(11-04-10) Portion size can be used strategically to increase vegetable consumption in adults1,2,3

Barbara J Rolls, Liane S Roe and Jennifer S Meengs

1 From the Department of Nutritional Sciences The Pennsylvania State University University Park PA.
2 Supported by the National Institutes of Health (grant DK059853).
3 Address correspondence to BJ Rolls, The Pennsylvania State University, 226 Henderson Building, University Park, PA 16802-6501. E-mail: [email protected] .
Background: An increase in the proportion of vegetables at meals could help achieve recommended vegetable intakes and facilitate weight management.
Objective: We investigated the effects on food and energy intakes of varying the portion size and energy density of a vegetable that was added to a meal or substituted for other foods.
Design: In 2 experiments with crossover designs, men and women were served a meal of a vegetable, grain, and meat. Across the meals, the vegetable was served in 3 portion sizes (180, 270, or 360 g) and 2 energy densities (0.8 or 0.4 kcal/g) by altering the type and amount of added fat. In the addition study (n = 49), as the vegetable portion was increased, amounts of the grain and meat were unchanged, whereas in the substitution study (n = 48), amounts of the grain and meat decreased equally.
Results: An increase in the vegetable portion size resulted in greater vegetable consumption in both studies (mean ? SE: 60 ? 5 g; P < 0.0001). The addition of more of the vegetable did not significantly affect meal energy intake, whereas substitution of the vegetable for the grain and meat decreased meal energy intake (40 ? 10 kcal; P < 0.0001). A reduction in vegetable energy density decreased meal energy intake independent of portion size (55 ? 9 kcal; P < 0.0001). By combining substitution with a reduction in energy density, meal energy intake decreased by 14 ? 3%.
Conclusions: Serving more vegetables, either by adding more or substituting them for other foods, is an effective strategy to increase vegetable intake at a meal. However, to moderate meal energy intake, vegetables should be low in energy density; furthermore, the substitution of vegetables for more energy-dense foods is more effective than simply adding extra vegetables.

Source: Am J Clin Nutr 91: 913-922, 2010

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