Effects of orange juice and proline betaine on glycine betaine and homocysteine in healthy male subjects.
BACKGROUND
Proline betaine (PB), a glycine betaine (GB) analogue found in citrus foods, increases urinary GB loss and plasma total homocysteine (tHcy) concentrations in rats. Its presence in human plasma is associated with increased GB excretion.


OBJECTIVE
To compare the effects of dietary levels of PB on GB excretion, and on plasma tHcy and GB concentrations in healthy volunteers.


METHODS
In a randomized crossover study, eight healthy males (18-50 years) ingested either 750 mL orange juice (containing 0.545 g PB), a PB supplement (0.545 g PB dissolved in 750 mL apple juice), or 750 mL apple juice (control). Plasma PB, GB and tHcy, and urine PB, GB and creatinine concentrations were measured hourly for 6 h and at 24 h post-treatment.


RESULTS
Plasma tHcy concentrations were not increased (relative to control) following ingestion of either orange juice or PB supplement. Both treatments produced a significant increase in plasma PB concentrations (P < 0.001), this effect being greater following orange juice compared with PB supplement (P < 0.05, 1-2 h). Urinary excretion of PB was greater than the control following both orange juice (P < 0.001) and PB supplement (P < 0.001), from 2 to 24 h post-treatment. This increase in PB excretion was significantly greater following orange juice compared with PB supplement with higher peak excretion (Cmax difference, P = 0.008). GB excretion was significantly greater following ingestion of orange juice compared with PB in apple juice (P = 0.007) and apple juice control (P < 0.001) in the first 2 h post-ingestion.


CONCLUSIONS
PB administered in dietary doses had little effect on plasma tHcy concentrations in healthy humans. Ingestion of PB in orange juice compared with PB alone resulted in greater increases in the urinary excretion of PB and GB.
Atkinson
Wendy
W
Clinical Biochemistry Unit, Canterbury Health Laboratories, PO Box 151, Christchurch, New Zealand.
Downer
Pamela
P
Lever
Michael
M
Chambers
Stephen T
ST
George
Peter M
PM
D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D001622:Betaine / Q000378:metabolism* / Q000652:urine; D001628:Beverages; D032084:Citrus sinensis / Q000737:chemistry*; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007408:Intestinal Absorption; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D011392:Proline / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology
D006710:Homocysteine; D001622:Betaine; D011392:Proline; C003342:stachydrine