Amino acids and Your Mental Health
The last major category of nutritional deficiencies seen in the mental health population that I’m going to explore is amino acids. Amino acids are organic compounds composed of hydrogen, oxygen, carbon and nitrogen that are essentially, what protein is made of. Our body needs a total of 20 different amino acids to function properly and 9 of these are considered essential. Essential amino acids refer to ones that cannot be made by our bodies and instead must be obtained through our diet, while non essential amino acids are produced by our bodies. Amino acids that are considered essential are the following: histidine, leucine, isoleucine, phenylalanine, methionine, threonine, valine and tryptophan. These amino acids contribute to a variety of functions in your body including boosting your immune health, increasing muscle growth, aiding in digestion, the sleep-wake cycle and contributes significantly to neurotransmitter production. Let’s take a look at some of the essential amino acids that are specifically used to produce neurotransmitters and boost mental health.
Phenylalanine
Phenylalanine is an essential amino acid that is converted in the body to tyrosine and is considered an important structural building block that is used to form proteins. Phenylalanine is used to make many other important compounds that include the neurotransmitters dopamine, norepinephrine and epinephrine. This is important because in this way, phenylalanine contributes to mental health functions like memory, learning and emotion, as well as mood. There is some emerging evidence that suggests that supplementing with Dl-phenylalanine (one of the 3 forms of phenylalanine) may improve several symptoms of depression, including agitation and low mood. One study that used 1-deprenyl and 1-phenylalanine (250 mg) supplements with individuals diagnosed with unipolar depression showed that both oral and intravenous administration demonstrated positive effects in 90% of outpatients and 80.5% of inpatients. This suggests that phenylalanine paired with other important compounds may help alleviate symptoms in depression for a portion of a clinical population. Another study from 1977 provided 20 individuals who were clinically depressed with dl-phenylalanine supplements in doses from 75-200mg/day. Measures used to assess progress included the Hamilton depression scale and the Von Zerssen self rating scale that assessed psychopathological, neurologic, and somatic changes. At the end of the 20 day trial, 60% of patients were no longer symptomatic and 20% were discharged due to the significant improvement in symptoms.
The importance of phenylalanine as it converts to tyrosine is important to know as well, since tyrosine, when lacking in an individual’s diet may affect a person’s mood. One study examined this in a group of healthy volunteers. One group was given a balanced amino acid mixture to consume and one group was given an amino acid mixture without tyrosine and phenylalanine and then was assessed using self report measures to assess their mood. Blood tests were taken right after the mixture was consumed and 5 hours later, and all participants completed a neuropsychological evaluation after the 5 hours. Results revealed that the group without the tyrosine and phenylalanine demonstrated apathetic behaviors as demonstrated in the neuropsych evaluation and reported low moods. The researchers found that their results paralleled the kind of behaviors and mood that occur in unipolar depression (major depression), which suggests that a lack of these amino acids even in a healthy population can affect a person’s mood and performance. There are some individuals who cannot supplement with phenylalanine that include women who are pregnant or breastfeeding, as well as those with schizophrenia and phenylketonuria (PKU). Phenylalanine is found naturally in a variety of food sources that include both plant based and animal based protein and the most is found in meat, fish, chicken, eggs, nuts, seeds and soy products.
Tryptophan
Tryptophan is a precurosor (something that is needed for the body to produce something else) to serotonin, a neurotransmitter responsible for lots of things that include digestion, regulating your sleep-wake cycle, and mood. If you are familiar with theories in psychology concerning depression, you may have heard of the monoamine hypothesis which states that depression is thought to be a consequence of low levels of the following: dopamine, epinephrine and serotonin. This hypothesis has been the prevailing one for decades regarding depression because of the way that psychiatric medications known as Serotonin Reuptake Inhibitors (SSRI’s) for depression operate (anti-depressants allow for more serotonin to be present in our brains). But there hasn’t been any conclusive evidence regarding support for this hypothesis especially with the lack of efficacy anti-depressant drugs exhibit. For example, sertraline or Zoloft NNT (number of patients that need to be treated for one of them to benefit) is 12. That means 1 in 12 people on average will benefit from taking sertraline for depression. Not such great odds. Study results of increasing dietary tryptophan and how that impacts mood is mixed when it comes to decreasing levels of anxiety. However, a meta-analysis of studies from 1966 to 2006 indicates that tryptophan depletion showed decreased mood states in participants with major depressive disorder, a family history of major depressive disorder, and with major depressive disorders in remission. This was not found in healthy subjects who had decreased levels of tryptophan.
