Table 3.

Main findings of the phase 1 study interviews with registered dietitians (N=15).

Theme	Findings	Quotes
Indication for starting a collagen supplementation	Most started their clients on collagen supplementation based on careful assessment of digestive problems	“So it’s everything from GIa symptoms, from constipation, diarrhea, bloating, [...] reflux [...]”
Recommended dosage	20 g per day as separated doses	“I definitely want people to have at least 12 grams a day. You probably have benefits right up through 25 grams a day”
Duration	6 to 8 weeks	“I would [...] say six weeks and then check in and see your response at that time”
Target group	Women aged 35 to 65 years	“[...] I would say 40s to 60s, but that’s certainly not to say that I haven’t started seeing more and more people in their early 30s”
Perceived benefits	Reduces bloating; heals gut lining; improves digestion	“It depends on the person, most people love continuing on them because not only are you getting the gut healing benefits from collagen [...]”
Monitoring progress	MSQ,b diary, repeat stool test	“We’re using one from the Institute of Functional Medicine and that one’s called the MSQ medical symptom questionnaire”

^aGI: gastrointestinal.

^bMSQ: Medical Symptoms Questionnaire.