Although we are what we eat, we are by no means only what we eat. Some people, for instance, can consume all the fatty foods they want—meat, cheese, butter, ice cream—but somehow manage to stay rail-thin and enjoy low blood triglyceride levels, whereas others living on the same rich fare would soon develop potbellies and clogged arteries. The significant genetic and metabolic variation among individuals makes it almost impossible for experts to prescribe detailed nutritional recommendations that work optimally for everybody. As nutritionist Marion Nestle recommends in her article “Eating Made Simple,” beginning on page 60, the best we can do today is to adhere to the time-honored advice to eat less; exercise more; eat mostly fruits, vegetables and grains; and avoid junk foods.

But this basic regimen leaves many concerned Americans with unresolved issues about dietary choices, especially those regarding specific foods promoted by food companies and their lobbyists: Is milk bad for adults? Should I eat more fish? Are organic foods better? More specific guidance regarding food selection would help.

Regrettably, determining the actual health value of organics, fish, milk or any other single foodstuff or nutrient is no easy task, nor is it cheap. The complexity of nutrition and its subtle effects on human well-being mean that researchers must mount large, long-term studies to try to distinguish among multiple, interrelated nutritional factors that affect health. But big test group populations are costly to monitor accurately and difficult to control over time.

Despite the complexities, such large-scale nutrition-related studies are important because they help to shape how government and professional authorities formulate dietary guidelines, how admin­is­trators design public health programs and how agencies regulate company health claims for food products. The popular media publicize these findings widely, which directly affects consumer behavior. More and more, the commercial success of food products depends on what science says about the effects of these foods on health. Yet all too often the sources of the science are the commercial interests themselves.

Although government agencies as well as some charities and activist groups sponsor major nutrition experiments in the public’s interest, these organizations often lack sufficient resources to conduct the research that might more fully inform people about what to eat. Given the chance to gain favorable, peer-reviewed publicity for their products, food companies frequently fill the research-study funding gap and then vigorously promote any results that support consuming a specified daily amount of one of their foods.

Unfortunately, food industry money seems to distort nutrition studies, according to the first systematic effort to measure sponsorship bias in nutritional research. That analysis appeared in a paper published this past January in the Public Library of Science Medicine. A research team at Children’s Hospital Boston performed a meta-analysis of 206 nutrition-related studies on milk, juice and soft drinks conducted from 1999 to 2003. Of the 111 that had declared financial sponsorship, 54 percent were at least partly funded by industry. Industry-supported studies were four to seven times more likely to favor their sponsors than research paid for by disinterested parties.

The influence of sponsors may be unconscious, the investigators suggest, and could occur at many levels, manifested by how researchers pose questions in the hypothesis, how they design studies, which data they collect or do not collect, how they analyze the data and how they derive their conclusions.

Critics have also noted that the Children’s Hospital group may have distorted the study’s findings by failing to include in their analysis nutrition research funded by the U.S. Department of Agriculture (presumably the critics believe that government-supported investigations are more likely to be free of industry influence).

The realization that all organizations—including the government, as well as industry and activist groups—tend to finance research that is aligned with their interests seems to lead to a straightforward solution. Because nutrition research is important to helping the public make healthy food choices, it only makes sense to find public monies with which to support the independent studies needed to develop the necessary guidelines. People, we think, are likely to deem it worthwhile to pay a bit to find out whatever science can legitimately say about what to eat.