One theory about migraines is that it is triggered by dropping serotonin levels. One medication, sumatriptan, acts by raising serotonin acting as a reuptake inhibitor. Since tryptophan is converted into serotonin, can tryptophan supplements aid in fighting migraines. Is there any study in this regard?
Sumatriptan activates vascular 5-HT1 receptors. This results in vasoconstriction, which is what is thought to help the migraines. This is the same idea for giving caffeine, which is also a vasoconstrictor. Taking tryptophan would likely be ineffective for a variety of reasons in terminating a migraine. First, it would have to be ingested and absorbed, which takes time, and then it would have to be metabolized to 5-HT (Serotonin). Even if tryptophan was absorbed in the stomach, it would be ineffective at terminating the migraine in a timely fashion and thus not well tolerated by a patient.
Second, there is little evidence that oral tryptophan supplementation increases serotonin levels (Cynober et al., 2016).
Cynober et al. (2016) states that the subjects urinated out the tryptophan in a "dose dependent fashion." Further, there was no significant change in their mood with tryptophan supplementation at any dose. This suggests that the tryptophan is not being metabolized into 5-HT. This makes sense, since tryptophan is in our diets, and it would be wild to think that our bodies didn't regulate 5-HT metabolism (that is to say that our bodies just automatically made 5-HT every time we ate something with tryptophan in it).
If patients do have a serotonin imbalance, it is likely involved in metabolism issues, say some mutation or problem with co-factors or enzymes. Therefore, tryptophan likely isn't a solution.
Cynober, L., Bier, D. M., Kadowaki, M., Morris Jr, S. M., Elango, R., & Smriga, M. (2016). Proposals for Upper Limits of Safe Intake for Arginine and Tryptophan in Young Adults and an Upper Limit of Safe Intake for Leucine in the Elderly–3. The Journal of nutrition, 146(12), 2652S-2654S. doi: 10.3945/jn.115.228478