Trans fats from cows and other animals (like butter) don’t seem to raise heart disease risk, but trans fats made in factories (like in margarine) do—so where the fat comes from matters.

Eating man-made trans fats found in fried and processed foods is linked to a higher chance of dying from heart disease or having a heart attack, but the natural trans fats in dairy and meat don’t seem to have the same effect.

Small experiments on ruminant trans fats and heart health markers haven't given clear answers — maybe because they used too few people or too much fat that you can't actually eat in real life.

Some studies suggest that the natural trans fats found in milk and meat might not raise heart disease risk the same way that artificial trans fats in fried and baked foods do.

Trans fats from dairy and meat don’t seem to harm cholesterol or cause inflammation like the ones made in factories — some might even be a little good for you.

A fat called trans-palmitoleic acid was once thought to protect against diabetes, but when scientists accounted for other similar fats in dairy, the link disappeared — meaning the earlier belief was probably wrong.