State of Science :: Hot Science
New Science Supports Old Advice "Eat a Variety of Foods" and Highlights the Need to Increase Nutrient Density
September 2005
Everyone has heard the advice "Eat a diverse diet," a recommendation that has been a part of government dietary guidelines for decades. But few studies have explored the relationship between dietary diversity and the adequacy of nutrient uptake. The few studies that have been done have reached different conclusions, in part because there is no standard definition, or way to measure, "dietary diversity."
With a grant from the USDA, scientists carried out a first-of-its-kind analysis of the adequacy of nutrient intakes as a function of diversity. Their study involved daily food consumption data on almost 10,000 healthy adults 19 years or older. Each had participated in the USDA's "Continuing Survey of Food Intakes for Individuals" (1994-1996). The study reached three important conclusions.
First, a surprising percent of men and women are not consuming an adequate intake of 15 key nutrients studied. For men, the probability of adequacy for five key nutrients was under 50 percent, with vitamin E at only 14.1 percent and magnesium and folate at 36 and 34 percent respectively. For women, only 6.8 percent were projected to consume an adequate amount of vitamin E, 20.9 percent for folate, and just as the case with men, there were a total of five nutrients under 50 percent.
Second, variety between and within the dairy and fruit food groups increased the odds of adequate energy-adjusted intake across the 15 nutrients more so than in the grains and meat food groups.
Third, because of the strong correlation between diversity in the diet and total caloric intake, advice to increase dietary diversity should be coupled with recommendations on how to diversify the diet without increasing, or even while decreasing caloric intake.
Across the fifteen nutrients studied, an average of 67 and 58 percent of men and women had adequate intakes, and so, on average, 34 and 42 percent had inadequate intakes. At least 15 percent of women had inadequate intakes of all 15 nutrients studied (15 percent of men had inadequate intakes of 12 of the 15 nutrients studied).
Accordingly, the ability to increase the density of vitamins and minerals in organically produced foods can help bridge the gap between adequate and inadequate consumption of common nutrients. A review by Worthington found significantly higher levels in organic crops compared to conventional crops of eight of the 15 nutrients studied in this research. In addition, greater nutrient density can increase the percent of people consuming adequate levels of nutrients without increasing caloric intake.
Sources: "Dietary Variety Increases the Probability of Nutrient Adequacy among Adults."
Authors: Janet Foote, Suzanne Murphy, Lynne Wilkens, Peter Basiotis, and Andrea Carlson.
The Journal of Nutrition, Volume 134, No. 7, July 2004
"Nutritional Quality of Organic Versus Conventional Fruits, Vegetables, and Grains."
Author: Virginia Worthington.
Journal of Alternative and Complimentary Medicine, Volume 7, No. 2, 2001
