A new study suggests a biomarker in the blood is linked to depression. (Photo: Getty Images / iStockphoto)

study suggests that low levels of a specific biomarker in your blood is related to the severity and duration of depression.

The collaborative study conducted by Stanford University and Rockefeller University found that depressed people had low levels of acetyl-L-carnitine. helps the body to produce energy.

Although it is naturally produced in the body, acetyl-L-carnitine is also available for sale in pharmacies and other retailers as a nutritional supplement.

In a statement, Natalie Rasgon, a study author and professor of psychiatry and behavioral science at Stanford, said that the study offers "an interesting addition to our understanding of mechanisms of depressive illness. "

The study was published o n July 30 in the Proceedings of the Journal of the National Academy of Sciences.

A series of experiments involving rodents found a deficiency in the biomarker was connected to more behaviors related to depression. When the animals received acetyl-L-carnitine in addition, their behavior returned to normal, according to the researchers.

In a separate human study, researchers examined patients diagnosed with depression. The results showed that depressed patients had much lower levels of acetyl-L-carnitine in their blood. The researchers also found that patients with the lowest levels had the most severe cases of depression.

"In patients with depression, something poses a problem in mechanisms related to the biology of acetyl-L-carnitine", a scientist at Rockefeller University and one authors of the study, in a statement. "And, surprisingly, the deficiency of (acetyl-L-carnitine) is even stronger in patients who do not respond to standard antidepressants."

Rasgon said that further research is needed to determine if acetyl-L-carnitine could improve symptoms. She also warned against taking medication supplements.

"We have many examples of nutritional supplements available over-the-counter and not regulated by the Food and Drug Administration – for example, omega-3 fatty acids or various herbal substances – touted as a panacea for you, name it then do not campaign, "she says.

Follow Brett Molina on Twitter: @ brettmolina23 .

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