Egg Yolk Consumption Research Articles

ODP152 Impact of Dietary Cholesterol on LDL: Lessons in Absorption and Overconsumption

Abstract Background The impact of dietary cholesterol on lipid profiles have remained controversial, highlighted by alterations in the 2015-2020 American Heart Association dietary guidelines abolishing the prior dietary cholesterol limit of 300mg/day. Eggs often are the example cited in this debate as they are a rich source of dietary cholesterol without comparative high levels of saturated fat, 1 of which the effects on LDL cholesterol are well established. To date, evidence has been mixed although most studies show only modest increases in LDL with dietary cholesterol. 1 However, recent research supports significant variation in these findings among predisposed individuals. 2 Heterogeneity in dietary cholesterol absorption can potentially account for these variations and has important clinical implications. Clinical Case A 58 year old woman with PMH ulcerative colitis, hyperlipidemia, and radiological evidence of CAD without prior CVD, presented for management of hyperlipidemia. At baseline, her lipid panel in 2015 noted an LDL-C of 125 mg/dL. In 2017, LDL-C was 255 mg/dL, prompting treatment with Atorvastatin. Following initiation of Atorvastatin, LDL-C improved to 137 mg/dL. However, on Atorvastatin, she experienced dermatitis and underwent Dermatology evaluation/biopsy. Medication reaction was favored as the etiology and Atorvastatin was discontinued. In Jan. 2019, off of Atorvastatin, LDL-C was 162 mg/dL. From around 2015-2018, the patient consumed a vegan diet. In 2019, she incorporated nine eggs per day (1600mg dietary cholesterol) into her diet. She denied additional changes to diet or consumption of other animal products. In Aug. 2019, LDL-C was 378 mg/dL. In Aug. 2020, LDL-C was 420 mg/dL. In Aug. 2020, she was advised that her goal LDL was 100 mg/dL or less. She was advised to limit her egg yolk consumption to four per week (∼100 mg/day of cholesterol). She continued to avoid all other animal products. In Oct. 2020, without addition of medication or other notable lifestyle changes her LDL-C decreased to 204 mg/dL. In Jan. 2021, her LDL-C was 130 mg/dL. From 2015-2021, her weight ranged 93-103lbs (BMI ∼16). In Aug. 2021, her LDL-C was 142 mg/dL. Ezetimibe 10mg daily was then added with reduction in LDL-C to a near-target of 103 mg/dL (27% reduction) within four months. Conclusion For the average American, current guidelines do not recommend egg restriction as an effective tool for LDL-C lowering. However, as shown in this case, certain individuals may be more prone to high LDL-C when consuming high cholesterol diets. Further study on how to better identify these susceptible individuals could help personalize nutritional and medication treatment plans for patients with dyslipidemia.

Bird-Egg syndrome

The bird-egg syndrome is often described in the literature as the association between initial sensitization to domestic birds proteins (parakeet, parrot, canary), and the allergic manifestations following egg yolk consumption, which appear later in time, through serum albumins cross-reactivity. The syndrome predominantly affects adults and less frequently children, who have a particular reactivity, due to the higher frequency of allergy to egg white. Chicken serum albumin (alpha-livetin, Gal d5), the allergen involved in the bird-egg syndrome, is a thermolabile and highly cross-reactive protein, capable to induce sensitization both by respiratory and digestive pathways. It is located in the plasma, in the muscle tissue of the birds, but also in the egg yolk. The most common clinical manifestations, also contact type dependent, are respiratory (asthma, rhino‑conjunctivitis) in the presence of birds aeroallergens and digestive (oral allergy syndrome, abdominal pain, vomiting, diarrhea) after consumption of partially cooked egg and chicken meat. Mild to moderate-severe systemic reactions (urticaria, angioedema, asthma) are also described in the literature. The diagnosis of the bird-egg syndrome requires the integration of patient`s history and paraclinical investigations into a clinical context. Allergy tests performed both in vivo and in vitro frequently show simultaneous reactivity to bird feathers, egg yolk and chicken meat. The bird-egg syndrome must be differentiated from the genuine allergy to poultry meat, which is considered to be a primary allergy and involves active sensitization to heat-resistant meat proteins. The main therapeutic method consists in strict avoidance of egg consumption and egg-derived products, including those containing traces, and avoidance, as much as possible, of aeroallergens such as feathers and bird droppings.

