More trace minerals • Zinc, copper, iodine, fluoride, and selenium Zinc • • A relatively recent addition to mineral requirements • Zinc supplementation reversed defects 1961--researchers in Iran found young men who were growth retarded, anemic, and some had night blindness Zinc’s functions in body • • • • Required in over 300 enzymes (text says only 80) Essential for proper immune function Needed for DNA replication and protein synthesis Zinc finger proteins can interact with hormones and influence their function Zinc absorption • As with iron, small intestinal cells act as security guards to avoid absorbing too much • • Factors inhibiting zinc absorption--phytates, fiber, iron supplements The protein metallothionein in gut cells binds zinc and slows its transport into blood Transport, distribution, etc. • • • Zinc is bound to albumin and alpha-macroglobulin in blood Muscle and bone contain 90% of body’s zinc Some recycling of zinc occurs, but body does not hold on to it as tightly or store it the way it does iron RDA’s • • • Men 11 mg/day; women 8 mg/day Pregnancy 11 mg/day; lactation 12 mg/day UL 40 mg/day Sources of Zinc • • • • Oysters--154 mg/3 ounces!!! Crab Beef Liver • Fortified cereals Zinc deficiency--who’s at risk • • • • Vegans Burn patients Persons with intestinal diseases Persons with diabetes, kidney disease, chronic diarrhea, sickle cell disease Zinc toxicity is rare • • • Very high intakes for long periods can depress immune function Increases LDL and decreases HDL High zinc intake can cause a copper deficiency Copper • • Iron and zinc’s partner Copper deficiency not a serious public health problem Copper’s functions • Required with zinc for the enzyme superoxide dismutase (quenches a free radical) • • • Required for an enzyme in electron transfer chain In ceruloplasmin, helps change Fe charge Also required for collagen, melanin, and norepinephrine synthesis Copper absorption, etc. • • • • • Absorbed in upper small intestine Gut cells also protect against overload Amino acid histidine increases absorption Iron and zinc supplements can reduce absorption Bound to albumin in blood until it gets to liver; then circulates bound to ceruloplasmin Dietary Copper Sources • • • • • Oysters--6.4 mg/3 ounces Liver, other seafood Nuts Chocolate Tofu, beans RDA for Copper • • • Men and women: 900 micrograms (µg)/day UL: 10 mg/day Typical US diet contains 1000-1600 µg Cu Copper deficiency • • • Causes microcytic anemia Bone disease in children Menkes’ disease--rare inherited disorder in which copper cannot get delivered into blood from gut or into brain Wilson’s Disease • • • A genetic copper storage disease analogous to hemochromatosis Can also cause liver failure Patients can be treated with high dose zinc (to reduce Cu absorption) and/or metal chelating agents Iodine • Iodized salt was the first fortified food Iodine’s function • As constituent of two thyroid hormones – Triiodothyronine (T3)-most active – Thyroxine (T4) Sources of dietary iodine • • • Fish and seafood Milk Iodized salt DRI’s for Iodine • • RDA 150 µg/day for adult men and women UL 1100 µg/day Iodine deficiency--goiter • Thyroid grows in volume in response to stimulus from thyroid stimulating hormone • Person with goiter has low metabolic rate, cold intolerance, weight gain, and decreased body temperature Maternal iodine deficiency causes cretinism in offspring • • • Child has irreparable mental retardation Stunted growth Often deafness as well Iodine toxicity can also cause goiter • BUT thyroid hormone production is also reduced by excess iodine Selenium • A fairly new mineral to worry about Selenium’s functions • • • • Part of selenocysteine and selenomethionine, where Se takes place of sulfur Required for glutathione peroxidase Works in concert with vitamin E as an antioxidant Also needed for thyroid function--deiodinase enzymes Absorption, etc. • • • Mostly absorbed from food as selenocysteine or selenomethionine Can be absorbed as inorganic (non-carbon) selenium salts Control of Se status is at level of kidneys--excess is excreted in urine Selenium Deficiency • Keshan disease-in China – Children died of heart disease secondary to viral infection – Selenium deficiency predisposed them to the problem • Heart problems and muscle weakness in patients who have been on IV nutrition without Se for long periods Sources of Selenium • • • • Oysters, other seafood Liver, pork Oatmeal Egg DRI’s for selenium • • RDA 55 µg/day UL 400 µg/day Fluoride • Good for your teeth--up to a point Fluoridation of water began in late 1940’s • Studies from areas with high fluoride in ground water showed fewer dental caries (cavities) in residents • Fluoride may also prevent osteoporosis Fluoride absorption • • • • Only nutrient absorbed mostly from stomach Circulates free in plasma > 99% found in bones and teeth Excess excreted in urine Function • Combines with Ca and P to form stronger crystal in bones and teeth-fluorapatite • Fluorapatite less easily reabsorbed than hydroxyapatite DRI’s for Fluoride • • • AI: 4 mg men, 3 mg women No RDA UL 10 mg/day Sources • • • Fluoridated water in some areas Toothpastes Mouthwashes Fluorosis • • Mottling of teeth--unsightly, but not hazardous Too much fluoride in supplement--headache, gastritis, stiff joints