How harmful are trans fats, exactly?
Industrial trans fats are demonstrably harmful to your heart and blood vessels, even in small amounts. Avoid them by checking ingredient lists for 'partially hydrogenated oil'.
Industrial trans fats raise LDL cholesterol (the 'bad' cholesterol) and lower HDL cholesterol (the 'good' cholesterol). The combination is particularly unfavourable: both controlled dietary trials and research confirm this effect consistently.
The cardiac risk is concrete: every 2% of your daily calories coming from industrial trans fats increases the risk of a heart attack or death from heart disease by 24 to 32%, compared with other fat sources. That is a large effect for a relatively small amount. Multiple large studies arrived at this estimate.
Beyond cholesterol, trans fats also damage the inner lining of blood vessels, an early sign of atherosclerosis. In addition, they raise substances that drive inflammation in the body, such as CRP and interleukin-6. Both effects have been established in dietary trials as well as in other research, although the certainty is somewhat lower than for the cardiac risk.
There are also indications of poorer insulin sensitivity and greater accumulation of abdominal fat, but those associations are still weak and insufficiently confirmed to make firm statements about. Possible effects on fertility or cognition are mentioned in review articles but have barely been studied.
Trans fats that occur naturally in dairy and beef or lamb appear, at the amounts people typically eat, to carry no demonstrably increased cardiac risk. Gram for gram they affect cholesterol just as unfavourably as the industrial variety, but intake is generally much smaller. The ban or strict restriction that has by now been introduced in several countries and by the WHO targets industrial trans fats exclusively, with the estimate that tens of thousands of heart-disease events per year would be prevented if they were removed from the global food supply.
All sources are reviews; no primary studies or combined analyses provided as separate PMIDs. The strong statements about cardiac risk are based on large studies as described within those reviews.
How dangerous is a fatty liver (hepatic steatosis)?
For most people, a fatty liver is not acutely dangerous in the short term, but it does raise the risk of cardiovascular disease and, with further progression, of serious liver damage. Discuss it with your doctor if you also have overweight, diabetes, or high blood pressure.
How dangerous is belly fat?
Belly fat is a serious risk factor for cardiovascular disease, heart failure, and premature death, and the risk increases the longer it remains elevated. A combination of a Mediterranean diet and regular physical activity is the best-supported approach for reducing it.
How bad is eating a lot of salt for me?
Eating a lot of salt is clearly harmful to your blood pressure and your heart, and the risk grows with the amount consumed. Eating more vegetables and fruit helps to temper the effect, but does not replace reducing salt intake.
How healthy is olive oil and what is it good for?
Olive oil, and extra-virgin olive oil in particular, is well supported as protective for the heart and blood vessels, especially when used in place of butter and as part of a varied, plant-based diet.
Is atrial fibrillation dangerous, and what can I do about it?
Atrial fibrillation substantially increases your risk of death, heart failure, and stroke, and requires active treatment. Discuss blood thinners for stroke prevention with your doctor, as well as which lifestyle changes are worthwhile in your specific situation.
How harmful is prolonged stress really for my heart?
Long-term stress measurably increases your risk of cardiovascular disease, particularly through work-related stress (10-40% extra risk in large population studies). The effect is real, but smaller than that of smoking or high blood pressure.