Applied Microbiology Lecture 4: Cholesterol and PUFAs

Cholesterol and Lipoproteins

• Cholesterol is a waxy, fat-like substance found in all human cells, essential for making hormones, vitamin D, and substances that help digest foods.
• High levels of cholesterol in the blood can combine with other substances to form plaque, leading to atherosclerosis and coronary artery disease.
• HDL (high-density lipoprotein) is considered "good" lipid because it carries cholesterol from other parts of the body back to the liver for removal.
• LDL (low-density lipoprotein) is considered "bad" lipid because high levels can lead to the buildup of plaque in arteries.
• VLDL (very low-density lipoprotein) also contributes to the buildup of plaque in arteries, mainly carrying triglycerides.

Causes and Health Problems of High Cholesterol

• Unhealthy eating habits, such as consuming saturated and trans fats, can raise LDL levels.
• Lack of physical activity and smoking can lower HDL levels.
• Genetics, certain medical conditions, and medications can also cause high cholesterol.
• High cholesterol can lead to plaque buildup in arteries, increasing the risk of angina, heart attack, carotid artery disease, stroke, and peripheral arterial disease.

Polyunsaturated Fatty Acids (PUFAs)

• PUFAs are long-chain fatty acids with 18 or more carbon atoms, containing two or more double bonds, essential for human health.
• They must be supplied by the diet or supplements, as the body cannot produce them.
• Examples of PUFAs include omega-3 fatty acids found in fish oil, such as DHA and EPA.
• PUFAs have various benefits, including regulating membrane architecture, controlling gene expression, affecting cholesterol transport, preventing heart disease, and playing a role in brain function and development.

Benefits and Sources of PUFAs

• PUFAs can inhibit tumor cell growth and are important for the formation of the outer retina of the eyes.
• The recommended daily intake of PUFAs is at least 3% of total lipid intake.
• The ideal omega-6 to omega-3 ratio is 4:1, but the average Western diet has a ratio of 12:1 to 25:1.
• Fish oil is a common source of PUFAs, but it has limitations, such as being an unsustainable source, containing high cholesterol, and requiring expensive purification.
• Alternative sources include marine microorganisms, which can be grown on waste products and produce only one type of PUFAs.

Applications of PUFAs

• EPA is used to treat various conditions, including high blood pressure in high-risk pregnancies, age-related macular degeneration, heart disease, schizophrenia, and depression.
• EPA is also used in combination with DHA in fish oil preparations and with RNA and L-arginine to reduce infections and improve wound healing.

Microbial PUFAs

• Microbial PUFAs can be produced throughout the year, regardless of season or climate.
• Production conditions can be easily manipulated to maximize productivity.
• Microorganisms can grow on waste products, reducing production costs, and lack unpleasant smells.
• Microbial PUFAs are typically of a single type, making them more desirable.