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Reading B

THE BASICS OF FOOD (PART II)

by Marshall Brain

Fats

We all know about the common fats that different foods contain. Meat contains animal fat. Most breads and pastries contain vegetable oils, shortening or lard. You commonly hear about two kinds of fats: saturated and unsaturated. Saturated fats are normally solid at room temperature, while unsaturated fats are liquid at room temperature. Vegetable oils are the best examples of unsaturated fats, while lard and shortening (along with the animal fat you see in raw meat) are saturated fats. However, most fats contain a mixture. Unsaturated fats are currently thought to be healthier than saturated fats, and monounsaturated fats (as found in olive oil and peanut oil) are thought to be healthier than polyunsaturated fats.

Fats that you eat enter the digestive system and meet with an enzyme called lipase. Lipase breaks the fat into its parts: glycerol and fatty acids. These components are then reassembled into triglycerides for transport in the bloodstream. Muscle cells and fat (adipose) cells absorb the triglycerides either to store them or to burn them as fuel.

You need to eat fat for several reasons. Firstly, fats help in the absorption of the fat-soluble vitamins A, D, E, and K. Secondly, in the same way that there are essential amino acids, there are essential fatty acids (for example, linoleic acid is used to build cell membranes). You must obtain these fatty acids from food you eat because your body has no way to make them. What is more, fat turns out to be a good source of energy because it contains twice as many calories per gram as do carbohydrates or proteins. So your body can burn fat as fuel when necessary.

Vitamins

The Merriam-Webster Collegiate Dictionary defines “vitamin” as: any of various organic substances that are essential in minute quantities to the nutrition of most animals and some plants, act esp. as coenzymes and precursors of coenzymes in the regulation of metabolic processes but do not provide energy or serve as building units, and are present in natural foodstuffs or sometimes produced within the body.

Vitamins are smallish molecules (Vitamin B₁₂ is the largest, with a molecular weight of 1,355) that your body needs to keep itself running properly. The human body needs 13 different vitamins: vitamin A (fat soluble, retinol) comes from beta-carotene in plants; vitamin B (water soluble, several specific vitamins in the complex) – vitamin B₁ (thiamine), vitamin B₂ (riboflavin), vitamin B₃ (niacin), vitamin B₆ (pyridoxine), vitamin B₁₂ (cyanocobalamin), folic acid; vitamin C (water soluble, ascorbic acid); vitamin D (fat soluble, calciferol); vitamin E (fat soluble, tocopherol); vitamin K (fat soluble, menaquinone); pantothenic acid (water soluble); biotin (water soluble).

In most cases, the lack of a vitamin causes severe problems. The diseases associated with the lack of different vitamins are: night blindness, xerophthalmia (the lack of vitamin A); beriberi (the lack of vitamin B₁); problems with lips, tongue, skin (the lack of vitamin B₂); pellagra (the lack of vitamin B₃); pernicious anemia (the lack of vitamin B₁₂); scurvy (the lack of vitamin C); rickets (the lack of vitamin D); malabsorption of fats and anemia (the lack of vitamin E); poor blood clotting and internal bleeding (the lack of vitamin K).

A diet of fresh, natural food usually provides all of the vitamins that you need. Processing tends to destroy vitamins, so many processed foods are “fortified” with man-made vitamins.

Minerals

Minerals are elements that our bodies must have in order to create specific molecules needed in the body. Here are some of the more common minerals our bodies need: calcium (used by teeth, bones), chlorine, chromium, copper, fluoride (strengthens teeth), iodine (combines with tryosine to create the hormone thyroxine), iron (transports oxygen in red blood cells), magnesium, manganese, molybdenum, phosphorus, potassium (important ion in nerve cells), selenium, sodium, zinc.

We do need other minerals, but they are supplied in the molecule that uses them. For example, sulfur comes in via the amino acid methionine, and cobalt comes in as part of vitamin B₁₂.

Food provides these minerals. If they are lacking in the diet, then various problems and diseases arise. However, vitamins and minerals are micronutrients and are required in the human diet in very small amounts.

Water

As mentioned above, your body is about 70-percent water. A person at rest loses about 40 ounces of water per day.

Water leaves your body in the urine, in your breath when you exhale, by evaporation through your skin, etc. Obviously, if you are working and sweating hard then you can lose much more water.

Because we are losing water all the time, we must replace it. We need to take in at least 40 ounces a day in the form of moist foods and liquids. In hot weather and when exercising, your body may need twice that amount. Many foods contain a surprising amount of water, especially fruits. Pure water and drinks provide the rest.

Fibers

Fiber is the broad name given to the things we eat that our bodies cannot digest. The three fibers we eat on a regular basis are: cellulose, hemicelluloses, pectin.

Hemicellulose is found in the hulls of different grains like wheat. Bran is hemicellulose. Cellulose is the structural component of plants and gives a vegetable its familiar shape. Pectin is found most often in fruits, and is soluble in water but non-digestible. Pectin is normally called “water-soluble fiber” and forms a gel. When we eat fiber, it simply passes straight through, untouched by the digestive system.

Reading Comprehension

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