For what reason Do We Get a High Blood Pressure

The next battle in the war against salt was set to kick off. In 1988 researchers set out to prove Dahl's "salt hypothesis" with the biggest study ever on the correlation between salt consumption and hypertension. BPS-5 Reviews This study observed 52 population groups spread over 32 countries worldwide and took four years to complete.

But once again, the evidence that came back was less than "unequivocal". It did conclude that part of the Dahl salt hypothesis was correct, that "there is a steady positive correlation between salt (sodium) intake and mean systolic blood pressure (MSBP). Specifically, that MSBP drops 1-6 mm HG for 100 mmol reduction in daily sodium intake".*

*British Medical Journal INTERSALT: an international study of electrolyte excretion and blood pressure: results for 24 hour urinary sodium and potassium excretion, INTERSALT Cooperative Research Group, BMJ, 1988)

But, again, there's a problem with these findings: Of the fifty-two social groups studied, four were primitive societies whose salt consumption and blood pressure were both extremely low. WITH these four groups included in the data there was a positive relationship between salt and blood pressure. But WITHOUT these four groups, data for the other forty-eight groups showed no relationship whatsoever.

There's more: the conclusions fail to take into account the fact that the four primitive societies experienced less stress, consumed a low fat/high fiber diet, had far less obesity and consumed much fewer processed foods. All or any of these factors could very well have influenced the group's blood pressure and thus the study's findings.

Perhaps the most significant finding of all was that, looking specifically at the other forty-eight groups revealed a small negative relationship: when sodium intakes increased, pressure levels went down!

Of course there have been other smaller studies showing that decreasing salt consumption does result in lower blood pressure. But in these cases the results are quite small, hardly significant statistically.

Participants typically see small reductions on the order of the 1-6 points systolic achieved through large reductions in salt in the INTERSALT research discussed above. In other words, statistically, you'd have to cut your salt consumption by more than half to expect pressure reductions of just a few points.

But even this does not reflect reality as it turns out that some people are more sensitive to sodium variations than others. Such individual differences further complicate research findings; levels of salt that negatively affect one person's blood pressure may have no effect at all on others.

Of course there's a common sense approach to salt (that applies to most aspects of diet) that should suit all but the most sodium-sensitive. Nobody still supports the sort of laissez-faire attitude that leads people to thoughtlessly shake salt over every meal before even tasting it.