Page 85 - Nutrition Essentials for Nursing Practice

CHAPTER 4 Lipids 73

more health benefits than those from arachidonic acid; EPA eicosanoids help lower blood
pressure, prevent blood clot formation, protect against arrhythmia, and reduce inflamma-
tion (Rolfes, Pinna, and Whitney, 2009). Prostaglandins made from arachidonic acid are
responsible for the inflammatory response (IFICF, 2011).
■ EPA and DHA may play a role in preventing and treating heart disease through their
anti-inflammatory, antiarrhythmic, and anticlotting effects (IFICF, 2009). They are
essential for normal growth and development. DHA, in particular, is abundant in the
structural lipids in the brain and in retinal membranes.

Phospholipids

Phospholipids: a Like triglycerides, phospholipids have a glycerol backbone with fatty acids attached. What
group of compound makes them different from triglycerides is that a phosphate group replaces one of the fatty
lipids that is similar acids. Although phospholipids occur naturally in almost all foods, they make up a very small
to triglycerides in that percentage of total fat intake.
they contain a glycerol
molecule and two Phospholipids are both fat soluble (because of the fatty acids) and water soluble
fatty acids. In place of (because of the phosphate group), a unique feature that enables them to act as emulsifiers.
the third fatty acid, This role is played out in the body as they emulsify fats to keep them suspended in blood
phospholipids have a and other body fluids. As a component of all cell membranes, phospholipids not only pro-
phosphate group and vide structure but also help to transport fat-soluble substances across cell membranes. Phos-
a molecule of choline pholipids are also precursors of prostaglandins.
or another nitrogen-
containing compound. Lecithin is the best-known phospholipid. Claims that it lowers blood cholesterol;
improves memory; controls weight; and cures arthritis, hypertension, and gallbladder prob-
Emulsifier: a stabiliz- lems are unfounded. Studies show no benefit from taking supplements because lecithin is
ing compound that digested in the gastrointestinal tract into its component parts and is not absorbed intact to
helps to keep both perform super functions. Lecithin is not even an essential nutrient because it is synthesized
parts of an emulsion in the body. Many people who take lecithin supplements do not realize that they provide
(oil and water mixture) 9 cal/g, just like all other fats.
from separating.

Cholesterol

Sterols: one of three Cholesterol is a sterol, a waxy substance whose carbon, hydrogen, and oxygen molecules
main classes of lipids are arranged in a ring. Cholesterol occurs in the tissues of all animals. It is found in all
that include cholesterol, cell membranes and in myelin. Brain and nerve cells are especially rich in cholesterol. The
bile acids, sex hormones, body synthesizes bile acids, steroid hormones, and vitamin D from cholesterol. Although
the adrenocortical hor- cholesterol is made from acetyl-coenzyme A (acetyl-CoA), the body cannot break down
mones, and vitamin D. cholesterol into CoA molecules to yield energy, so cholesterol does not provide calories.

QUICK BITE

Cholesterol content of selected foods

Beef brains, 3 oz Cholesterol (mg) Shrimp, 4 Cholesterol (mg)
Beef liver, 3 oz 1746 Whole milk, 1 cup 37
Beef kidney, 3 oz 375 2% milk, 1 cup 30
Egg yolk, 1 329 Butter, 1 tbsp 15
Broiled lobster, 1 cup 213 Nonfat milk, 1 cup 12
Broiled steak, 4 oz 110 Egg whites 7
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