IS SALT THE NEW TOBACCO?

That kind of talk exasperates the Wolfson Institute’s MacGregor, one of the most vocal advocates of salt reduction anywhere. Along with Franco Cappuccio, head of the WHO’s collaborating center for nutrition at Warwick University and Simon Capewell, a professor of clinical epidemiology at Liverpool University, McGregor argues that salt - most of it hidden in processed and packaged foods - is a huge problem.

It’s perhaps an indication of his conviction that MacGregor equates the argument about salt to past rows over tobacco, even though unlike tobacco, salt is a fundamental nutritional requirement for humans to survive.

“We’re in exactly the same position as we were with tobacco 20 or 30 years ago when people were still arguing about whether tobacco caused lung cancer or heart disease,” MacGregor says. “It obviously did, there was no doubt about it - and the only people arguing were people who had commercial interest.”

WASH and its UK counterpart CASH (Consensus Action on Salt and Health), which is also chaired by MacGregor, are funded by donations from individuals and charities.

Cappuccio and Capewell point to scores of scientific analyses to make their point. A 2007 study predicted that reducing salt intake around the world by 15 percent could prevent almost 9 million deaths by 2015. Another study published in March 2010 found that cutting salt intake by 10 percent in the United States could prevent hundreds of thousands of heart attacks and strokes over decades and save the government $32 billion in healthcare costs.

In a recent British Medical Journal commentary, Capewell and Cappuccio cautioned: “Denial and procrastination will be costly in terms of both avoidable illness and expenses.”

When confronted with the two most recent scientific studies suggesting the contrary, MacGregor dismissed them as flawed or paradoxical. “There is absolutely no evidence of any harm from reducing salt intake. Absolutely none,” he said.

In the case of the Cochrane review, MacGregor set about re-crunching the numbers and swiftly published a fresh analysis of the data in a rival medical journal, The Lancet, which drew the opposite conclusion.

Taylor responded by saying MacGregor had taken two of the sets of data in the study - one from people with normal blood pressure and one from people with hypertension - and grouped them together. This, he said, is like comparing apples and oranges, and breaks a central tenet of statistical analysis.

Manchester University’s Tony Heagerty has a wry observation of this to-and-fro: “If you torture data long enough it will give you the answer you want.”