Naturalistic studies like ours can help unravel the evolutionary history and function of these hormones. Basically, the fact that hormone mechanisms have been tweaked during evolution suggests that the behaviors they promote have provided fitness benefits in the past. In this case, hunting and sharing meat must have increased men’s reproductive success.
5-HTP can affect a brain chemical called serotonin. Dextromethorphan (Robitussin DM, others) can also affect serotonin. Taking 5-HTP along with dextromethorphan (Robitussin DM, others) might cause too much serotonin in the brain and can result in serious side effects including heart problems, shivering, and anxiety. Do not take 5-HTP if you are taking dextromethorphan (Robitussin DM, and others).
According to recent research, this hormone “is now believed to be involved in a wide variety of physiological and pathological functions such as sexual activity, penile erection, ejaculation, pregnancy, uterine contraction, milk ejection, maternal behavior, social bonding, stress and probably many more, which makes oxytocin and its receptor potential candidates as targets for drug therapy. From an innocuous agent as an aid in labor and delivery, oxytocin has come a long way in being touted as the latest party drug.”4
At least one study has actively differentiated between 'an increase in satiety' (sensation of fullness from food) and a 'decrease in appetite' (less desire to eat) and noted that 5-HTP causes an increase in satiety without a concomitant decrease in appetite. Additionally, most studies are in exclusively females which may have more significance with interventions pertaining to serotonin metabolism; only one study mentioned above was conducted in men as well but appears to suggest that it benefits both genders.
Potential side effects of 5-HTP include heartburn, stomach pain, nausea, vomiting, diarrhea, drowsiness, sexual problems, vivid dreams or nightmares, and muscle problems. Because 5-HTP has not been thoroughly studied in a clinical setting, possible side effects and interactions with other drugs are not well known. According to the US National Institute of Health TOXNET, 5-HTP has not been associated with serotonin syndrome or any serious adverse events in humans. Across multiple studies, 5-HTP also been reported to not cause any noticeable hematological or cardiovascular changes. 5-HTP also has not been associated with eosinophilia.