In This Chapter
Your body needs minerals in various amounts for good health. Some minerals help regulate fluid balance, strengthen bones, aid in muscle movement, and communication between cells. Your body can also store some minerals, too, unlike water-soluble vitamins.
In this chapter, we’ll take a look at the role of minerals and how your body uses them along with how much you need every day. You’ll learn what happens when you don’t get a sufficient amount of the required minerals and the effects on your body. You’ll also discover the best food sources for them.
Minerals are inorganic elements, meaning they do not contain carbon and occur naturally in soil and water. Plants absorb minerals through their roots, and you obtain the minerals when you eat the plant or the animal that consumed the plant. Minerals are very stable compounds and water-soluble. They’re not adversely affected by stomach acid, heat, exposure to oxygen, or ultraviolet light.
Minerals are divided into two groups: major minerals and trace minerals. The major minerals are those required in amounts more than 100mg per day, and trace minerals are required in amounts less than 20mg per day. Calcium is an example of a major mineral and iron is a trace mineral. In this chapter, we’ll take a detailed look at the many ways your body uses these minerals.
How Minerals Are Broken Down in the Body
Minerals are charged molecules and are unable to travel freely through the digestive tract without the aid of a protein molecule carrier so they can be absorbed. Minerals also compete with one another in the GI tract. If you overload your system with an abundance of calcium, it may use all the available protein carriers in the GI tract and prevent other minerals from being absorbed in the correct proportions.
Vitamins can also impact mineral absorption. Vitamin C enhances iron absorption from plant food sources. Vitamin D increases the absorption of calcium, phosphorus, and magnesium. Your body has the ability to increase or decrease the absorption rates of minerals based on how much of a particular mineral it has stored away. For example, if you need more calcium, your body will absorb more from the food you eat. If the body’s stores of calcium are high, it will absorb less calcium from a meal and utilize what is stored.
There are also some compounds that block the absorption of minerals. For example, oxalates are found in some vegetables such as spinach, and they prevent calcium from being absorbed by the body. Other examples include the polyphenols in tea and phytates in grains.
The major minerals are calcium, magnesium, sodium, phosphorus, sulfate, potassium, sodium, and chloride. The primary role of these minerals in the body is to build bones and blood cells, support immune health, maintain fluid balance, and activate enzymes.
Some minerals are referred to as electrolytes, which aid in the maintenance of your body’s fluid balance inside and outside of the cells. Electrolytes are positively and negatively charged molecules. Protein is also involved in the body’s fluid balance, as discussed in Chapter 7.
Water follows electrolytes by moving to wherever there’s a higher electrolyte concentration. Sodium and chloride are on the outside of the cell and other electrolytes reside on the inside of the cell. A cell only allows certain molecules to pass freely across its membrane, and water is one of these molecules. If there’s an elevated amount of sodium outside the cell than electrolytes inside the cell, water will pass freely to the outside of the cell to equalize the concentration inside and outside the cell. The ratio of solids to liquids is therefore changed. This process is called osmosis.
Let’s take a look at each mineral and its role in your body.
Calcium is the most abundant mineral in the body, with 99 percent located in the bones and teeth. We know calcium is needed for strong bones, but it’s also involved in muscle movement, neurotransmissions to help the cells communicate, and the movement of blood throughout the body. Additionally, it works with a variety of hormones and enzymes. Most people fall short when it comes to an adequate intake (AI) of calcium. Postmenopausal women, people with lactose intolerance, and vegans are at a higher risk for calcium deficiency.
Calcium intake is critical during periods of peak bone mass formation. From birth to age 20 is the first phase, in which about 90 percent of bone mass is acquired. Bone mass can continue to grow until age 30. The calcium laid down during these periods will affect your bone density rate as you age. After age 30, bone density begins a steady decline and a low intake of calcium early on can lead to osteomalacia and osteoporosis.
