Dietary Guidelines Part 6:
Copyright 2013 by Mark Walters
Tracker Book LLC
Nutrition can be such an in-depth and involved science, and unless one is studying to become a dietitian, it can be all too easy to get buried under the weight of food groups, macronutrients, and micronutrients to keep track of. The good news is that as long as one keeps to the general recommendations outlined by the dietary guidelines--that is, monitoring carbohydrates, proteins, and fats and boosting intake of fruits, vegetables, and whole grains--then it should follow that one receives adequate intake of the myriad vitamins and minerals. Still, it can be advantageous to have a basic knowledge of vitamins and minerals, of their specific role in keeping the body in optimal health and which foods are good sources of these nutrients. It is perhaps a marvel of science that we can isolate the more than 40 vitamins and minerals in foods and furthermore that we can determine their specific functions within the body.
I first set out to learn the basics and fundamentals of good nutrition so that I could make immediate and beneficial changes to my diet, but I quickly became more interested in learning more about the specific nutrients and their unique roles in good health. I researched the “2010 Dietary Guidelines for Americans” as well as the “American Dietetic Association Complete Food and Nutrition Guide” by Roberta Larson Duyff (3rd edition, 2006) for information in this series of articles summarizing the basics, and some of the specifics, of nutrition.
This article will discuss some of the micronutrients essential for human health, their functions within the body and which foods are good sources of these nutrients. Note that some of the most vital vitamins and minerals are discussed elsewhere in my “Dietary Guidelines” series and are therefore not mentioned here. These nutrients are designated “nutrients of concern” because of their above-and-beyond importance for good health, ones that individuals ought to pay special attention to and ensure adequate intake. Vitamins A, B9, B12, C, and D and the minerals calcium, potassium, and iron are discussed in the article, “Dietary Guidelines: Nutrients of Concern,” while sodium is discussed in the article, “Dietary Guidelines: “Food Components to Reduce.”
Let’s quickly review some nutritional terms before we look closely at some specific vitamins and minerals. The term macronutrient—carbohydrates, proteins, and fats—refers to nutrients that the body needs in relatively larger quantities. Micronutrients are still considered vital for body functions but are required in lesser amounts. Micronutrients can be vitamins or minerals. Vitamins are organic substances that regulate body processes, either on their own or in tandem with enzymes. They are classified as either fat-soluble (stored in the body) or water-soluble (not stored in the body and must be constantly replaced). Minerals are inorganic substances that, even though they make up just about 4% of one’s body, are essential for giving structure to the body, regulating fluids, and helping to facilitate nerve impulses and muscle contractions. Major minerals are those required in amounts of 250 mg or more daily, while trace minerals are needed in amounts less than 20 mg daily. The major minerals are calcium, phosphorous, and magnesium, as well as the electrolytes sodium, potassium, and chloride. Trace minerals include chromium, copper, fluoride, iodine, iron, manganese, molybdenum, selenium, and zinc.
Food vs. Supplement Sources
The dietary guidelines recommends that individuals consume vitamins and minerals from food sources whenever possible, rather than from supplements or pills. There are a number of key reasons for this. First, when people obtain their nutrients from fruits and vegetables and other food sources, they receive additional beneficial substances such as dietary fiber, carbohydrates, and proteins. Second, if one is tempted to turn to supplements to obtain daily vitamins and minerals, it may be a sign that the person is consuming too many nutrient-poor foods such as those with added sugars or saturated fats. Third, taking supplements may lead to an overconsumption of vitamins and minerals, which could have a detrimental, not beneficial, effect on the body. This is especially true for vitamins A, B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B9 (folate), C, and D.
Vitamin B (thiamin) helps the body obtain energy from carbohydrates. Because it is found in all grain products, deficiency is rare, but it could be a factor for people who suffer from alcoholism, who may experience fatigue, weak muscles, and damage to the nerves. Vitamin B is water-soluble, so the body excretes excess amounts. Males are advised to obtain 1.2 mg and females 1.1 mg of vitamin B daily.
