Small Dense Low-Density Lipoprotein Subfraction 1

sdLDL-1 is a small, dense, and more dangerous form of LDL cholesterol, linked to higher risk of heart disease and metabolic issues.

📋 About This Biomarker

Small Dense LDL 1 is a type of LDL (low-density lipoprotein) cholesterol, often referred to as “bad cholesterol.” What makes this type more concerning is its small size and higher density - these particles are tiny enough to slip into the lining of your arteries, where they can trigger inflammation and build up plaque. While LDL 1 (large, fluffy particles) are less risky, small dense LDL particles, especially sdLDL-1, are considered more harmful because they stay in the bloodstream longer and are more likely to become oxidised (damaged), which raises the risk of heart disease. These particles are often increased in people with insulin resistance, type 2 diabetes, metabolic syndrome, or a high-sugar, low-fibre diet. Measuring sdLDL-1 can help uncover hidden cardiovascular risks, even if your overall cholesterol levels seem normal. It’s like checking for the sneaky troublemakers in your bloodstream - not just the total number of passengers, but the ones most likely to cause damage.

🎯 Why We Test This

Testing sdLDL-1 gives you a deeper insight into your cardiovascular risk than standard cholesterol tests. It helps identify people whose cholesterol may look normal on basic blood tests but who are still at risk of heart disease or stroke due to the type of LDL particles they carry. It’s especially useful for people with diabetes, metabolic syndrome, or a family history of heart disease.

⚠️ What Affects It

A high intake of sugar, refined carbohydrates, and processed foods can increase small dense LDL particles. So can low physical activity, excess belly fat, insulin resistance, and type 2 diabetes. Other influences include smoking, stress, genetics, and hormonal shifts (like menopause in women). People with high triglycerides and low HDL (“good cholesterol”) often have higher levels of sdLDL-1.

📈 How to Improve

If sdLDL-1 is high or approaching high, focus on cutting down on sugar, processed carbs, and alcohol, while increasing your intake of healthy fats (like omega-3s), fibre, and plant-based foods. Exercise regularly, especially cardio and resistance training, to improve insulin sensitivity and reduce harmful cholesterol patterns. If levels are low, that’s great - keep doing what’s working! There’s usually no need to “raise” sdLDL-1, as lower is better in this case. Monitor your levels over time to track progress.

📊 Understanding Your Results (mmol/L)

Low (< 0 mmol/L)
Low sdLDL-1 levels are usually a very positive finding and are rarely cause for concern. It means your cholesterol is mostly in the form of large, fluffy particles that are less likely to cause harm. This may reflect a heart-healthy lifestyle and good metabolic balance.
Optimal (0 - 0.3 mmol/L)
sdLDL-1 within the normal range suggests your body is producing fewer of the harmful small LDL particles. This is a positive sign, as it means your risk of cholesterol-related artery damage is lower. Keep up your healthy habits to maintain this balance.
High (> 0.3 mmol/L)
High levels of sdLDL-1 suggest a greater number of small, dense LDL particles in the bloodstream - this is a strong indicator of increased cardiovascular risk. These particles can sneak into artery walls, get stuck, and lead to plaque build-up, potentially causing heart attacks or strokes over time. This is especially concerning if paired with high triglycerides or low HDL.
Also known as: Small Dense LDL 1, sdLDL-1