Iron across the life span
Among the essential vitamins and minerals, the variability in iron requirements between sexes and across the lifespan can be significant. The different RDAs of the Dietary Reference Intakes (DRIs) reflect the critical role of iron in oxygen transport, enzyme function, and growth and development.
Using the Interactive DRI for Health Professionals (http:/
| Sex | Age | Height | Weight | Activity Level | RDA Iron (mg) |
|---|---|---|---|---|---|
| Male | 9 | 4 feet 2 inches | 62 pounds | Low active | |
| Female (Not Pregnant or Lactating) | 9 | 4 feet | 62 pounds | Low active | |
| Male | 29 | 5 feet 10 inches | 165 pounds | Low active | |
| Female (Not Pregnant or Lactating) | 29 | 5 feet 7 inches | 135 pounds | Low active | |
| Female (Pregnant, 25 Weeks) | 29 | 5 feet 7 inches | 150 pounds | Low active | |
| Female (Lactating) | 29 | 5 feet 7 inches | 145 pounds | Low active | |
| Male | 59 | 5 feet 10 inches | 170 pounds | Low active | |
| Female (Not Pregnant or Lactating) | 59 | 5 feet 7 inches | 140 pounds | Low active |
After completing the chart with the RDA for iron for each of the individuals listed address the following questions.
1. Do the requirements for iron differ for boys and girls at age 9?
YES NO
2. Do the requirements for iron differ for men and women at age 29?
YES NO
What factors might influence the difference in iron needs?
How might iron requirements change if either the man or woman followed a vegan diet?
3. How do iron requirements for women aged 19 to 50 years change with pregnancy and lactation?
4. Why do you think the RDA for a woman at age 59 is actually lower than for a man of the same age?
5. Using the sample day’s intake below:
Identify two “good” sources of heme and non-
1. 2.
1. 2.
Underline the dietary components that might enhance the iron absorption and circle those that might inhibit iron absorption or bioavailability.
Sample Day’s Intake
BREAKFAST
1 cup whole-
1 cup low-
2 tablespoons raisins
1 cup coffee
LUNCH
2 ounces sliced turkey breast
1 ounce Swiss cheese
2 slices whole wheat bread
1 tablespoon mayonnaise
2 sliced tomatoes
1⁄2 cup baby carrots
SNACK
2 tablespoons peanut butter
4 graham cracker squares
1 apple
1 cup hot tea
DINNER
3 ounces lean beef steak, broiled
1 medium potato, baked
1 tablespoon sour cream
2 cups raw spinach with 2 tablespoons slivered almonds and 1⁄2 cup fresh orange segments
2 tablespoons salad dressing
1 ounce French bread
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Trace minerals are essential nutrients that are required in very small amounts in human nutrition. These include chromium, copper, fluoride, iodine, iron, manganese, molybdenum, selenium, and zinc.
Trace minerals have vital roles in the body such as acting as co-
Trace minerals are found in both plant and animal foods, but their actual bioavailability is influenced by many factors.
Trace mineral deficiencies can have varied, yet serious, consequences, particularly of concern in pregnant women and growing children.
Chromium may enhance the action of insulin in maintaining blood glucose levels.
Copper is a component of certain enzymes and has critical roles in the body including energy metabolism, iron transport and storage, and antioxidant function.
Fluoride is important for hardening tooth enamel and the prevention of dental caries.
Iodine is a component of thyroid hormones that helps regulate energy metabolism.
Iron is a component of many enzymes, as well as proteins, that transport oxygen in the body.
Heme iron is the predominant form of iron in the body and is found only in animal foods, while non-
Iron deficiency is the most prevalent nutritional disorder in the United States and globally. It is caused not only by insufficient intake, but also by blood loss or impaired absorption.
Selenium is a component of certain human proteins and functions as a co-
Zinc is present in many enzyme systems and regulatory proteins making it essential for all body processes.
Trace minerals are found across all food groups, thus sufficient intake can generally be achieved by consuming a varied and balanced diet.
Ultratrace minerals are not currently classified as essential nutrients, but may have important roles in the body. They include arsenic, boron, nickel, silicon, and vanadium.
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Review Questions
1. Trace minerals differ from major minerals in all of the following ways, EXCEPT:
their daily requirement is less than 100 milligrams.
their safe range of intake is more narrow.
they are found in smaller amounts in the body.
they are less essential in human health.
they include iodine and iron.
1. d
2. All of the following are general properties of trace minerals, EXCEPT:
they are found only in foods of animal origin.
many are co-
very little digestion is required.
they are absorbed primarily in the small intestine.
they circulate freely in the blood.
2. a
3. The majority of iodine intake in the United States comes from:
fruits and vegetables.
iodized salt.
milk and processed grains.
nuts and vegetable oils.
3. c
4. Which trace mineral is an essential component of thyroid hormones?
chromium
iodine
iron
selenium
zinc
4. b
5. According to the World Health Organization, the number one nutritional disorder worldwide is:
beriberi.
goiter.
iron deficiency anemia.
pellagra.
zinc deficiency.
5. c
6. In contrast to heme iron, non-
is found only in animal foods.
makes up the majority of iron we consume.
is better absorbed by the body.
is less influenced by dietary components that inhibit absorption.
is the most prominent form of iron in the body.
6. b
7. Of the trace minerals, only _______ cannot be excreted in the urine or bile.
chromium
copper
iodine
iron
zinc
7. d
8. Which trace mineral has been demonstrated to play a role in slowing progression of age-
chromium
copper
manganese
selenium
zinc
8. b
9. Which trace mineral is required for the function of perhaps more proteins in the body than any other mineral?
copper
chromium
iron
selenium
zinc
9. e
10. Which of the following is NOT an ultratrace mineral?
boron
manganese
nickel
silicon
vanadium
10. b
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Discovering the trace minerals in your meals
1. Log on to the United States Department of Agriculture (USDA) website at www.supertracker.usda.gov. If you have not done so already, you will need to create a profile to get a personalized diet plan. This profile will allow you to save your information and diet intake for future reference. Do not use the general plan.
2. Click the Track Food and Activity option.
3. Record your food and beverage intake for one day that most reflects your typical eating patterns. Enter each food and beverage you consumed into the food tracker. Note that there may not always be an exact match to the food or beverage that you consumed, so select the best match available.
4. Once you have entered all of your food and beverage choices into the food tracker, on the right side of the page under the bar graph, you will see Related Links: View by Meal and Nutrient Intake Report. Print these reports and use them to answer the following questions:
Did you meet the target recommendations for the trace minerals (iron, iodine, chromium, fluoride, copper, zinc, selenium, molybdenum, and manganese) for the day you selected? If not, what minerals fall below the target numbers?
For each trace mineral target that you missed, list two specific foods you could consume to increase your intake of that mineral.
Were you above the targets for any of the trace minerals? If so, which ones? Are any of these numbers above the toxicity level for that mineral?
Iron deficiency anemia is the number one nutritional deficiency in the United States. What groups are most at risk for this deficiency? If you developed iron deficiency anemia, what physical symptoms would you be likely to experience?