A nutrient re-evaluation of shell eggs

Consumption of eggs and the 15-year incidence of age-related macular degeneration

BACKGROUND AND AIMS

A naturally rich source of lutein and zeaxanthin are eggs. There is scarce epidemiological data on the temporal association between total egg consumption and age-related macular degeneration (AMD) incidence. We aimed to establish the prospective and independent association between consumption of eggs with the incidence of AMD over a 15-year follow-up.

METHODS

In this population-based cohort study of 3,654 participants aged 49 + years examined at baseline, 2034 participants had complete information on baseline egg consumption and AMD signs over 15 years. AMD was determined from retinal photographs. Egg consumption was assessed using a semi-quantitative food-frequency questionnaire. Total egg intake was calculated through summing up intakes in all forms e.g. boiled, poached, fried, scrambled and/or omelette. We summarized total egg consumption into the following categories: ≤1 egg/week; 2-4 eggs/week; 5-6 eggs/week; and ≥1 egg/day.

RESULTS

At baseline, participants who consumed 2-4 eggs/week compared to those who consumed ≤1 egg/week (reference group) had reduced risk of incident late-stage AMD after 15 years: multivariable-adjusted odds ratio, OR, 0.51 (95% confidence intervals, CI, 0.28-0.92). Participants who consumed 2-4 eggs/week versus ≤1 egg/week at baseline had 62% reduced risk of developing neovascular AMD. Among those whose AMD onset was at or before the 10-year follow-up, consumption of 2-4 and 5-6 eggs/week was associated with 54% and 65% reduced risk of incident late AMD, respectively. When analyzed as a dichotomized variable, participants who consumed >1 egg/week versus ≤1 egg/week at baseline, had 46% reduced risk of developing late-stage AMD 15 years later: multivariable-adjusted OR 0.54 (95% CI 0.3-0.90). Non-significant associations were observed between egg consumption and incident early AMD.

CONCLUSIONS

Our findings suggest that moderate consumption of eggs significantly reduces the risk of developing incident late-stage AMD over 15 years.

Whole egg, but not egg white, ingestion induces mTOR colocalization with the lysosome after resistance exercise

We have recently demonstrated that whole egg ingestion induces a greater muscle protein synthetic (MPS) response when compared with isonitrogenous egg white ingestion after resistance exercise in young men. Our aim was to determine whether whole egg or egg white ingestion differentially influenced colocalization of key regulators of mechanistic target of rapamycin complex 1 (mTORC1) as means to explain our previously observed divergent postexercise MPS response. In crossover trials, 10 healthy resistance-trained men (21 ± 1 yr; 88 ± 3 kg; body fat: 16 ± 1%; means ± SE) completed lower body resistance exercise before ingesting whole eggs (18 g protein, 17 g fat) or egg whites (18 g protein, 0 g fat). Muscle biopsies were obtained before exercise and at 120 and 300 min after egg ingestion to assess, by immunofluorescence, protein colocalization of key anabolic signaling molecules. After resistance exercise, tuberous sclerosis 2-Ras homolog enriched in brain (Rheb) colocalization decreased ( P < 0.01) at 120 and 300 min after whole egg and egg white ingestion with concomitant increases ( P < 0.01) in mTOR-Rheb colocalization. After resistance exercise, mTOR-lysosome-associated membrane protein 2 (LAMP2) colocalization significantly increased at 120 and 300 min only after whole egg ingestion ( P < 0.01), and mTOR-LAMP2 colocalization correlated with rates of MPS at rest and after exercise ( r = 0.40, P < 0.05). We demonstrated that the greater postexercise MPS response with whole egg ingestion is related in part to an enhanced recruitment of mTORC1-Rheb complexes to the lysosome during recovery. These data suggest nonprotein dietary factors influence the postexercise regulation of mRNA translation in human skeletal muscle.

