Sterols
Sterols
Sterols are lipids with a typical 4-ring structure. Sterols occur in the membranes of plants, animals, and microorganisms and are termed phytosterols, zoosterols, and mycosterols, respectively. Cholesterol is the main zoosterol, but sterols in plants commonly occur as mixtures with β-sitosterol, campesterol, and stigmasterol representing three of the major phytosterols.Â
Plant sterols are especially concentrated in seeds, nuts, and grain products. These compounds lower serum cholesterol by competing for cholesterol absorption in the gastrointestinal tract.Â
Sterols as nutrients include:
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Cholesterol is a zoosterol. It has a typical 4 ring structure. Cholesterol is not an essential nutrient, since it can be produced in our liver and intestine, from fatty acids and other nutrients.  Some researchers believe some critically ill patients might not be able to produce enough cholesterol, so for them it would be a conditionally essential nutrient.
Cholesterol is:
- A part of the cell membranes and myelin sheaths of the nerves.
- A precursor for the steroid hormones (cortisol, aldosterone, estrogens, progesterone, testosterone), bile acids (in the bile) and vitamin D.
- Some foods that are high in cholesterol include: chicken liver, egg yolk, shrimps, beef brain, cheeseburger and chicken legs.