Dietary Guidelines Part 4:
Copyright 2013 by Mark Walters
Tracker Book LLC
There are supposedly more than 40 different nutrients in the various kinds of food we eat, and each plays a specific role in maintaining important bodily functions. Of course we ought to strive to eat a plethora of healthy foods to ensure we consume as many of these nutrients as possible, but practically speaking, who has the time or dedication to keep track of more than 40 nutrients? Thankfully, the U.S. Department of Health and Human Services’ “2010 Dietary Guidelines for Americans” highlights some of the most important vitamins and minerals that individuals ought to put at the forefront of their diet and consume in sufficient amounts to ensure proper nutrition. These are designated as “nutrients of concern” and included in the dietary guidelines chapter 4, “Foods and Nutrients to Increase.”
These nutrients of concern consist of the minerals calcium, iron, and potassium; the vitamins B9 (folate), B12, and D; and dietary fiber, which, because it is not digested, is neither a vitamin nor a mineral but has a number of beneficial effects upon the body. In this article we will also discuss the importance of vitamins A and C because, even though these vitamins are not included under the nutrients of concern, they are listed prominently on the Nutrition Facts label and so warrant special attention.
In addition to the “2010 Dietary Guidelines for Americans,” this article also references the comprehensive and fact-filled “American Dietetic Association Complete Food and Nutrition Guide” by Roberta Larson Duyff (3rd edition, 2006).
Most Americans need to increase their consumption of dairy products, according to the dietary guidelines. One of the key reasons for consuming dairy products is the importance of calcium in the diet that provide nutrients to bones. Calcium, the most abundant mineral in the human body, also helps regulate the blood vessels and assists in nerve function and muscle contraction. It is especially important for children and adolescents to get adequate calcium intake, since most of one’s bone mass is completed by age 20. After about age 30, the intake of calcium is vital to help prevent or at least slow down any subsequent bone loss.
The dietary guidelines are concerned that Americans are not getting enough calcium in their diet, which could put individuals at risk for osteoporosis in their later years. According to the American Dietetic Association, only about 14% of girls and 36% of boys ages 12-19 consume adequate amounts of calcium. Insufficient calcium intake during these adolescent years may limit a young person’s growth so that he or she may not reach optimum height and could lead to brittle bone disease later in life.
The recommendation for youths ages 9-18 is to consume 1,300 mg of calcium a day; adults up to age 50 should get 1,000 mg a day; and older adults 51 years or older should boost consumption back up to 1,200 mg a day.
Beneficial sources of calcium include milk, yogurt, and cheese, as well as some dark-green leafy vegetables such as kale, broccoli, and bok choy. Additional sources can come from fish and any food that is fortified with calcium.
Iron’s important functions include working with hemoglobin to carry oxygen in the blood to all body cells, assisting in brain development, and supporting a healthy immune system. Children and adolescents especially need iron during periods of rapid growth, while women require it especially during childbearing years and during pregnancy. The dietary guidelines points out that many women are iron-deficient, which could result in anemia, fatigue, and infections. Iron is said to be the most common nutrient deficiency.
Iron can be obtained from both animal and plant foods. Iron from animal sources is called heme iron, and from plant sources is known as nonheme. Although both sources are beneficial, the heme iron is said to be more easily absorbed by the body than nonheme. Vegetarians are recommended to consume vitamin C alongside nonheme consumption at meals, as the vitamin is believed to assist in nonheme absorption. Beverages that have tannins, such as coffee and tea, however, may work to inhibit nonheme absorption, so it is suggested that individuals consume these beverages in between meals rather than during meals.
The Recommended Daily Allowance (RDA) of iron for males is: 11 mg for youths ages 14-18, and 8 mg for adults. The RDA of iron for females is: 15 mg for girls ages 14-18, and 18 mg for adults ages 19-50. Pregnant women should boost iron intake to 27 mg a day.
Excellent animal sources of iron include lean meat, poultry, and seafood; while good plant sources consist of white beans, lentils, spinach, and most breads and cereals.
Like sodium and chloride, potassium is known as an electrolyte because it helps regulate body fluids in and out of cells. But whereas the dietary guidelines recommends sodium as one nutrient to reduce in the diet, potassium is one that individuals ought to increase. Potassium can help reverse the effects of sodium, which Americans consume in far too high amounts. Potassium can also help reduce the risk of developing kidney stones and help slow bone loss.
The dietary guidelines recommends that adults boost their potassium intake to 4,700 mg a day, with breast-feeding women requiring 5,100 mg. Potassium can be found in many milk and milk products as well as in fruits and vegetables, including high amounts in bananas, broccoli, carrots, mushrooms, oranges, potatoes, prunes, raisins, spinach, baked or sweet potatoes, watermelon, winter squash, soybeans, tomatoes, and cooked dry beans.
Dietary fiber is classified as a carbohydrate, even though technically it cannot be broken down in the same way complex carbohydrates and sugars are. Because dietary fiber is not digested, it technically is not a nutrient but does provide essential benefits to health. Fiber promotes healthy laxation and is generally found in foods that are low-calorie and tend to be whole grains. Foods rich in fiber may also promote weight control because they tend to take longer to chew, in essence slowing down eating and providing a sense of fullness, according to the American Dietetic Association. Studies have also linked dietary fiber to a lower risk of cardiovascular disease, obesity, and type 2 diabetes.