Egg white hydrolysate inhibits oxidation in mayonnaise and a model system

The flavor deterioration of mayonnaise is induced by iron, which is released from egg yolk phosvitin under acidic conditions and promotes lipid oxidation. To prevent oxidative deterioration, natural components, rather than synthetic chemicals such as ethylenediaminetetraacetic acid have been required by consumers. In the present study, we evaluated the inhibitory effects of three egg white components with the same amino acid composition, namely egg white protein, hydrolysate, and the amino acid mixture, on lipid oxidation in mayonnaise and an acidic egg yolk solution as a model system. We found that the hydrolysate had the strongest inhibitory effect on lipid oxidation among the three components. The mechanism underlying the antioxidant effect was associated with Fe2+-chelating activity. Thus, egg white hydrolysate may have the potential as natural inhibitors of lipid oxidation in mayonnaise.

Effects of egg consumption on carotenoid absorption from co-consumed, raw vegetables

BACKGROUND

Dietary lipids are one of the most effective stimulators of carotenoid absorption, but very limited data exist on the impact of endogenous food sources of lipids to enhance carotenoid absorption. The co-consumption of whole egg with carotenoid-rich foods may increase overall carotenoid absorption via lipid-rich egg yolk.

OBJECTIVE

We designed this study to assess the effects of egg consumption on carotenoid absorption from a carotenoid-rich, raw mixed-vegetable salad.

DESIGN

Healthy young men (n = 16) consumed the same salad (all served with 3 g canola oil) with no egg (control), 75 g scrambled whole eggs (1.5 eggs) [low egg (LE)], and 150 g scrambled whole eggs (3 eggs) [high egg (HE)] (a randomized crossover design). Control, LE, and HE meals contained 23 mg, 23.4 mg (0.4 mg from eggs), and 23.8 mg (0.8 mg from eggs) total carotenoids and 3 g, 10.5 g (7.5 g from eggs), and 18 g (15 g from eggs) total lipids, respectively. Blood was collected hourly for 10 h, and the triacylglycerol-rich lipoprotein (TRL) fraction was isolated. Total and individual carotenoid contents, including lutein, zeaxanthin , α-carotene, β-carotene, and lycopene in TRL were analyzed, and composite areas under the curve (AUCs) were calculated.

RESULTS

The total mean (±SE) carotenoid AUC0-10h in TRL was higher for the HE meal than for LE and control meals [125.7 ± 19.4(a) compared with 44.8 ± 9.2(b) compared with 14.9 ± 5.2(b) nmol/L · 10 h, respectively (values without a common superscript letter differ); P < 0.0001]. The TRL AUC(0-10h) of lutein and zeaxanthin increased 4-5-fold (P < 0.001), and the TRL AUC(0-10h) of carotenoid not present in eggs, including α-carotene, β-carotene, and lycopene, increased 3-8-fold (P < 0.01) for the HE meal compared with the control meal.

CONCLUSION

These findings support the claim that co-consuming cooked whole eggs is an effective way to enhance carotenoid absorption from other carotenoid-rich foods such as a raw mixed-vegetable salad. This trial was registered at clinicaltrials.gov as NCT01951313.

Effect of pasteurization of shell egg on its quality characteristics under ambient storage

Three thermal processes viz. dry (55°C, 2 h), moist (57°C, 5 min) and microwave (power 9, 20 sec) were studied to determine their efficacy for the pasteurization of intact chicken eggs based on the extent of inactivation of artificially inoculated Salmonella typhimurium (ST) in the yolk of shell eggs and alteration in albumen protein solubility (APS). Moist heat treatment was superior to others as it brought about 2 log cfu/ml reduction of inoculated ST in much less time than dry heating but changes in APS were not significant. Subsequent quality evaluation of normal (uninoculated) eggs subjected to moist heat pasteurization during 15 days of ambient (35°C, 36% RH) (35 ± 0.5°C, 36 ± 2% RH)storage revealed no significant effect on percent loss in egg weight, albumen pH, viscosity of albumen and yolk and thiobarbituric acid values between pasteurized and unpasteurized eggs. Pasteurization had no adverse effect on foam volume and foam stability of albumen during storage in comparison to those of raw eggs. Naturally occurring aerobic mesophilic bacteria, coliforms, staphylococci, yeast and moulds on the egg shell surface and in egg contents got markedly reduced by pasteurization of shell eggs and their multiplication also retarded during storage. Both pasteurized and raw eggs remained fairly acceptable sensorily up to 10 days of storage at ambient conditions.

