According to the researchers, led by Brett Carter, of the Center for Public Health Nutrition at the University of Washington, “fortification can provide an effective way to increase the nutrient-to-calorie ratio of the diet.”
“A nutrient fortified beverage and a 100 percent orange juice delivered similar amounts of folic acid and ascorbic acid. However, the fortified beverage contained far fewer calories than the juice,” stated the researchers.
Improving the nutrients-to-energy ratio in the American diet is a stated goal of the 2005 Dietary Guidelines for Americans published by the USDA and HSS.
According to the authors, one way to increase the dietary nutrient-to-energy ratio is to consume more nutrient-dense foods or consume more nutrient-fortified foods and beverages.
However, one concern is that the bioavailability of fortified nutrients may be different than the bioavailability of naturally occurring nutrients with some research suggesting the bioavailability to differ between foods fortified with micronutrients and those that naturally contain equivalent levels of the same nutrient.
Previous studies have also shown that ingestion of folic acid in fortified foods can result in greater bioavailability than that of naturally occurring food folate, but studies on the bioavailability of ascorbic acid have been inconsistent.
The new study compared the bioavailability of ascorbic acid and folic acid from a low calorie fortified beverage, 100 percent orange juice, and 1 percent low fat milk.
Twelve adult men consumed a 591 milliliter serving of the each of the beverages, before blood plasma concentrations of ascorbic acid and serum concentrations of folic acid were assayed by serial blood draws made at 30 min intervals for 4.5 hours.
Analysis of the blood samples revealed that plasma ascorbic acid concentrations rose to the highest levels after consumption of the fortified beverage.
Plasma concentrations increased to a peak of approximately 0.6 mg per deciliter relative to baseline levels after consumption of the fortified beverage, by comparison, orange juice only elicited a peak change approximately mg per deciliter relative to baseline, while levels declined relative to baseline after milk consumption.
The researchers reported that bioavailability following the fortified beverage consumption was approximately the same as that for 100 percent orange juice, with no statistical difference between the two conditions.
Serum folic acid concentrations were also observed to rise to the highest levels after consumption of the fortified beverage. However the response to the fortified beverage was not significantly different than the response to orange juice and the bioavailability of folic acid post ingestion was reported as not significantly different for orange juice and the fortified beverage.
The authors concluded that there was no significant difference in terms of the bioavailability between 100 percent orange juice and a low calorie beverage fortified with folic acid and ascorbic acid, and as such a fortified low calorie beverage provides a better nutrients-to-energy ratio than orange juice.
“The results indicate that beverages fortified with ascorbic acid and folic acid can provide the same nutrient bioavailability as orange juice, but with fewer calories and sugars per serving,” stated Carter and colleagues.
Source: Journal of Food Science
Volume 75, Issue 9, pages H289–H293, doi: 10.1111/j.1750-3841.2010.01844.x
“Absorption of Folic Acid and Ascorbic Acid from Nutrient Comparable Beverages”
Authors: B. Carter, P. Monsivais, A. Drewnowski