OPTIMIZING YOUR DIET

Best Foods for Specific Minerals

 

Major minerals are considered major because they are required by the body in doses of 100 mg/day or greater; i.e. greater than 0.01% of body weight. Calcium and phosphorous are the greatest in amounts in the body. Minor minerals are required by the body in amounts of less than 100 mg/day; i.e. less than 0.01% of body weight and are also called trace minerals or trace elements. Minerals, made of metals and other inorganic compounds, are as essential to bodily functions as vitamins. They form the structure of our bodies and help our systems work. Major minerals are: calcium, phosphorus, potassium, sodium, chloride, magnesium, and sulfur. Minor minerals are: chromium, cobalt, flouride, zinc, selenium, silicon, boron, iron, copper, iodine, manganese, molybdenum, nickel, arsenic and vanadium. For more information on some of the minerals not described on this page one good source is: http://lpi.oregonstate.edu/infocenter/minerals.html.

Electrolyte: A mineral salt that can conduct electricity when dissolved in water (e.g., sodium, potassium, chloride).

Most accessible food sources for students are in bold black font.

CALCIUM (A major mineral)

Calcium is the most common and abundant mineral in the body and is found primarily in the bones and teeth. A small but absolutely essential amount of calcium is found in the blood and soft tissue. As a result of homeostasis, the body will take calcium from the bones if there is not enough circulating in the blood and extracellular fluid. The skeleton is constantly being absorbed and remodeled. Bone is made from calcium and phosphate combined into one crystal called hydroxyapatite. Osteoporosis results from many factors some of which are inadequate calcium intake or absorption along with accompanying adequate vitamin D levels, hereditary factors, lack of bone stressors (exercise) throughout one's life, and hormone function.

Vitamin D is required for maximum calcium absorption. Calcium helps vitamin K function in blood clotting, functions in blood pressure regulation, and may be useful in lowering moderate hypertension, functions in many enzyme reactions inside and outside cells and is a cofactor for enzymes and proteins, functions in nerve impulse conduction, in neurotransmitter release, in hormone secretion, and in heart, smooth and skeletal muscle cell contraction. Calcium interracts with zinc, magnesium, vitamin D and vitamin K. Calcium limits the absorption of lead and exposure to lead stored in the skeleton which can be mobilized by demineralization.

Calcium is available in many foods. Most people think of dairy when they think of calcium. Though cheese is a good source of calcium it is high in saturated fat. Eat a varied diet to get the best calcium absorption. It is estimated that only 30% of dietary calcium is absorbed. Factors which inhibit calcium absorption and may contribute to calcium loss are: aluminum (foods cooked in aluminum cookware including the use of acidic foods with the cookware), aluminum foil, antacids containing aluminum and high levels of magnesium. Zinc, oxylates (a chemical that is found in sweet potatoes, dried beans, rhubarb and spinach), concentrated forms of phytic acid (such as found in wheat bran and dried beans)and dietary fiber inhibit calcium absorption. Alcohol, phosphates (in soft drinks and meats), sugar, and protein increase calcium excretion. High levels of sodium may also be linked to calcium excretion.

There is not enough research to state definitely how much effect caffeine has on calcium excretion but it may be very little. Athletes should focus on ingesting milk and other calcium healthy drinks rather than ingesting soft drinks and caffeinated beverages.

Increased levels of protein may also increase calcium excretion. **"An increase of 1.75 mg of calcium per day may be needed to offset calcium loss set forth by increased protein intake of 1 g each over the RDA of 46 grams of protein per day for adult women and 56 grams of protein per day for adult men." Most people in American society eat far more protein than the RDA.

During the peak bone development years, 9-17, it is reported that this age group drinks more soft drinks than milk, thereby limiting calcium intake and contributing to calcium excretion during their formative years. Pre-pubescent and adolescence are critical years in the formation of a strong skeleton. A strong skeleton can be developed through engaging in physical activity and a healthy diet which may prevent the development of or decrease the degree of osteoporosis in later years. Peak bone mass is achieved around the age of 30.