Egg yolk consumption history and food protein-induced enterocolitis syndrome.

Egg yolk consumption history and food protein-induced enterocolitis syndrome.

Lipidomics of the chicken egg yolk: high-resolution mass spectrometric characterization of nutritional lipid families

While previous studies have characterized the fatty acids and global lipid families of the chicken egg yolk, there have been no publications characterizing the individual lipids in these lipid families. Such an in-depth characterization of egg yolk lipids is essential to define the potential benefits of egg yolk consumption for the supply of structural and anti-inflammatory lipids. Historically, the major focus has been on the cholesterol content of eggs and the potential negative health benefits of this lipid, while ignoring the essential roles of cholesterol in membranes and as a precursor to other essential sterols. A detailed analysis of egg yolk lipids, using high-resolution mass spectrometric analyses and tandem mass spectrometry to characterize the fatty acid substituents of complex structural lipids, was used to generate the first in-depth characterization of individual lipids within lipid families. Egg yolks were isolated from commercial eggs (Full Circle Market) and lipids extracted with methyl-t-butylether before analyses via high-resolution mass spectrometry. This analytical platform demonstrates that chicken egg yolks provide a rich nutritional source of complex structural lipids required for lipid homeostasis. These include dominant glycerophosphocholines (GPC) (34:2 and 36:2), plasmalogen GPC (34:1, 36:1), glycerophosphoethanolamines (GPE) 38:4 and 36:2), plasmalogen GPE (36:2 and 34:1), glycerophosphoserines (36:2 and 38:4), glycerophosphoinositols (38:4), glycerophosphoglycerols (36:2), N-acylphosphatidylethanolamines (NAPE) (56:6), plasmalogen NAPE (54:4 and 56:6), sphingomyelins (16:0), ceramides (22:0 and 24:0), cyclic phosphatidic acids (16:0 and 18:0), monoacylglycerols (18:1 and 18:2), diacylglycerols (36:3 and 36:2), and triacylglycerols (52:3). Our data indicate that the egg yolk is a rich source of structural and energy-rich lipids. In addition, the structural lipids possess ω-3 and ω-6 fatty acids that are essential precursors of endogenous anti-inflammatory lipid mediators. These data indicate that eggs are a valuable nutritional addition to the diets of individuals that do not have cholesterol issues.

Safe egg yolk consumption after a negative result for low-dose egg oral food challenge.

BackgroundHen's egg is one of the most common allergens causing infantile food allergy. Consuming heated egg yolk slightly contaminated with egg white (EY with scEW) improves diet quality. Most children with egg allergies can safely consume 1/25 of a heated whole egg (low‐dose egg). Although low‐dose egg has similar antigenicity to EY with scEW, clinical reproducibility is unknown. We aimed to examine the safety of EY with scEW consumption after a negative result of low‐dose egg oral food challenge (OFC).MethodsIn this prospective study, children aged <18 years with a history of immediate reaction to eggs were enrolled. We advised children and guardians to consume EY with scEW after a negative result of low‐dose egg OFC and to record symptoms, if any.ResultsWe evaluated 276 children with negative results for low‐dose egg OFC who had previously shown reactivity to eggs. Their median age was 1.2 years. Boys accounted for 188 (68%) of the children. The median egg white‐specific immunoglobulin E level was 11.7 kUA/L. At home, six children experienced mild symptoms. Skin symptoms were the most common. Among the six children, five were confirmed to continue the consumption of EY with scEW and one developed mild respiratory symptoms and continued to avoid eating eggs.ConclusionAlthough a few children with egg allergies experience mild symptoms, most of them can ultimately consume EY with scEW. Consumption of EY with scEW after low‐dose egg OFC seems safe and may improve their quality of life by making egg yolk products available.

