To investigate the impact of consumption of dairy yogurt with rhamnogalacturonan (RG) in Korean citrus Hallabong peel polysaccharide on Natural Killer (NK) cell activity and circulating cytokine levels.

A randomized, double-blind, placebo-controlled study was conducted on 120 nondiabetic and nonobese subjects. Over an 8 week period, the test group consumed one pack (150ml) of dairy yogurt with 50mg probiotics and 100mg Korean citrus Hallabong peel polysaccharide (60% RG, 20% mono- and di-saccharide, 5% polyphenol) each day, whereas the placebo group consumed the same product without Korean citrus Hallabong peel polysaccharide. NK cell activities (%) were measured based on the ratios of effector cells (E) (peripheral blood mononuclear cell, PBMC) from each participant to Target cell (T) (K562 cells) as 10:1, 5:1, 2.5:1 or 1.25:1.

Inclusion Criteria:

• The levels of white blood cells under 8x10^3/μL
• males and females
• 30-69 years old
• nondiabetic and nonobese subjects
• able to give informed consent

Exclusion Criteria:

• consumption of any probiotic products within 1 month before screening
• unstable body weight (body-weight change > 2 kg within 3 months before screening)
• diabetes
• history/presence of significant metabolic disease
• pregnancy or breast-feeding
• acute or chronic infection
• liver disease, kidney disease, gastrointestinal disease, or any other acute or chronic disease requiring treatment
• subjects taking any drugs or supplements