Excellent sources of dietary fiber come from any foods in the beans and pea category, including lentils, navy beans, pinto beans, black beans, split peas, and bran. Other good sources include many fruits and vegetables, whole grains, and nuts. The dietary guidelines points out that many Americans eat insufficient amounts of dietary fiber and should boost their Adequate Intake (AI) level to 25 grams a day for women and 38 grams a day for men.
Vitamin D often works in consort with calcium and phosphorous, and this is one reason why many milk products are fortified with vitamin D. Vitamin D helps regulate how much calcium stays in the blood, regulates cell growth, helps deposit calcium and phosphorous in bones and teeth, and contributes to the body’s immune defenses.
The dietary guidelines points out that many individuals, especially teenagers and adult women, neglect the dairy category, which can have adverse health effects, including putting individuals at risk for bone fractures and osteoporosis later in life. The RDA for vitamin D is 15 micrograms (mcg) for youths and most adults, and 20 mcg for adults 70 years of age or older. Visually speaking, this is approximately 3 cups a day of milk or the equivalent of any milk product. Children ages 2-8 should consume about 2 cups a day.
Vitamin D is somewhat unique because the human body can manufacture some on its own from sun exposure. With about 10-15 minutes of sunlight exposure, the body uses the ultraviolet light to make its own vitamin D. (The guidelines caution, however, that individuals should not overexpose themselves to sunlight and should remember to use sunscreen most of the time when outdoors.) Good food sources of vitamin D include fluid milk, some yogurts, certain kinds of fish such as salmon and tuna, egg yolks, breakfast cereals, and of course, any food fortified with vitamin D.
Vitamin B9 (Folate or Folic Acid)
Vitamin B9, known commonly as folate, is a vitamin that works with vitamin B12 to make hemoglobin in red blood cells. It plays a vital role in helping manufacture DNA and RNA. In addition, folate has been linked to a lower risk of cardiovascular disease. Folate is especially important for women who are pregnant or who may become pregnant, as it lowers the chances of spina bifida and other neural tube defects in the developing fetus. Women who are capable of becoming pregnant are advised to consume 400 mcg of synthetic folic acid a day from supplements and fortified foods in addition to natural foods. Women who are pregnant should boost their intake to 600 mcg a day.
Beneficial sources of folate include beans and peas, oranges and orange juice, dark-green leafy vegetables such as spinach and broccoli, lentils, peanuts, avocados, and some breakfast cereals.
Vitamin B12 works in tandem with folate to produce red blood cells. It also helps the body use fatty acids and some amino acids. Two demographics in particular are urged to keep a close eye on their B12 levels: adults 50 years of age and older and those who consume a strictly vegan diet. Those with insufficient vitamin B12 intake can suffer from anemia, fatigue, nerve damage, and sensitive skin.
Vitamin B12 is found strictly in animal foods including meat, fish, poultry, eggs, milk, and other dairy foods.
Although vitamin A is not one of the dietary guidelines’ nutrients of concern, it is listed prominently on the Nutrition Facts label, so let us take a look at its importance. Vitamin A performs a number of useful functions for the body: it assists in the growth of cells and tissues; it is linked to good vision, especially at night; it protects the body from infections; it helps regulate the immune system; it is an antioxidant that may reduce the chance of certain cancers; and it is beneficial for the development of the embryo.
Vitamin A can come from either plant sources, in the form of carotenoids, or from animal sources, in the form of retinol. Good sources of vitamin A include vegetables of the yellow, orange, and dark-green variety, as well as fish oil, eggs, and milk that has been fortified with the vitamin.
Vitamin C (Ascorbic Acid)
Like vitamin A, vitamin C is not a “nutrient of concern” but it is listed at the top of the Nutrition Facts label, and therefore warrants special attention. Vitamin C helps the body perform a multitude of actions: it helps make collagen, which holds together muscles, bones, and other tissues; it assists the body in absorbing iron and folate; it works to keep gums healthy; it helps heal cuts and wounds; it is an antioxidant that counteracts damage to cells; and it helps give firmness to capillary walls and blood vessels.
Since vitamin C is a water-soluble vitamin, it is not stored in excess amounts in the body, so daily replenishment is required. Adult males are recommended to consume 90 mg and adult females 75 mg of vitamin C a day.
Nutrient-rich sources of vitamin C include all types of citrus fruits, peppers, dark green leafy vegetables, potatoes, broccoli, cabbage, and tomatoes.
Food vs. Supplement Sources
The dietary guidelines make clear that individuals should strive to consume all vitamins and minerals from natural food sources whenever possible rather than from supplements. Obtaining these vital substances from nutrient-dense food sources means one also receives other important nutritional benefits, such as the intake of dietary fiber and carbohydrates. In addition, if people look to supplements to get their dietary requirement of vitamins and minerals, it may be a sign that they are consuming foods with too many empty calories, such as those from added sugars and solid fats that have little nutritional value. For many vitamins and minerals, consuming excess amounts from supplements may have detrimental health effects. There may be certain populations of people that could benefit from taking supplements, and these individuals should consult their doctor.
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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