Long Term Egg Yolk Consumption Alters Lipid Metabolism and Attenuates Hyperlipidemia in Mice Fed a High‐Fat Diet Based on Lipidomics Analysis

Studies on the association between egg yolk (EY) consumption and obesity are limited and the involved mechanism still needs to be further explored. In this study, the effects of EY consumption under normal and high fat diets on mice based on lipidomics approach is compared. A total of 893 and 925 individual lipid species are determined in serum and liver, respectively. The results reveal that EY can alleviate the hyperlipidemia in HFD‐induced obese mice by increasing serum high‐density lipoprotein cholesterol (HDL‐C) and neutral glycerolipid, hepatic fatty acids (FAs), and the size of adipose tissue cells. OPLS‐DA and S‐plots show that 29 lipid biomarkers in serum, mainly including phosphatidylcholine (PC), triglyceride (TG), and phosphatidylinositol (PI), and 44 lipid biomarkers in liver including TG, lysophosphatidylcholine (lysoPC), and lysophosphatidylethanolamine (lysoPE) are related to obesity caused by HFD. In addition, the regulation of EY on lipid disorders is mainly related to the decreases in serum TG and PC, and hepatic fatty acids (FAs), TG and diacylglycerol (DG), which is closely associated with glycerophospholipid metabolism. These findings suggest that long‐term treatment of EY consumption may not increase NAFLD risk factors in normal diet‐fed mice, further improving the hyperlipidemia in HFD‐induced mice.Practical Applications: This study investigates the overall effects of EY on normal and high‐fat diet by lipidomic analysis. It is concluded that the intake of EY can improve the hyperlipidemia in HFD‐induced obese mice by improving glycerophospholipid metabolism. These results facilitate to comprehensively evaluate the nutrition of EY and help elucidate the favorable effect of eggs.The flow chart of the egg yolk nutritional evaluation based on 100‐d mice experiment. The lipid profiles in serum and liver are further investigated using UPLC‐MS/MS method to elucidate its favorable effect on lipid metabolism.

Effects of Eggs and Egg Components on Cognitive Performance, Glycemic Response, and Subjective Appetite in Children Aged 9–14 Years (P14-017-19)

ObjectivesChildhood is a critical time for regular intake of high-quality nutrients to aid developing brains. Dietary protein and fat independently and additively enhance cognitive performance in adults, however there are limited studies in children. The objective of this study was to determine the effects of whole eggs and its components (egg whites [protein-rich, fat-free] vs. egg yolks [containing protein and essential fatty acids]) on cognitive performance, glycemic response, and subjective appetite in children. MethodsUsing a randomized within-subject repeated-measures design, 19 children (age: 12.2 ± 0.4 years) completed five test conditions, at least seven days apart. Following the consumption of a standardized breakfast 3 h prior to arriving at the laboratory, children consumed one of the following treatments: whole eggs (147 kcal), egg yolks (112 kcal), egg whites (35 kcal), full fat yogurt (147 kcal), or continued to fast. Cognitive performance, blood glucose, and subjective appetite were assessed at baseline and 15, 30, 60, and 90-min post-treatment. A battery of cognitive performance tests assessed attention, learning and memory, executive functioning, and spatial working memory. ResultsWord recall (learning and memory) was higher after egg yolks (Δ = 1.7 ± 0.6 words; P = 0.03) compared with egg whites. Change from baseline cognitive processing test scores (attention) were significantly higher (P < 0.05) after egg yolks by 1.11, 1.25, and 1.21 trials compared with whole eggs, egg whites, and yogurt, respectively. Change from baseline subjective average appetite was lower after yogurt compared with snack skipping (Δ = 9.7 ± 2.9 mm; P = 0.01). Change from baseline blood glucose was lower after yogurt compared with egg yolks (P = 0.001) and egg whites (P = 0.01); and blood glucose was lower after whole eggs compared with egg yolks (P = 0.02). ConclusionsEgg yolks resulted in higher short-term learning and memory scores compared with egg whites, and attention was higher after egg yolks compared with egg whites, whole eggs and yogurt. In conclusion, consumption of egg yolks may be beneficial for supporting cognitive performance in children. Funding SourcesEgg Nutrition Center.

