Minerals (Lesson 8)

Karen Overstreet, Roy, Heli J.  |  1/28/2010 10:45:52 PM

What You Will Learn

In this lesson, you will learn about the two main groups of minerals - major minerals and trace minerals. You will learn why minerals are important. You will also learn which foods are the best sources of the minerals. You will learn about the minerals that are required to be on the nutrition label - sodium, calcium and iron.


Introduction

Do you want to be as healthy as you can when you get older? Do you want to stay at about the same height as when you reached adult height? Do you want your bones to stay as dense as possible and be less likely to fracture? You don't want your bones to become more porous and break more easily or lose height and get curvature of the spine as you get older.

Hip fractures cause the greatest health problems and the most deaths. Half of all elderly adults hospitalized for hip fracture cannot return home or live independently after the fracture. Breaking a hip is one of the leading causes of admissions into a nursing home. Elderly people are more likely to die within six months to one year once they have broken a hip, mainly because of immobility and complications arising from immobility, as well as from the increased strain on the heart and other body organs.

We want to stay as mobile as we can for as long as we can to be able to take care of ourselves in our old age. Maintaining healthy bones is critical in preventing bone fractures and in staying more mobile.

To stay mobile, we also need to keep our muscles in good working order. We can do that by doing some weight bearing exercises and getting the minerals we need by eating mineral-rich food, Both bones and muscles have important roles in mobility and flexibility. Minerals play a key role in bone health and in muscle function. Muscles can't contract without certain minerals.

Minerals are also important for our heart and circulatory system to function as they should. Minerals are important for our heart to beat regularly and to help prevent a buildup of fluid in our feet or other body parts. Excessive fluid buildup increases the workload on our heart.

Do you eat enough low fat meats, fruits, vegetables, milk and other foods that are our best sources of minerals? Minerals are very important, but tend to be low in our diet. According to the Dietary Guidelines 2010, intake levels of the following minerals may be of concern for adults, adolescents and children: calcium, potassium and magnesium. Likewise, intake of iron is a concern for women of childbearing age who may become pregnant. Be sure to include mineral-rich foods such as low fat meats, fruits, vegetables, milk and others.

We want to be as healthy as we can be for as long as we live. If we eat a poor quality diet that lacks minerals, the result is poor bones that become brittle and break easily. We become more at risk for heart complications which can result in swelling in our feet, legs or other parts of our body.

USDA MyPlate Review

A balanced diet that provides a variety of foods is the best guarantee of our getting all essential nutrients. Use the USDA MyPlate when planning a menu for each day. Make sure you include foods from from all food groups. Get the recommended number of servings from each food group since no food group contains all of the nutrients needed. The number of servings from each food groups depends on person's age, gender and physical activity level.


What Are Minerals?

Minerals are a group of nutrients needed by your body. They are important in regulating body processes and in giving your body structure. Have you ever experienced swelling in your fingers, ankles or feet? Minerals have an important role in keeping a healthy fluid balance. Minerals are also needed for your muscles to work proprerly and for impulses to be carried over the nerve pathways. Certain minerals help form bones. Bones make up the structure of your body. With such important jobs, we need to be sure to eat foods rich in this important group of nutrients.

Minerals can be classified into two main groups, based on how much you need. You need all the minerals though, no matter whether you need just a little or a lot. Major minerals are those needed in amounts of more than 250 milligrams (mg) daily. Calcium, phosphorus and magnesium are in this group, along with three electrolytes - sodium, chloride and potassium. Trace minerals are those needed in very small or trace amounts of less than 20 mg daily. These include chromium, copper, fluoride, iodine, iron, manganese, molybdenum, selenium and zinc. This lesson will focus on the minerals required on the nutrition label. They include sodium, calcium and iron.


Sodium

Sodium is one of the most plentiful minerals in the body. Sodium is chiefly found in the fluids that circulate outside the cells, and only a small amount of it is inside the cells. We need to understand a little about the relationship between sodium and potassium to understand how sodium functions in our body, because they work as partners. Potassium, another mineral, is located mainly inside the cells. The interrelation between these minerals and their concentrations permits fluid to pass back and forth between the cells and the surrounding areas. This movement of fluids across cell membranes is called osmosis.

Sodium and potassium are important in keeping a normal balance of water between the cells and the fluids. A lowering in the sodium content of the fluids results in a transfer of water from the fluids into the cells. An increase in sodium causes a transfer of water from the cells into the fluids. All types of muscles including the heart muscle are influenced by sodium and potassium. Although potassium is important, it is not required to be listed on the nutrition label.