Calcium in too high amounts can interfere with the absorption of other minerals such as iron and zinc. It will also cause constipation. In some adults, it can increase the formation of kidney stones. The upper limit for calcium for adults age 19 to 50 is 2,500mg per day and for adults 51 and older 2,000mg per day.
The best sources of calcium in the diet are found in dairy products. However, broccoli, kale, cabbage, fish with soft bones (sardines), and fortified products like breakfast cereals, dairy alternatives, and tofu can also provide calcium.
Phosphorus is the second most abundant mineral in the body with the majority stored in bones and teeth. The role of phosphorus in the body is to act as a buffer in regulating acid-base balance and aid in energy metabolism and cell communication. It’s also part of DNA, RNA, and the structure of some lipids.
The RDA for phosphorus for adults is 700mg per day. Deficiencies of phosphorus would be a rare occurrence as it’s found in most food sources, with liver and dairy being the highest.
The tolerable UL of phosphorus for adults is 4,000mg per day. However, hyperphosphatemia is more commonly seen in those with abnormal kidney function.
When considering food sources of phosphorus, it’s important to note that only about 50 percent of phosphorus in beans, peas, cereals, and nuts are absorbable due to phosphorus being bound by phytates. Eggs, milk, salmon, beef, turkey, and chicken are all excellent sources.
Research has shown that an increase in blood phosphorus levels can be an indicator for high levels of calcification in the coronary arteries.
Sulfate helps form the shapes of proteins, especially in hair, nails, and skin. Sulfate is the only mineral that does not have an RDA. The reasoning behind this is that sulfate can be found in a variety of foods and animal proteins. Additionally, sulfate is provided in the body by the amino acids methionine and cysteine.
Therefore, a sulfate deficiency is unlikely to occur unless there was an insufficient protein intake in the diet. Toxicity is also unlikely to occur. Sulfate is present in all protein-containing foods like eggs, meats, fish, poultry, legumes, and nuts.
Potassium aids in the maintenance of acid-base balance, electrical activity of the heart, building proteins, and carbohydrate metabolism. Potassium is a positively charged ion. Potassium can decrease calcium excretion when the body needs more calcium present. When the body has too much circulating potassium, it’s excreted in urine. The hormone aldosterone regulates this mechanism.
The RDA for potassium for adults 19 and older is 4.7 grams per day.
A deficiency of potassium is called hypokalemia. It causes muscle weakness, abnormal heart rhythms, and increased blood pressure. Potassium can also be toxic in high levels, and this is called hyperkalemia. High levels of potassium could lead to a dangerous disruption of heart rhythms. Typical causes of hyperkalemia are kidney disease, medications, and infections.
A variety of foods contain potassium, including meats, fish, dairy, soy products, fruits, and vegetables.
Sodium is part of a molecule bound with chlorine that makes up table salt (sodium chloride). Sodium has many important functions, such as regulation of fluid balance, maintaining blood pressure, and aiding in nerve and muscle function.
The intake of sodium for Americans is quite high; the average U.S. daily intake ranges from 4 to 6 grams. The RDA for adults is 2,300mg or 1,500mg if you have hypertension. One teaspoon of salt contains about 2,300mg of sodium. However, most people don’t exceed sodium recommendations from the salt they add to foods when cooking. Excess sodium comes from processed foods and meals eaten away from home.
Sodium deficiency can lead to low sodium levels in the blood, known as hyponatremia, which can cause headaches, muscle weakness, spasms, or cramps, along with nausea and vomiting. It can also lead to seizures or even coma. Diseases such as kidney disease and congestive heart failure can also cause hyponatremia. Other causes include certain medications, alteration in hormone levels, and drinking too much water. Acute illnesses that cause excessive diarrhea and vomiting can lead to low sodium levels as well.
Hypernatremia is an excess of sodium in the blood, usually caused by a deficit of water in the body. It typically occurs in elderly individuals who are dependent on others for food and fluid needs. Intravenous feeding solutions or excessive fluid loss due to diarrhea and vomiting can lead to hypernatremia.
