Comparison between Egg Intake versus Choline Supplementation on Gut Microbiota and Plasma Carotenoids in Subjects with Metabolic Syndrome

Abstract

We previously demonstrated that intake of three eggs/d for 4 weeks increased plasma choline and decreased inflammation in subjects with metabolic syndrome (MetS). The purpose of the current study was to further explore the effects of phosphatidylcholine (PC) provided by eggs versus a choline bitartrate (CB) supplement on the gut microbiota, trimethylamine N-oxide (TMAO) formation, and plasma carotenoids lutein and zeaxanthin in MetS. This randomized, controlled crossover clinical trial included 23 subjects with MetS. Following a washout period of 2 weeks without consuming any choline-containing foods, subjects were randomly allocated to consume either three eggs/d or a CB supplement for 4 weeks (both diets had a choline equivalent of 400 mg/day). DNA was extracted from stool samples to sequence the 16S rRNA gene region for community analysis. Operational taxonomic units (OTUs) and the α-diversity of the community were determined using QIIME software. Plasma TMAO, methionine, betaine, and dimethylglycine (DMG) were quantified by stable isotope dilution liquid chromatography with tandem mass spectrometry. Plasma carotenoids, lutein, and zeaxanthin were measured using reversed-phase high-performance liquid chromatography. There were significant increases in plasma lutein and zeaxanthin after egg intake compared to the baseline or intake of CB supplement (p < 0.01). In contrast, TMAO was not different between treatments compared to the baseline (p > 0.05). Additionally, while diet intervention had no effects on microbiota diversity measures or relative taxa abundances, a correlation between bacterial biodiversity and HDL was observed. Following egg intake, the observed increases in plasma lutein and zeaxanthin may suggest additional protection against oxidative stress, a common condition in MetS.

Eggs Improve Plasma Biomarkers in Patients with Metabolic Syndrome Following a Plant-Based Diet—A Randomized Crossover Study

“…The dietary betaine and choline-derived betaine might have significantly increased DMG after EGG and SUB intake. We did not observe higher TMAO concentrations compared to baseline in agreement with previous studies in our lab that have shown increases in plasma choline with no significant increases in TMAO after three eggs per day [ 7 , 48 ]. The higher concentrations of TMAO after the SUB breakfast may be due to the increased dietary betaine from spinach.…”

“…Eggs being the richest and most bioavailable source of choline resulted in significant increases in dietary choline. Betaine, another critical nutrient, is abundant in spinach (600–645 mg/100 g serving) [ 48 ] resulting in significant increases after SUB and EGG periods and not at baseline.…”

“…Dietary interventions have documented that whole-egg consumption increases dietary intake and improves plasma carotenoids in overweight individuals as part of a carbohydrate-restricted diet [ 64 , 65 ], in young men and women [ 66 ], metabolic syndrome participants [ 8 , 48 ], pre-menopausal women [ 25 ], elderly adults with altered lipid profile [ 67 , 68 ], after intake of regular, lutein-enriched and n-3 fatty-acid-enriched eggs [ 69 ] as well as in a healthy lacto-ovo-vegetarian population predominately on a plant-based diet consuming both n-3 fatty acid-enriched eggs and organic eggs [ 69 ]. In most of the above studies, plasma choline increased after consumption of eggs, whereas the choline metabolites’ TMAO levels did not increase [ 7 , 67 ].…”

The Effects of Eggs in a Plant-Based Diet on Oxidative Stress and Inflammation in Metabolic Syndrome

“…This is supported by the significant findings reported earlier from this 13-week intervention, that two eggs/day complement a PBD by lowering body weight and BMI and improving HDL-C, especially the large HDL [16]. Egg intake improved the plasma concentrations of choline, lutein, and zeaxanthin without increasing plasma glucose or LDL, consistent with previous studies in MetS patients [26,27].…”

“…Similarly, GlycA is a reliable cardiometabolic marker that can track the systemic acute phase responses, capturing inflammatory responses and providing information about progression to type 2 diabetes [44]. TMAO, the controversial atherogenic metabolite [45], was earlier shown to have no significant changes after egg consumption [16,27]. This evidence strongly suggests that consumption of two eggs/day did not detrimentally affect these key atherogenic risk factors of MetS.…”