Sodium is needed for nerves and muscles to function as they should. Sodium helps maintain normal blood volume and blood pressure. It occurs naturally in many foods. Sodium is added during processing to foods to preserve or enhance flavorings. We need some sodium, but we need to be careful not to get too much sodium. Getting too much sodium increases our risk of high blood pressure. The higher the salt (sodium) intake, the higher the blood pressure. Keeping blood pressure in the normal range helps reduce the risk of coronary heart disease, stroke, congestive heart failure and kidney disease. A person might experience fluid retention or swelling with high intake of sodium. Decreasing salt intake is advised to reduce the risk of high blood pressure.

Sodium is required nutrient on the nutrition facts panel. The Dietary Guidelines 2010  recommends consuming less than 2,300 mg (1 teaspoon of salt) of sodium per day. Many Americans consume substantially more. . People with hypertension, diabetes, or chronic kidney disease, African-Americans and adults 51 years of age and older should aim to consume no more than 1,500 mg of sodium per day. Foods that are low in sodium are those containing less than 140 milligrams or 5 percent of the Daily Value (DV).

We get excess sodium in our diet from table salt, soy sauce and monosodium glutamate. Table salt is 40% sodium. The natural salt content of foods accounts for only about 10 percent of our total sodium intake. To keep sodium intake within a healthier level, avoid highly salted foods and remove the salt shaker from the table. About 5 percent to 10 percent of the total salt we eat comes from salt added at the table or while cooking. About 75 percent comes from processed food with added salt. Foods served by restaurants may also be high in sodium.

Read the labels on canned, frozen and instant foods. Many are high in sodium. Unprocessed, whole foods are lower in sodium - and higher in potassium- than processed foods. Don't use taste as a guide to how much sodium the food contains. Many foods high in sodium don't taste salty. For example, some cereals don't taste salty, yet cocktail peanuts do; however, those cereals may have more sodium in them than the peanuts. Salt has been added to the outside of the peanuts and our taste buds pick up on that. Read the labels to be sure!

A good guideline to follow is to choose and prepare foods with little salt while consuming potassium-rich foods such as fruits and vegetables. A potassium-rich diet blunts the effects of salt on blood pressure, may reduce the risk of developing kidney stones and may decrease bone loss with age. The recommended intake of potassium for adolescents and adults is 4,700 mg/day.

The government definitions for sodium on the nutrition label are:

Label Claim Definition - Per Standard Serving Size

Sodium Free: Less than 5 mg sodium
Very Low Sodium: 35 mg or less sodium
Low Sodium: 140 mg or less sodium
Reduced Sodium: At least 25 percent less sodium
Light in Sodium: 50 percent less sodium


To avoid too much sodium:
• Enjoy foods without added salt.
• Cook most foods with only small amounts of added salt.
• Add little or no salt to food at the table.
• Eat pickles, olives and other pickled foods less often.
• Cut back on eating salty or smoked meats such as lunch meats and franks, or select the lower-salt choices.
• Select food products prepared with less sodium.
• Read labels for sodium content. Look in the list of ingredients for words that would tell you if sodium is in that food: soda, sodium or the symbol for sodium, Na. Examples would be sodium bicarbonate for baking soda, monosodium glutamate, di-sodium phosphate and others.
• Eat plenty of fresh fruit and vegetables.

Calcium

Calcium content of food is required on the nutrition label. Calcium has many important uses in the body. It is an important mineral in building bones and teeth. High dietary intake of calcium at maturity helps keep bones strong by slowing the rate of bone loss that can occur with aging. If you get a cut that bleeds, the clotting that occurs is due to calcium. Calcium is important for maintaining regular heartbeat. It is also necessary for muscle contraction as well as maintaining healthy cell membranes. As you can see, calcium is a very important mineral, yet many of us don't get the amount of calcium that we need.

Calcium is found in three classes of food - milk and milk products, green vegetables and a few fish and shellfish. Calcium absorption is enhanced by vitamin D, phosphorus and lactose in milk. A high protein diet leads to increased losses of calcium. When we increase our fiber intake, we need to increase our calcium intake also since fiber decreases the absorption of calcium. We need the fiber, though, for its beneficial effects.