Comparison of long-term effects of egg yolk consumption under normal and high fat diet on lipid metabolism and fatty acids profile in mice.

This study compared the long-term effects of EY consumption under two diet conditions: normal (ND + EY) and high fat diet (HFD + EY), on lipid metabolism in mice. ND + EY did not increase serum triglycerides, total cholesterol hepatic triglyceride concentrations, adipose tissue accumulation and glucose impairment, not leading to fatty liver. HFD + EY markedly decreased adipose tissue accumulation, the triglyceride and total cholesterol, and improved serum HDL-C and blood glucose impairment compared with HFD. PLS-DA analyzes showed both ND + EY and HFD + EY could decrease serum C18:1 and MUFA. HFD + EY could further decrease hepatic C18:2 and PUFA and increase C18:1 and MUFA excretion, which were associated with lower expression of Elovl6 and higher expression of Scd1 in liver. These results suggest that HFD + EY significantly improved dyslipidemia caused by HFD through modifying lipid metabolism, and ND + EY did not adversely affect the biomarkers associated with dyslipidemia risk, but showed less obvious regulation of lipid metabolism than HFD + EY.

Study of egg white oral food challenges under three years of age―Comparison of the results of egg avoidance group with egg yolk consumption group―

【目的】乳児期より卵黄を継続摂取する食事指導がその後の卵白の早期摂取につながるか検討する.

High-fat Feeding Paradigm for Larval Zebrafish: Feeding, Live Imaging, and Quantification of Food Intake.

Zebrafish are emerging as a model of dietary lipid processing and metabolic disease. This protocol describes how to feed larval zebrafish a lipid-rich meal, which consists of an emulsion of chicken egg yolk liposomes created by sonicating egg yolk in embryo media. Detailed instructions are provided to screen larvae for egg yolk consumption so that larvae that fail to feed will not confound experimental results. The chicken egg yolk liposomes can be spiked with fluorescent lipid analogs, including fatty acids and cholesterol, enabling both systemic and subcellular visualization of dietary lipid processing. Several methods are described to mount larvae that are conducive to short- and long-term live imaging with both upright and inverted objectives at high and low magnification. Additionally presented is an assay to quantify larval food intake by extracting the lipids of larvae fed fluorescent lipid analogs, spotting the lipids on a thin layer chromatography plate, and quantifying the fluorescence. Finally, critical aspects of the procedures, important controls, options for modifying the protocols to address specific experimental questions, and potential limitations are discussed. These techniques can be applied not only to focused, hypothesis driven inquiries, but also to a variety of screens and live imaging techniques to study dietary lipid metabolism and the control of food intake.

Dietary cholesterol and egg yolk should be avoided by patients at risk of vascular disease.

