Cholesterol is a soft, waxy, fat-like substance that is found in the blood and in all cells of the body. It is important for good health in the right amount, mainly in building cells and making bile acids for fat digestion. Cholesterol comes from two sources. First is the liver which makes all the cholesterol (80%) we need. The remainder of the cholesterol (20%) comes from animal foods like meat, poultry, and dairy products. These are called dietary cholesterol.

There are two most common types of cholesterol: good (high-density lipoprotein-HDL) and bad (low-density lipoprotein-LDL). There is also another type of fat (lipid) called triglycerides which is not cholesterol but is an important measure of heart disease. While our body needs both cholesterol and triglycerides to function, having too much of them can cause them to build up in arteries, thus, increasing the risks of heart attack, stroke, and heart disease.

Also Read: Healthy Liver and Immunity: How Does the Liver Affect Our Immune System?

Causes of High ‘Bad’ LDL Cholesterol

1. Poor diet: Eating too much saturated fat or trans fats can result in unhealthy cholesterol levels. Saturated fats are found in fatty cuts of meat and full-fat dairy products. Trans fats are often found in packaged snacks or desserts. 
2. Obesity: Having a body mass index (BMI) of 30 or greater puts you at risk of high cholesterol.
3. Lack of physical activity: Less exercise and walking and a sedentary life increase body weight which results in an increase in the risk of high bad cholesterol.
4. Smoking: It reduces good cholesterol and increases bad cholesterol.
5. Alcohol: Drinking too much alcohol can increase cholesterol levels.
6. Age:  Unhealthy levels of cholesterol can affect people of all ages, even young children. Even a 2-year-old child can develop high cholesterol. Cholesterol levels in children are linked to three factors: heredity, diet, and obesity. In most cases, kids with high cholesterol have a parent who has a family history of elevated cholesterol.  7% of U.S. children and adolescents ages 6 to 19 have high total cholesterol. More than 43% of children with obesity have high cholesterol compared to less than 14% of kids who are not obese. Children who have hypothyroidism, diabetes, or kidney or liver disease, are also at risk of developing high cholesterol during childhood. However, high cholesterol is most commonly diagnosed in people between the ages of 40 and 59. As one gets older, the body’s metabolism changes. The liver does not remove “bad” LDL cholesterol as well as it did when young. 
7. Stress: Stress triggers hormonal changes that cause our body to produce cholesterol.
8. Heredity: Some people inherit genes from their mother, father, or even grandparents that cause them to have too much cholesterol. This is called familial hypercholesterolemia (FH).
9. Chronic kidney disease: In this disease, inflammation can be a chronic condition triggered by many things which can cause bad (LDL) cholesterol to stick around in the body.
10. Diabetes: Poor blood sugar control raises the level of bad cholesterol and triglyceride in the blood and decreases good cholesterol. This condition is called diabetic dyslipidemia.
11. Hypothyroidism: If metabolism is slowed, as occurs in hypothyroidism, the breakdown or elimination of cholesterol is also reduced, which leads to higher circulating cholesterol levels in the bloodstream.
12. Medications: Cholesterol levels can also be worsened by some types of medications one might be taking for other health problems, such as cancer, high blood pressure, irregular heartbeats, and organ transplants.