Food Sources

Kelp, cheddar cheese, sesame seeds, sardines with bones, bean curd, molasses, carob flour, milk, yogurt, cheese food, pinto beans, red beans, white beans, tofu, bok choy, kale, chinese cabbage, broccoli, spinach, rhubarb, fortified cereals, fortified fruit juices, dried figs, turnip greens, almonds, brewer's yeast, spring greens (such as dandelion leaves, salad mix), watercress, parsley, brazil nuts, cooked shrimp, sunflower seeds, ripe olives, walnuts, cottage cheese, canned salmon, cooked soybeans, pecans, wheat germ, miso paste, romaine lettuce, dried apricots, roasted peanuts, blackcurrants, cabbage, whole wheat bread, Boston baked beans, eggs, globe artichoke, pumpkin seeds, celery, cashews, barley, carrots, sweet potatoes, brown rice, and fish.

Examples:

Milk, 1 cup/8 oz. = 300 mg

Pinto beans, 1/2 cup, cooked = 45 mg

Broccoli, 1/2 cup, cooked = 35 mg

Rhubarb, 1/2 cup, cooked = 174 mg

AI (Adequate Intake)

Male and female adolescents 14-18 years of age = 1,300 mg/day

Male and female adults 19-50 years of age = 1,000 mg/day

UL (Upper Limit)

Everyone (except infants) = 2,500 mg/day

There are no reports of calcium toxicity resulting from food intake, only supplements.

Calcium citrate and calcium malate are types of calcium supplements that can be taken any time. Other calcium supplements must be take with food for maximum absorption. It is recommended that 500 mg or less be taken in supplemental (elemental) form at one time. It is best to get as much calcium as possible from food sources and use a supplement only if necessary. Supplements are not food substitutes. Calcium inhibits iron absorption from non-meat sources. Wait at least 2 hours before taking an iron supplement following a calcium supplement or vice versa for best iron absorption. Do not take any supplement without consultation with your medical provider.

 

IRON ( A trace mineral)

Iron is essential for metabolism, DNA synthesis, growth, healing, immune function, reproduction, as a cofactor in many enzyme reactions, preventing anemia, and is found in hemoglobin and myoglobin, proteins which transport oxygen through the blood and muscles (important for athletic performance). Hemoglobin acquires and transports oxygen from the lungs and releases it as blood courses through the tissues. Myoglobin also functions in transport and storage of oxygen in the working muscles. Cytochromes also contain iron and help with cellular energy metabolism. Nonheme iron containing enzymes also assist in energy metabolism.

There are two types of iron: heme and nonheme. Heme iron, found in animal products like meat, is easily absorbed while nonheme iron is found in plants and is less easily absorbed. Copper is needed for normal iron metabolism. Vitamin A assists with iron in elininating anemia. Zinc and iron taken together may limit the absorption of zinc. Calcium and iron combined in a meal may decrease the absorption of iron. Other products that inhibit absorption are: phosphates (sodas), polyphenols (red wine, purple grape juice, coffee, tea, spices, some fruits, some vegetables), wheat bran, phytates (phytic acids found in legumes, grains and rice can decrease absorption by 50%), tannins (teas, coffees), manganese, cobalt, copper, cadmium (in cigarette smoke), calcium, legume protein (soybeans, lentils, black beans, mung beans, and split peas), lignin (fibrous tissued vegetables) and soy protein. Nonheme iron is more affected by the above inhibitors than heme iron.

Nonheme iron helpers that increase absorption: Vitaminc C, citric (fruit), malic, tartaric (tart fruit and baking powder) and lactic acids, alcohol, fructose, sorbitol, meat, fish and poultry.

Food Sources

Kelp, curry powder, brewer's yeast, shellfish, fortified cereals, blackstrap molasses, pumpkin seeds, sesame seeds, sunflower seeds, parsley, almonds, canned sardines, dried apricots, prunes, cashews, tomato paste, artichokes, brazil nuts, beet greens, dandelion leaves, walnuts, whole wheat bread, semisweet chocolate, lentils, peanuts, eggs, bean curd, beef, great northern beans, corned beef, watercress, kidney beans, green peas, brown rice, ripe olives, Boston baked beans, broccoli, cauliflower, cabbage, red wine, white fish, wheat germ, soy flour, unsweetened cocoa powder, firm tofu, raisins, light tuna, oysters, dark meat of chicken, shrimp, and baked potato with skin.