Vitamin B2 (Riboflavin) also assists the body in producing energy at the cellular level. It works to convert tryptophan, an amino acid, into niacin. Good sources of vitamin B2 include milk and dairy products, grains, eggs, meat, and green leafy vegetables. Deficiency of vitamin B2 is unlikely, but symptoms include cataracts and other eye disorders as well as dry, flaky skin. Males are advised to consume 1.3 mg and females 1.1 mg a day.
Vitamin B3 (Niacin) is another vitamin that helps the body produce energy by using sugars and fatty acids. It also promotes normal enzyme function. As long as one consumes adequate amounts of protein, niacin deficiency is unlikely, but symptoms include skin problems, mental disorientation, and diarrhea. Good sources of niacin include any food that is high in protein, such as fish, poultry, beef, peanut butter, and legumes, as well as grain products. The recommendation is 16 mg a day for men and 14 mg for women.
Vitamin B5 (Pantothenic Acid), another member of the B-vitamin family, helps the body make energy at the cellular level by metabolizing proteins, fats, and carbohydrates so cells can produce energy. Vitamin B5 deficiency is rare because the vitamin is found in a wide range of foods, including meat, poultry, and fish, as well as whole-grain cereals and legumes. Smaller amounts are even found in milk, vegetables, and fruit.
Vitamin B6 (Pyridoxine), like vitamin B2, is important for its work with the amino acid tryptophan, as well as nonessential amino acids, or protein components. Vitamin B6 also assists in making other body chemicals such as hemoglobin, insulin, and antibodies that counteract infections. Good sources of vitamin B6 include chicken and fish, as well as smaller amounts in whole grains, nuts, and legumes. The recommended daily allowance (RDA) is 1.3 mg for all adults.
Vitamin B7 (Biotin), like vitamin B5, helps metabolize proteins, fats, and carbohydrates. It is rare for one to be deficient in biotin, but symptoms include appetite loss, fatigue, depression, dry skin, and heart abnormalities. The adequate intake (AI) level for biotin is 30 mcg (micrograms) for adults and 35 mcg for women who are breastfeeding. A variety of foods contain biotin, including eggs, yeast breads, and cereals.
Vitamin E provides beneficial antioxidant properties, which could work to limit the risk of cancer. Vitamin E is also valuable in limiting LDL cholesterol, which could cut the risk of heart disease and stroke. Although many Americans consume enough vitamin E, it is still something to watch out for. The RDA for vitamin E is 15 mg, which can be obtained from vegetable oils, such as soybean and safflower oil, as well as nuts, seeds, and some breakfast cereals.
Vitamin K is valuable in helping the body make a range of proteins that are good for the blood, bones, and kidneys. The adequate intake (AI) of vitamin K is set at 120 mcg for men, and 90 mcg for women. Good sources of vitamin K include green, leafy vegetables such as broccoli and spinach, while smaller amounts can be found in fruits, other vegetables, and nuts.
Choline is a vitamin-like substance usually included in the B-vitamin family. It helps neurotransmitters with a wide-range of functions, including muscle control and storing memories. It also aids in liver function and reproductive health, as well as in the transport of fats. Adult males are advised to obtain 550 mg and adult females 425 mg a day. Good sources of choline include meat, eggs, soybeans, and peanuts, but it can be found in a wide range of foods.
Phosphorous is a major mineral that is second only to calcium as a major constituent of bones and teeth. Its other vital roles include helping regulate energy metabolism, producing energy in all cells, and making up DNA and RNA, which help the body grow and repair cells. Phosphorous is found in many foods that are high in protein, including meat, poultry, fish, eggs, and milk, as well as legumes and nuts. The RDA for children ages 9-18 is 1,250 mg, and for adults it is 700 mg.
Magnesium, another major mineral, is a vital component that assists more than 300 enzymes, which work with important cell functions such as muscle and nerve functions. Although magnesium is found in all kinds of foods, the best sources are legumes, nuts, and whole grains. The RDA for males is 400 mg up to age 30, then increasing to 420 mg after age 30. For females, the RDA is 310 mg for individuals up to age 30, then increasing to 320 mg for persons 30 years and older.
Calcium, the other major mineral, is discussed in another article in this series, “Dietary Guidelines: Nutrients of Concern.”
