Photo by Ingorrr/Flickr CC

It is one of the great oddities of nutrition that public health guidelines invariably recommend salt reduction but the science is so hard to do that the value of doing so can't be proven unequivocally. Hypertension specialists insist that salt reduction is essential for controlling high blood pressure, and many people with high blood pressure can demonstrate that this is true.

So why can't the science show it? I'd say because even the lowest salt intakes are higher than recommended. Because everyone consumes higher-than-recommended amounts, it's impossible to divide people into meaningful groups of salt eaters and see whether low-salt diets work.

With that said, here are the latest events in the salt wars:

1. An article by a group of investigators in California and Washington state, "Can dietary sodium be modified by public policy," argues that it makes no difference who you are, everybody consumes salt in the same range. Therefore, there is no point in trying to lower it.

2. Not so, say critics, who point out that the authors of that study consult with the food and salt industries (and, therefore, have conscious or unconscious biases) and that plenty of evidence demonstrates the value of salt reduction.

3. ConAgra says it will cut the salt in its products by 20 percent in the next few years, according to an article in Bloomberg News (in which I am quoted).  Why is ConAgra doing this? To lower the salt before the company is forced to. Regulators are well aware that nearly 80 percent of the salt in American diets comes from processed and pre-prepared foods, not salt shakers.

Expect to hear lots more about the need to reduce salt intake this year.