Whole Egg Consumption Increases Serum 25‐hydroxyvitamin D Concentrations in Rats with DSS‐Induced Colitis
Authors: Jones Samantha Karen , Rowling Matthew , Schalinske Kevin 
Published: November 2023

The etiology of inflammatory bowel disease (IBD) is multifactorial. Some studies suggest that vitamin D deficiency has a role in both the development of IBD and disease severity. Moreover, it has also been shown that IBD results in a vitamin D deficient condition. Thus, the goal of this study was to evaluate the ability of a diet containing whole egg to maintain vitamin D balance in rats with dextran sodium sulfate (DSS)‐induced colitis. We hypothesized that because eggs are an excellent source of vitamin D, particularly 25‐(OH)‐vitamin D (25D), they represent a viable dietary strategy to maintain vitamin D balance during colitis development. In an initial dose response study, 5‐wk old Sprague‐Dawley rats (N=24) were randomly assigned to 4 groups (n=6 per group) of DSS‐treated drinking water (%, w/v): 0, 3, 4, and 5%. All rats were maintained on an AIN93 casein‐based diet for 5 wk. DSS‐treated drinking water replaced tap water for the final 7 d of the study period. Food and water were provided ad libitum. Prior to sacrifice, animals were placed in metabolism cages for 12 h for the collection of urine and to ensure they were in a fasted state. Urinary creatinine, 25D, and vitamin D binding protein (DBP), as well as serum 25D, were analyzed. Mean values were compared using a one‐way ANOVA (P< 0.05). Although urinary creatinine and 25D concentrations were not different across DSS groups, urinary DBP was significantly higher in the 3, 4 and 5% DSS groups compared to the 0% control (P= 0.025). Serum 25D concentrations exhibited a dose‐response with respect to DSS concentration and were significantly lower in the 4 and 5% DSS groups as compared to the 0 and 3% DSS‐treated rats. In a follow‐up study, rats (N=36) were randomly assigned to three diet groups (n=12 per group): a control AIN93 casein‐based diet, the same diet containing whole egg in place of casein, or a casein‐based diet with supplemented cholecalciferol (i.e., vitamin D3) at the same concentration (12.6 μg/kg diet) provided by the whole egg‐based diet. All diets were formulated to provide 20% (w/w) protein; thus, corn oil was added to the casein‐based diets to achieve the same total lipid content as the whole egg‐based diet. For the final 7 d of the 6 wk study, half of the rats in each diet group received 3.5% DSS drinking water. Control and DSS‐treated rats fed the whole egg‐based diet had serum 25D concentrations that were 61% higher than rats fed the casein‐based diets (P<0.001). Control casein‐fed rats supplemented with cholecalciferol had serum 25D concentrations that were 20% higher than control rats not receiving cholecalciferol supplementation (P= 0.009); however, cholecalciferol supplementation was without effect on serum 25D concentrations in DSS‐treated rats. These data strongly suggest that dietary consumption of whole egg results in: (1) an increase in serum 25D concentrations in control and IBD rats; and (2) increased serum 25D concentrations that were greater than an equivalent amount of supplemental cholecalciferol. Taken together, these results may support new dietary recommendations regarding whole egg consumption as a viable strategy for the management and/or prevention of vitamin D deficiency in IBD.

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Egg Nutrition Center, Park Ridge, IL.