Marissa DiBella

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.

Metabolic syndrome (MetS) is characterized by low-grade inflammation and insulin resistance, which increase the risk of heart disease. Eggs have numerous nutrients including choline, carotenoids, and fat-soluble vitamins that may protect against these conditions. Egg phosphatidylcholine (PC) is a major contributor of dietary choline in the American diet. However, uncertainty remains regarding eggs due to their high concentration of cholesterol. In this study, we evaluated the effect of two sources of choline, whole eggs (a source of PC) and a choline supplement (choline bitartrate, CB), on plasma lipids, glucose, insulin resistance, and inflammatory biomarkers. We recruited 23 subjects with MetS to participate in this randomized cross-over intervention. After a 2-week washout, with no choline intake, participants were randomly allocated to consume three eggs/day or CB (~400 mg choline/d for both) for 4 weeks. After a 3-week washout period, they were allocated to the alternate treatment. Dietary records indicated higher concentrations of vitamin E and selenium during the egg period (p < 0.01). Interestingly, there were no changes in plasma total, low density lipoprotein (LDL)- or high density lipoprotein (HDL)-cholesterol, triglycerides, or glucose, compared either to baseline or between treatments. In contrast, interleukin-6 was reduced, with both sources of choline compared to baseline, while eggs also had an effect on lowering C-reactive protein, insulin, and insulin resistance compared to baseline. This study demonstrates that in a MetS population, intake of three eggs per day does not increase plasma LDL cholesterol, and has additional benefits on biomarkers of disease compared to a choline supplement, possibly due to the presence of other antioxidants in eggs.

The purpose of this study was to compare equivalent amounts of two choline sources on plasma cholesterol and the parameters of metabolic syndrome (MetS) in adults aged 32 to 70 years. Twenty-three subjects with MetS participated in this randomized, crossover clinical trial. Subjects underwent an initial period of 2 weeks without consuming any eggs, followed by a random allocation to consume either 3 eggs/day or a choline-bitartrate supplement for 4 weeks (choline equivalent of ∼400 mg/day for both interventions). After a 3 week washout period, participants were allocated to the alternate diet. We measured body weight, waist circumference, blood pressure, plasma lipids and glucose at the beginning and end of each dietary intervention and after the washout period. Three-day dietary and exercise records were collected concurrently with these measurements. Compliance was assessed weekly by self-reported consumed product. There was a 90% compliance among subjects. No differences in physical activity were reported between periods. Dietary records indicated that subjects were consuming more fat (P < 0.001), more protein (P < 0.009) and fewer carbohydrates (P < 0.001) and more cholesterol (P < 0.001) during the egg period. When dietary fat was analyzed separately, there were no differences in intake of saturated or polyunsaturated fatty acids. In contrast, consumption of monounsaturated fatty acids, known to lower plasma cholesterol, was higher during the egg compared to the supplement period (31.2 ± 11.2 vs. 24.3 ± 10.9 g/d), reflecting the fatty acid composition of eggs. Surprisingly, although dietary cholesterol was higher during the egg period, plasma total cholesterol, LDL and HDL cholesterol were not different between treatments or when compared to baseline (P > 0.05). LDL cholesterol was 111.4 ± 20.5 mg/dL during the egg and 110.8 ± 21.4 during the supplement period. Percent changes in LDL from baseline were +2.4% for eggs (P = 0.375) and +6.7% for choline (P = 0.111). Similarly, blood pressure, plasma glucose and insulin did not differ between periods (P > 0.05). Body weight and waist circumference did not change. This study indicates that in this population with MetS, consumption of 3 eggs/day for 4 weeks did not increase a select group of biomarkers associated with increased risk for heart disease. The Egg Nutrition Center.

Our previous study in a young healthy population indicated that choline from eggs (phosphatidylcholine) was more bioavailable than choline from a supplement (choline bitartrate) as determined by plasma choline concentrations. The purpose of this study was to compare equivalent amounts of two choline sources on plasma choline and its derivatives including trimethylamine N-oxide (TMAO) and inflammatory markers in men and women aged 32 to 70 years old with metabolic syndrome (MetS). Twenty-three subjects with MetS were included in this randomized, crossover clinical trial. Participants underwent an initial period of 2 weeks without consuming any eggs, which was followed by a random allocation to either 3 eggs/day or a choline-supplement for 4 weeks (both diets had a choline equivalent of 400 mg per day). Following a 3-week washout period, participants were allocated to the alternate diet. We measured plasma choline and plasma TMAO as well as C-reactive protein (CRP), inflammatory markers and liver enzymes. Although there was an overall significant increase in plasma choline after egg intake, compared to baseline (P < 0.01), there were no significant differences between egg and supplement at the end of the respective interventions (P > 0.05). Baseline values were 7.9 ± 2.1 nmol/ml compared to 9.9 ± 2.2 and 9.5 ± 2.1 nmol/ml for the egg and supplement, respectively (P < 0.01). In addition, plasma TMAO was not different between baseline, or at the end of the egg and supplement periods (P > 0.1). When we measured inflammatory markers, compared to baseline CRP was lower after the egg period (0.49 ± 0.50 vs. 0.36 ± 0.37 mg/dL, P < 0.01) while no differences in this parameter were observed at the end of the egg or the supplement period. Liver enzymes were not affected by treatment. These studies indicate that in contrast to healthy individuals, the plasma choline response appears to be similar in MetS participants, independent of its source or chemical composition. Analyzing the microbiota of these subjects will provide additional information regarding how choline is metabolized in individuals with MetS. The Egg Nutrition Center.