SALT IS BAD FOR YOU, UNLESS IT’S NOT. SCIENCE CAN’T AGREE

Q HOW MUCH SALT IS HEALTHY?

A Given the marvels of technology, it seems like that ought to be an easy one. But a new review of hundreds of papers on the topic indicates that the inability to reach a consensus stems at least partially from the fact that the two groups of scientists operate, in essence, in parallel scientific universes. In one, the scientists write papers about the dangers of our salt consumption, and typically cite other papers that point to the same conclusion. In the other, the scientists write papers dismissing or minimizing the danger, and cite papers agreeing with their position.

Q BUT SURELY EVIDENCE SHOULD DECIDE THIS?

A Ludovic Trinquart and colleagues at Columbia University and Boston University say it appears scientists could not even agree on what ought to be counted as evidence. This finding arose from their review of 10 “systematic reviews” of the evidence that have been conducted. In systematic reviews, scientists collect all of the primary research on a topic and, in effect, weight it on the whole. But there appears to have been widespread disagreement about what research papers ought to be included. If a research paper was selected for one systematic review, it was more than likely not selected for another, the researchers found.

Q SO SHOULD WE AVOID SALT OR NOT?

A Science will have to get back to you on that one. The review found evidence of bias arising from scientists reluctant to change their view in light of new facts. Advocates of salt restrictions often disparage their opponents by saying the food industry has funded their efforts. In truth, some milestones in the research were not funded by corporate interests.