I just read in the latest Vitacost newsletter about a study suggesting that vitamin C and garlic together did better than either alone. The abstract can be read in the Nutrition Research journal.
Here's an excerpt from the abstract:
Vitamin C alone did not result in any changes in systolic or diastolic blood pressure. In contrast, garlic resulted in a significant lowering (P < .05) of mean systolic but not diastolic blood pressure. In contrast, garlic plus vitamin C resulted in a distinct lowering of mean systolic and diastolic blood pressures to reference ranges.
Stephen