Reductionism and the narrowing nutrition perspective: Time for reevaluation and emphasis on food synergy. (Commentary).

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Technological advances have provided nutrition scientists with unprecedented capabilities for identifying and isolating food components and for evaluating their possible health effects. Consequently, there is greater recognition of, and appreciation for, the complex mixture of chemicals to which humans are exposed in their diets.

Nevertheless, disappointing results from recently published observational studies and intervention trials (1-3), especially those involving isolated nutrients (4-7), have raised questions about the role of diet in the etiology of certain disease processes. Increasingly however, it appears that these "negative" findings often result from an overly reductionist approach (emphasizing the role of a single chemical, or occasionaly a combination of a small number of chemicals) to understanding diet-disease relationships, which hinders, rather than facilitates, progress on the public health front.

The consequences of reductionism on consumer dietary behavior should not be underestimated. Even single studies that fail to support the prevailing scientific view can negatively impact consumer attitudes about the importance of nutrition and contribute to a lack of confidence about the utility of making dietary changes to promote health. This is especially so because of the extent to which the news media cover health and nutrition information (8). In contrast to scientists who understand that each study is at best an incremental advance over previous research and that single studies are rarely if ever decisive, journalists often emphasize the short-term newsworthiness of new studies by highlighting the extent to which they contradict existing data, or conversely, represent a new breakthrough. It is imperative that researchers and health professionals be more mindful about the way they communicate with the media, making sure to place the findings from any single study in the proper context, regardless of whe ther or not the results support a given hypothesis.

REDUCTIONISM AND FOOD SYNERGY DEFINED

Because biochemical and molecular studies in the area of nutrition have primarliy focused on discovering mechanisms of dietary effects in biologic systems, a reductionist approach using single nutrients or dietary constituents has dominated this area of research. Zeisel and colleagues define reductionism as "the scientific approach aimed at identifying the molecules involved in biological events and examining them in their purified form or in simple systems" (10). Generally, isolated nutrients or dietary constituents are added to purified cell or cell-free systems. In order to understand mechanisms it is critical to reduce the experimental system to minimal elements so that complex interactions do not make interpretation of the experimental results impossible. However, foods contain hundreds of biologically active constituents and the etiologies of chronic disease involve extremely complex processes that occur over a period of many years, likely decades. Thus, understanding the full impact of diet when considering only food components in isolation is an uncertain undertaking at best, and one which can lead to misunderstandings about the importance of any single dietary constituent relative to other factors on the entire dietary pattern.

This is not to say that reductionism has no place within nutrition research; it does, especially because new technologies are being developed that make it possible to study multiple levels of cellular processing by following thousands of genes or proteins simultaneously. Functional, genome-wide approaches will allow scientists to obtain information on the impact of a complex dietary intervention on a multitude …