Recent recommendations that limits to dietary cholesterol be dropped were probably heavily influenced by propaganda from the egg industry. After conviction for false advertising, the industry has spent hundreds of millions of dollars to convince the public, physicians, and policy makers that dietary cholesterol and egg yolk are harmless. However, there are good reasons for longstanding recommendations that dietary cholesterol be limited to <200 mg/ day in persons at risk of vascular disease. It is seldom understood that this essentially means all people in developed countries who expect to attain an advanced age. There is abundant evidence that dietary cholesterol increases cardiovascular risk. The misdirection of the egg industry focuses on fasting levels of LDL cholesterol, which are only raised by ~ 10% by consumption of egg yolks. However, the main effect of diet is on the post-prandial state: for ~ 4 hours after a high fat/high cholesterol meal, there is oxidative stress, endothelial dysfunction, and arterial inflammation. One large (65 g) egg yolk contains 237 mg of cholesterol, well above the recommended limit-nearly as much as a 12-ounce hamburger. Besides the very high cholesterol content of egg yolk, the phosphatidylcholine in egg yolk leads, via action of the intestinal microbiome, to production of trimethylamine n-oxide (TMAO), which causes atherosclerosis in animal models. Levels of TMAO in the top quartile after a test dose of two egg yolks were associated with a 2.5-fold increase in the 3-year risk of stroke, death, or myocardial infarction among patients referred for coronary angiography. Persons at risk of cardiovascular disease should limit their intake of cholesterol and egg yolk.

Abstract 83: Effect of Dietary Cholesterol and Egg Consumption On Mortality And Cardiovascular Risk in the REGARDS Study

Background and purpose: It has long been recommended that patients at risk of cardiovascular events limit their intake of dietary cholesterol to &lt;200 mg/day. One large egg yolk contains more than 200mg of cholesterol, and also contains 250mg of phosphatidylcholine, which is converted by intestinal bacterial to trimethylamine. In the face of increasingly widespread belief that consumption of dietary cholesterol and eggs is harmless, we analyzed the effects of these dietary constituents on mortality and cardiovascular outcomes in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study population. Methods: A longitudinal cohort study of 30,239 community-dwelling black and white individuals aged 45+ years, recruited between January 2003 and October 2007 from the 48 contiguous states. The study oversampled black participants (44%), and residents of the southeastern “stroke belt” (56%). We analyzed total mortality and atherosclerotic events (ischemic stroke, myocardial infarction and revascularization) after 4.9 (SD 1.7) years of followup. Hazard ratios were computed for egg consumption and cholesterol consumption by quartiles, adjusted for race, age, sex, income, education, region, dyslipidemia, exercise, hypertension, diabetes, smoking, atrial fibrillation and caloric intake. Results: As shown in the table, there was a dose-related increase in all-cause mortality and atherosclerotic events with both cholesterol intake and egg consumption. Conclusions: Recommendations to limit the intake of cholesterol remain good advice for patients at risk of cardiovascular events. As one large egg yolk contains more than the daily recommended intake of cholesterol, egg yolk consumption should also be limited.

Effects of lutein-enriched egg yolk in buttermilk or skimmed milk on serum lipids & lipoproteins of mildly hypercholesterolemic subjects

Background and aimsEarlier studies in our group suggested that traditionally prepared buttermilk influences cholesterol metabolism. We therefore designed a study to evaluate whether traditionally prepared buttermilk lowers serum low-density lipoprotein cholesterol (LDL-C) and/or prevents the LDL-C raising effect of egg yolks. Methods and resultsMildly hypercholesterolemic subjects were randomly allocated to one of four diet groups consuming daily at lunch 80 ml skimmed milk with (n = 23) or without (n = 25) lutein-enriched egg yolk (28 g from 1.5 eggs providing 323 mg cholesterol) or traditionally prepared buttermilk with (n = 23) or without (n = 21) lutein-enriched egg yolk during a 12 week period. Fasting blood samples were taken to measure concentrations of serum lipids, (apo)lipoproteins, liver and kidney function markers, and plasma lutein, zeaxanthin and high-sensitive C-reactive protein (hsCRP). Egg yolk consumption significantly increased serum total cholesterol (total-C) (p = 0.035) and LDL-C concentrations (p = 0.022). Buttermilk did not change the effects of egg yolk on serum lipids and (apo)lipoproteins. There was a trend towards significant lower total-C (p = 0.077), but not LDL-C (p = 0.204) concentrations in the buttermilk groups. Plasma lutein and zeaxanthin concentrations increased significantly (p < 0.001) in the egg yolk groups. ConclusionIn mildly hypercholesterolemic subjects, daily consumption of traditionally prepared buttermilk for 12 weeks did not lower serum total-C or LDL-C concentrations, nor did it prevent the serum total-C and LDL-C raising effect of daily egg yolk consumption. Registration numberThis study is registered at www.clinicaltrials.gov as NCT01566305.

