Is it haram to eat foods containing hydrogenated oils?
Question

I read that hydrogenated oils are detrimental to human health, and they are found in many foods. What is the ruling on eating these foods, if it is proven that they are detrimental to health?
Praise be to Allah.Firstly:
Hydrogenation is a chemical process in which hydrogen is added to another substance.
This refers to a substance the molecules of which contain particles of hydrogen, but it can absorb more particles thereof, so it is called unsaturated."(Al-Mawsu‘ah al-‘Arabiyyah al-‘Alamiyyah).
Hydrogenation of oils refers to a process by means of which liquid oils that are found in plants and various foods are transformed into solid fats by the addition of hydrogen.
Fresh, natural plant oils are heated in large containers until they reach a temperature of 400°C, then hydrogen gas is pumped into them under high pressure, until the unsaturated oils become saturated with particles of hydrogen gas. Other metal elements, such as aluminum and nickel, are added to speed up the process (catalysts).
Companies like to produce hydrogenated oils for a number of reasons, which are all aimed at increasing profits:
1. Extending the shelf life of goods, as hydrogenation is a process that preserves food.
2. Making food more palatable.
3. Increasing profits by selling more goods and reducing waste.
Global health agencies have warned against excessive consumption of this type of oil, because it has long-term impacts on health if it is consumed excessively.
The harm that it leads to includes:

Obesity
Raising levels of bad cholesterol (low-density lipoprotein (LDL))
Hardening of the arteries (arteriosclerosis) and heart disease
Digestive problems
Degenerative diseases

Hydrogenated oils are found in many processed foods, including the following:

Fats and margarines
Frozen vegetables
Canned foods
Baked goods and starchy foods
Ready-made pastries
Fried foods
Synthetic milk or nondairy coffee creamer

Secondly:
The basic principle is that life is to be protected and it is haram to consume anything that is clearly harmful or most likely to cause harm, because Allah, may He be exalted, says (interpretation of the meaning):
{And do not kill yourselves [or one another]} [An-Nisa’ 4:29].
And the Prophet (blessings and peace of Allah be upon him) said: “There should be neither harm nor reciprocating harm.” Narrated by Ahmad, Ibn Majah (2341); classed as sahih by al-Albani in Sahih Ibn Majah.
So if it is proven that some food will clearly or most likely cause immediate harm, it is haram to consume the amount that will lead to such harm.
But these oils are used in a certain ratio that varies from one type of food to another, and the harm does not appear immediately. Perhaps many people consume them but are not harmed, because they exercise or burn it off by means of physical activity. Hence we have not come across anyone who forbids consuming foods that contain these oils. But they should be avoided as much as possible, and there are sufficient beneficial and permissible foods so that we have no need of those foods.
And Allah knows best.