There are tools that can help us determine if we get the amount of calcium we need. One is the USDA Food Guide and the other is the nutrition facts panel on food labels. If we get the recommended number of servings of each of the basic food groups in the USDA Food Guide, we will get enough calcium. The Dietary Guidelines for Americans 2010 encourages consuming 3 cups of fat-free or low-fat milk or equivalent milk products each day to get the proper of amount of calcium. On the nutrition facts panel, the daily reference value for calcium is one gram. The lesson on milk provides more information on calcium.

Iron

Iron is necessary for the making new cells, amino acids, and hormones. It is also required for proper functioning of the nerve cells. Most of the iron in the body is a part of hemoglobin which is in the red blood cells. Hemoglobin in the red blood cells carries oxygen in to all the cells. The red blood cells act as a shuttle service, traveling back and forth between the lungs and the muscles and other parts of the body to carry and maintain a fresh supply of oxygen. Iron helps to use energy and prevents iron deficiency anemia. Iron increases resistance to infection. About 80% of the iron is found in the blood. Smaller amounts of iron are found in the muscle bound to myoglobin.

Since most of the iron in the body is found in the blood, whenever you lose blood, you lose iron. Be sure to eat iron-rich foods and eat other foods with them to help increase the absorption of iron. If iron stores in the body are low and used up, the body cannot make enough hemoglobin to fill its new red blood cells. Without enough hemoglobin, the red blood cells are small and are lighter red than normal. Since hemoglobin is the bright red pigment of the blood, the skin of a fair person who is anemic may become pale. These smaller cells can't carry enough oxygen from the lungs to the tissues, so energy release in the muscle cells is impaired or doesn't function as it should. This affects every cell in your body. You could then feel tired, weak, have headaches and be apathetic. You also could have lower resistance to colds and infections. Your body isn't able to regulate your body temperature as well. You may feel cold. Children with low intakes of iron become irritable and restless. Some people who are iron-deficient crave ice, clay or other unusual substances. Iron-deficiency results from eating foods that are not high in iron, or it can result from blood loss, or from parasitic infections of the gastro-intestinal tract resulting in intestinal blood loss.

Sources of Iron
The meat group is the best source of iron in the USDA Food Guide. Meat, fish, poultry and legumes are good sources. Vegetables, especially dark greens, are good sources of iron. Foods in the milk group are poor iron sources.

Grain foods are good sources of iron. Iron is one of the nutrients replaced in processed foods during enrichment therefore elect whole-grain or enriched breads and cereals. About 25% of all the iron consumed in the United States comes from foods to which iron has been added, including enriched breads and cereals and fortified breakfast cereals. Although a single serving contributes little iron, these food sources become significant sources of iron because we eat several servings each day.

Types of Iron
Iron occurs in two forms in foods. One is heme iron, which is the type found in iron-carrying proteins hemoglobin and myoglobin in meats, poultry and fish. The other form of iron is called nonheme iron. Normally, about 10% of the iron in food is actually absorbed by our body.

Heme iron provides about one to two milligrams of the 10 to 20 milligrams of iron the average person consumes in a day. Most of the dietary iron is nonheme iron. About one-fourth of the iron in heme iron is absorbed, but nonheme iron's absorption is affected by many factors. By thinking about these factors and planning accordingly, you can double or triple the amount of iron your body actually gets from foods. Small amounts of meat, fish, poultry or vitamin C help you better absorb the iron from other foods. To absorb the most iron, use one or both of these enhancing factors at every meal. The more vitamin C-rich foods consumed, the better. Coffee and tea inhibit iron absorption. Orange juice enhances iron absorption because of the high vitamin C content.

The Nutrition Label

Iron is one of the three minerals required to be on nutrition labels. Calcium and sodium are the other minerals. The nutrients listed on the nutrition labels reflect a focus on nutrients of public health concern that may help reduce the risk for certain diseases, instead of those that prevent vitamin and mineral deficiencies. The % Daily Value shows how the amount of iron in a serving of that particular food compares to 18 milligrams, the Daily Value for iron for the nutrition panel on the label.

Summary

Minerals are a very important group of nutrients for us to consume daily. Eating according to the USDA MyPlate assures that we get the kinds and amounts of minerals we need for the day. Be sure to read the nutrition facts panel on the food labels. Make a concentrated effort to include healthy amounts of sodium, calcium and iron in our diets daily. Include a vitamin C food or a small amount of meat, poultry or fish with a non-heme source of iron to help our body better absorb the iron.

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