Nutrient Digestibility and Mass Balance in Laying Hens Fed a Commercial or Acidifying Diet

The objectives of the current study were to evaluate the effect of an acidifying diet (gypsum) combined with zeolite and slightly reduced crude protein (R) vs. a control diet (C) on nutrient retention in laying hens and compare 3 approaches to estimating nutrient excretion from hens: 1) mass balance calculation (feed nutrients - egg nutrient), 2) use of an indigestible marker with analyzed feed and excreta nutrient content, and 3) an environmental chamber that allowed for capturing all excreted and volatilized nutrients. Hens (n = 640) were allocated randomly to 8 environmental chambers for 3-wk periods. Excreta samples were collected at the end of each trial to estimate apparent retention of N, S, P, and Ca. No diet effects on apparent retention of N were observed (53.44%, P > 0.05). Apparent retention of S, P, and Ca decreased in hens fed R diet (18.7, - 11.4, and 22.6%, respectively) compared with hens fed the C diet (40.7, 0.3, and 28.6%, respectively; P < 0.05). Total N excretion from hens fed the C and R diet was not different (1.16 g/hen/d); however, mass of chamber N remaining in excreta following the 3-wk period was less from hens fed the C diet (1.27 kg) than from hens fed the R diet (1.43 kg). Gaseous emissions of NH(3) over the 3-wk period from hens fed the C diet (0.74 kg per chamber) were greater than emissions from hens fed the R diet (0.45 kg). The 3-wk S excretion mass (estimated using the calculation, indigestible marker, and environmental chamber methods, respectively) was greater from hens fed the R diet (1.85, 1.54, and 1.27 kg, respectively) compared with hens fed the C diet (0.24, 0.20, and 0.14 kg, respectively). The 3-wk P excretion was similar between diets (0.68 kg). Results demonstrate that feeding the acidified diet resulted in decreased N emissions, but because of the acidulant fed, greatly increased S excretion and emissions.

Correlations between breeder age, egg cholesterol content, blood cholesterol level and hatchability of broiler breeders

1. The research was carried out to investigate correlations between breeder age, egg cholesterol content, blood cholesterol level and hatchability of broiler breeders. 2. Egg cholesterol content increased with increased breeder age. The mean yolk cholesterol contents (mg per g yolk) were 10.47+/-0.28, 15.34+/-0.65 and 15.64+/-0.71 mg/g at 28, 45 and 65 weeks of age, respectively. 3. There were positive correlations between yolk weight and yolk cholesterol content (mg/g yolk) (r=01.941; P<0.01) and egg cholesterol content (mg/egg) (r=0.980; P<0.01). 4. Negative correlations were found between egg yolk cholesterol content and hatchability of fertile eggs (r=-0.345; P<0.05), fertility ratio (r=-0.609; P<0.01) and hatchability of total eggs (r=-0.574; P<0.01). 5. The mean blood cholesterol levels were 165.1+/-11.04, 166.5+/-11.97 and 179.5+/-11.33 mg/dl at 28, 45 and 65 weeks of age, respectively.

Lipid profile in eggs of Araucana hens compared with Lohmann Selected Leghorn and ISA Brown hens given diets with different fat sources

1. In a cross-over trial, the egg cholesterol and fatty acid composition of Araucana hens was compared with those of two commercial breeds (Lohmann Selected Leghorn and ISA Brown) under two feeding regimes, either high (Hn-3) or low (Ln-3) in long-chain n-3 fatty acids. 2. The Hn-3 diet was formed by isocaloric substitution of animal fat in the control diet (Ln-3) by a dry product containing stabilised fish oil with standardised concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). 3. Both breed and diet had influences on egg composition, without interactions. 4. The Araucana breed showed lower feed intake and lower egg weights than the other two breeds. The yolk weight was similar, leading to a much higher yolk:albumen ratio in the Araucana eggs. 5. In comparison to commercial breeds, Araucanas produced eggs with higher cholesterol content per g of yolk, which was even more pronounced when expressed per g of egg, due to the high yolk content of the eggs. The cholesterol content of an egg remained unchanged by the diet, irrespective of the dietary fat source. 6. Changing to the Hn-3 diet led to greater concentrations of polyunsaturated fatty acids (PUFA) and lower concentrations of monounsaturated fatty acids (MUFA) contents in the yolk, without a change in the ratio of saturated (SFA) to unsaturated fatty acids (UFA). 7. Within the PUFA, the n-3 fatty acids increased at the expense of the n-6 fatty acids, indicating a competition between n-3 and n-6 fatty acids for incorporation in the yolk.

