DIET FINAL CHP. 13 TRACE MINERALS

selenium toxicity

Because high doses of selenium are toxic, a UL has been set. Selenium toxicity causes loss and brittleness of hair and nails, garlic breath odor, and nervous system abnormalities.

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In mild cases, the teeth develop small white flecks; in severe cases, the enamel becomes pitted and permanently stained

fluorosis

SUMMARIZE KEY FACTOS UNIQUE TO THE TRACE MINERALS

Although the body uses only tiny amounts of the trace minerals, they are vital to health. Because so little is required, the trace minerals can be toxic at levels not far above estimated requirements—a consideration for supplement users. Like the other nutrients, the trace minerals are best obtained by eating a variety of foods.

iodine toxicity

Excessive intakes of iodine can interfere with thyroid function and enlarge the gland, just as deficiency can. During pregnancy, exposure to excessive iodine from foods, prenatal supplements, or medications is especially damaging to the developing infant. An infant exposed to toxic amounts of iodine during gestation may develop a goiter so severe as to block the airways and cause suffocation. The UL is 1100 micrograms per day for an adult—several times higher than average or recommended intakes (review Figure 13-1). For perspective, most foods provide 3 to 75 micrograms of iodine per serving.

zinc toxicity

High doses (more than 50 milligrams) of zinc may cause vomiting, diarrhea, headaches, exhaustion, and other symptoms. The UL for adults was set at 40 milligrams based on zinc's interference in copper metabolism—an effect that, in animals, leads to degeneration of the heart muscle.

zinc supplementation

In developed countries, most people obtain enough zinc from the diet without resorting to supplements. In developing countries, zinc supplementation plays a major role in effectively reducing the incidence of disease and death associated with diarrhea and pneumonia

many plant foods contain significant amounts of this trace mineral, so deficiencies are rare.

MANGANESE

chromium supplements

Supplement advertisements have succeeded in convincing consumers that they can lose fat and build muscle by taking chromium picolinate. Whether chromium supplements (either picolinate or plain) reduce body fat or improve muscle strength remains controversial.

____ is needed to produce the active form of vitamin A (retinal) in visual pigments and the retinol-binding protein that transports vitamin A

ZINC

The rate of zinc absorption varies from about 15 to 40 percent, depending on the ________ —as zinc intake increases, the rate of absorption decreases, and as zinc intake decreases, the rate of absorption increases.

amount of zinc consumed

how does the bodies handling of zinc and iron differ?

circular passage of zinc from the small intestine to the body and back again.

A UL of ______ has been established based on intakes from food, water, and supplements.

manganese

______ plays a key role in storing and distributing zinc throughout the body.

metallothionein

Like iron, dietary factors such as ______ influence absorption, limiting its bioavailability

phytates

iron deficiency among toddlers is common in what country

the US

iodine recommendations

the recommended intake of iodine for adults is a minuscule amount. The need for iodine is easily met by consuming seafood, vegetables grown in iodine-rich soil, and iodized salt. Just one-half teaspoon of iodized salt provides the RDA for iodine. In the United States, labels indicate whether salt is iodized.

is essential to normal taste perception, wound healing, sperm production, and fetal development.

zinc

is needed to produce the active form of vitamin A (retinal) in visual pigments and the retinol-binding protein that transports vitamin A.

zinc