What raises Low-Density Lipoprotein (LDL) levels?

Factors That Raise LDL Cholesterol

Saturated fats are the strongest dietary determinant of elevated LDL cholesterol levels, with each 1% increase in energy from saturated fat raising LDL-C by 0.8-1.6 mg/dL. 1

Dietary Factors That Raise LDL

Fats and Oils

• Saturated fatty acids - particularly lauric (12:0), myristic (14:0), and palmitic (16:0) acids 2, 3

  • Found in animal fats (meat and dairy), tropical oils (coconut, palm)
  • Raise LDL by decreasing LDL receptor activity and reducing LDL turnover 4, 3
  • The American Heart Association recommends limiting saturated fat to less than 7% of total calories 2

• Trans fatty acids - found in partially hydrogenated oils 2, 5

  • Have a similar or worse effect on LDL compared to saturated fats 5
  • Also lower beneficial HDL cholesterol, creating a doubly negative effect 5
  • The AHA recommends limiting trans fat to less than 1% of energy intake 2

• Dietary cholesterol - found in animal products 2

  • Has a smaller effect than saturated and trans fats but still contributes to elevated LDL 1
  • The AHA recommends limiting dietary cholesterol to less than 300 mg per day 2

Other Dietary Factors

• Excess caloric intake leading to weight gain 6
• High-carbohydrate diets, particularly those high in refined carbohydrates and added sugars 1
• Excessive alcohol consumption 2

Non-Dietary Factors That Raise LDL

Physiological Factors

• Obesity - excess body weight adversely affects LDL cholesterol levels 2
• Aging - LDL tends to increase with age 7
• Genetic factors - familial hypercholesterolemia and other genetic disorders 7, 4

Medical Conditions

• Hypothyroidism - slows LDL clearance from the bloodstream 2
• Diabetes - particularly poorly controlled diabetes 2
• Chronic kidney disease 2

Medications

• Certain medications can raise LDL, including:
  • Some antipsychotics (particularly atypical) 2
  • Beta-blockers (such as atenolol) 2
  • Steroids 2
  • Retinoic acid drugs 2
  • Protease inhibitors 2
  • Estrogens (oral) 2

Mechanisms of LDL Elevation

LDL elevation occurs through several mechanisms:

1. Decreased LDL receptor activity - saturated fats and trans fats reduce the number and activity of LDL receptors in the liver, decreasing LDL clearance from the bloodstream 4, 3

2. Increased LDL production - some saturated fatty acids increase the formation of LDL in the plasma compartment 8, 3

3. Shift in cholesterol distribution - saturated fats can cause a shift in cholesterol from tissues to the plasma cholesteryl ester pool 8

Clinical Approach to Managing Elevated LDL

1. Dietary modifications:

   • Reduce saturated fat to less than 7% of total calories 2
   • Limit trans fat to less than 1% of energy 2
   • Limit dietary cholesterol to less than 300 mg/day 2
   • Choose lean meats and vegetable alternatives 2
   • Select fat-free or low-fat dairy products 2
   • Consume a diet rich in vegetables, fruits, and whole grains 2, 1
   • Include fish, especially oily fish, at least twice a week 2

2. Lifestyle modifications:

   • Achieve and maintain a healthy body weight 2
   • Engage in regular physical activity 2, 1
   • Limit alcohol consumption 2
   • Avoid smoking 2

3. Pharmacological therapy when lifestyle modifications are insufficient:

   • Statins (like rosuvastatin) inhibit HMG-CoA reductase, the rate-limiting enzyme in cholesterol synthesis 7
   • Other medications may include bile acid sequestrants, fibric acids, or nicotinic acid 2

Common Pitfalls and Caveats

• Not all saturated fatty acids have the same effect - stearic acid (18:0) appears to have a neutral effect on LDL cholesterol 6, 3

• The PUFA/SFA ratio matters - increasing polyunsaturated fatty acids can help offset the effects of saturated fats 8

• Trans fats are particularly harmful - they not only raise LDL but also lower beneficial HDL cholesterol 5

• Focus on overall dietary pattern - the combined effect of all dietary components is more important than any single nutrient 2, 1

• Individual variation exists - genetic factors can influence how strongly dietary factors affect LDL levels 8, 4