Effect of dietary phosphorus and phytase levels on the reproductive performance of large white turkey breeder hens

An experiment was conducted to determine the effect of dietary P levels and dietary phytase enzyme (E) inclusion on Large White turkey breeder hen reproductive performance from 31 to 62 wk of age. Hens were placed in a curtain-sided house with 48 pens (10 birds per pen; 8 pens per treatment) at 31 wk and were fed a breeder ration with treatments as follows: HP, dietary available P = 0.55%; HPE, HP + E; MP, dietary available P = 0.35%; MPE, MP + E; LP, dietary available P = 0.17%; and LPE, LP + E. Feed and water were available ad libitum for 28 wk of lay. Diets were fed in mash form, and all other nutrients were formulated to meet or exceed NRC requirements. All hens were photostimulated in January (31 wk) with 15.5 h of light daily. Production data were recorded on a pen basis. Individual bird BW and feed consumption, by pen, were determined at monthly intervals from 31 to 62 wk. Hens were observed for weekly reproductive performance for hen housed egg production, hen-day egg production, settable eggs, cumulative settable eggs, hens out of lay, and hen mortality and for biweekly performance for egg fertility, hatchability of all eggs, hatchability of fertile eggs, egg weight loss, conductance, conductance constant (k), and embryonic mortality. Egg weight, eggshell thickness, egg components, and albumen and yolk P were measured monthly. At 62 wk of age, hen tibia P, plasma P, total fecal P, and water-soluble fecal P were determined. Decreasing dietary P resulted in no decreases in reproductive performance for turkey breeder hens to 62 wk. Additionally, decreased dietary P resulted in decreased total fecal P and water-soluble fecal P. Feeding turkey breeder hens dietary phytase enzyme resulted in significantly fewer hens going out of lay; however, this was not reflected in hen housed egg production. It was concluded that phosphorus could be lowered in turkey breeder hen diets, compared with current surveyed industry levels, without impairing reproductive performance.

Lutein bioavailability is higher from lutein-enriched eggs than from supplements and spinach in men

Lutein may be protective against diseases such as age-related macular degeneration (ARMD). At present, data regarding bioavailability of lutein from various sources are insufficient. Healthy men (n = 10) participated in an intervention study with a crossover design. After a 2-wk washout period during which they consumed a low-carotenoid diet, the men were administered 1 of 4 lutein doses (lutein supplement, lutein ester supplement, spinach, and lutein-enriched egg) for 9 d. All lutein doses provided 6 mg lutein except for the lutein ester dose, which provided 5.5 mg lutein equivalents. Serum samples were collected from fasting subjects on d -14, 1 (baseline), 2, 3, and 10 and analyzed for changes in lutein concentration. Triacylglycerol-rich lipoproteins (TRL) were separated from postprandial blood samples (0-24 h) after the first lutein dose and analyzed for lutein concentration. Subjects completed all 4 treatments of the study in random order. Results from repeated-measures 1-way ANOVA showed that the baseline and dose-adjusted lutein response in serum was significantly higher after egg consumption than after lutein, lutein ester, and spinach consumption on d 10. There was no significant difference in TRL response. In conclusion, the lutein bioavailability from egg is higher than that from other sources such as lutein, lutein ester supplements, and spinach. The lutein bioavailability from lutein, lutein ester supplements, and spinach did not differ. This finding may have implications for dietary recommendations that may decrease the risk of certain diseases, e.g., ARMD.