Examples:

Oysters, 6 medium = 5.04 mg

Raisin bran, 1 cup = 5.0 mg

Baked potato with skin = 2.75 mg

Cashews, 1 oz. (about 13 nuts) = 1.70 mg

RDA

Male adolescents 14 - 18 years of age = 11 mg/day

Female adolescents 14 - 18 years of age = 15 mg/day

Male adults 19 - 50 years old = 8 mg/day

Female adults 19 - 50 years old = 18 mg/day

**Full vegetarian diet:

Female adolescents = 26 mg/day

Adult men and post menopausal women = 14 mg/day

Premenopausal women = 33 mg/day

UL (Not applied to individuals with close medical supervision)

Adolescents 14 - 18 years = 45 mg/day

Adults 19 years and older = 45 mg/day

Large doses of nonheme iron can cause constipation, diarrhea, nausea, vomiting, and gastrointestinal irritation. Nonheme iron supplements: ferrous fumarate, ferrous sulfate and ferric iron. Ferric iron will destroy vitamin E. Different types of iron supplements contain varying percentage levels of elemental iron. Though heme iron is best for absorption the best nonheme form is ferrous sulfate. Individuals who are more deficient in iron will absorb more than those who are not deficient. Individuals who are not at risk for iron deficiency should not take iron supplements. Typically those not at risk are adult men and postmenopausal women.

Iron overload may occur in individuals with hereditary hemochromatosis (an accumulation of iron in the liver and tissues) and hereditary anemias (several types of these). Accumulated excess iron can cause oxidative stress. Older individuals (over 65) more commonly have excess iron stores rather than iron deficiency.

Many medications such as, antacids, histamine receptor antagonists, proton pump inhibitor can interfere with iron absorption. Iron supplements may also interfere with the absorption of some medications. Toxicity to overdoses (**"20-60 mg/kg of body weight") of iron through supplements and food products can occur and is a very serious emergency situation that can be fatal. Young children are particularly susceptible. Do not take iron supplements without consulting your health care provider.

 

MAGNESIUM (A major mineral)

Most magnesium found in the human body is found in the skeleton, the next highest accounting is in the muscle tissues and the rest is found in other tissues and fluids. Magnesium is essential for energy production, protein formation and cellular replication (e.g., DNA, RNA). It is as important as, if not more important than calcium and phosophorus. Magnesium works with calcium in muscle contraction and relaxation (calcium-contraction, magnesium-relaxation). It also works with vitamin D, potassium and other minerals. It is employed in at least 300 enzymatic reactions within the body, many relating to energy. It helps reduce blood pressure, reduce vascular spasm and improve heart function and also helps regulate calcium metabolism.

Depletion of magnesium may result from high consumption of coffee, tea, chronic diarrhea, irritable bowel, laxatives, oral contraceptives, overexercising and emotional stress. Magnesium depletion may also result in people with gastrointestinal disorders, diabetes mellitus, old age, chronic alcoholism, and in long-term use of diuretics. High doses of supplemental zinc and high protein intake interfere with magnesium absorption.

Food Sources

Green leafy vegetables (kelp, parsley, dandelion leaves, chopped spinach, swiss chard), whole grains (wheat bran, wheat germ, buckwheat, whole wheat bread, brown rice, millet, barley, rye, shredded wheat, 100% bran cereal, oat bran), nuts (cashews, almonds, brazil, peanuts, pecans, hazelnuts, dried coconut), sunflower seeds, bean curd, blackstrap molasses, dried apricots, corn, avocado, garlic, fresh green peas, sweet potato, blackberries, broccoli florets, cheddar cheese, cauliflower, carrots, white fish, celery, chicken, asparagus, stewing beef, potatoes, tomatoes, oranges, whole milk, eggs, black-eyed peas, lima beans, 1% milk, okra, hard water, and banana.

