Thursday, 9 January 2014

Dietary guidelines and health

[An excerpt from Chapter 8 in Food Policy in the United States: An Introduction (Routledge/Earthscan, 2013).]

It is sometimes said that there is no need for a government role in dietary guidance, because people know how to eat well and simply lack the willpower to do so. Is it true that people in the United States already know how to eat healthfully? While many nutrition and health experts say that something is wrong with U.S. eating patterns, they disagree about what is unhealthy.

Consider four perspectives, which each have a large public following:

  • A long tradition, including the physician Robert Atkins and the science writer Gary Taubes, blames carbohydrates for weight problems and recommends a diet that may be high in meat and saturated fat (Taubes, 2007).
  • An equally well-developed tradition encourages a low-fat plant-based diet and blames meat consumption for health problems (Campbell and Campbell, 2007).
  • The respected epidemiologist Walter Willett and colleagues at the Harvard School of Public Health advise a mostly plant-based diet that is not necessarily low in fat, allowing plenty of vegetable oils (Willett et al., 2005).
  • Others, including former FDA Commissioner David Kessler and journalist Michael Pollan, are most concerned about the highly palatable artificial creations of an industrial food system (Kessler, 2009). 
These views about diet and health are partly overlapping and partly contradictory. Yet at least some scientific research in peer-reviewed journals can be found to support each one. To make sound judgments, a layperson needs a skeptical attitude towards dietary fads and a trustworthy summary of the balance of the scientific evidence.

One influential summary of the scientific evidence is the federal government’s Dietary Guidelines for Americans (U.S. Department of Agriculture and U.S. Department of Health and Human Services, 2011). The federal government issued the first Dietary Guidelines in 1980 and has revised the document every five years since then. Regardless of a reader’s own views on diet and health, it is useful to understand the mainstream position of the Dietary Guidelines on controversial questions in nutrition science.

The Dietary Guidelines for Americans is used as a source of evidence for claims about diet and health on food labels (see Chapter 9). It provides key inputs for USDA’s Thrifty Food Plan and other model diets for people at different income levels (see Chapter 10). It informs policies and regulations for nutrition assistance programs, including school lunch and school breakfast (see Chapter 11).

This chapter covers how the federal government develops and uses dietary guidance. The chapter:

  • reviews historical trends in chronic disease and nutrition, so that we can pay the most attention to the most important health concerns (Section 8.2); 
  • considers several market failures that have been cited as motivation for a government role in dietary guidance (Section 8.3);
  • explains the process of creating the Dietary Guidelines for Americans and related consumer-oriented graphics (Section 8.4);
  • compares current U.S. consumption patterns to the Dietary Guidelines (Section 8.5); and
  • explores several policy instruments that have been proposed to guide Americans toward healthier food choices (Section 8.6).

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