Thanks for the compliment. I'm usually more bitter than informative but alas, I'll take any undue credit whenever possible. *yoink*
There aren't any studies to suggest negative side effects associated with regular 5-HTP supplementation. Some people use it regularly to control hunger as well as aid sleep. But most of these people are the fruity tree hugger types who'd probably gargle with whale sperm if they thought it would prolong their life by 15 seconds.
How this would impact your body's normal production of serotonin is difficult to say. There are a lot of steps in the metabolism of neurochemicals that influence whether or not a neurochemical is produced. The rate of reuptake, the rate of enzymatic breakdown, synaptic distance, etc. etc. For example, while testosterone supplementation means long term decreases in endogenous [naturally produced] testosterone, the same may not be true for serotonin. It depends on how much you have to begin with, how much your body can produce from raw substrates, and what genetic homeostatic limitations your body has on circulating neurochemicals.
The community college version of what I just wrote: too many factors to know for sure.
With neurochemicals the only real, practical way we have of measuring whether changes in supplementation are positive or negative are observeable impacts on behaviour. Of course, you have to take into account the placebo effect and the fact that people [unless trained otherwise] tend to see only what they want to see. But so long as you enjoy the changes [if any] of 5-HTP supplementation, and don't find any reprehensible side effects, who cares?
You should observe more intense dreaming, deeper sleep states, and maybe some impact on your hunger. Subjectively you may feel a greater feeling of warmth, sociability and positivity. Or you may just get explosive diarrhea, in which case, I cannot be held responsible for what I just said.