Chloride, like potassium and sodium, is an electrolyte that helps regulate fluids in and out of cells. Chloride is found in stomach acid, and so helps digest food and absorb nutrients. It also helps in the transmission of nerve impulses. Chloride is found in salty foods, and because salt is so prevalent in the American diet, deficiency is unlikely, but excess amounts may lead to high blood pressure. Potassium and sodium are two other important electrolytes but are discussed elsewhere in this nutrition series; potassium is mentioned in the article, “Dietary Guidelines: Nutrients of Concern,” while sodium is discussed in the article, “Dietary Guidelines: Food Components to Reduce.”
Chromium is a trace mineral that works in tandem with insulin to help the body use glucose, or blood sugar. Good sources of chromium include meat, eggs, cheese, and whole grains. For males, the AI is 35 mcg for those ages 14-50, and 30 mcg for those over 51. For females, the AI is 24 mcg for those ages 14-18; 25 mcg for those ages 19-50; and 20 mcg for those 51 and older. Women who are pregnant are advised to consume an additional 5 mcg, and those breastfeeding are recommended to consume an additional 20 mcg.
Copper provides a number of key functions for the body, including working with enzymes, making hemoglobin, producing myelin and other connective tissues, and making energy at the cellular level. Good sources of copper include seafood, nuts, and seeds. Cooking with a copper pot will also add copper to your diet. The RDA for youths ages 14-18 is 890 mcg, and for adults it is 900 mcg. Women who are pregnant should get 1,000 mcg, and those who are breastfeeding are advised to boost their intake to 1,300 mcg.
Fluoride works to make tooth enamel harder and protect against tooth decay. It may also combat osteoporosis by helping to strengthen bones. Since fluoride is not widely available in foods, it is added to most municipal water supplies. In addition, tea made with fluoridated water can offer additional fluoride, as well as salmon and other fish.
Iodine works with thyroxin and other thyroid hormones to regulate the body’s use of energy. It is found naturally in saltwater fish and also added to most salts. A one-half teaspoon of salt supplies almost a day’s total iodine requirement. Those who do not get enough iodine may suffer from goiter.
Iron is discussed in another article in this series, “Dietary Guidelines: Nutrients of Concern.”
Manganese helps the body form bones, metabolize energy from macronutrients, and work with many enzymes. Because this trace mineral is found in a wide range of foods, deficiency is quite rare. Good sources of manganese include whole-grain foods, as well as some fruits and vegetables, and tea.
Molybdenum is another trace mineral that works in conjunction with many body enzymes. It also works in tandem with riboflavin to make hemoglobin from stored iron. Those who consume an adequate diet will naturally consume enough molybdenum, but especially good sources include milk, legumes, and grain products.
Selenium is an antioxidant that works in conjunction with vitamin E to protect cells from damage, and so may help limit the risk of heart disease and some cancers. Good sources of selenium include seafood, some meats, grain products, and seeds. Individuals ages 14 and over are advised to consume 55 mcg per day, while women who are breastfeeding should get 70 mcg.
Zinc has been linked to helping more than 200 enzymes and also helps the body with cell reproduction and tissue repair. Proper zinc intake is vital for body growth. Good sources of zinc include meat, seafood, eggs, and milk. Smaller quantities can be obtained from whole grains. The RDA for males ages 14 and over is 11 mg; for females ages 14-18 the RDA is 9 mg; and for adult females it is 7 mg. Females who are pregnant are advised to consume 11 mg, and those who are breastfeeding should consume 12 mg. Teenagers who are pregnant or breastfeeding should boost their amounts by an additional 2 mg.
U.S. Department of Agriculture and U.S. Department of Health and Human Services. "Dietary Guidelines for Americans, 2010." 7th Edition, Washington, DC: U.S. Government Printing Office, 2010. PDF.
Duyff, Roberta Larson and American Dietetic Association. "American Dietetic Association Complete Food and Nutrition Guide." 6th Edition. Hoboken: Wiley & Sons, 2006.
The information presented in this newsletter is meant for general purposes only and is not meant to diagnose or treat any ailments. If you have a question about exercise or nutrition that pertains to your specific condition, please consult your physician before beginning an exercise program or changing your diet.
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