A study of more than 100,000 healthy Chinese citizens followed for nine years showed that having very low levels of LDL cholesterol (<70 mg/dl) is associated with increased risk for bleeding into the brain, and the lower the LDL, the greater the risk (Neurology, July 2, 2019). Normal blood levels of LDL cholesterol are 70 to 99 mg/dl. (Note: if you live in Canada, you can make the metric conversion by dividing the U.S. numbers by 40). The risk for strokes was the same for people taking no medication and those taking cholesterol-lowering and/or anti-clotting drugs.
The authors of this study feel that it may be safer to keep blood levels of LDL cholesterol between 70 and 99 mg/dl, but caution that lower levels might be more protective for some people to balance the risks of bleeding and clotting. Another study done nine years ago found the same results (Ann Indian Acad Neurol, 2012 Jan-Mar; 15(1):19–22). LDL cholesterol helps to form all cell membranes and clotting, so very low levels of LDL can weaken membranes on red blood cells and platelets to increase bleeding.
Heart Attack Risk Starts at LDL Cholesterol Levels of 50
Having a high LDL cholesterol (>100 mg/dL) has long been associated with increased risk for heart attacks, but you can form plaques and be at risk for a heart attack even if your LDL cholesterol is as low as 50 (Journal of the Am Coll of Cardiol, December 19, 2017;70:2979-2991). Researchers used ultrasound or cardiac CT scans on 1779 middle-aged adults who had no obvious heart attack risk factors such as diabetes, high blood pressure, smoking or high LDL cholesterol, and 740 of these people had all of their heart attack risk factors in the optimum range. They found that almost half of their subjects had extensive plaques in their arteries. They also found that plaques started to regress when blood levels of LDL went below 50.
Most doctors in North America do not have any patients who are not on cholesterol-lowering drugs and have blood levels of LDL below 50, probably because almost all of us eat too much of the wrong foods. The new studies show that plaques can form in arteries even in people who have low LDL cholesterol levels, and that very low cholesterol levels increase risk for strokes. This suggests that we should be looking instead at other heart attack risk factors and encouraging all patients to make heart-heathly lifestyle changes, no matter what cholesterol numbers they may have.
Risk Factors for a Heart Attack
All of the factors listed below increase your risk for a heart attack. Your doctor can examine you and order these tests:
• Blood pressure >120/80 at bedtime (when blood pressure is lowest)
• HBA1C >5.7 (diabetes)
• High blood sugar >140 mg/dl one hour after meals
• C-reactive protein (CRP) >1 (a measure of inflammation)
• Abdominal obesity (increased risk for diabetes)
• Resting heart rate >70
• Lp(a) >125 (a genetic clotting disorder)
• Triglycerides >150 (increased risk for diabetes)
• Homocysteine >10 (genetic risk factor or vitamin deficiency)
• Small LDL particle size (an indicator of diabetes)
• Family history of heart attacks
• Having autoimmune or inflammatory conditions such as psoriasis, rheumatoid arthritis, lupus or kidney disease
Try Lifestyle Changes First
If you have any of the risk factors listed above, see if you can correct them with lifestyle changes. I believe that everyone should:
• lose weight if overweight
• avoid smoking
• not take in alcohol regularly or excessively
• eat a healthful diet with plenty of vegetables, fruits, nuts and other seeds
• avoid sugared drinks including fruit juices, sugar-added foods, red meat, processed meats and fried foods
• keep hydroxy vitamin D levels above 20 ng/ml
More on Heart Attack Prevention