Re: Consumption of fried foods and risk of coronary heart disease: Spanish cohort of the European Prospective Investigation into Cancer and Nutrition study
Health effects of frying foods in different oils: Is it a question of quality, amount or time?
We find this a very interesting study, both in design and in its development. Planning circumstances and calculated data will lead to the relevant estimates. However the study conclusion is surprising, although rarely work of this excellence is found.
In our opinion, to address these effects could be not enough when considering this protocol. The fact that no differences exist between transformations produced by frying in different types of oils is due to the various overlaps that eliminate or offset proven factors. The introduction of other underlying variables: whether biased or through nested queries, could lead to shifted interpretations of this conclusion. This will allow more light to be shed upon the well known differences due to nutritional facts affecting final conclusions.
Since it is well known e.g. the different chemical fatty acid composition of oils changes the rupture lability and transformation in frying due to double bonds. Fried olive oil, the main component of which is monounsaturated, produces fewer toxic products than those with PUFA as its main components.
There are other interesting nutritional factors: oil quality plays a role on the nutritive value of protein. This changes the amount absorbed. Also, the effect of frying affects carbohydrates.
According to the authors accepted limits, focus only on the nutritional factors:
• The third limit of the study: frying procedure influence. Sauteing uses up all the oil at once. Deep frying in an oil bath produced toxic products, which would be cumulative by reuse, but its presence is difficult to calculate, because the oil carried out is replaced by fresh oil, diminishing its concentration.
• The fifth limitation of the study: PUFA contribution from fish, would have to be regarded in the dietary history variables, beyond other possible effects.
These could lead one to conclude a wave-like role among other expressed limits.
Consumption of fried foods and risk of coronary heart disease: Spanish cohort of the European Prospective Investigation into Cancer and Nutrition study. BMJ 2012; 344 doi: 10.1136/bmj.e363 (Published 24 January 2012) Cite this as: BMJ 2012;344:e363
Varela G. Current facts about the frying food. On: Frying of food. Ed. Varela G, Bender AE & Morton D. Ellis Horwood Series in Food Science and Technology. Chischester, England, 0-25, 1988.
Joyanes Mª, Ruiz E, Santillana I. Modifications de la graisse et vitamine A dans quelques aliments comme resultats des procesus culinaires. Coongres International Chevreul. Angers, June 1989, France.
Competing interests: No competing interests