Health Options Alan Titchenal  & Joannie Dobbs                    Wednesday, February 27, 2002

Consider the source when taking diet advice

In the last few decades, many people have forgotten that nutrition is a science based on a body of scientific research that has been accumulated for well over a century. It is from this broad base of knowledge that new studies and popular ideas should be interpreted.

Too often, one or two new studies are reported as if they are the final word, without putting them into the perspective of the broader knowledge base. The result is a plethora of partially true, and often misleading, nutrition information that can affect the types and amounts of foods and supplements that people choose to consume.

Because ongoing research adds to existing knowledge, the Food and Nutrition Board of the Institute of Medicine/National Academy of Sciences periodically updates nutrition recommendations. Committees of experts do this by reviewing the basis for previous nutrient-intake recommendations along with recently published scientific studies. Their recommendations are a key component of the foundation for food guidelines.

However, the explosion of desktop-published nutrition books and misinformation posted on Web sites has caused a great deal of confusion. A prime example is the misrepresentation of the USDA's Food Guide Pyramid.

Approximately 50 nutrients are required for human growth, reproduction and overall health. No one single food contains all of these nutrients in the proportions required for optimal function and health.

Since 1958, the USDA has provided food-group eating plans in an effort to simplify the other­wise complicated task of meeting nutrient requirements. The latest is the Food Guide Pyramid, a plan based on the premise that consuming specified amounts of foods from five food groups will provide enough essential nutrients.

The concept is a great deal more than just setting up five major food groups. The eating plan is based on three key elements: proportionality, variety and moderation. Proportionality refers to eating appro­priate amounts from each food group. By choosing a variety of foods each day within each group, the likelihood of obtaining all essential nutrients is increased. The concept of moderation, especially with respect to consuming exces­sive fats and sweets, was incorporated into the plan to help control calories and foods associated with various diseases.

An additional feature of the Food Guide Pyramid is the list of recommended ranges of servings from each group. This helps indi­viduals meet their nutrient needs without exceeding their calorie needs. For example, a person who consumes the lower number of recommended servings from each food group consumes about 1,600 calories. Someone who consumes the largest number of recommended servings consumes about 2,800 calories.

Probably the greatest confusion people have with the Food Guide Pyramid is understanding serving sizes. When the plan was devised, it used typical serving sizes of nearly 20 years ago. Today's typical serving sizes tend to be much larger. For example, 20 years ago the typical muffin weighed 2 ounces and equaled two grain servings. Today's mega-muffin equals 5 to 8 grain servings.

It has become popular to criticize the USDA pyramid and create alternative pyramids based on particular biases. Next week, we will address the benefits and drawbacks of some of the food pyramids created by the USDA and other groups.