There’s no toxicity level associated with sodium. Sodium is naturally present in fruits and vegetables in very low amounts. An apple, for example, contains approximately 2mg of sodium.
Chloride helps regulate fluid balance and maintain blood pressure and pH balance in the body. It’s also part of stomach acid or gastric acid. The primary source of chloride is salt (sodium chloride).
There’s no RDA for chloride, but the AI for males and females age 14 to 50 is 2.3g per day. The AI for males and females age 51 to 70 is 2g per day.
Toxicity hasn’t been reported in humans. Chloride is excreted in urine, sweat, and feces. Food sources for chloride include table salt, sea salt, seaweed, rye, tomatoes, lettuce, and celery.
Magnesium is involved in maintaining bone health, and about 50 percent of the body's can be found in bone. The remaining magnesium is located in soft tissue cells where it assists with energy metabolism and a variety of other functions. Magnesium is a cofactor in hundreds of enzymes that aid in protein synthesis, glucose regulation, blood pressure regulation, and muscle and nerve functions. This mineral also participates in the active transport of calcium and potassium, which is involved in muscle contraction and blood clotting.
The RDA for magnesium for males age 19 to 30 years old is 400mg and for females 310mg. Deficiency is rare and is typically related to chronic conditions like alcoholism.
Magnesium toxicity from food sources is not possible due to the tight regulation of magnesium levels in the body by the kidneys. The tolerable UL for adults from nonfood sources is 350mg per day. However, supplementation of greater than 5,000mg per day can lead to nausea, cramping, and diarrhea.
Good sources of magnesium can be found in fibrous foods such as legumes, nuts, seeds, and whole grains. It’s also found in vegetables and fruits like spinach, edamame, avocados, and bananas. Animal proteins and fish also contain magnesium.
Trace minerals include iron, iodine, chromium, molybdenum, copper, zinc, fluoride, selenium, and manganese. Your body requires these minerals in small amounts for optimal health. They’re involved in many different functions, such as aiding in hormone production, bone strength, and heartbeat regulation. Your body must obtain these from your diet because it’s unable to make minerals. However, it can recycle, reuse, and store some of them in your body, which is why only small amounts are required.
Iron provides many functions in your body. It’s a necessary component for growth, normal cell function, and hormone and connective tissue development. It’s also a key element of myoglobin and hemoglobin, which is an oxygen-carrying protein molecule found in your blood cells.
Most of the iron in your body is found in hemoglobin, with the remaining being stored in the liver, bone marrow, spleen, or muscle tissue as a part of myoglobin. Iron is stored in the form of ferritin or hemosiderin. Iron is not usually excreted through urine or feces; however, if it needs to be, it can be excreted in small amounts.
The RDA for iron for males age 19 to 50 is 8mg for males and for females 18mg. See the table at the end of this chapter for more detailed information.
Iron deficiency can be determined by a simple lab test that measures iron levels in your blood. Hemoglobin levels less than 13g/dL in men and 12g/dL in women are labeled as iron-deficiency anemia (IDA). Anemia causes symptoms of fatigue and exhaustion because without sufficient iron stores your blood can’t carry enough oxygen.
Some people, like vegans who only consume plant-based foods, are at a greater risk of becoming iron deficient. This occurs because the more absorbable form of iron is called heme, which is found in animal-based foods like meat, poultry, and seafood. Plant-based foods contain nonheme iron, which is not as readily absorbed by the body. Other people at risk include pregnant women, infants and children, frequent blood donors, people with cancer, and those with GI disease or heart failure.
Iron toxicity can occur. The UL for iron for adults age 19 and older is 45mg per day.
The best sources of heme iron include lean meats such as beef, pork, chicken, and seafood. Nonheme iron can be found in nuts, vegetables, beans, and fortified grains such as cereals. Cereals or grains fortified with iron contain the most iron, with about 18mg per serving.
