Does tryptophan cause depression? (5 factors)

In this article, we will discuss whether tryptophan causes depression. Furthermore, we will talk about the related research findings, the effect of a tryptophan-rich diet or supplements on mood, factors affecting tryptophan and depression and what to do if tryptophan causes depression. 

Does tryptophan cause depression?

Tryptophan does not cause depression. Tryptophan supplements are used to treat depression, anxiety, or sleep disorders. Tryptophan is an essential amino acid, which means it can not be synthesized by the human body itself. 

Tryptophan can be consumed from other sources such as diet or supplements. The levels of plasma tryptophan can also be used by health practitioners in the diagnosis of certain disorders. Tryptophan when consumed, passes through enzymatic metabolism and is converted into serotonin, melatonin, niacin, or other important compounds (1). 

Depression is a mood disorder in which patients do not feel happiness in anything they do or experience. In depression, patients feel sadness, irritable mood, and cognitive issues such as memory or concentration problems. Due to these changes, depressed patients may not function normally in their daily lives (2). 

What does research suggest about tryptophan’s effect on depression?

According to a research study, tryptophan when given to depressed patients, exhibited an antidepressant effect and patients experienced improvement in their symptoms (3). Another study suggested that when tryptophan is given in a dose of 0.14 to 3gm per day, along with tryptophan-rich foods, it may improve mood and decrease stress, anxiety, or depression in patients (4). 

So far research studies have suggested that serotonin, produced by tryptophan is the main reason behind depression. However, another study indicated that sometimes stress hormones may cause tryptophan to be converted into a harmful compound quinolinic acid instead of serotonin which might cause depression in susceptible individuals (5). 

Tryptophan deficiency may lead to depression. When tryptophan is not consumed at sufficient levels, it can cause low serotonin levels in the synaptic regions of the brain. These low levels of serotonin impact cognitive functions such as mood, behaviour, irritability, anxiety, stress, aggression, or depression (6). 

What is the impact of tryptophan-rich diet and supplements on mood?

The impact of tryptophan-rich diets or supplements on mood has been of utmost importance. Tryptophan can be sourced from tryptophan-rich diets or supplements. Foods such as chicken, turkey, tuna fish, bread, cheese, eggs, nuts, lentils, or chocolates are common sources of tryptophan.

Tryptophan supplements are also available to overcome tryptophan deficiency in susceptible individuals. The usual adult dose of tryptophan supplements is 60mg taken for 3 months. The safety of tryptophan supplements beyond this duration and in pregnant women or nursing mothers has not been developed yet (7). 

Which factors influence tryptophan levels and depression risk?

The factors which might influence tryptophan levels and depression risk may include the following:

  • Low tryptophan levels caused by intake of low dietary tryptophan, may cause an increased risk of depression (8). 
  • Genetic variations among individuals such as the genes responsible for metabolizing tryptophan, may also increase depression susceptibility (9). 
  • Stress hormones can shift the metabolism of tryptophan to harmful compounds instead of serotonin, causing depression (5). 
  • Certain antidepressants such as Celexa, Prozac or Trintellex when used along with tryptophan supplements or diet, may also reduce tryptophan levels (10). 
  • Inflammatory conditions may also cause reduced availability of tryptophan causing depression (11). 
  • Medical conditions such as neurologic or psychiatric disorders may also cause alteration in tryptophan metabolism, hence causing depression (12).

What to do if tryptophan causes depression?

Tryptophan does not cause depression, however, if you experience depression, please watch out for your symptoms and consult your healthcare provider. They will evaluate your current condition, family, medical history, dose, and duration of tryptophan. You may experience depression due to a lack of tryptophan or other factors. 

Your healthcare provider may also recommend alternative antidepressants which might suit you best, such as Wellbutrin, Luvox, Celexa, or others. Antidepressant treatment is a trial-and-error therapy, one medicine suitable for one individual might not be appropriate for another individual. 

In my opinion, tryptophan does not cause depression, however, tryptophan supplements are used to treat depression, anxiety, or sleep disorders. Lack of tryptophan may cause certain cognitive problems in susceptible individuals.

There are certain factors which may influence tryptophan levels and ultimately increase the risk of depression such as genetic factors, a low tryptophan diet, antidepressants, inflammatory conditions, and other underlying health conditions. 

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