Multiple theories and trains of thoughts exist for margarine:

- it plastic no food

- it’s vegetable good

- it’s cholesterol bad

- it’s trans fat bad, butter no trans good

- cholesterol ain’t real, margarine good

I don’t care :p

- Accepted fact 1: eating saturated fat causes more coronary heart disease thank unsaturated fat (very high correlation, and accepted as causal)

- Accepted fact 2: eating trans fat is bad. A diet high in trans fats can contribute to obesity, high blood pressure, and higher risk for heart disease, because intake of dietary trans fat disrupts the body's ability to metabolize essential fatty acids. Trans fat is also implicated in Type 2 diabetes.

Historically margarine was low in saturated fat but high in trans fat due to partial hydrogenation - hence the questionable "health benefits" of it vs butter.

Currently in most of the developed world vegetable spreads are not allowed to contain significant amounts of partially hydrogenated oils, and thus margarine should be healthier - but there is a powerful dairy lobby so the bad reputation will last for a long while...

> Accepted fact 1: eating saturated fat causes more coronary heart disease thank unsaturated fat

Several studies suggest that eating diets high in saturated fat do not raise the risk of heart disease, with one report analyzing the findings of 21 studies that followed 350,000 people for up to 23 years.

https://www.hsph.harvard.edu/nutritionsource/what-should-you...

It's made of hydrogenated oil, which is bad for your vascular system.