Impact of Diet and Maternal Obesity on Human Milk Hyaluronan

<b>Background:</b> Human milk hyaluronan (HA), a glycosaminoglycan with barrier-protective and immunomodulatory functions, may be influenced by maternal characteristics. The effects of maternal obesity and acute dietary intake on milk HA concentrations remain unclear. <b>Methods:</b> This secondary analysis included 35 lactating mothers (<i>n</i> = 19 normal weight [NW], <i>n</i> = 16 obese [OB]) at 6 weeks postpartum who participated in two separate, but standardized, protocols: (1) Study One, which consisted of hourly milk collections for six hours following a standardized high-fat meal with a sugar-sweetened beverage beginning at 6:00 am, and (2) Study Two, which consisted of daily morning milk collections for seven consecutive days to assess temporal stability (Monday-Sunday). HA concentrations were quantified by an ELISA and analyzed using a mixed-effects and repeated-measures ANOVA. <b>Results:</b> In Study One, postprandial HA concentrations remained stable with no effect of time, BMI, or time × BMI interaction (<i>p</i> > 0.05). In Study Two, HA did not vary significantly by day (<i>p</i> = 0.082) but was higher in OB versus NW mothers (151.9 ± 18.7 vs. 96.5 ± 12.4 ng/mL; <i>p</i> = 0.0396), with the largest difference observed on Day 1 (<i>p</i> = 0.0117). Mean HA values trended upward later in the week (Day 6 and 7), suggesting potential influences of habitual dietary intake or weekend energy patterns. <b>Conclusions:</b> Milk HA concentrations were not altered by acute dietary intake but were consistently higher across multiple days in mothers with obesity. These results indicate that milk HA varies with maternal metabolic status and may also be influenced by habitual dietary patterns, including fluctuations between weekday and weekend intake.