Cholesterol is found in every cell of the body and has important natural functions when it comes to digesting foods, producing hormones, and generating vitamin D. It is manufactured by the body but can also be taken in from food. It is waxy and fat-like in appearance.

There are two types of cholesterol; LDL (low-density lipoproteins, bad cholesterol) and HDL (high-density lipoproteins, good cholesterol).

In this article, we will explain the role of cholesterol. We will also discuss the causes of high cholesterol, and its symptoms, treatment, and prevention.

What is cholesterol?

Cholesterol is an oil-based substance and does not mix with the blood, which is water-based. It is carried around the body by lipoproteins.

Two types of lipoprotein carry the parcels of cholesterol:

• Low-density lipoprotein (LDL) – cholesterol carried by this type is known as “bad” cholesterol.
• High-density lipoprotein (HDL) – cholesterol carried by this type is known as “good” cholesterol.

Cholesterol has four primary functions, without which we could not survive, these are:

• contributing to the structure of cell walls
• making up digestive bile acids in the intestine
• allowing the body to produce vitamin D
• enabling the body to make certain hormones

Causes of high cholesterol

High cholesterol is a significant risk factor for coronary heart disease and a cause of heart attacks. A build-up of cholesterol is part of the process that narrows arteries, called atherosclerosis, in which plaques form and cause restriction of blood flow.

Reducing intake of fat in the diet helps manage cholesterol levels. In particular, it is helpful to limit foods that contain:

• Cholesterol – from animal foods, meat, and cheese.
• Saturated fat – found in some meats, dairy products, chocolate, baked goods, deep-fried, and processed foods.
• Trans fats – found in some fried and processed foods.

Being overweight or obese can also lead to higher blood LDL levels. Genetics can contribute to high cholesterol – very high LDL levels are found in the inherited condition familial hypercholesterolemia. Abnormal cholesterol levels can also arise due to other conditions, including:

• diabetes
• liver or kidney disease
• polycystic ovary syndrome
• pregnancy and other conditions that increase levels of female hormones
• underactive thyroid gland
• drugs that increase LDL cholesterol and decrease HDL cholesterol (progestins, anabolic steroids, and corticosteroids)

High cholesterol symptoms

Having high cholesterol levels, while a risk factor for other conditions, does not itself present any signs or symptoms. Unless routinely screened through regular blood testing, high cholesterol levels will go unnoticed and could present a silent threat of heart attack or stroke.

Cholesterol in foods

A report from Harvard Health has identified “11 cholesterol lowering foods” that actively decrease cholesterol levels:

• oats
• barley and whole grains
• beans
• eggplant and okra
• nuts
• vegetable oil (canola, sunflower)
• fruits (mainly apples, grapes, strawberries, and citrus)
• soy and soy-based foods
• fatty fish (particularly salmon, tuna, and sardines)
• foods rich in fiber

Adding these to a balanced diet can help keep cholesterol in check. The same report also lists foods that are bad for cholesterol levels, including:

• red meat
• full-fat dairy
• margarine
• hydrogenated oils
• baked goods

Various low cholesterol recipe books are available to purchase online.

Levels and ranges

In adults, total cholesterol levels less than 200 milligrams per deciliter (mg/dL) are considered healthy.

• A reading between 200 and 239 mg/dL is borderline high.
• A reading of 240 mg/dL and above is considered high.

LDL cholesterol levels should be less than 100 mg/dL.

• 100–129 mg/dL is acceptable for people with no health problems but may be a concern for anyone with heart disease or heart disease risk factors.
• 130—159 mg/dL is borderline high.
• 160–189 mg/dL is high.
• 190 mg/dL or higher is considered very high.

HDL levels should be kept higher. The optimal reading for HDL levels is of 60 mg/dL or higher.

• A reading of less than 40 mg/dL is considered a major risk factor for heart disease.
• A reading from 41 mg/dL to 59 mg/dL is borderline low.