Essential Vitamins & Nutrients


Introduction

What are the different parts of my diet that give me energy?

What role do vitamins and minerals play in nutrition?

Why am I hearing so much about the importance of water and fiber for a healthy diet?

Where does all this talk about cholesterol, salt, sugar, caffeine, and food additives fit in?

Introduction

Food provides the body with the materials it needs for energy, growth, repair, and reproduction. These materials are called nutrients. Nutritionists divide nutrients into two main groups: macronutrients and micronutrients. Macronutrients, so called because the body needs more of them, include carbohydrates, fats, and proteins. These are the foods our bodies use for energy and growth. Micronutrients, or nutrients required in only small amounts, include vitamins and minerals. Most foods contain a combination of the two groups.

What are the different parts of my diet that give me energy?

Macronutrients provide the body with the energy it needs to work, grow, reproduce, and repair. Carbohydrates and fats are the body's primary energy sources. Protein is essential to growth and maintenance.

Here is a rundown of what each macronutrient does and some good sources.

Carbohydrates Carbohydrates include all starches and sugars. They are the body's main source of energy. Each gram of carbohydrate provides 4 calories. Most foods contain carbohydrates. The main sugar in food is sucrose, which is everyday white or brown sugar. Other sugars include lactose (found in milk) and fructose (found in most fruits and many vegetables). Starches are a more complex form of carbohydrate. They are more filling and contain more nutrients than foods with lots of sugars, fats, or oils. Foods containing starches include beans, breads, cereals, pasta, and potatoes.

Fats Fats pack a lot of energy. Each gram of fat provides 9 calories. There are three kinds of fat: saturated, monounsaturated, and polyunsaturated. Animal and dairy fats, which remain solid at room temperature, are saturated fats. Saturated fat is often called "bad" fat. Unsaturated fats include vegetable fat and oils; they remain liquid at room temperature.

Proteins Proteins provide energy at 4 calories per gram, but they are more important as the body's building materials. Muscle, skin, bone, and hair are made up largely of proteins. In addition, every cell contains proteins called enzymes, which speed up chemical reactions in the body. Cells could not function without these enzymes. The body uses proteins to make antibodies, or disease-fighting chemicals, and certain hormones such as insulin, which serve as chemical messengers in the body. (Other hormones, such as the female hormone estrogen, are not made from proteins.) Meat, poultry, fish, dairy products, eggs, cereals, legumes, and nuts are all good sources of protein.

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What role do vitamins and minerals play in nutrition?

Vitamins help the body turn food into energy and tissues. There are 13 vitamins in all: vitamin A; the vitamin B complex, which includes thiamine, riboflavin, niacin, vitamin B₆, folic acid, vitamin B₁₂ pantothenic acid, and biotin; and vitamins C, D, E, and K.

Minerals are needed for growth and maintenance of body structures. They also help to maintain digestive juices and the fluids found in and around cells.

Unlike vitamins, carbohydrates, fats, and proteins, minerals are not made by plants and animals. Plants get minerals from water or soil, and animals get minerals by eating plants or plant-eating animals.

The minerals the body needs in large amounts include calcium, chlorine, magnesium, phosphorus, potassium, sodium, and sulfur.

Other minerals, called trace elements, are needed in much smaller amounts. Trace elements include iron, copper, fluorine, iodine, selenium, zinc, chromium, cobalt, manganese, and molybdenum.

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Why am I hearing so much about the importance of water and fiber for a healthy diet?

Water just may be the most important nutrient. In fact, the body is more than half water. You can live without food for several weeks, but you can go less than a week without water.

The body needs water to function. It is necessary for maintaining body temperature, transporting nutrients throughout the body, keeping joints moist, digesting food, ridding the body of waste products, and cooling the body.

Adults should consume about 2 quarts of water a day; children about half this much. The best way to get this water is by drinking plain water. But other beverages, such as fruit juices, milk, and noncaffeinated drinks are also good sources of water. Fruits and vegetables can also be good sources of water. Caffeinated and alcoholic beverages, while they do supply water to the body initially, contain diuretics that cause the body to lose water.

Fiber has been shown in studies to help reduce the rates of some forms of cancer, namely colon and breast cancer. Certain kinds of fiber have been found to lower levels of cholesterol in the blood. A number of foods are good sources of fiber, including fruits, vegetables, legumes, nuts, and whole grains.

There are two kinds of fiber: soluble and insoluble. Insoluble fiber is the indigestible part of food—the bran in grain, the pulp of fruit, and the skin of vegetables. Insoluble fiber helps move food and digestive by-products through the large intestine (colon) and out of the body. The faster that food and by-products travel through the digestive tract, the less time there is for potential cancer-causing substances to work.

Soluble fiber can be partially digested by the body. Only soluble fiber appears to have the ability to lower cholesterol levels in the blood. Soluble fiber can be found in a wide variety of foods, including apples, oats, guar gum, dried beans, and green vegetables. How fiber acts on cholesterol is not fully understood.

