Nutrition for nursing Dr. Fahad Aldhafiri

lipids

Lipids commonly referred to as fats, include triglycerides (fats, oils), phospholipids and sterols (e.g. cholesterol).

1. Triglycerides Account for about 98% of the lipids in foods. Major storage form fat in the body. An individual triglyceride molecule may contain one, two, or three different types of fatty acids.

Fatty acids are basically chains of carbon atoms with hydrogen atoms attached (See the fig.). At one end of the chain is a methyl group (CH3), and at the other end is an acid group (COOH). Fatty acids vary in the length of their carbon chain and in the degree of unsaturation.

Saturated and unsaturated fatty acids Saturated fatty acids: all the carbon atoms have four single bonds with hydrogen atoms. Unsaturated: fatty acids does not have all the hydrogen atoms so, one or more bonds form between the carbon atoms.

Unsaturated fatty acids Are soft or liquid at the room temperature e.g.: oils. Are susceptible to rancidity when exposed to light and oxygen. Include: 1.Monounsaturated fatty acids: (if one double bond exists between 2 carbon atoms). e.g. Canola, olive oil and peanut oils.

2.Polyunsaturated fatty acids: (if there is more than one double bond between carbon atoms). Polyunsaturated fatty acids have 2 types: Omega- 6 Polyunsaturated fatty acids (in plant oils): e.g. Safflower and sunflower oils Omega- 3 Polyunsaturated fatty acids (in fish oils): e.g. Salmon

Saturated fatty acid Solid at room temperature. occur naturally in all most fat but are highest in meats, dairy products. Raise LDL cholesterol in the blood.

Important note All food fats contain a mixture of saturated, monounsaturated, and polyunsaturated fatty acids. When applied to sources of fat in the diet, “unsaturated” and “saturated” are not absolute terms used to describe the only types of fatty acids present (As shown in the fig. below).

Hydrogenated fats A process of adding hydrogen atoms to unsaturated fatty acids (e.g. margarine) to make them less susceptible to rancidity and to stay fresher longer.

Bad fats Bad fat raise LDL-cholesterol, which is a major cause of coronary heart disease. Saturated fat is commonly known as a “bad” fat. A strong body of evidence shows that a high intake of most saturated fatty acids is linked with high total and low-density lipoprotein (LDL) cholesterol, which are risk factors for cardiovascular disease.

Unsaturated Fatty Acids: are commonly known as “good fats” because they are linked to lower blood cholesterol levels and thus a reduced risk of cardiovascular disease when they are eaten in place of saturated fats. Hydrogenated fats are bad because they are more saturated than the oil from which they are made.

2. cholesterol Cholesterol is a sterol, a waxy substance whose carbon, hydrogen, and oxygen molecules are arranged in a ring. Cholesterol occurs in the tissues of all animals. It is found in all cell membranes and in myelin. Brain and nerve cells are especially rich in cholesterol. The body synthesizes bile acids, steroid hormones, and vitamin D from cholesterol.

Cholesterol is found exclusively in animals, with organ meats (kidney, heart, liver and brain) and egg yolks the richest sources. Please, note that: The cholesterol in food is just cholesterol; descriptions of “good” and “bad” cholesterol refer to the lipoprotein packages that move cholesterol through the blood

Digestion

Function of the fats Fat provides energy and it provides about 60% of the body’s calorie needs. All fat, whether saturated or unsaturated, provides 9 cal/g. Fat has other important functions in the body. Fat deposits insulate and cushion internal organs to protect them from mechanical injury.

Fat under the skin helps to regulate body temperature by serving as a layer of insulation against the cold. And dietary fat facilitates the absorption of the fat- soluble vitamins A, D, E, and K when consumed at the same meal.