Why western-style diets may increase depression

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Researchers from Macquarie University have found a link between Western-style diets and lower levels of kynurenic acid (KA), a small molecule that plays a key role in various bodily functions.

The study revealed that people who followed a Western-style diet were more likely to report higher levels of depression compared to those who consumed diets rich in fresh fruit and vegetables.

Significance of Kynurenic Acid

KA is derived from the breakdown of tryptophan, an essential amino acid that the body cannot produce on its own and needs to be acquired through certain foods, such as dairy products, poultry, bananas, oats, nuts, and seeds.

The metabolites produced when our bodies break down tryptophan are critical in regulating behavior, protecting the brain, and controlling inflammation, which is linked to diseases such as certain cancers, heart disease, stroke, and dementia.

Study Details

The study, led by Dr. Edwin Lim and published in the journal Frontiers in Nutrition, involved examining 169 adults aged between 17 and 35.

The researchers tested participants’ urine for several biological markers, including KA and inflammation, and compared them with how healthy their diet was and the severity of their depression symptoms.

The results indicated that individuals consuming an unhealthy diet had lower levels of KA and exhibited more severe symptoms of depression. This suggests that KA may help protect against depression.

Impact on Tryptophan Metabolism

The findings reveal the influence of a Western-style diet on how tryptophan is metabolized in otherwise healthy young people. This is the first time such a correlation has been identified.

The study also highlighted that urine analysis might serve as a practical alternative to blood tests when collecting valuable biological information on tryptophan metabolism.

This non-invasive method could be especially beneficial for vulnerable populations such as children and older adults.

Conclusion and Future Directions

The researchers emphasize the clear relationship between an increased risk of depression and consuming an unhealthy diet that is high in fat, sugar, and processed foods.

They advocate for an increased intake of fresh fruits and vegetables.

While the role of KA is critical, it’s important to note that the level of KA in the body needs to be balanced, as too little is associated with depression, while excess KA has been linked to schizophrenia.

Further studies are required to deepen our understanding of how diet influences mental health and the role of KA in this complex process.

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