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Where does all this talk about cholesterol, salt, sugar, caffeine, and food additives fit in?

People nowadays eat a lot of processed and prepared foods. While convenient, these extras take their toll on health. Most are high in fat, cholesterol, sodium, and/or sugar. These extras plus caffeine are all things most people could stand to cut back on.

Cholesterol The body needs cholesterol. It is necessary to the cells and helps the body make hormones. It is found in all animals and animal products. Plant products do not have cholesterol. If you did not eat cholesterol, your liver would make enough.

Too much cholesterol in the blood can make its way to the arteries, where it stays in the form of a thick, fatty substance called plaque. The buildup of plaque narrows the arteries and makes it increasingly difficult for blood to make its way through them. This creates a condition called atherosclerosis. There may be no signs or symptoms of atherosclerosis until a heart attack or stroke occurs.

Cholesterol is not all bad. In fact, there is good high-density lipoprotein (HDL) cholesterol and bad low-density lipoprotein (LDL) cholesterol. High levels of LDL in the bloodstream are associated with an increased risk of heart disease. High levels of HDL appear to prevent the disease; low levels seem to encourage it. The lower your total and LDL cholesterol levels and the higher your HDL level, the better off you are.

Controlling cholesterol The amount of cholesterol in your bloodstream depends on the following three factors:

• Heredity: Some families have a tendency to high cholesterol levels. Know your family history of all major health problems and ask your doctor about adjusting your diet.
• Diet. Cutting out cholesterol is only part of the answer. Saturated fat also affects your cholesterol level; in fact, it's a worse offender. Keep your saturated fat intake under 10 percent of your calories each day, and you're on your way to lower cholesterol levels. Use the Food Guide Pyramid to help you lower your intake of fat and cholesterol.
• Lifestyle: The more physical activity you get, the higher your good (HDL) cholesterol levels and the lower your bad (LDL) cholesterol levels are likely to be. Physical inactivity leads to high LDL cholesterol levels.

Children and cholesterol While you don't have to eliminate all high-fat, high-calorie foods, most doctors suggest that children older than age 2 cut back on fat and cholesterol. This helps reduce the risk of heart disease later in their lives. For children older than age 2, follow the adult dietary guidelines for fat and saturated fat. Keep cholesterol consumption to no more than 100 milligrams for every 1,000 calories they eat. Remember that this information is on all food labels.

It's important that you don't start your children on a low-fat diet until after they turn 2 years old. Dietary fat and cholesterol are essential for normal brain development in infants and toddlers.

Sodium/salt Most adults eat too much sodium. And among those with a family history of heart disease, eating too much sodium can increase their risk of heart disease. All people older than age 2 should limit their daily salt consumption to 2,400 milligrams.

If you're like most people, you add salt to your cooking and at the table. Cutting back on salt is not as hard as it might seem. Simply do so gradually. Taste food before shaking on the salt. Choose low-sodium and sodium-free products such as tomato sauces and soups. Eventually you will find that you prefer the taste of foods without salt.

Sugar Yes, too much sugar can contribute to weight problems and cavities in both adults and children. But it is not the evil it was once thought to be. And while it may or may not cause excitability in some children, most children do not experience this side effect.

If children eat too much sugar, however, they are probably not eating enough healthy, nutrient-rich foods. Most high-sugar foods provide few nutrients; they are empty calories. And when children fill up on empty calories, they are too full to eat anything else. If you struggle with the question of how much sugar your children should eat, the answer is pretty simple. Don't let sugary foods ruin their appetites.

Food additives Additives are put into foods to help delay spoilage, enhance flavor, and improve appearance. There has been concern that some additives, such as nitrites (preservatives found in hot dogs, dried meats, and other foods), might cause cancer. Most experts agree, however, that the risk of cancer from food additives is small. A few people report that they get headaches, allergic reactions, or other symptoms from eating foods with certain additives, though in most cases the link between the additive and the reaction has not been scientifically proven. If you think you may be sensitive or allergic to a food additive, talk to your doctor.

Caffeine Coffee, tea, cola drinks, chocolate, some pain relievers, and many over-the-counter energy aids all contain caffeine. Caffeine is a drug that stimulates the central nervous system, making you feel more energetic. As a diuretic, it increases the blood flow through your kidneys, which produce more urine. This is why cola drinks are not recommended for quenching thirst.

The average cup of coffee offers about 100 milligrams of caffeine. Tea and cocoa have much less, and most caffeinated cola drinks even less. Large doses of caffeine—1,000 milligrams or more—can cause restlessness, sleeplessness, palpitations, and diarrhea. There is not a lot of evidence that caffeine causes any major long-term health effects. Even so, it is a good idea to keep your average intake below three cups of coffee a day, especially if you experience any side effects. You can become dependent on caffeine.

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Sections of this site have been excerpted from the AMA Complete Guide to Women's Health