Food and nutrition.pdf

72 Nutrientsa diuretic, causing vast quantities to be lost in the urine. There is noevidence that large dietary intakes of magnesium are harmful to peoplewith normal renal function. In cases of impaired renal function and useof magnesium-containing drugs hypermagnesemia may occur. Symptomsinclude nausea, vomiting and hypotension. As conditions worsenrespiratory depression, coma and asystolic arrest may occur.ManganeseBecause of the lack of manganese deficiency in adults, the currentdietary intakes satisfy the needs for this mineral. A provisional dailydietary intake of 5.0 milligrams is recommended.It is necessary for the use of biotin, Bl and C, by the body. It can helpeliminate fatigue, improve memory, reduce nervous irritability and assurethe proper digestion and utilization of food. A deficiency can cause poorreproductive performance, growth retardation, abnormal formation ofbone and cartilage, and an impaired glucose tolerance.The best natural sources are whole grains, cereal products, nuts andgreen leafy vegetables. Dairy products, meat, fish, and poultry are poorsources.Toxicity has only been observed with workers exposed to highconcentrations of manganese dust or fumes in the air.NickelNickel is now quite firmly established as an essential nutrient, butno Recommended Dietary Allowance (RDA) or Estimated Safe andAdequate Intake (ESADI) has yet been set for nickel.Research showed that nickel was to be found in blood and tissues atquite consistent levels, that it is associated with DNA and RNA in amountsthat suggest physiological significance, and that it occurs also in blood inamounts which appear biologically meaningful. Nickel is required fornormal growth and reproduction in animals, and presumably in humanbeings as well. It appears to have a role in the modulation of the b;nmunesystem and in development of the brain. Since brain is depleted indeficiency more than other tissues, the brain and immune system shouldreceive attention in future studies of nickel deficiency.·The best sources of nickel include oatmeal, legumes, nuts, cocoa,whole wheat bread, and some leafy vegetables such as kale and lettuce.The danger of nickel toxicity from food appears to be very low, sincelarge amounts of nickel are required to produce any toxic effects throughingestion. But in susceptible people, contact with nickel or nickel saltscause skin irritations.Chronic exposure at lower levels can cause cancer. Workers exposed