Consumption of 12 eggs per week for 1 year increases serum zeaxanthin concentrations but not other major carotenoids, tocopherols, and retinol in humans (645.25)

Previous work has shown that egg yolk consumption yields increase bioavailability of lutein and zeaxanthin compared to dietary supplements. However, little is known of the effects of an egg‐rich diet on serum levels of the other carotenoids, vitamin A and vitamin E. This study investigated how a diet of 12 eggs per week for 1 year influenced serum carotenoid, tocopherol, and retinol concentrations in adults. A group of 45 adults were placed into either the intervention group (n=27; consumed 12 eggs per week for 12 months) or control group (n=18; consumed no eggs or high egg products for 12 months) after 6 weeks of an egg‐free diet. Serum carotenoid and vitamin concentrations were measured by high performance liquid chromatography (HPLC) at baseline and 12 months. Seven day diet records were collected and analyzed on a monthly basis to help ensure the egg consumption protocol. Results showed that the intervention group demonstrated a statistically significant increase (83%) in serum zeaxanthin concentrations after 12 months. A notable, but not statistically significant, increase in serum lutein concentration was also observed in the intervention group (52%) after 12 months. Although serum alpha‐carotene concentration did not change in the intervention group, it significantly increased in the control group (18%) after 12 months. No other serum carotenoid, retinol, or alpha‐ or gamma‐tocopherol concentrations changed significantly during the 12 months. The findings of this study suggest that egg yolk consumption does not significantly alter the serum concentrations of tocopherols, retinol, and carotenoids other than alpha‐carotene and zeaxanthin.Grant Funding Source: Supported by the Egg Nutrition Center

Egg yolk consumption and carotid plaque

BackgroundIncreasingly the potential harm from high cholesterol intake, and specifically from egg yolks, is considered insignificant. We therefore assessed total plaque area (TPA) in patients attending Canadian vascular prevention clinics to determine if the atherosclerosis burden, as a marker of arterial damage, was related to egg intake. To provide perspective on the magnitude of the effect, we also analysed the effect of smoking (pack-years). MethodsConsecutive patients attending vascular prevention clinics at University Hospital had baseline measurement of TPA by duplex ultrasound, and filled out questionnaires regarding their lifestyle and medications, including pack-years of smoking, and the number of egg yolks consumed per week times the number of years consumed (egg-yolk years). ResultsData were available in 1262 patients; mean (SD) age was 61.5 (14.8) years; 47% were women. Carotid plaque area increased linearly with age after age 40, but increased exponentially with pack-years of smoking and with egg-yolk years. Plaque area in patients consuming <2 eggs per week (n = 388) was 125 ± 129 mm2, versus 132 ± 142 mm2 in those consuming 3 or more eggs per week (n = 603); (p < 0.0001 after adjustment for age). In multiple regression, egg-yolk years remained significant after adjusting for coronary risk factors. InterpretationOur findings suggest that regular consumption of egg yolk should be avoided by persons at risk of cardiovascular disease. This hypothesis should be tested in a prospective study with more detailed information about diet, and other possible confounders such as exercise and waist circumference.

