What is the slowest food to digest?

In terms of slow digestion, there are foods that, due to their particular composition, are digested by the body more slowly. In this way, a sudden release of histamine by body cells is avoided, which can cause discomfort, in particular to people sensitized to certain foods.

As for digestion times, there is a notable difference between one and the other in general terms: a food can take from 2 to 10 hours and even days to digest. In this complex process of crossing the nine meters of digestive tract, from the mouth to the anus, many factors influence: from the amount of food ingested, its state (liquid or solid), its composition (proteins, fats, carbohydrates, fiber, etc.) or the method of prior preparation and cooking, but it also affects the age of the person who eats it or their state of digestive health (mouth, stomach, pancreas, liver, gallbladder, and not just the intestines).

Thus, a cooked fish, white rice or a soft-boiled egg are quickly digested, in less than 2 hours. Twice as long (between 3 and 5 hours) the digestive system must work to digest a ham sandwich, some chips, a piece of cured cheese or a plate of lentils. And it can take up to 7 or 9 hours to break down into their elemental nutrients (amino acids, free fatty acids, vitamins, minerals) the fattiest parts of the pork or some sardines preserved in oil.

Foods fried in overheated oils, old, spoiled or of poor quality, are absolutely indigestible.They take up to 7 or more hours to finish the decomposition and in this meantime, powerful irritating substances of the gastric mucosa, such as acrolein, are generated. That is why you should avoid eating fried foods or pinchos in bars and restaurants where, when entering or approaching the kitchen door, there is a certain smell of fried food, of overheated oil. In addition, fried foods and foods fried in overheated oils can be a source of stomach upset, as more acrolein and trans fats are inadvertently added to the diet. 
However, also during the frying process, when heating any vegetable oil, the impact will be less the more care is taken in preparing a good fry, although it is advisable to consume all kinds of fried foods on time and in moderation, from croquettes and breaded, even battered,

Ignorance of this data makes it confusing to interpret symptoms in digestive discomfort. Particularly those who suffer from food intolerances or food histaminosis, who tend to experience digestive discomfort more persistently and intensely. If the symptoms appear in the afternoon, it is not only necessary to think about what has been eaten that can explain the discomfort, but what has been eaten since breakfast. Similarly, if the feeling of heaviness or satiety appears throughout the morning, rather than paying attention to breakfast, it is worth thinking about dinner the day before.