Contemporary Nutrition 6 th th ed. Chapter 9 Minerals
Minerals Various functions in the body Major Minerals Require >100 mg /day Calcium, phosphorus Trace Minerals Require < 100 mg/day Iron, zinc
Bioavailability of Minerals Degree of absorption Variations due to Presence of Binders oxalic acid binds calcium in spinach Fiber phytic acid binds minerals Animal products are better absorbed Plants depend on mineral content of soil Refinement lowers mineral content Not all are replaced
Bioavailability of Minerals Mineral-mineral competition Similar size Similar exlectrical charges Ex: magnesium, calcium, iron, copper Competition for absorption Vitamins-mineral mineral competition Vitamin C improves iron absorption Vitamin D improves calcium absorption
Mineral Toxicity Trace minerals are more toxic Harmful interactions Supplementation Presence of contaminants Look for the United States Pharmacopeia (USP)-approved brands
Sodium Table salt (NaCl): 40% sodium, 60% chloride Diet processed foods 95% of ingested sodium is absorbed Positive ion in extracellular fluid Na +
Sodium
Sodium Aldosterone regulates sodium balance Key for retaining body water Excretion regulated by the kidneys Antidiuretic hormone conserves water Aldosterone hormone conserves sodium Membrane potential Muscle contraction Conduction of nerve impulses
Sodium Deficiency Deficiency is rare Persistent vomiting/ diarrhea Excessive perspiration Hypotonic to plasma (2/3 Na level in plasma) Losing 2-3% 2 of body weight Adaptation to hot environment Depletion of sodium in the body Signs of deficiency: Muscle cramp, nausea, vomiting, dizziness, shock, coma Normally kidney will respond by conserving sodium
Food Sources of Sodium Most sodium is added by food manufacturers and restaurants Milk and dairy products Processed foods Sodium content listed on the labels
Sodium Needs Adequate intake is 1500 mg for adults Body only needs 200 mg to function Daily Value is 2400 mg/day Upper Level is 2300 mg Typical intake is 4700 mg/day Sodium-sensitive individuals should restrict intake hypertension
Potassium Positive ion in intracelluar fluid Functions Fluid balance Nerve impulse transmission Associated with lowering blood pressure 90% of potassium consumed is absorbed Low blood potassium Muscle cramps, confusion, constipation, irregular heart beat, heart failure
Potassium Sources and Needs Fruits, vegetables, milk, grains, meats, dried beans Adequate Intake is 4700 mg/day Daily Value is 3500 mg/day Typical intake is 2000-3000 mg/day Diuretics may deplete potassium Excess potassium is excreted by the kidneys; no Upper Level
Chloride Negative ion for extracellular fluid Cl - Component of NaCl Hydrochloric acid (HCl) Functions Immune response, nerve function
Chloride Needs Excess excreted by the kidneys, perspiration Adequate Intake is 2300 mg/day Daily Value is 3400 mg Upper level is 3600 mg High intake may cause high blood pressure
Calcium 99% is in bones and teeth Makes up 40% of all the minerals present in the body Amount in body is dependent on amount absorbed Growth and bone development
Absorption of Calcium Requires slightly acidic environment and vitamin D Absorbed in upper part of small intestine Normally absorb 25% of calcium in food Increase to ~60% during time of need (pregnancy, infancy) Parathyroid hormone
Decreased Absorption of Calcium Rapid intestinal motility High fiber intake Excess phosphorus Vitamin D deficiency Polyphenols (tannins) in tea Menopause Aging
Retaining Calcium
Blood Calcium is Regulated Blood level is maintained at the price of bone calcium Blood level can be maintained despite inadequate calcium intake Setting stage for future bone fractures
Functions of Calcium Bone formation and maintenance Blood clotting Nerve impulse transmission Muscle contraction Cell metabolism Activates various enzymes
Building Higher Bone Mass Adequate diet Healthy body weight Normal menses, estrogen production Triad Weight-bearing physical activity Moderate intakes of protein 1 g consumed, lose 1.5 g calcium phosphorus, sodium, caffeine
Building Higher Bone Mass Non-smoker Smoker More alcohol Less activity Poor diets Earlier menopause
Other Roles of Calcium May lower blood pressure May reduce colon cancer May reduce PMS symptoms May lower blood cholesterol May reduce kidney stones Reduces lead absorption Promotes weight loss?
Osteoporosis Calcium deficiency A A pediatric disease with geriatric consequences Leads to ~1.5 million fractures / year Slender, inactive women who smoke are most at risk Less bones
Osteoporosis
Bone Structure
Bone Strength Dependent on bone mass and bone mineral density The more there is, the stronger the bone Rapid and continual throughout adolescence Peak bone mass
Bone Growth and Mass Determined by gender, race, familial pattern, other genetic factors Bone loss begin ~age 30 Women experience increased bone loss after menopause DEXA bone scan
Factors Associated with Bone Status
Bone Mineral Density
Food Sources of Calcium
Calcium Needs Daily Value is 1000 mg/day Adequate Intake is 1000-1200 mg/day for adults Adequate Intake is 1300 mg/day for adolescents (9-18 yrs. old) Average intake: 800 mg/day for women and 1000 mg/day for men Upper Level is 2500 mg/day
Calcium Supplements Recommended for people who cannot incorporate Ca into their diets Not recommended with high-zinc meal Calcium carbonate (40% calcium) For those with ample stomach acid Found in antacids Calcium citrate (21% calcium) Enhances absorption due to acidity content Recommended for older adults