ADD corn oil to the list of foods that the Food and Drug Administration says might be healthful.
Last month, the agency said corn oil manufacturers could claim that their product might reduce the risk of heart disease, even while acknowledging that there is little scientific evidence to support the link. Called a "qualified health claim," these bragging rights raised more than a few eyebrows among nutritionists.
"It's hilarious," says Marion Nestle, professor of nutrition at New York University. "They get funnier and funnier. This one is at the far end of hilarity."
Like Nestle, many nutrition experts say qualified claims can confuse consumers, who may assume the science is more definitive than it actually is. "I worry about these qualified health claims," says Susan Roberts, a professor of nutrition at Tufts University in Boston. "I worry, agonize and don't honestly know the right answer to this general big issue."
Before 2002, the FDA only allowed "unqualified health claims" for food. Such claims require so-called significant scientific agreement -- a general consensus among experts who have considered all publicly available scientific evidence and decided that the claim is valid.
As the name implies, unqualified claims can be stated plainly, without qualification, on packaging and in marketing. Here is the claim for low-sodium foods, for example: "Diets low in sodium may reduce the risk of high blood pressure, a disease associated with many factors."
A qualified claim does not require significant scientific agreement. But it does require a qualifying statement -- or disclaimer -- describing how strong the supporting evidence is thought to be.
The strongest of such statements is: "Although there is scientific evidence supporting the claim, the evidence is not conclusive." The mid-level statement is: "Some scientific evidence suggests.... However, FDA has determined that this evidence is limited and not conclusive." And the weakest statement is: "Very limited and preliminary scientific research suggests.... FDA concludes that there is little scientific evidence supporting this claim."
The FDA determined that the corn oil claim has the weakest level of supporting evidence.
The agency says the broader allowances for qualified claims give Americans more information than they would have if only unqualified claims -- with their hard-to-meet requirements -- were allowed. And the agency believes that the qualifying statements should keep consumers from being misled.
But Bruce Silverglade, legal director for the Center for Science in the Public Interest, suspects that the looser standards do more harm than good. "It's almost disingenuous of a public health agency to authorize claims that are unlikely to be true," he says.
He disputes the agency's assertion that the qualifying statements it requires will prevent the claims from causing any harm. He says consumers don't understand these disclaimers and cites an FDA study, released in 2005, which found exactly that. A second study is ongoing.
The corn oil claim that manufacturers are now allowed to make reads:
"Very limited and preliminary scientific evidence suggests that eating about 1 tablespoon (16 grams) of corn oil daily may reduce the risk of heart disease due to the unsaturated fat content in corn oil. FDA concludes that there is little scientific evidence supporting this claim. To achieve this possible benefit, corn oil is to replace a similar amount of saturated fat and not increase the total number of calories you eat in a day. One serving of this product contains [x] grams of corn oil."
This is similar to qualified claims that were allowed for olive oil in 2004 and for canola oil in 2006. But in both those cases, the scientific evidence was described as "limited and not conclusive," instead of the even less confident "very limited and preliminary."
Nestle calls "very limited" an enormous red flag.
Like olive and canola, corn oil consists mainly of unsaturated fats, and the health claim says any possible benefits will come only if it's substituted for a similar amount of saturated fats, which are associated with more health risks. There would be no benefit -- and, most likely, just the opposite -- from adding more fat, and more calories, to your diet.
To support the corn oil claim, the FDA found only three relevant studies, all small (12 to 27 subjects in each), comparing a diet containing corn oil with a diet high in saturated fats. Two of these studies found that corn oil reduced cholesterol levels, but the third study did not.