Zinc is found in your body’s cells. Its primary responsibility is to support your immune system, but it’s also involved in cell growth and division, wound healing, taste, and smell. Zinc is a key nutrient in pregnancy and early childhood because of rapid growth and development.
The RDA for zinc for males is 11mg and for females 8mg. See the table at the end of the chapter for more detailed information.
A zinc deficiency is rare in the United States. However, it can cause stunted growth and sexual development in children and adolescents. It also causes slow wound healing, hair loss, loss of appetite, and decreased ability to taste.
The UL for zinc for adults is 40mg. Zinc taken in high amounts can be toxic and cause headaches, nausea, vomiting, and diarrhea. It may also lead to low copper levels and decreased HDL levels.
Zinc can be found in foods that contain high amounts of protein such as beef, pork, and lamb, which all contain more zinc than fish. However, seafood such as oysters contains 73mg per serving, which is five times greater than the daily requirements. Other sources include whole grains, legumes, and nuts.
Fluoride is found in teeth and bones. Its primary role is mineralization of bones and teeth, which makes them stronger and protects them from decay.
There is no RDA for fluoride, but the AI for males is 3.8mg/day and for females 3.1mg/day. A deficiency of fluoride could cause dental problems such as cavities. A toxicity of fluoride is called fluorosis, which causes pitting and staining of teeth during tooth development and it cannot be reversed.
Fluoridated tap water is the best fluoride source in the diet. It has been shown to reduce childhood cavities by more than half. Toothpaste and mouthwash are also fortified with fluoride. Fluoride does occur naturally in some teas and seafood.
Iodine plays a key role in thyroid function and helps produce thyroid hormones. These hormones help regulate bone formation and brain development in the fetus. They’re also involved in a variety of other functions, including regulating body temperature and energy metabolism.
The RDA for iodine for adults is 150mcg. An iodine deficiency causes the thyroid gland to enlarge as it tries to collect more iodine resulting a visible protuberance in the neck called goiter. There are two types of deficiencies: a simple goiter caused from not enough iodine in the diet, and goiter caused from a deficiency or malfunction of the thyroid gland. During pregnancy, if the mother has an iodine deficiency, it will cause cretinism in the baby. Cretinism is a congenital disease that causes brain damage along with mental and physical retardation.
The UL for iodine for adults is 1,100mcg. Toxicity of iodine can also lead to goiters in adults and in a developing infant.
The best source for iodine is iodized table salt. In fact, salt is iodized to prevent goiters. Seafood such as cod, bass, perch, and haddock are high in naturally occurring iodine. Iodine can also be found in fruits and vegetables that are grown in iodine-rich soils. One fourth of a teaspoon of table salt contains 95mcg of iodine, whereas a 3-ounce serving of fish caught in the ocean contains 325mcg.
Chromium’s primary function is to enhance the action of insulin, which aids in glucose metabolism.
There’s no RDA for chromium, but the AI for males age 19 to 50 is 35mcg and for females 25mcg. A deficiency of chromium will cause diabetes-like symptoms and impaired glucose utilization. There’s no known toxicity for chromium.
Chromium is widely available in foods such as brewer’s yeast, beef, turkey, liver, whole grains, and some fruits and vegetables. Broccoli is the best source of chromium, with 11mcg in ½ cup.
Molybdenum acts as a catalyst for enzymes in the body. The RDA for molybdenum for adults is 45mcg per day. There are no known deficiencies or toxicities associated with molybdenum; however, the UL for adults is 2mg per day.
Food sources of molybdenum include legumes, nuts, whole grains, leafy greens, and liver.
Selenium is required to protect cells from oxidative damage. It’s also used in DNA synthesis, reproduction, and hormone metabolism. Selenium is stored in your body’s muscles.
Oxidative damage (stress) is an imbalance between the body’s ability to detoxify the harmful effects of free radicals and their rate of production. The body uses antioxidants to neutralize the free radicals and protect the cells.
