A Healthy Diet

A healthful diet is important for good health and long life. There are many diseases one can acquire later on in life if one does not eat right (e.g. diabetes, high blood pressure, certain cancers, obesity). WHY

DO WE EAT?

We eat because our bodies require energy (like a car requires fuel) for its normal metabolic functions. Our bodies also need water, vitamins and minerals.

HOW

DO WE OBTAIN THIS ENERGY?

We obtain this energy from the breakdown of certain classes of food called carbohydrates, fats and proteins. Each of these classes of food has a fuel or energy value (otherwise known as calorie/gm). Carbohydrates have a fuel value of 4cal/gm and so do proteins. Fats have a fuel value of 9cal/gm. Adults require between 2000 and 2800 calories per day in order to maintain their body weight. 55% of

these calories should come from carbohydrate, 30% from fat and 1015% from protein. When we consistently consume more calories than we expend, the excess calories are stored in body fat. 1 lb of adipose tissue contains 3500 calories. A good way to know whether or not one’s body weight is healthy is to measure one’s body mass index or BMI. This is calculated by dividing one’s weight by height squared. Ideally one’s BMI should be between 18 and 25. One is underweight if one’s BMI is

less than 18. Between 25 and 30 one is overweight and one should consider losing weight; between 30 and 40 one is obese and losing weight is recommended because health is at risk; anything greater than 40 means one is morbidly obese and losing weight immediately is strongly recommended. Carbohydrates from plants are the main dietary source of energy for bodily functions. They can be divided into simple and complex carbohydrates. Examples of simple

carbohydrates are sugars such as sucrose (found in sugarcane and sugar beet), fructose (found in fruits and honey), maltose, lactose (found in milk), and glucose. Complex carbohydrates include starch (from plant sources) and glycogen (from animal sources). These complex sugars can be broken down in the human body into simple sugars like glucose and absorbed. Starch is a major component of the bread group of which the following types of food are included- bread, cereal, pasta, potatoes, yams,

cocoyams, cassava, etc.

You require

nine and eleven servings a day (one serving is equivalent to one slice of bread or one ounce of cereal or one cup of cooked rice or pasta) from this food group. Dietary fiber is mainly composed of cellulose that makes up the cell walls of plants. The human body cannot digest cellulose; nevertheless it is an important component of the diet because it delays gastric emptying, slows absorption of carbohydrate and increases the water content and bulk

of faeces. Dietary fiber is found in vegetables and most fruits, especially in their skin; it is also found in oat bran, wheat bran, corn bran and dried peas and beans. Ideally one requires 25-30 gm/day of dietary fiber a day. Proteins are called the “building blocks” of the body. They are important components of many organs and tissues in the body including muscles, eyes, blood, nails, skin, and connective tissues. They are broken down into amino acids in the body. There are twenty-one amino acids of

which nine are essential i.e. the body cannot synthesize them and they need to be obtained from the diet. Proteins that are obtained from animal sources are complete proteins and are found in meat, poultry, fish, eggs, milk, and cheese. These foods are rich sources of protein as they contain the nine essential amino acids. Proteins are also found in nuts and legumes (peas, beans etc.) but those proteins are regarded as incomplete proteins because they do not contain all the nine essential amino acids.

In the diet milk and meats constitute the food group that represents protein. The recommended daily allowance (RDA) for protein for an adult is 0.8 gm/kg; that comes to between 1-2 servings a day (2-3 pieces of chicken /beef/turkey). Red meat has a higher saturated fat content and cholesterol content so it is not a healthy source of protein. Fish and white meat like chicken and turkey are much more healthy sources of protein as they contain much less fat and cholesterol. Eggs and milk are also good sources of protein but eggs are high in cholesterol

(the yolk) so it is recommended that you eat an average of one egg a day or less. Cholesterol is not a fat but an alcohol (sterol). It is found in foods of animal origin such as eggs (the yolk) and organ meats such as liver and kidney. One’s intake of cholesterol correlates with the likelihood of developing coronary artery disease (a disease affecting the blood vessels of the heart which may cause one to have a heart attack) later in life. The metabolism of cholesterol is linked to that of fat such

that if the intake of saturated fat were high this would lead to an increase in the cholesterol level. The RDA of cholesterol is about 300gm/day (one egg yolk is equivalent to 300gm cholesterol!) Dietary fat is also an important source of energy. It can be divided into (1) saturated (2) polyunsaturated (3) monounsaturated. Fats from animal sources contain saturated fat e.g. meat, poultry, milk, butter and eggs. Saturated fat is also found in some plant sources such as coconut, cocoa

butter and palm oil. Polyunsaturated fat is found in vegetable sources such as sunflower oil, corn oil and soybean oil. Fish oil is an animal source of polyunsaturated fat. Margarine is made from vegetable oils and it is therefore healthier for us than butter. Monounsaturated fat is also obtained from vegetable sources such as olive oil, canola oil and peanut oil. Mediterranean peoples such as the Italians use mostly olive oil to cook, and the incidence of heart disease is relatively low in that region of the world.

Nutritionists recommend that not more than 30% of total calories should be from dietary fat; only 10% of this should come from saturated fat. In order to reduce our intake of saturated fat it is best to cook with polyunsaturated oils such as corn oil, or monounsaturated oils such as olive oil and canola oil. Palm oil is saturated oil that should be used sparingly in cooking. It is better to restrict one’s fat intake when one is still young because one develops a healthy food habit that one is able to maintain when one gets older.

Fruits and vegetables are just above the bread group in the food pyramid. One should eat between 7 and 9 servings daily (that usually means some vegetable/fruit with every meal). Fresh fruit and vegetables (especially citrus fruits such as oranges, grapefruit, lemon, and lime) are rich in vitamin C, dietary fiber, and a mineral called potassium. Legumes such as peas, beans and soybeans are also good sources of both complex carbohydrates and protein.

Sweets are high in calories and low in nutritional value. They include such things as ice cream, cakes, candy, chocolate, soft drinks etc. Excessive intake of sweets will surely lead to weight gain that may prove difficult to shed, as one gets older. The human body also requires 13 vitamins and 16 minerals for good health. Vitamins are found in a number of foods including fresh fruits and vegetables. Minerals include sodium (a component of salt), potassium, calcium, and iron among

others. The RDA for salt is 3gm/day; most of us take much more than this amount on a daily basis. Salt are a hidden component of many processed foods (e.g. canned food and processed meats such as bacon and sausage). People with high blood pressure (hypertension) usually need to cut down on their salt intake in order to achieve adequate control of their blood pressure in addition to being on antihypertensive medication. Potassium is found in fresh fruits especially in citrus fruits and bananas. Calcium is found in milk and eggs and

is a major component of the bones and teeth; iron is found mostly in liver. A shortage of iron in the body (which is quite common in women and children) usually leads to iron deficiency anemia because iron is a major component of red blood cells that carry oxygen to different parts of the body. A deficiency of calcium in children leads to a disease called rickets in which the bones become soft and the limbs bend in an abnormal fashion. In adults the disease is called osteomalacia and results in easily broken bones and loss of the teeth.

Last but not least, water is an essential component of a healthy diet. The body is composed of about 60% water. We require 3 liters of water daily, of which 2/3 is usually obtained from water and beverages and 1/3 from food. This usually comes to about six glasses of water a day.