Increased plasma triglycerides, cholesterol and apolipoprotein E during prolonged fasting in normal subjects

Area of Science:

• Metabolic studies
• Lipid metabolism
• Nutritional science

Background:

• Fasting impacts plasma lipid profiles.
• High-density lipoprotein (HDL) plays a crucial role in cholesterol transport.
• Apolipoprotein E (apo E) is vital for lipoprotein metabolism and is synthesized in the liver.

Purpose of the Study:

• To investigate the effects of prolonged fasting on plasma lipid and lipoprotein levels in healthy males.
• To assess changes in high density lipoprotein (HDL) cholesterol and apolipoprotein E during fasting.
• To evaluate potential impacts on liver function.

Main Methods:

• 20 healthy, non-obese males underwent a 6-day fast (150 kcal/d).
• Plasma triglyceride, cholesterol, and HDL-cholesterol levels were measured.
• Complete lipoprotein analysis, including apolipoprotein E, was performed on 3 subjects after 9 days.
• Liver function tests were conducted.

Main Results:

• Plasma triglyceride and cholesterol increased by 18% after 6 days of fasting.
• HDL-cholesterol decreased by 22% after 6 days.
• Very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) levels were elevated, while HDL was reduced after 9 days.
• A significant reduction in apolipoprotein E was observed in VLDL and HDL.
• Hepatic enzyme activity decreased, suggesting reduced liver function.

Conclusions:

• Prolonged fasting significantly alters plasma lipid profiles, increasing triglycerides and cholesterol while decreasing HDL.
• The reduction in apolipoprotein E and hepatic enzyme activity indicates that extended fasting inhibits liver function in healthy individuals.