Backlash UK: Panic Nation
tanley Feldman and Vincent Marks' book Panic Nation explores "the myths we're told about food and health." While the genre is growing in reaction to the current global spate of myth-information, the book's appearance in the UK is timely since the Brits seem furthest off-base regarding the scientific issues of salt and health.
Chapter 9 by Dr. Sandy Macnair deals with salt and has been generating news coverage since publication . While much of Dr. Macnair's review tracks earlier work such as ABC-TV's "20/20" and "The (Political) Science of Salt" in Science magazine , a couple of observations may be new even to close readers on the issue.
We're often told that humans today eat "too much" salt -- more than our cave-dwellilng progenitors. Intakes in acculaturated societies range from about 2,300 mg/day sodium to 4,600 mg/day (6 - 12 grams of salt). While most people's healthy kidneys effectively process salt-laden body fluids, excreting the "excess," some people's kidneys malfunction and problems occur. Explained this way, you get the idea that the kidney is processing roughly ten grams of salt a day. Not so, explains Dr. Macnair. The kidneys filter water from the blood in the amount of 170 liters of water a day and, get this, handle 1,500 grams of salt a day. How our bodies can distinguish one or two milligrams out of this 1,500 grams (that's 3.3 POUNDS of salt a day) is absolutely amazing, but the main point is that we shouldn't think that the kidneys are straining to hand more than a gram or two a day.
Dr. Macnair makes another interesting point in his discussion of human evolution. Fourteen million years ago, he says, our ancestors in the Rift Valley in Africa split into two evolutionary streams, one heading off to the jungles to the west to evolve into great apes while those remaining in the Valley, with ready access to salt and the need for food preservation in the seasonal climate, produced a very different diet incorporating unique essential fatty acids that produced brains three times larger than their departed primate cousins and homo sapiens learned how to salt cure meats to ensure their survival.
You can read more in the South African magazine Food Review (as mentioned in our February blog ).
Perhaps Dr. Macnair's compatriots can reconsider the wisdom in his article.