The RDA for selenium for men is 134mg per day and for women 93mg. Selenium deficiency is rare in the United States; however, prior to the 1970s it led to Keshan disease and Keshan-Beck disease in China. Keshan disease damages the heart muscle and Keshan-Beck disease is a type of osteoarthritis that occurred in China, Tibet, and Siberia.
The UL for selenium is 400mcg per day. Toxicity called selenosis can occur, which can cause fatigue, skin rash, hair loss, nail loss or brittleness, garlic odor in the mouth, and a metallic taste.
The best food source of selenium is seafood. Other choices include whole grains, lean meats, poultry, and eggs. A 3-ounce portion of yellow fin tuna contains 92 mcg, which exceeds the daily requirement for this trace mineral.
Copper is found in a variety of cells and tissues in the body. Its primary function is to act as a coenzyme in all chemical reactions that involve oxygen.
The RDA for copper for adults is 900mcg per day. Copper toxicity can lead to liver damage, and the UL for adults is 10mg per day. A deficiency of copper is rare, but it can be the result of a genetic disease called Menkes. This disease doesn’t allow the release of absorbed copper into the body. Wilson’s disease is a genetic disorder that allows copper to accumulate in the liver and the brain.
Good food sources of copper are nuts, seeds, legumes, beans, whole grains, dark leafy greens, and shellfish.
Manganese functions as a coenzyme involved in the metabolism of energy nutrients and bone formation.
There is no RDA for manganese; however, the AI for men is 2.3mg per day and for women is 1.8mg per day. Deficiency or toxicity caused by food intake is rare. Toxicity would be more likely to occur from environmental factors, such as in miners who inhale manganese dust, which leads to brain damage and nervous system disorders.
Good sources of manganese include nuts, seeds, legumes, whole grains, leafy green vegetables, and tea. A ¼ cup serving of oats contains 1.92mcg of manganese, which is 96 percent of the daily requirement for adults.
Oatmeal is known for its health benefits. It’s not only a good source of fiber, but also an excellent source of manganese, molybdenum, phosphorus, and copper and a good source of magnesium, zinc, and chromium.
RDA/UL for Trace Minerals
Vitamin and Mineral Supplements
The 2010 Dietary Guidelines for Americans identifies calcium, vitamin D, fiber, and potassium as nutrients that are low in everyone’s diet. Ideally you should attempt to get your nutrients through food sources, but sometimes a supplement is necessary.
Taking your supplements with food is the best way to maximize the mineral or vitamin absorption.
What Makes a Supplement Good?
The Food and Drug Administration (FDA) regulates vitamin and mineral supplements. However, manufacturers are responsible for evaluating the safety of their products. This gives companies the ability to be dishonest, so ingredients on the labels don’t always match what is actually in the product. Also, manufacturers don’t have to prove that the product is pure and free of contaminants. Typically, a product is only removed from the shelves after many consumer complaints and a lawsuit has been brought against the company. Here are a few key things to consider when you shop for a multivitamin supplement:
Who Needs Supplements?
Some people are at greater risk of being low in particular vitamin and minerals. This may be due to age, certain diseases, pregnancy, or avoidance of certain food groups. Supplements are recommended for the following population groups:
According to the CDC, more than 50 percent of all U.S. adults take multivitamin supplements. The supplement industry is a multibillion-dollar business. The National Institutes of Health (NIH) reported that the amount made from vitamin and mineral supplement sales in 2012 was approximately $13.1 billion dollars, and it increases each year.
Vitamin and mineral supplements are available for children, women, men, women and men over 50, etc. There are high-energy, high-stress, and specialty supplements to improve cardiovascular health, too. Many multivitamin supplements exceed the RDAs for nutrient values. The pills also come in micro pills, capsules, enteric-coated pills, liquid gel capsules, time-release capsules, and chewable and liquid forms. It can be a daunting process to find a supplement.
The Least You Need to Know