Eggs have been known to be a rich protein source as well as great source of various nutrients such as antioxidants. They are considered one of the most important sources of xanthophylls. Xanthophylls, one of the major groups of carotenoids, have a potential protective role in eye health and prevention of heart disease and stroke. Cooking and intestinal conditions affect the nutritional value of the eggs due to the changes in protein and lipid digestibility.
Asencio-Grau et. al explores the effects of various cooking methods and intestinal conditions on the different levels of digestibility of macronutrients and micronutrients in eggs. Their matrix of tests included boiled eggs, poached eggs, and omelets in two main sets of experiments. One set was fixing the pH and bile salt concentration while changing the enzyme concentration. Another set of experiments was fixing the enzyme concentration while varying the pH and bile salt concentration.
To analyze the bioavailability of the xanthophylls, Asencio-Grau et. al uses a method to obtain a fine powder from the raw and cooked egg samples before and after digestion. The method consists of homogenization and freeze-drying steps. The xanthophylls are subsequently extracted using a combination of solvents and analyzed using HPLC-DAD with a gradient mobile phase consisting of methanol, tert-methyl-butyl-ether, and water and a Develosil C30, 5 µm column (4.6 x 250 mm).
Overall, their findings indicated that there are massive differences in the bioaccessibility of xanthophylls in their array of tests. For exocrine pancreatic insufficiency (EPI) conditions (pH 6 – 1 mM) and healthy intestinal conditions (pH 7 – 10 mM), boiling eggs seem to be only cooking that negatively affected in terms of lipid digestibility. Based on the data from the study, it can be suggested that:
-If you suffer from EPI, then poaching your eggs would be the most advisable due to their fat and protein digestibility.
-If you have healthy intestines, then boiling your eggs would be the most advisable due to their fat and protein digestibility.
1. Andrea Asensio-Grau, Irene Peinado, Ana Heredia, Ana Andrés, Effect of cooking methods and intestinal conditions on lipolysis, proteolysis and xanthophylls bioaccessibility of eggs, Journal of Functional Foods, Volume 46, 2018, Pages 579-586, ISSN 1756-4646, https://doi.org/10.1016/j.jff.2018.05.025.
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