Tryptophan competes to cross the blood brain barrier (a blood barrier literally separating the circulating blood from the brain and extracellular fluid from the nervous system) because, it must be transported by a carrier protein, which is also responsible for transporting other amino acids like leucine and tyrosine. Because there is competition, the amount of tryptophan that can enter the brain is limited and thus the amount of serotonin that can be made is limited. Other studies have demonstrated that the ratio of protein to carbohydrates in meals directly relates to the ability of tryptophan to cross the blood brain barrier, enter the brain, and be used for serotonin production. Both animal and human studies reveal that the more carbohydrates and less protein a meal has, the more tryptophan can be carried and used in the brain (since there is less competition from other amino acids when you ingest less proteins). There are still mixed results concerning this but it may be that increasing dietary foods containing tryptophan or supplementing with tryptophan when there isn’t already a compromised ability to produce serotonin, might not have significant benefit on improving depression. The one consistent finding in the literature seems to be that increasing foods containing tryptophan can have a significant benefit in mood if you are currently experiencing clinical depression, have a history of depression or have major depressive disorder that is in remission. On an interesting note, eating meals deficient in tryptophan may make depression symptoms worse even in a healthy population even with no history of depression. 5-Hydroxytryptophan (5-HTP) on the other hand, is an amino acid that your body produces which in combination with tryptophan, produces serotonin. 5-HTP crosses the blood brain barrier more easily than tryptophan and some studies suggest that supplementing with 5-HTP may help reduce feelings of anxiety. After eating foods that contain tryptophan, it is absorbed from the small intestine and then metabolized in the liver. 5-HTP has a shorter process and is more easily converted into serotonin in the small intestine, which speaks to the importance of digestion and making sure your body is able to properly digest and break down these proteins. Foods containing higher amounts of tryptophan include eggs, pineapple, cheese, turkey, salmon, and nuts and seeds.
Tryptophan and serotonin are also involved in cognitive functions like long term memory and cognitive flexibility, or the ability to shift your thinking from one concept to another. One study tested this idea by giving healthy participants an oral solution of 15 amino acids, depleting the amount of tryptophan in the blood, also providing a large amount of the other competitive amino acids to help limit the amount of remaining tryptophan that can enter the brain. This in turn reduced the amount of serotonin production. They were then tested on their short and long term memory. Turns out their short term memory was just fine but their long term memory was significantly compromised, which occurred only 30 min after ingesting the solution. Other studies have replicated this finding showing that focused attention can significantly be impaired if the brain is depleted in serotonin. Please be aware that Tryptophan and 5-HTP need to be used cautiously with those who have been diagnosed with diabetes or have a history of diabetes.
Of course, there’s a bit of a catch. Several nutrients are needed for both tyrosine and tryptophan to be used properly. For example, in order for tryptophan to be converted into serotonin, the body needs Vitamin B6, niacin and glutathione. What does this tell you? We can’t isolate nutrients if we want to improve the functioning of our minds and bodies. Unless there is a significant depletion, then yes, work up to nutrient sufficiency using foods that are higher in that nutrient. But all vitamins and minerals need their cofactors, or buddies, to help them do what they need to do in the body. The good news is that nature has already done the work for us. Food from nature already has the spectrum of vitamins and minerals we need in order for our bodies and mentals to function to their fullest potential. If you are looking to improve your mental health or improve your depression if you are experiencing this right now, what is most beneficial is eating a whole foods diet that has a balanced macronutrient profile (proteins, fats, and carbs). The right ratio for your body and your mental using whole foods will help you get all the nutrients, cofactors, vitamins and minerals you need in order to establish mental, physical and emotional wellness. If you have a history of depression, are currently clinically depressed or have a family history of depressive disorders, increasing the foods containing tryptophan could have the potential of benefiting your mood. Other great ways to help boost your serotonin levels include exercise and light therapy. As always, please consult your doctor before taking any supplements.
References
https://link.springer.com/article/10.1007/s00213-003-1586-8
https://www.ncbi.nlm.nih.gov/pubmed/19026250
https://www.ncbi.nlm.nih.gov/pubmed/17389902
https://www.sciencedirect.com/topics/neuroscience/tryptophan
http://www.anaturalhealingcenter.com/documents/Thorne/monos/DLPA%20mono.pdf
https://www.ncbi.nlm.nih.gov/books/NBK224629/
