"Trans fat," if by that is meant a molecule that was unsaturated but is
now saturated, does no harm. There is some ridiculous notion about
"lipid bilayer membranes" being rendered dysfuntional, but proteins do
the actual work, and the fatty acids are there due to electrostatic
forces. They provide some protection, especially if saturated, but a
"trans fatty acid" molecule has no mechanism to do harm. Put a bunch
of them in a tube with cells, and yes, they have an anti-growth effect,
because they act as a barrier to biochemical activity.
As to "oxidized fats:" Exposing a highly unsaturated fat source (let's
say safflower oil), to oxygen leads to the the fatty acids bonding with
each other, due to "stolen" electrons, and a plastic-like substance is
formed. This is how oil paintings are possible. It is best to
"refine" the antioxidants out of the oil, because then the process is
quick enough to meet the practical demands of the painter. However,
you do not want this happening in your body, because electrons will be
stolen from vital biomolecules, leading to cellular death or
dysfunction, and then possibly worse (tissue/organ failure). "Stones"
can form as well, leading to blockages. Oxidized cholesterol leads to
arterial damage that is known as "coronary artery disease," meaning you
could get a heart attack. Boiling is okay, because there is little
oxygen exposure that way, but you also don't want to eat food that not
fresh. If you eat any major source of unsaturated fatty acids, you
need to have antioxidant protection, because the fatty acids will go
rancid ("lipid peroxiation") in your body. Even some olive oils are
very bad, because the antioxidants have been refined out of them.
Eating organic purples olives that taste fresh is a better idea.
Now, for something you probably want to know: why is "saturated fat"
called the "bad fat." This seems to be related to how "nutritional
science" got established in the first place. There was a need to
essentially make up their own language, as other scientific disciplines
have, and so all kinds of abstract categories were invented. The
problem is that they are often misleading or dangerous.
Let's take an example: both lard and coconut oil are classified as
"saturated fats." Lard is 39% saturated and has no antioxidants.
Coconut oil is 92% saturated and has some natural antioxidants in it.
There is a food industry standard test to determine how dangerous a
food item might be, in terms of lipid peroxidation. It is called the
Rancimat. Here it is described:
"The Rancimat works according to the following principle: Lard is
heated with and without a test substance to 110 °C and air is
constantly blown into the mixture. After all components with
antioxidative effects have been consumed, easily volatile substances
are formed from the lard. They are expelled with the airstream and
collected in bidistilled water, where they increase the conductance
according to the quantity added. The time of increase in conductance is
registered."
Source:
https://www.barthhaasgroup.com/cmsdk/content/bhg/research/scientific2/69.htm
Now you could run this same test with fresh coconut oil, but the
results would be remarkably different. Sometimes this test is used to
determine how good herbs and spices are as antioxidants, and either
lard or a low quality olive oil are used. However, if you mixed herbs
and spices with fresh coconut oil, you would see that there is hardly
any activity.
The key point is that if underlying cause of "chronic disease" is
cellular-level stress, and if oxidative stress is the most common
stressor (and there is a proverbial mountain of evidence supporting
this idea), then one "saturated fat" is "good" and the other is "bad,"
rendering the classification scheme of the "nutritional experts" to be
worse than useless. It is dangerous.