鶏卵の健康・栄養機能の新展開

Japan is one of the top consumer countries in the world of chicken eggs at almost one egg per person per day. Chicken eggs contain eight essential amino acids in an ideal balance, giving an amino acid score that is as high as that for milk and beef (100) and the biological value that exceeds that of the latter foods (94). Furthermore, among animal-source foods, eggs are relatively rich in unsaturated fatty acids, fat-soluble vitamins and minerals such as phosphorus, calcium and iron. Despite these beneficial attributes, many consumers are worried about the relationship between chicken egg consumption and heart disease since chicken eggs are a high cholesterol food. Human studies in Japan reveal that consumption of egg yolk for 4 weeks did not result in an elevation of serum cholesterol level and there was no direct relationship between frequency of egg consumption and a risk of myocardial infarction in a 10-year follow-up study of 90,000 Japanese subjects. Rat studies provide evidence of the hypocholesterolemic action of egg yolk phospholipids and egg white proteins. Furthermore, feeding egg yolk phospholipids to rats with brain injuries and senescence-accelerated mice resulted in enhanced learning ability. These results indicate that chicken egg is an attractive food from the aspects of health promotion and nutritional function.

Increased consumption of dietary cholesterol, lutein, and zeaxanthin as egg yolks does not decrease serum concentrations and lipoprotein distribution of other carotenoids, retinol, and tocopherols

We have previously reported that consumption of lutein and zeaxanthin as 2 and 4 egg yolks per day for 5 weeks significantly increased serum lutein and zeaxanthin concentrations in older adults taking cholesterol-lowering statins. We hypothesized that increased consumption of eggs, lutein, and zeaxanthin may correlate with decreased absorption of other carotenoids and increased absorption of vitamins A and E, thus affecting their serum concentrations and lipoprotein distribution. Fifty-two subjects aged at least 60 years consumed 2 egg yolks per day followed by 4 egg yolks per day for 5 weeks each with a 4-week egg-free period at baseline and between the 2 interventions. Mean serum β-cryptoxanthin, lycopene, α-carotene, β-carotene, α-tocopherol, and retinol concentrations did not change during the 2 and 4 egg yolk phases. Mean serum α-cryptoxanthin and γ-tocopherol concentrations did not change after the 2 egg yolk phase, but increased by 47% (P < .001) and 19% (P < .05), respectively, after the 4 egg yolk phase. The percentage distribution of carotenoids and tocopherols between the high-density lipoprotein (HDL) and non-HDL fractions was not significantly different during the egg yolk phases compared with baseline despite the significant increases in lutein and zeaxanthin carried on HDL and non-HDL fractions. In conclusion, increased dietary cholesterol, lutein, and zeaxanthin consumed as egg yolks did not decrease the absorption of other carotenoids, and increased γ-tocopherol but not retinol as evidenced by their serum and lipoprotein concentrations. Two and 4 egg yolk consumption increases serum and retinal lutein and zeaxanthin without altering the serum status of the other carotenoids, tocopherol, and retinol.

Consumption of 2 and 4 egg yolks/d for 5 wk increases macular pigment concentrations in older adults with low macular pigment taking cholesterol-lowering statins

BackgroundLutein and zeaxanthin may reduce the risk of dry, age-related macular degeneration because of their photo-oxidative role as macular pigment. ObjectiveThe present study evaluated serum lutein, zeaxanthin, and macular pigment optical density (MPOD) responses at 0.25°, 0.5°, and 1° retinal eccentricities to the consumption of 2 and 4 egg yolks/d by older adults taking cholesterol-lowering medications. DesignSubjects consumed foods containing 2 followed by 4 egg yolks/d for 5 wk each with a 4-wk egg-free period at baseline and between the 2 interventions. ResultsChanges in MPOD (n = 37) with egg yolk consumption were inversely associated (P < 0.05) with baseline MPOD. Subjects with low-baseline MPOD (defined as MPOD ≤0.5 at 0.25°, ≤0.4 at 0.5°, and ≤0.35 at 1°) showed increases of ≤50% (P < 0.05) with 4 egg yolks at the 3 retinal eccentricities. MPOD increased by 31% (P = 0.059) at 0.5° with 2 egg yolks. Serum lutein increased by only 16% and 24% (P < 0.05) compared with increases of 36% and 82% (P < 0.001) in serum zeaxanthin (n = 52) after consumption of 2 and 4 egg yolks, respectively. Serum HDL cholesterol increased by 5% (P < 0.05) after consumption of 2 and 4 egg yolks. Serum LDL cholesterol did not change with either egg yolk treatment. ConclusionsConsumption of 4 egg yolks/d, and possibly of 2 egg yolks/d, for 5 wk benefited macular health in older adults with low MPOD. Serum HDL cholesterol increased without an increase in LDL cholesterol in this study population, most of whom were taking cholesterol-lowering statins.

