Thursday, June 7, 2012

Guessing and Advising

In 1972, when the National Institutes of Health introduced the National High Blood Pressure Education Program to help prevent hypertension, no meaningful experiments had yet been done. The best evidence on the connection between salt and hypertension came from two pieces of research. One was the observation that populations that ate little salt had virtually no hypertension. But those populations didn’t eat a lot of things — sugar, for instance — and any one of those could have been the causal factor. The second was a strain of “salt-sensitive” rats that reliably developed hypertension on a high-salt diet. The catch was that “high salt” to these rats was 60 times more than what the average American consumes.
Still, the program was founded to help prevent hypertension, and prevention programs require preventive measures to recommend. Eating less salt seemed to be the only available option at the time, short of losing weight. Although researchers quietly acknowledged that the data were “inconclusive and contradictory” or “inconsistent and contradictory” — two quotes from the cardiologist Jeremiah Stamler, a leading proponent of the eat-less-salt campaign, in 1967 and 1981 — publicly, the link between salt and blood pressure was upgraded from hypothesis to fact.
In the years since, the N.I.H. has spent enormous sums of money on studies to test the hypothesis, and those studies have singularly failed to make the evidence any more conclusive. Instead, the organizations advocating salt restriction today — the U.S.D.A., the Institute of Medicine, the C.D.C. and the N.I.H. — all essentially rely on the results from a 30-day trial of salt, the 2001 DASH-Sodium study. It suggested that eating significantly less salt would modestly lower blood pressure; it said nothing about whether this would reduce hypertension, prevent heart disease or lengthen life.

So who pays for the damage if the government says "eating less salt with help you live longer", but in fact, eating less salt raises the liklihood that you perish early? 

You do. 

Which is why the government should constrain itself from offering dietary advice until the science is rock solid, confirmed by interventions studies, and well publicized and critiqued. 

1 comment:

  1. I've always wondered about that.
    I have borderline HBP.
    But I just love salt!
    I remember during a deployment to Antarctica...I think my tastebuds would get dulled there and I would just heap on the salt.

    And I still like salt.
    I think that's why my fav veggie is corn (I know...not pale).
    Corn on the cob is a salt and butter delivery system for yum.
    Good article.
    Thanks for sharing.