Clinical Investigations: Nutritional Formula Enhanced Immune Function and Reduced Days of Symptoms of Upper Respiratory Tract Infection in Seniors

To assess whether an experimental nutritional formula, given as a supplement, would reduce days of symptoms of upper respiratory tract infection (URTI) and affect antibody and lymphocyte proliferative responses to influenza vaccine. A prospective, randomized, double-blind, controlled trial was conducted between October 1999 and April 2000. Assisted- and independent-living facilities in North Central Florida. Sixty-six individuals, aged 65 and older. Subjects received 8 oz/d of an experimental formula containing antioxidants, zinc, selenium, fermentable oligosaccharides, and structured triacylglycerol or an isoenergetic, isonitrogenous control formula for 183 days. Subjects recorded daily symptoms of URTI. Antibody titers and lymphocyte proliferation to three influenza vaccine components were measured on Days 57 and 183. Eighteen subjects in the control group and 16 subjects in the experimental group consumed an average of 7 ounces of formula daily and completed the 183-day study. Median days of symptoms of URTI were 3 (range 0-69, total days=156) and 0 (range 0-49, total days=78) for the control and experimental groups, respectively (P= .049). On Day 57, seven of 17 (41%) subjects in the control group and 13 of 15 (87%) subjects in the experimental group achieved a fourfold or greater increase in serum antibody titer to A/Beijing (P=.012). Lymphocyte proliferation to influenza vaccine components was greater in the experimental (median=1,365 cpm, range=0-14,955 cpm) than the control group (median=136 cpm, range=0-4,270 cpm) (P=.013). Subjects consuming an experimental nutritional formula experienced enhanced immune function and fewer days of URTI symptoms.