There is little doubt that the incidence of depression is increasing worldwide. Some argue that it is purely psychological and best dealt with by therapy. Others consider depression purely as a biochemical imbalance, best treated with anti-depressants. A third aspect that is often not considered, however, is nutrition.

Food is the building block of important neurotransmitters, and, therefore, could play an essential role in improving mood. One such building block is tryptophan, an essential amino acid, found in protein-based foods including seeds, dairy and meats. Tryptophan is a precursor to serotonin, our feel-good hormone.

Chantelle van der Merwe, registered dietician, told the Epoch Times that “the brain is a high-performance machine, constantly buzzing with activity, processing information, and regulating your emotions. Just like any machine, it needs the right fuel to function optimally. This is where proper nutrition steps in, it’s like the premium-grade fuel for your brain. Nutrition directly affects the complex network of neurons that influence our mood, behaviour and cognitive functions.” She further said: “People with depression often lack essential nutrients, which can exacerbate their symptoms. It’s like trying to run a race with one shoe – you’re at a disadvantage from the start.”

The Effectiveness of Tryptophan to Enhance Mood

A meta-analysis done by Dr Philip Cowen and colleagues from Oxford University’s psychiatry department investigated what would happen if you deprived people of tryptophan. What they found was that acute tryptophan depletion (ATD) “elicits a clinically significant recurrence of depressive symptoms in approximately 50% of remitted depressed patients,” and 20 percent of the patients experienced a ‘full-blown relapse’. This study concluded that ATD causes a near or complete return of depression and is described as “depressive exacerbation” or as a “partial relapse”. This is because when dietary tryptophan levels are lowered, a lowering of brain serotonin levels is also seen.

One strategy to enhance the synthesis of serotonin, is, therefore, to take in optimal amounts of the precursor nutrients. Tryptophan is the precursor to 5-hydroxytryptophan, or 5-HTP for short, which is the precursor to serotonin. This means that supplementing with 5-HTP could, also be an option if anti-depressants or dietary tryptophan sources are not your first choice.

Patrick Holford told the Epoch Times that “a year or so on anti-depressants really drives serotonin low and may account for the severity of withdrawal effects. In these cases, supplementing the most potent form of tryptophan, 5-HTP, from 100 to 300mg, could be effective in relieving depression.”

A study done by Nakajima et al. gave participants a daily dose of 5-HTP for three weeks, and what they found was that 69% of patients improved their mood.

How to Optimize Tryptophan Conversion to Serotonin

Unfortunately, if you want to increase the tryptophan levels in your brain, it might not be as easy as including more tryptophan-rich foods in your diet. This is because we need to consider how tryptophan is allowed into the brain at the level of the blood-brain barrier.

At the blood-brain barrier, large amino acids are given priority. They include valine, isoleucine, leucine, tyrosine, phenylalanine and methionine. Tryptophan is, therefore, not favoured, as it is not an abundant amino acid. What this means is that when we’re eating a protein-rich meal, the plasma level of the large amino acids will compete with tryptophan and, therefore, prevent the rise of brain tryptophan levels.

Luckily, this can be remedied by including a carbohydrate-rich food to the protein, as this will increase the availability of brain tryptophan. Carbohydrates release insulin, which stimulates large and abundant amino acids’ uptake into the muscle, instead of the brain. This means that tryptophan gets a chance to move through the blood-brain barrier with less competition from the large amino acids.

Another element that needs to be taken into consideration for optimal absorption and conversion of tryptophan into serotonin are other enzymes and nutrients. “For tryptophan to become serotonin it needs the help of several enzymes and nutrients including vitamin B6,” says van der Merwe. She mentioned that vitamin B6 is found in foods like beef liver, tuna, salmon, chickpeas, chicken, dark leafy greens, bananas, papayas, oranges, and cantaloupe.

A Healthy Gut is Key for Adequate Serotonin

When looking at optimal serotonin production, the health of the digestive system is also key. The gut-brain axis is a bi-directional communication system, that links the functioning of the gut and the cognitive and emotional centers of the brain. Serotonin production by neurons located in the central nervous system accounts for only 5 percent of total serotonin synthesis, while 90 percent of serotonin synthesis occurs in the periphery, of which the largest source is the lining of the gut.

Interestingly enough, people suffering from irritable bowel syndrome experience changes in the balance of their gut bacteria, and this is associated with alterations in both brain and gut serotonin levels, researchers showed. A 2014 study also showed that the metabolic activity and composition of the gut microbiome play a role in brain disorders such as depression, anxiety and autism.

Serotonin Production is Lowered When Stressed

Something else that needs to be taken into account in the conversion of tryptophan to serotonin is stress levels, as long-term stress may result in a decrease in brain tryptophan availability. This is because chronic stress tends to shunt available tryptophan metabolism away from 5-HTP and serotonin production and toward a pathway called the kynurenic pathway (a major route for the breakdown of tryptophan).

What Can You Do to Optimize Brain Tryptophan Levels

  • Get enough tryptophan-rich foods in your diet, including chicken, turkey, nuts and seeds.
  • Make sure to have some form of carbohydrate with this food to enhance tryptophan absorption at a blood-brain barrier level.
  • Several enzymes and nutrients are needed for the tryptophan-5-HTP-serotonin conversion. Eating a varied diet could be helpful.
  • Focus specifically on getting enough vitamin B6, found in foods like beef liver, salmon, chickpeas, dark leafy greens and bananas.
  • Keep your digestive system healthy for optimal serotonin production.
  • Find ways to manage stress to make sure available tryptophan is not moved away from serotonin production.

Chantelle van der Merwe Registered Dietician: @chantellevdmdietitian (Insta) / Chantelle van der Merwe Registered Dietitian (Fb) 

A version of this article has been published by the Epoch Times newspaper.

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