By Sheila Halder
Many of us enjoy an egg for breakfast, lunch, or supper, and as scientists we quite reasonably take a moment to think about our food: how does the way we store it and cook it have an impact on the nutrition we get?
Fortunately for the members of the Pharmora Journal Club, this question was addressed in a recent publication from Newcastle University in a study entitled “The Influence of Storage and Cooking on the Vitamin D Content of 25-Hydroxyvitamin D3-Enriched Eggs”.
An internal Pharmora survey showed about 1/3 of us keep eggs in the fridge; the rest preferred the larder or on the counter-top.
Newcastle University looked specifically at Vitamin D enriched eggs. These were obtained through a process of fortification of poultry layer food and collection of the eggs in batches over a period of 6 months (additional analysis was later made for age of hens at lay). Composite samples were cooked by 5 different methods following ambient or refrigerated storage.
The results demonstrated that there is an effect of time of lay that impacted Vitamin D levels in the end food dish as well as the storage and cooking method.
Biological variables
Biological processes and organisms (such as chickens, or people!) are very varied in their genetic make-up, biological processes and behaviour and this makes replicable studies hard to do. This study demonstrates how performance of processes such as cooking or combining samples needs to be uniform, yet allowances must be made for other variables. In this example there are the potential differences between hens: their genes, their eggs, feed intake, and stage of lay.
Study findings
There was a difference between treatments especially when storage and cooking were combined: ambient egg storage plus scrambling was the best method. A Pharmora scientist pointed out that there would be a lot of variability in ambient temperature outside of the study – could this have an effect? Key points were that Vitamin D migrates into fat and its oxidation takes place at high temperatures – so boiling and frying are not so good; scrambling is best as anything that has gone into the fat is incorporated. Some members said they would no longer fry their eggs or would instead eat all the oil!
Study design
Reviewing this trial Pharmora scientists appreciated the complexity and considerations required for good study design. It was interesting to consider if AI could design better studies, or, if being aware of potential areas where logic could be overridden by behaviour and choice in a real-world setting means that humans are still required? In clinical trials, for example, participants may choose to remain on a treatment or not due to different priorities: quality of life, or ability to take part in certain activities. Is this possible to allow for in study design without empathy or lived experience? The number of variables in this study also led to qualification of the findings; more discrete simpler trials would be easier to implement, however they approximate less well to real world situations.
Publication influences and the power of communication
None of the Pharmora team admitted to changing their mind on egg storage as the press headlines that linked to the paper appeared to be more confident about the conclusions than was justified. Pharmora’s scrutiny of this paper and the news articles around it reinforced to us how public perception of a product or trial can be influenced by media headlines.
Sponsors and the common good
There are always interests and conflicts of interests in a study: Pharmora scientists spotted that the authors in this one included employees and owners in both industry and farming, thus promoting the feed manufacturer and the egg company as suppliers of their respective products regardless of study finding. There are very few wholly altruistic sources of funding and being aware of this is important in any understanding of study design and intent.
Pharmora team members found the paper quite hard to read due to the lack of diagrams and visual aids to support the raw data. Pharmora scientists suggested that a potential innovation could be a device to standardise optimal egg storage temperatures in the absence of larders in modern homes.