Consumption of Menus Containing the Equivalent of Two and Four Egg Yolks in Older Adults on Cholesterol Lowering Medication is Associated with Significant Changes in Serum Lutein and Zeaxanthin Concentrations and Macular Pigment Optical Density (MPOD)

Lutein and zeaxanthin are carotenoids which are deposited in the macula and protect against Age Related Macular Degeneration. This 18 week study consisted of Phases 1 and 3 of 4 week duration where subjects refrained from eating eggs. Phases 2 and 4 of 5 week duration consisted of consuming the daily equivalent of 2 and 4 egg yolks, respectively with a 4 week washout period in between. Serum lutein concentrations in both phase 2 and 4 increased by 25% (p<0.001) compared to washout (n = 26). Serum zeaxanthin levels increased by 26.7% (p=0.019) following phase 2 and by 63.7% (p<0.001) following phase 4 compared to washout (n = 26). HDL was also analyzed for lutein and zeaxanthin and was found to contain approximately 60% of the total amount of each carotenoid. MPOD which was measured using heterochromatic flicker photometry increased by 26.5% in subjects following phase 2 and by 30% (p=0.039) following phase 4 compared to washout at 0.25° retinal eccentricity (n = 26). Preliminary results indicate that increasing the intake of zeaxanthin through egg yolk consumption significantly increases its blood levels, whereas with lutein, a plateau effect was observed even after consumption of 4 egg yolks per day for 5 weeks. Egg yolk consumption also increased the macular pigment density. Supported by the American Egg Board, Egg Nutrition Center, Washington, DC and The Massachusetts Lions Eye Research Fund Inc., New Bedford, MA.

High Cholesterol Intake Modifies Chylomicron Metabolism in Normolipidemic Young Men

Whether the consumption of egg yolk, which has a very high cholesterol content without excess saturated fats, has deleterious effects on lipid metabolism is controversial. Absorbed dietary cholesterol enters the bloodstream as chylomicrons, but the effects of regular consumption of large amounts of cholesterol on the metabolism of this lipoprotein have not been explored even though the accumulation of chylomicron remnants is associated with coronary artery disease (CAD). We investigated the effects of high dietary cholesterol on chylomicron metabolism in normolipidemic, healthy young men. The plasma kinetics of a chylomicron-like emulsion, doubly-labeled with 14C-cholesteryl ester (14C-CE) and 3H-triolein (3H-TG) were assessed in 25 men (17-22 y old, BMI 24.1 +/- 3.4 kg/m2). One group (n = 13) consumed 174 +/- 41 mg cholesterol/d and no egg yolk. The other group (n = 12) consumed 3 whole eggs/d for a total cholesterol intake of 804 +/- 40 mg/d. The nutritional composition of diets was the same for both groups, including total lipids and saturated fat, which comprised 25 and 7%, respectively, of energy intake. Serum LDL and HDL cholesterol and apoprotein B concentrations were higher in the group consuming the high-cholesterol diet (P < 0.05), but serum triacylglycerol, apo AI, and lipoprotein (a) did not differ between the 2 groups. The fractional clearance rate (FCR) of the 14C-CE emulsion, obtained by compartmental analysis, was 52% slower in the high-cholesterol than in the low-cholesterol group (P < 0.001); the 3H-TG FCR did not differ between the groups. Finally, we concluded that high cholesterol intakes increase the residence time of chylomicron remnants, as indicated by the 14C-CE kinetics, which may have undesirable effects related to the development of CAD.