Nutrition Science and Everyday Application - beta v 0.1

LIPID TYPES AND STRUCTURES 265
However, cholesterol also has many essential functions in the body. Like phospholipids,
cholesterol is present in all body cells as it is an important substance in cell membrane
structure. Cholesterol is also used in the body as a precursor in the synthesis of a number
of important substances, including vitamin D, bile, and sex hormones such as progesterone,
testosterone, and estrogens.
Figure 5.11. Cholesterol is made up of multiple carbon rings bonded together.
Cholesterol is not an essential nutrient; it does not need to be consumed in the diet,
because it is manufactured in the liver. Only foods that come from animal sources
contain cholesterol. Cholesterol is found in foods like meat, poultry, fish, egg yolks, butter,
and dairy products made from whole milk.
Plant foods do not contain cholesterol, but sterols found in plants resemble cholesterol
in structure. Plant sterols inhibit cholesterol absorption in the human body, which can
contribute to lower cholesterol levels, particularly lower LDL (“bad”) cholesterol levels. Plant
sterols occur naturally in vegetable oils, nuts, seeds, and whole grains. In addition, some
foods like margarines and dressings are fortified with plant sterols.
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