fiber and depression symptom: A systematic review and meta-analysis of observational studies. Complementary Therapies in Medicine, 56, 102621. https://doi.org/10.1016/j.ctim.2020.102621

Huang, H., Fu, J., Lu, K., Fu, Y., Zhuge, P., & Yao, Y. (2024). Association between dietary fiber intake and suicidal ideation: A cross-sectional survey. Frontiers in Nutrition, 11, 1465736. https://doi.org/10.3389/fnut.2024.1465736

Klonsky, E. D., & May, A. M. (2015). The Three-Step Theory (3ST): A New Theory of Suicide Rooted in the “Ideation-to-Action” Framework. International Journal of Cognitive Therapy, 8(2), 114–129. https://doi.org/10.1521/ijct.2015.8.2.114

Russell, G., & Lightman, S. (2019). The human stress response. Nature Reviews Endocrinology, 15(9), 525–534. https://doi.org/10.1038/s41574-019-0228-0

Takiishi, T., Fenero, C. I. M., & Câmara, N. O. S. (2017). Intestinal barrier and gut microbiota: Shaping our immune responses throughout life. Tissue Barriers, 5(4), e1373208. https://doi.org/10.1080/21688370.2017.1373208

 

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