The effect of protease inhibitors derived from potato formulated in a minidrink on appetite, food intake and plasma cholecystokinin levels in humans.
BACKGROUND
Protease inhibitor 2 derived from potato (PI2) is claimed to reduce appetite and food intake, stimulate the satiety hormone cholecystokinin (CCK) and lower postprandial glucose peaks when taken before a meal. However, current literature is inconclusive with regard to its efficacy and mechanism. Furthermore, the potential effect of PI2 on appetite motivational ratings without an immediately following meal has not previously been reported.


OBJECTIVE
To comprehensively test the effects of 30 mg PI2 in a minidrink on appetite ratings, subsequent food intake, and plasma CCK and glucose responses.


METHODS
Minidrinks with or without 30 mg PI2 were compared in three separate substudies (A, B and C), each using a two-way, placebo-controlled, balanced-order, cross-over design and 23 or 24 subjects (mean over groups: body mass index 25.0 kg m(-2), range 22.5-30.7 kg m(-2); age 41.3, range 18-62 years). The minidrink was given (A) 120 or (B) 30 min before an ad libitum lunch or (C) 30 min before a fixed lunch. Study parameters were self-reported satiety (substudies A and C), ad libitum meal intake (substudies A and B), and (in an n=12 subset) plasma CCK and blood glucose in all substudies. All results were analyzed using analysis of covariance. Protease-inhibitory activity of the PI2-containing minidrinks was assessed under simulated gut conditions.


RESULTS
PI2 did not differ from control for any study parameters, in any substudy, despite confirmation of the inhibitory activity of PI2.


CONCLUSIONS
In this study protease inhibition using PI2 in a minidrink at a dose of 30 mg, as commercially used, had no (functional) efficacy on a range of behavioral and physiological appetite and intake control measures.
Peters
H P F
HP
Unilever Research & Development, Vlaardingen, The Netherlands. harry.peters@unilever.com
Foltz
M
M
Kovacs
E M R
EM
Mela
D J
DJ
Schuring
E A H
EA
Wiseman
S A
SA
D000293:Adolescent; D000328:Adult; D001069:Appetite Regulation / Q000187:drug effects* / Q000502:physiology; D001628:Beverages; D002766:Cholecystokinin / Q000097:blood*; D018592:Cross-Over Studies; D004435:Eating / Q000187:drug effects* / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008517:Phytotherapy; D028321:Plant Preparations / Q000008:administration & dosage / Q000494:pharmacology*; D019518:Postprandial Period; D011480:Protease Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D012527:Satiation / Q000187:drug effects* / Q000502:physiology; D011198:Solanum tuberosum / Q000737:chemistry*; D006113:United Kingdom; D055815:Young Adult
D028321:Plant Preparations; D011480:Protease Inhibitors; D002766:Cholecystokinin