A new study published in the Journal of Affective Disorders highlights a potential link between dietary intake of spermidine, a naturally occurring compound found in many foods, and a reduced risk of depression. Researchers discovered that higher levels of dietary spermidine were associated with lower rates of depressive symptoms in adults, suggesting that spermidine-rich foods might benefit mental health.
Depression is a widespread mental health disorder that affects millions of people globally. It is characterized by persistent feelings of sadness, loss of interest in activities, and a range of physical and emotional symptoms, such as fatigue, irritability, and difficulty concentrating. Depression can arise from various factors, including genetic predisposition, brain chemistry, environmental stressors, and lifestyle factors like diet.
The impact of depression on quality of life is profound, and it ranks as one of the leading causes of disability worldwide. Given the high prevalence and significant toll of depression, there is a growing interest in identifying modifiable factors, such as diet, that may help in its prevention and management.
Spermidine is a naturally occurring compound found in various foods, including soybeans, red kidney beans, wheat germ, hazelnuts, peas, mushrooms, spinach, cauliflower, broccoli, almonds, pistachios, chestnuts, rice, white bread, apples, bananas, avocados, kiwis, as well as meats like beef, chicken, pork, turkey, and duck, and animal products such as milk and eggs.
It is part of a group of molecules called polyamines, which are essential for cell health and play key roles in supporting cellular processes like growth, repair, and protection against stress. Spermidine has been shown to support cell longevity by inducing autophagy, a process that helps cells remove damaged components and maintain optimal function.
Beyond cellular health, spermidine’s anti-inflammatory and antioxidant properties have made it a subject of interest in research on aging, neurodegenerative diseases, and now, mental health. Some studies have suggested that spermidine may improve heart health, reduce inflammation, and enhance cognitive function, leading scientists to investigate whether it may also have protective effects against depression.
In the new study, researchers analyzed data from the National Health and Nutrition Examination Survey (NHANES), a cross-sectional study that assesses health and dietary patterns among a representative sample of American adults. This study incorporated data collected from five NHANES cycles spanning from 2005 to 2014, involving over 19,000 participants. Participants provided dietary information through a 24-hour recall interview, which was then cross-referenced with known spermidine content in various foods to estimate daily intake levels.
To gauge depression symptoms, the researchers used the Patient Health Questionnaire-9 (PHQ-9), a validated survey tool that measures symptoms of depression over the past two weeks. Those who scored above a certain threshold on the PHQ-9 were classified as having significant depressive symptoms. Researchers also considered other factors that might influence depression risk, including age, sex, race, marital status, income, smoking, exercise habits, and medical conditions like diabetes or high blood pressure.
The analysis revealed that participants with higher spermidine intake were less likely to report depressive symptoms than those with lower intake levels. This association held true across different types of spermidine-rich foods, including fruits, vegetables, cereals, nuts, eggs, and seafood. These findings were supported by statistical models showing that those in the highest spermidine intake group had lower odds of depression than those in the lowest intake group.
Interestingly, not all sources of spermidine were associated with a lower risk of depression. For example, spermidine from legumes, fresh meats, and dairy products did not show a significant association with depression risk in this study. The researchers speculate that certain compounds in cooked meats, such as saturated fats and trans fats, could counteract spermidine’s protective effects on mental health. Thus, while foods like fruits, vegetables, nuts, eggs, and seafood were linked to lower depression risk, other dietary sources did not show the same benefit.
The study controlled for various demographic, health, lifestyle, and dietary factors, including age, sex, race, marital status, education, income, body mass index, smoking, alcohol consumption, physical activity, pre-existing conditions (like hypertension, diabetes, and hyperlipidemia), as well as dietary quality, caffeine, carbohydrate, calorie, and fiber intake, to isolate the potential effect of spermidine on depression. But the study is not without limitations.
First, because it is cross-sectional, it cannot prove causation—meaning it cannot confirm that spermidine intake directly prevents or reduces depression. It’s also possible that participants’ dietary habits or other unmeasured factors contributed to the observed associations.
Moreover, the study relied on participants’ self-reported dietary recall, which can introduce inaccuracies. Future studies could benefit from tracking dietary intake over a longer period or from using biological markers of spermidine levels in the body for more accurate measurements. Researchers also suggest that additional studies could investigate whether spermidine directly affects brain health through its anti-inflammatory and antioxidant properties, or if it interacts with other nutrients in ways that influence mood.
The study, “Association between dietary spermidine intake and depressive symptoms among US adults: National Health and Nutrition Examination Survey (NHANES) 2005-2014,” was authored by Guolian Qi, Jianing Wang, Yunyan Chen, Wei Wei, and Changhao Sun.