I am constantly searching for the best chemical intervention that can help manage my anxiety. Today, I may have found that intervention. On the 1st of May, 2018, I started a review of all literature written on the amino acid, tryptophan. My search included an examination of all published articles on tryptophan between June 2013 to June 2018, which included the criteria of key words such as 'Anxiety', 'Tryptophan', 'Supplementation' 'Clinical Trials' and 'Human Trials'. The database used to complete a search of the literature was 'science-direct'. My aim was to determine if there was any evidence to support use of tryptophan to manage my anxiety. What I found could be a game-changer. However, there is regulation on the use of tryptophan, and, for that reason its use in practice may be limited.
So, What is Tryptophan?:
Tryptophan is the only precursor for the neurochemical serotonin. Which means, that tryptophan helps you, and me, create serotonin. Serotonin is the chemical that helps to balance your mood, increase a sense of happiness and limit recognition to fear. Tryptophan is capable of mediating the activity of serotonin in the brain. Chemically, when serotonin is moderated by tryptophan we are less likely to present with feelings of panic and anxiety. I say this, given that the majority of findings on tryptophan deficiency or depletion indicate increased risk to anxiety and panic disorder.
Tryptophan is an essential amino acid, meaning that our body does not naturally produce tryptophan and so it must come from our diet. Tryptophan can be found across a wide range of foods such as oats, chocolate, red meat, milk, yoghurt, seasame seeds, dates, eggs, fish, chicken, buckwheat, spirulina and peanuts. The question then becomes, can we extract enough tryptophan from our diet to have any affect on anxiety? Well, some researchers say yes and others say no.
Please Tell Me That I Can Get Tryptophan From My Diet:
Recently, a team of researchers found that a dietary intake of tryptophan at a dose of 10 milligrams per kilogram of body weight was capable of reducing anxiety, depression and irritability scores for a cohort of 700 university students when compared to a dosage of 5 milligrams per kilogram of body weight. This study has been considered the largest study carried out to examine the effects of dietary tryptophan on anxiety (Lindseth et al., 2015). Nonetheless, others studies suggest no association between tryptophan intake, depression, anxiety and mood. So why is that? One argument, is that the study undertaken by Lindseth et al. (2015) identifies a therapeutic dietary dosage that is capable of reducing anxiety, to which other researchers have not yet defined. It is the work of Lindseth et al. (2015) and Bradrasawe et al. (2013) which challenge the notion that plasma levels of tryptophan in the human body cannot change through diet alone.
One of the concerns I have found with dietary sources of tryptophan is that most dietary proteins contain little tryptophan. The majority of dietary proteins contain large neutral amino acids (LNAA's) which compete against tryptophan for uptake across the blood brain barrier. Technically, this means that tryptophan must work hard to be noticed, so that it can reach its destination. Another concern is that excessive dieting and food restriction can lead to tryptophan depletion. It is this behaviour that increases risk for affective behaviours such as anxiety. I do not know about you, but when I have heavily restricted my intake of food for long periods of time I am not a very nice person to live with! This does not mean one should not clean up their diet, it just means that 500 calories a day for 42 days could lead to low mood, risk of anxiety, aggression and irritability.
There will always be more research, but for now a balanced meal rich in carbohydrates combined with protein is considered the most effective way to maximise levels of tryptophan in the body, because carbohdyrates allow LNAA's to be taken up by the tissues of the body, giving tryptophan the opportunity to reach its destination without competing with other proteins. Interestingly, carbohydrates are often the first fuel source we restrict when commencing a dietary regime. For this reason, I think it is important to highlight to everyone that such restrictions may negatively influence our mental health in the long term. In cases where individuals are using selective serotonin reuptake inhibitors such as Zoloft or Prozac, heavy dietary restriction could limit the effectiveness of medication, with recent findings suggesting that increased blood levels of tryptophan improve the effectiveness of selective serotonin reuptake inhibitors.
Should I Supplement My Diet With Tryptophan if I have Anxiety?
This is a hard one to answer for two reasons. The first reason is that the dosage of supplementation required to generate an effect is beyond what can be prescibed by a naturopath in Australia. For example, the dosage most common to elicit a positive effect is 3 grams. This is the case for individuals who have not been diagnosed with anxiety as well as individuals who present with genetic variation that affects their ability to make serotonin (5HTTLPR). Unfortunately or fortunately, whichever way you wish to look at it, a naturopath can only prescribe a dosage of 100 mg which will not even put a dint in the effect one presenting with anxiety would be looking for. Steenbergen et al. (2016) provides a review of the research to date on tryptophan and its effects on social interaction, prosocial behaviour and antisocial behaviour. It is clear from this review that an intake of 3 grams would be necessary to enhance serotonin levels to the point where behaviour would noticeably change. When tryptophan supplementation has been used at levels of 1.8 grams per day there was no indication that tryptophan could mitigate symptoms of depression (Attenburraw et al. 2003). Despite an intake of 3 grams showing positive results which indicate a decrease in antisocial behaviour, Hogenelst et al. (2015) demonstrated that a dosage of 3 grams increased quarrelsome behaviour in men, and reduced agreeable behaviour when undertaking supplementation with L-tryptophan.
The second reason is that high dosages of tryptophan carry risk. It is also important to point out that adverse effects are significant at dosages of 6 grams. However, dosages of 3 grams have resulted in diarrhoea, epigastric pain and dizziness when administered for a period of 3 weeks. If a patient was to combine high dose tryptophan with an antidepressant, patients are likely to experience tremor, nausea, drowsiness and dizziness. In some cases, a condition known as serotonin syndrome could present whereby a patient is at risk of delerium, seizure, hyperthermia and in extreme cases, coma.
But Could I Use 5HTP?
No. Although 5HTP (5-hydroxytryptophan) does not face the challenges of tryptophan when competing with other amino acids to cross the blood brain barrier, there is limited research to suggest it has a significant place to abate the effects of anxiety and/or depression. The only research I have come across so far on use of 5HTP is for panic disorder. Schruers et al. (2002) found that acute administration of 200 mg of 5HTP has a potential response to reduce episodes of panic for individuals diagnosed with panic disorder. Again, further evidence is required to confirm this intervention for clinical practice. Moreover, one should not readily prescribe greater than 100 milligrams of 5HTP per day.
So for now, it looks like tryptophan cannot manage my anxiety.
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