Examples:

All bran, 1/2 cup = 128.7 mg

Peanuts, 1 oz.(, = 49.8 mg

Almonds, 1 oz., (22 almonds) = 81.1 mg

Spinach, 1/2 cup cooked = 78.3 mg

RDA

Male adolescents 14 - 18 years of age = 410mg/day

Female adolescents 14 - 18 years of age - 360 mg/day

Male adults 19 - 30 years of age = 400 mg/day

Female adults 19 - 30 years of age = 310 mg/day

Male adults 31 years of age and older = 420 mg/day

Female adults 31 years of age and older = 320 mg/day

UL

Adults = 350 mg/day (supplemental form).

No toxicity reported from foods but may occur with supplements.

Magnesium interferes with the absorption of some heart medications, osteoporosis medications, tranquilizers, antibiotics, oral anticoagulants, and penicillamine. Tell medical staff if undergoing surgery using anasthesia if using any product containing magnesium. Eating a varied diet should provide the RDA for magnesium for most people. Do not take a supplement without consulting your healthcare provider.

 

POTASSIUM (A major mineral)

Potassium is also known as an electrolyte. It is an essential (major) mineral. As an electrolyte it regulates membrane potential, using positively charged ions and interacts with sodium (positively charged) and chloride (negatively charged) for membrane potential. Sodium is located outside the cell, potassium inside the cell. Chloride keeps sodium and potassium balanced. The sodium-potassium pump is found within cell membranes and keeps the cell in balance. The pump also maintains the electrical charge of the cell which is critical for nerve and muscle function and contraction.

Potassium needs to be replenished after hard exercise and profuse sweating. Low potassium results in low levels of stored glycogen or muscle fuel. Potassium deficiency results in fatigue and muscle weakness. Eating fresh fruits and vegetable juices replenishes potassium most healthily and inexpensively. Too much sodium or too much potassium upsets the balance (fluid balance) which is critical to optimal performance. Most people eat far too much sodium which is found in processed foods, fast foods, and condiments. Fresh fruit and vegetables (alkalis) may decrease the risk of stroke, may decrease risk of osteoporosis by balancing increased acid (meat, cheese, fish) intake in the diet, may decrease the risk of developing kidney stones, and may reduce the risk of hypertension.

Potassium also functions in regulation of the heart beat, protein and nucleic acid synthesis, energy production, and conversion of blood sugar into glycogen.

Food Sources

Raisins, raisin bran cereal, prunes, prune juice, baked potato with skin, avocados, cooked lima beans, salmon, bananas, cod, pork, cauliflower, dried apricots, tomatoes, tomato juice, chicken, canned tuna, whole wheat bread, frozen peas, oranges, orange juice, whole milk, eggs, artichoke, cooked spinach, sunflower seeds, almonds, molasses, cooked acorn squash, peanuts, peanut butter, dried peaches, dried pears, cooked split peas, cheese meat and vegetable pizza, and cheddar cheese.

Examples:

Banana, 1 medium = 467 mg

Baked potato with skin, medium = 721mg

Raisins, 1/2 cup = 598 mg

Tomato juice, 6 fluid oz., = 400 mg

AI or Adequate Intake

Adolescents 14 - 18 years of age = 4.7 g/day

Adults 19 years of age and older = 4.7 g/day

UL

Hyperkalemia is an elevated serum potassium level. This occurs when the kidneys cannot eliminate it adequately which causes kidney failure. Increased potassium levels may result. Certain conditions such as severe burns, trauma, or tissue damage and many medication families increase the probability of developing hyperkalemia. See http://lpi.oregonstate.edu/infocenter/minerals.html for more specific information. Do not use a supplement without the advice of a health care professional.

