Possible Interaction: Proline and Vitamin C

“Intake of fruit juices and … tea extracts (containing 75 mg vitamin C ) or of orange peel powder (containing 3 … vitamin C) together with 300 mg L-proline inhibited NPRO formation effectively to the baseline level or to levels significantly lower than the baseline level (P < 0.05-0.005).”

“The urinary NPRO level after proline intake was higher in children from the high-risk area (P < 0.04) and markedly reduced after ingestion of ascorbic acid together with proline (P < 0.05).”

“After intake of proline , the NPRO level increased (p < 0.02) only in subjects in the high‐risk area; intake of vitamin C tended to inhibit this increase in NPRO and lowered the levels of other nitrosamino acids.”

“Supplementation of the same meal (plus proline ) with vitamin C from dietary sources resulted in a significant decrease in mean urinary NPRO levels in healthy subjects.”

“After intake of proline , the NPRO level increased significantly only in subjects of the high-risk area, but not in those of the low-risk area; intake of vitamin C inhibited this increase of NPRO and lowered the levels of other nitrosamino acids only in the high-risk subjects.”

“When Linxian subjects were given 100 mg vitamin C three times a day (after each meal) together with proline , the level of urinary N-nitrosamino acids was reduced to that found in Fanxian.”

“The simultaneous intake of ascorbic acid or alpha-tocopherol inhibited nitrosation of proline in vivo.”

“Rats chronically treated with proline plus alpha-tocopherol and ascorbic acid had above effects prevented, suggesting the participation of oxidative stress in such effects.”

“Combined treatment with ascorbic acid and proline is additive to delay further jaundice and mortality.”

“If no ascorbic acid is added, the proline :hydroxyproline ratio becomes greater than 2:1, and intermediate concentrations of ascorbic acid give an intermediate ratio.”