Physical characteristics and chemical composition of Greater Rhea (Rhea americana) eggs from wild and captive populations

1. Eggs from wild and captive populations of Greater Rhea (Rhea americana) were studied to determine their physical and chemical characteristics. 2. Significant differences were found among populations in almost all chemical parameters studied, whereas within physical parameters only shell weight (as a proportion of the entire egg) and density showed differences. 3. Eggs from wild populations had the highest protein and linolenic acid and the lowest total lipid contents, while cholesterol levels of these eggs and of those from the largest captive area were the lowest.

Variation among individual White-Leghorn hens in the concentration of minerals in the albumen and yolk content of their eggs

1. The mineral composition of the albumen and yolk was determined in several eggs from each of a number of individual hens from the same White-Leghorn strain. X-ray fluorescent spectrometry was used to undertake two independent series of analyses. A total of 8 minerals (calcium, chlorine, iron, magnesium, phosphorus, potassium, sodium, sulphur) were included in the analyses of the yolk and the same minerals, but excluding iron (which is present in only small amounts), in the albumen. 2. There was considerable variation between individuals in the mineral concentration in their eggs (coefficients of variation ranged between 3.8% for sodium to 19.9% for calcium in the albumen, and between 4.3% for phosphorus to 11.8% for iron in the yolk). 3. At the same time, the moderately high repeatability of mineral concentration (t = 0.4-0.6) in successive eggs from the same hen for several of the minerals analysed is indicative of some positive control by the hen of the mineral composition of her eggs. 4. There was a highly significant correlation (P < or = 0.001) between the mean concentration of potassium in the albumen and the hatchability of the eggs, supporting the claim that a deficiency of potassium in the egg could be the basis of some failures in hatchability. 5. The study also revealed variation among individual birds in the concentration of iron in the yolk which was negatively correlated (P < or = 0.01) with hatchability. No clear basis could be suggested for this variation among individual birds.

Amino acid compartmentation in chick blood during the peri-hatching period

Individual amino acid levels and compartmentation in chick blood were measured on day 20 of incubation, at hatching (day 0), or after 1 or 5 days of free life, and compared with those of adult chickens. Blood cell amino acid concentrations were almost one order of magnitude higher than those of plasma, with higher values than those found in mammalian erythrocytes. This difference may be due to the capability for protein synthesis of the nucleated cells coupled with a postulated utilization of amino acids as fuel. The most common pattern of individual plasma amino acid levels was a slight rise at hatching followed by a large decrease, with minimal values for adults. The patterns in the cells did not always coincide with those for plasma. Total blood amino acid levels increased steadily during the period studied due to the increase in intracellular amino acids, giving rise to increasing blood-cell/plasma concentration ratios. These changes showed higher availability of plasma amino acids just after hatching, while the cell concentrations increased steadily to the maximum values in adults. The increase in alanine levels in cells with little changes in plasma can be correlated with the role of this amino acid as the main 2-amino nitrogen carrier in the avian bloodstream. The high amino acid levels in the cells suggest that these cells act as inter-organ transporters and reservoirs of amino acids, they have a different role in their handling and metabolism from those of mammals.

Yolk cholesterol in eggs from various avian species

Studies were conducted to establish the differences in yolk cholesterol concentrations in eggs from various avian species. Cholesterol was determined by a modification of the colorimetric procedure of Pearson et al. (1953). Species listed in increasing concentrations of cholesterol per gram of yolk, were guinea fowl, chicken, pheasant, quail, turkey, duck, goose, and dove with an overall range of 12.77 to 21.99 mg of cholesterol per gram of yolk. Significant differences in cholesterol concentrations also were found between domestic and wild genetic groups for turkeys and ducks. In a second study, eggs from 7 inbred lines of chickens showed significant differences in yolk cholesterol. The same general result was found in an analysis of eggs from 17 commercial test strains of chickens at two different ages. Yolk cholesterol tended to decrease as age of hen increased. These results confirm the possibility of genetically selecting for decreased yolk cholesterol if economic or other conditions warrant. The increased efforts required to decrease yolk cholesterol by this approach would undoubtedly be expensive.