What is Cholesterol?
Cholesterol is a sterol, a type of fat, which is essential for normal functioning of the body. Examples of cholesterol health benefits include maintenance of the integrity of cell membranes of all tissues, synthesis of bile acids in the liver, and synthesis of lipids such as steroid hormones. It is required for the synthesis of hormones such as estrogen, testosterone and aldosterone.
Unfortunately, when cholesterol level in blood, especially that of LDL ("bad") cholesterol, rises beyond the normal range it causes health complications, including heart diseases. One of the causes of high blood cholesterol is consumption of foods high in cholesterol. Therefore, one approach to acheive and maintain normal, healthy, blood cholesterol level is to avoid or reduce intake of high cholesterol foods. However, the same foods with high cholesterol levels are also good sources of other essential nutrients such as protein, fatty acids, amino acids, and macro- and micro-nutrients. And therefore, it is a balancing act to reduce cholesterol intake with the need to ensure healthy diet.
Additionally, some of the nutrients also lower the rate of increase of serum cholesterol level. Several studies have demonstrated that diets high in phytosterol (cholesterol-like chemicals found in plants) reduce accumulation of serum cholesterol. Therefore, a healthy holistic diet needs to be part of a choleterol management plan.
Is Dietary Cholesterol Required?
Human body is capable of meeting its cholesterol requirements by synthesizing cholesterol indigenously. As such, there is no requirement for cholesterol from dietary sources. For the same reason, there is no Adequate Intake (AI) or Recommended Dietary Allowance (RDA) set for cholesterol, for humans of any age.
According to the USDA Continuing Survey of Food Intakes by Individuals (CSFII, 1994-1996, 1998), on average, an American adult man and woman consume 265 - 345 and 190 - 280 mg of dietary cholesterol per day, respectively. On average, an increase of dietary cholesterol intake by 100 mg per day is predicted to increase total serum cholesterol concentration by 0.05 to 0.1 mmol/L, 80 per cent of that increase being in LDL ("bad") cholesterol and the other 20% in HDL ("good") cholesterol. The effect of dietary cholesterol on increasing serum cholesterol varies from person to person. Some people have high efficiency, upto 80%, in absorbing cholesterol from their ingested diet, whereas others have lower efficiency (as low as 20%). In most people, however, 40 - 60% of the cholesterol in their diet ends up in their blood stream.
Fielding CJ, Havel RJ, Todd KM, Yeo KE, Schloetter MC, Weinberg V, Frost PH. 1995. Effects of dietary cholesterol and fat saturation on plasma lipoproteins in an ethnically diverse population of healthy young men. J Clin Invest 95:611–618.
Ros E. 2000. Intestinal absorption of triglyceride and cholesterol. Dietary and pharmacological inhibition to reduce cardiovascular risk. Atherosclerosis 151:357–379.