Dietary cholesterol and egg yolk should be avoided by patients at risk of vascular disease.
David Spence J.
J Transl Int Med. 2016 Apr 1;4(1):20-24. doi: 10.1515/jtim-2016-0005.

Extraction of phospholipid-rich fractions from egg yolk and development of liposomes entrapping a dietary polyphenol with neuroactive potential.
Bernardo J, Videira RA, Valentão P, Veiga F, Andrade PB.
Food Chem Toxicol. 2019 Aug 1;133:110749. doi: 10.1016/j.fct.2019.110749.

Comparison of long-term effects of egg yolk consumption under normal and high fat diet on lipid metabolism and fatty acids profile in mice.
Yu Z, Wang N, Hu G, Ma M.
Food Sci Biotechnol. 2019 Jan 23;28(4):1195-1206. doi: 10.1007/s10068-018-00545-w

Egg yolk antibodies (IgY) and their applications in human and veterinary health: A review.
Pereira EPV, van Tilburg MF, Florean EOPT, Guedes MIF.
Int Immunopharmacol. 2019 Aug;73:293-303. doi: 10.1016/j.intimp.2019.05.015.

Food protein-induced enterocolitis syndrome caused by egg yolk in an infant.
Doi M, Matsubara Y, Iwakoshi N, Furuichi Y.
Pediatr Int. 2019 Apr;61(4):411-412. doi: 10.1111/ped.13785.

High Density Lipoprotein from Egg Yolk (EYHDL) Improves Dyslipidemia by Mediating Fatty Acids Metabolism in High Fat Diet-induced Obese Mice.
Yu Z, Mao C, Fu X, Ma M.
Food Sci Anim Resour. 2019 Apr;39(2):179-196. doi: 10.5851/kosfa.2018.e38.

Advances in techniques for reducing cholesterol in egg yolk: A review.
Puertas G, Vázquez M.
Crit Rev Food Sci Nutr. 2019;59(14):2276-2286. doi: 10.1080/10408398.2018.1448357.

Consuming a buttermilk drink containing lutein-enriched egg yolk daily for 1 year increased plasma lutein but did not affect serum lipid or lipoprotein concentrations in adults with early signs of age-related macular degeneration.
van der Made SM, Kelly ER, Berendschot TT, Kijlstra A, Lütjohann D, Plat J.
J Nutr. 2014 Sep;144(9):1370-7. doi: 10.3945/jn.114.195503.

Egg yolk proteins and peptides with biological activity.
Zambrowicz A, Dąbrowska A, Bobak Ł, Szołtysik M.
Postepy Hig Med Dosw (Online). 2014 Dec 24;68:1524-9. doi: 10.5604/17322693.1133600.

Specific Chicken Egg Yolk Antibody Improves the Protective Response against Gallibacterium anatis Infection.
Zhang JJ, Kang TY, Kwon T, Koh H, Chandimali N, Huynh DL, Wang XZ, Kim N, Jeong DK.
Infect Immun. 2019 Feb 21;87(3). pii: e00619-18. doi: 10.1128/IAI.00619-18

Egg Yolk Immunoglobulin Supplementation Prevents Rat Liver from Aflatoxin B1-Induced Oxidative Damage and Genotoxicity.
Qiu T, Shen X, Li X, Gong Y, Zou Z, Liu C, Ye F, Mi C, Xu Z, Sun Y, Lin J, Zhang H, Lei H.
J Agric Food Chem. 2018 Dec 19;66(50):13260-13267. doi: 10.1021/acs.jafc.8b04659.

Egg yolk is composed of 70% lipids and 30% proteins. It contains carotenoids such as zeaxanthin and lutein, vitamins.

Egg yolk has a high content of cholesterol and saturated fatty acids, which can promote cardiovascular disease. One egg yolk  contains between 200 mg and 300 mg of cholesterol/100 g (1).

Egg yolk can increase the risk of microbial contamination and reduce the shelf life of products (2) ; for this reason, there is more interest in introducing new emulsifiers as alternatives to egg yolk. Some suitable options are hydrocolloids and polysaccharides (3).

Hen egg yolk has been studied and the effects of its antibodies on the immune responses of the intestinal mucosa of laboratory animals with Salmonella typhimurium have been determined. The results suggest a positive immune response (4).

Oral administration of hen's egg yolk influenced behaviour and cognitive functions in young and aged rats. It primarily led to mitigating the behavioural symptoms of aging and supported cognitive and memory learning in rats of both age groups (5).

Egg yolk studies

References______________________________________________________________________

(1)  Bautista Villarreal M, Gallardo Rivera CT, García Márquez E, Rodríguez Rodríguez J, Núñez González MA, Chávez Montes A, Báez González JG. Comparative Reduction of Egg Yolk Cholesterol Using Anionic Chelating Agents.  Molecules. 2018 Dec 5;23(12). pii: E3204. doi: 10.3390/molecules23123204.

(2) Abedinzadeh S, Torbati M, Azadmard-Damirchi S. Some Qualitative and Rheological Properties of Virgin Olive Oil- Apple Vinegar Salad Dressing Stabilized With Xanthan Gum   -   Adv Pharm Bull. 2016 Dec;6(4):597-606. doi: 10.15171/apb.2016.074. 

(3) Dickinson E. Hydrocolloids at interfaces and the influence on the properties of dispersed systems. Food Hydrocoll. 2003;17(1):25–39. doi: 10.1016/S0268-005X(01)00120-5

(4)  Li X, Yao Y, Wang X, Zhen Y,  Chicken egg yolk antibodies (IgY) modulate the intestinal mucosal immune response in a mouse model of Salmonella typhimurium infection.  Thacker PA, Wang L, Shi M, Zhao J, Zong Y, Wang N, Xu Y.   -   Int Immunopharmacol. 2016 Jul

(5)  Lemieszewska M, Jakubik-Witkowska M, Stańczykiewicz B, Zambrowicz A, Zabłocka A, Polanowski A, Trziszka T, Rymaszewska  Pro-Cognitive Properties of the Immunomodulatory Polypeptide Complex, Yolkin, from Chicken Egg Yolk and Colostrum-Derived Substances: Analyses Based on Animal Model of Age-Related Cognitive Deficits.  J.  Arch Immunol Ther Exp (Warsz). 2016 Oct