Published in this month's Journal of the American Dietetic Association, the latest findings reveal that only 40 percent of Americans have been consuming at least five servings of fruits and vegetables per day.
And dark green and orange vegetables and legumes were the most lacking from people's diets, with current intake of these being less than a third of the recommended amounts.
The researchers said they used the "most accurate and reliable data available and appropriate statistical methods" to estimate the nation's fruit and vegetable consumption, and to determine whether this meets the combined recommendations found in the USDA Food Guide Pyramid, and in the more recent MyPyramid guide.
Fruit and vegetable consumption has been linked to a reduced risk of cancer and cardiovascular disease, and is also said to play a role in weight management by helping to promote satiety and decrease energy intakes. Such science is partly what prompted the USDA to increase its recommendations for fruit and vegetable consumption in its new 2005 MyPyramid guidelines.
As well as recommending greater amounts of fruits and vegetables, MyPyramid differs from the Food Guide Pyramid also includes more specific recommendations about types of vegetables.
MyPyramid recommends 1-2.5 cups of fruit and 1-4 cups of vegetables per day, depending on age, sex and activity level, for a total of 2-6.5 cups. In both the 1992 Food Guide Pyramid and the 5 A Day Program, a 'serving' of most fruits and vegetables is half a cup. So when the new recommendations are combined, they are equivalent to about 4 to 13 servings.
But this is not nearly the amounts actually being consumed by Americans, with the latest research revealing that average intake currently stands at 4.7 servings per day.
Mean intakes by all age and sex groups are below the recommended amounts for fruits, total vegetables, and all subgroups of vegetables with one exception: 12-15 year-olds are currently consuming more than the recommended levels of starchy vegetables, mainly white potatoes, corn and peas.
Based on single food intake data for 8,070 people participating in a 1999-2000 National Health and Nutrition Examination Survey, the research indicated that adequate intake of fruits and vegetables ranged from a low of 0.7 percent of boys aged 14-18, whose combined recommendation is five cups, to a high of 48 percent of children aged 2-3, whose combined recommendation is one cup.
Among women aged 51-70, only 17 percent met their combined recommendation. Among all other sex-age groups, fewer than 11 percent met their goals.
"A large proportion of the US population needs to increase their fruit and vegetable intake if recommendations are to be met," wrote the researchers.
"Barriers to increasing consumption (…) should be investigated, and strategies for appropriate programs and interventions should be developed," they added.