Sure, it might be the salty food, but Science Daily says, based on work by the American Physiological Society, that the microbes in your intestines can have a stronger effect on hypertension:
Scientists studied two sets of rats, one group with high blood pressure (“hypertensive”) and one with normal blood pressure (“normal”). The research team removed a portion of the biological material from the large intestine of each group. All animals were then given antibiotics for 10 days to reduce their natural microbiota. After the course of antibiotics, the researchers transplanted hypertensive microbiota to normal blood pressure rats and normal microbiota to the hypertensive group.
The researchers found that the group treated with hypertensive microbiota developed elevated blood pressure. A more surprising result is that the rats treated with normal microbiota did not have a significant drop in blood pressure, although readings did decrease slightly.