Half-baked science

Posted: Aug 31, 2005 12:00 AM

Have you cut down on salt? Forced the kids to eat spinach because it's uniquely healthy? You may think you're eating healthy food, but you're really swallowing junk science.

 When I was a kid, my mother thought spinach was the healthiest food in the world because it contained so much iron. Getting enough iron was a big deal then because we didn't have "iron-fortified" bread. It turns out that spinach is an OK source of iron but no better than pizza, pistachio nuts or dried peaches. The spinach-iron myth grew out of a simple mathematical miscalculation: A researcher accidentally moved a decimal point one space, so he thought spinach had 10 times more iron than it did. The press reported it, and I had to eat spinach.

 Moving the decimal point was an honest mistake -- but it's seldom that simple. If it happened today, I'd suspect a spinach lobby was behind it. Businesses often twist science to make money. Lawyers do it to win cases. Political activists distort science to fit their agenda, bureaucrats to protect their turf. Reporters, like other people who aren't scientists, keep falling for it.

 And so does the government. Consider salt. Uncle Sugar hasn't tried banning salt -- yet -- but he has decided to make all of us pay for a program to tell us salt is no good. But it's the science that's no good.

 The federal anti-salt bureaucracy launched expensive public service announcements that warn Americans to cut back on salt. The ads intoned, ominously, "You eat more than 20 times the salt your body needs."

 Eat "no more than 2,400 milligrams a day," said Dr. Jeffrey Cutler, the official behind the government's anti-salt campaign.

 I feel sorry for you if you follow your government's recommendations. A maximum of 2,400 milligrams a day makes for a miserable diet. Three dill pickles put you over the limit.

 Cutler decided that Americans should eat less salt because high blood pressure can lead to heart disease and eating less salt can lower blood pressure. It's a plausible theory, but it doesn't prove that less salt leads to less heart disease. Too many other things may be going on.

 Many experts on blood pressure told us there isn't enough scientific research to justify the government's anti-salt campaign, and there definitely isn't enough to justify Cutler's 2,400-milligram limit.

 "I can't imagine how they came up with that number. I mean, there isn't a single bit of evidence that suggests 2,400 milligrams is better than 2,100 or 3,700," said Dr. Michael Alderman, who headed the American Society of Hypertension, America's biggest organization of specialists in high blood pressure. He says some people should cut back on salt, but for most people, it's pointless. Some studies have found that those who ate the least salt were four times more likely to have heart attacks.

 I couldn't read Cutler's mind, so I don't know that he pushed his anti-salt campaign because he wanted to build himself a little empire. But consider the choices of the bureaucrat: If he finds that you're probably eating "more than 20 times the salt your body needs," his findings may be on "Good Morning America," and he's important.

 If he finds no threat, he is just another bureaucrat.

 Scientific communication is very stilted, as if to convey impartiality. Scientists are happy to have non-scientists view them as uniquely unbiased, and reporters fall into the trap of believing them. But supposedly "dispassionate" scientists are as passionate about their ideas as any entrepreneur. They have all sorts of reasons to lose perspective and get carried away with hope and excitement. If they discover something, they may be famous. If they don't, they may have spent years in some windowless laboratory for little good. So if they can convince themselves their theory is right, they are eager for the public to hear about it.

 When there's a broad scientific consensus behind a theory, it's quite likely -- though still not certain -- to be right. But some theories, including some backed by the government, deserve to be taken only with a grain of salt.

 Give Me a Break.