ZINC (A trace mineral)

Zinc functions in cell/energy metabolism for growth and development, in cell signaling systems, in the immune system, in neurological development, and in reproduction. It is found in all body tissues and is particularly important in enzyme function (over 200) and hormone function, and in vision, taste, smell, and in wound-healing. Its highest concentration is in muscles (65%), in red and white blood cells, bone, skin, liver, kidneys, pancreas, eye retina, in the male prostate gland and sperm; it helps make cell membranes strong. Zinc absorption is decreased by drinking tea or coffee or eating vegetables or whole grains with phytic acid (found in fiber) with meals. Zinc joins the phytic acid and forms zinc-phytate which is not absorbed. High intakes of calcium, iron and copper may also limit zinc absorption. Cysteine and methionine (amino acids) improve zinc absorption as does yeast found in leavened bread.

Food Sources

Fresh oysters, popcorn, sesame seeds, pumpkin seeds, ginger root, crab, pecans, brazil nuts, cheddar cheese, stewing steak, whole wheat, rye, oats, peanuts, lima beans, almonds, walnuts, cooked lobster, canned sardines, buckwheat, hazelnuts, whole wheat bread, green peas, eggs, turnips, chicken, cooked soybeans, parsley, cooked whole wheat pasta, garlic, carrots, Boston baked beans, white fish, old potatoes, shellfish, red meats, pork, nuts, legumes, chicken and turkey dark meat, fruit yogurt, milk, cashews, chickpeas or garbanzo beans and seafood.

Examples:

Oysters, 6 medium, cooked = 43.4 mg

Milk, 8 oz. or 1 cup = 1.0 mg

Fruit yogurt, 1 cup = 1.8 mg

Chicken, dark meat (3 oz.) = 2.4 mg

RDA

Male adolescents 14 - 18 years of age = 11 mg/day

Female adolescents 14 - 18 years of age = 8 mg/day

Male adults 19 years and older = 11 mg/day

Female adults 19 years and older = 8 mg/day

UL (combined dietary and supplemental)

Adolescents 14 - 18 years of age = 34 mg/day

Adults 19 years of age and older = 40 mg/day

Excessive long-term use of zinc (**"60 mg/day or >") may cause copper deficiency. Do not use intranasal zinc sprays or gel as these may cause permanent loss of smell. Avoid drinking fluids or eating foods from galvanized metal containers. Zinc absorption may be decreased if combined with certain medications such as antibiotics. Some medications may cause zinc deficiency.

Individuals at risk for zinc deficiency are strict vegetarians because zinc in plant food sources may be bio unavailable or are poorly absorbed, bowel inflammation diseases, long-term diarrhea, anorexic individuals, malabsorption syndromes, sickle cell anemia, infants and children, older adults, intravenously fed individuals, pregnant women and teens, lactating women and teens, HIV and AIDS infected individuals and those with liver disease. Zinc deficient individuals are more susceptible to infection and have an increased susceptibility to disease as the immune system is affected. Most individuals should be able to obtain enough zinc naturally in their diets but if not, a daily multivitamin/mineral supplement should be adequate. Do not take a supplement without consulting your health care provider.

 

To check any food composition go to the USDA food composition database at: http://www.ars.usda.gov/Services/docs.htm?docid=7783

 

References

Christian, JL, Greger, JL. Nutrition for Living (4th Ed.) Reading, MA: The Benjamin/Cummings Publishing Company, Inc. 1994.

McArdle WD, Katch FI, Katch VL. Sports and Exercise Nutrition (2nd Ed.) Philadelphia: Lippincott Williams and Wilkins. 2005.

Natow, AB, Heslin, J-A. The Vitamin and Mineral Food Counter. New York: Pocketbooks. 2004.

**Linus Pauling Institute's Micronutrient Information Center. Available at: http://lpi.oregonstate.edu/infocenter/minerals.html. Accessed January 3, 2006, January 10, 2006, January 13, 2006, January 30, 2006, February 1, 2006, February 3, 2006, February 11, 2006.

USDA Nutrient Database for National Reference. Available at: http://www.nal.usda.gov/fnic/foodcomp/search. Accessed April 13, 2006.

USDA Food and Nutrition Products and Services. Available at: http://www.ars.usda.gov/Services/docs.htm?docid=7783. Accessed April 17, 2006.

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Last updated 5/30/2007 by MIT Sports Medicine: K Davis


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