Which type of fatty acids are most harmful to blood LDL cholesterol levels?

Trans isomers of unsaturated fatty acids are considered the most harmful to blood LDL cholesterol levels due to their unique chemical structure and the way they interact with lipid metabolism. Unlike other types of fatty acids, trans fats increase LDL cholesterol levels while simultaneously lowering high-density lipoprotein (HDL) cholesterol, which is known as the "good" cholesterol. This imbalance contributes to an increased risk of cardiovascular diseases.

Trans fats are typically found in partially hydrogenated oils, which are used in many processed foods, baked goods, and margarine. The body does not metabolize trans fats in the same way it does natural unsaturated fats, leading to adverse effects on heart health. This mechanism highlights why trans fats are especially detrimental and makes them a key focus in dietary recommendations aimed at reducing cholesterol levels and improving overall cardiovascular health.

In contrast, while saturated fatty acids have also been shown to raise LDL cholesterol levels, their impact is less severe compared to trans fats. The different types of polyunsaturated fatty acids, such as n-3 and n-6, generally have beneficial effects on heart health when consumed in appropriate amounts and ratios, thereby supporting their distinction from trans fats in terms of cholesterol impact.