Zinc daily intake

Humans given zinc supplements should be aware of possible complications (Fosmire 1990). Low intakes of 100 to 300 mg of zinc daily in excess of the recommended dietary allowance of 15 mg Zn daily may produce induced copper deficiency, impaired immune function, and disrupted blood lipid profiles. Patients treated with zinc supplements (150 mg daily) to control sickle cell anemia and nonresponsive celiac disease developed a severe copper deficiency in 13 to 23 months normal copper status was restored by cessation of zinc supplements and increased dietary copper (Fosmire 1990). 

In several studies (e.g., 30-36, Table I), the effects of including "processed" fiber sources (fiber isolated from natural sources) have been investigated. Results have been contradictory for example, lOgm/day cellulose decreased zinc balances in one study (3.0) but 30 to 40g/day did not affect zinc absorption in another study (36). Processed fiber may have effects which are not indicative of the effect of a similar level of endogenous fiber from foods. In summary, daily intake levels of fiber equivalent to 20 to 30g NDF/day from food sources would not be expected to have long-term deleterious effects on mineral utilization. 

Zinc plays a number of important roles in the body and deficiency results in serious adverse effects. Recommended daily intake is 12 to 15 mg. Zinc is very common in the environment and readily available in many foods, including grains, nuts, legumes, meats, seafood, and dairy products. Numerous enzymes require zinc, as do proteins that regulate gene expression. Zinc plays a role in the immune system and is also important in the development and function of the nervous system. 

Tin. The widespread use of canned foods results m a daily intake ol tin that is ea I - 17 mg for an adult nude. At this level it has not been shown to be toxic. Some grains also contain tin Too much tin can adversely affect zinc balance and iron metabolism. Essentiality has not been conlirmcd for humans. It has been shown for the rat. An enhanced growth rate results from tin supplementation of low tin diets. Animals on delie lent diets exhibit poor growth and decreased feed efficiency. 

J. P. Buchet, R. Lauwerys, A. Vandevoorde, J. M. Pycke, Oral daily intake of cadmium, lead, manganese, copper, chromium, mercury, calcium, zinc, and arsenic in Belgium duplicate meal study, Food Chem. Toxicol., 21 (1983), 19-24. 

The effect on zinc balance of a 10-fold difference in dietary molar ratio of phytate/zinc was tested in a metabolic balance study with 10 adult men. The mean zinc balance was 2.7 mg per day vrtien the dietary molar ratio of phytate/zinc was about 12 and 2.0 mg per day when the ratio was about 1. Menus consisted of foods commonly consumed in the United States. The mean daily intake of zinc was 17 mg and of neutral detergent fiber 16 g. The molar ratios of phytate/zinc were attained by using 36 g per day of whole or dephytinized wheat bran. Analysis of hospital and self-chosen diets Indicate that the majority of the United States population consume diets with molar ratios of phytate/zinc less than 10, but which provide less than the recommended dietary allowance of zinc. The balance results are discussed in relation to magnitude of the zinc intake, the type of food consumed and the role of adaptive responses in maintaining adequate zinc nutriture. 

Nutrient intake. Table II summarizes the daily intakes of zinc and phytic acid. The range of zinc intake is the result of the different caloric levels consumed. About one-third of the zinc consumed was contained in the muffins. About 95% of the phytic acid was derived from the muffins and, since the same number of muffins was eaten regardless of caloric level, there was no difference due to the caloric level in phytic acid intakes. There was, however, a ten-fold difference in phytic acid intakes by type of bran muffin. The mean calculated molar ratio of phytate/zinc was about 12 when whole bran muffins were consumed and just greater than 1 when dephytinized bran muffins were... 

Table II. Daily Intakes of Zinc and Phytic Acid...

The amount of zinc that the diet must contain,depends on the availability of zinc for absorption. The WHO committee gives no data for diets, and the suggested daily dietary requirement range from 2.8 mg in infancy to 54.5 mg for lactating women. The United States Food and Nutrition Board suggest a daily intake of 15 mg a day for adults O). 

Taper e al. (39) from the same laboratory as the aforementioned geriatric study, found no significant effect of dietary zinc levels when they studied 18 young women of childbearing age. Dietary copper intake was 2.0 mg day with 0.86 mg from food and 1.14 mg as supplement. Foodstuffs provided 5.63 mg of zinc, and total daily Intakes were adjusted to 8 mg (N = 7), 16 mg (N = 6) and 24 mg (N = 5). The experimental details of the supplementation with zinc and copper salts were not provided. The dietary Zn/Cu ratios were 4.0, 8.0, and 12.0 respectively the mean fecal excretion (mean SD) for the respective diets was 2.01 + 0.15, 2.10 + 0.14 and 2.02 + 0.23, respectively. Neither the fecal outputs nor the derivative apparent retention values differed significantly one from another. 

Implications for Human Nutrition. The human studies cited have examined the effect of zinc on copper uptake, and evidence suggests that Zn/Cu ratios of greater than 10 1 can produce a nutritional impact. The source of the discrepancies among the three metabolic studies reviewed is not immediately evident. One possibility would be a different susceptibility to copper malabsorption at different ages. Another might have to do with the actual Zn/Cu ratios in those meals which provided the bulk of the daily Intake of the two minerals or with their chemical forms. Studies in which all of the copper and zinc are derived from natural foodstuffs would complement the foregoing human studies in this area. 

Zinc is not considered to be toxic or dangerous. It is an essential element for humans, animals and plants [2.85]. The human body contains ca. 2 g of zinc and a daily intake of 15 mg for humans is recommended. The oral LD50 value for rats is >15,000 mg ZnO kg- (OECD 401). 

Stable isotopes of iron zinc and copper have been given to subjects in a variety of studies at our Center Standard doses were 4 nig Fe> 4 mg Zn and 2 mg of Cu for adult subjects Isotopes were fed in a single dose in juice at breakfast or in Trutol (a flavored glucose solution) While doses of this size are not truly tracer doses they are in the physiological range of intake Recommended daily intakes are 10 mg Fe 15 mg Zn and 2- 3 mg Cu for adult males (11) Table II shows the average absorption values obtained from subjects who were consuming diets adequate in all minerals and other dietary components ... 

Vitamins In particular, water-soluble vitamins have to be provided in adequate quantities. With a carbohydrate diet and alcoholic liver disease, the daily requirement is higher. A daily intake of multivitamins, best combined with trace elements and minerals, is recommended. As a rule, liposoluble vitamins are best administered by parenteral route due to inadequate absorption. The therapeutic significance of zinc (s. pp 50, 99) should always be borne in mind. (34, 153, 155,169)... 

The patients were kept under strict metabolic conditions. The first group of subjects (1 and 2), received hospital diet for two weeks, and then they received the experimental diet with 10 mg of supplemental zinc (as zinc acetate) orally for six weeks. Following this, they were given only experimental diet (daily zinc intake of 2.7 mg) for 24 weeks. At the end of this phase, while continuing the experimental diet the two subjects received 30 mg of zinc (as zinc acetate) supplement daily, orally for 12 weeks. Finally these were maintained on hospital diet with total daily intake of 10 mg zinc plus 30 mg of oral zinc (as zinc acetate) supplement for eight weeks. The hospital diet provided the same amount of calories and protein as the experimental diet. Thus these two subjects were observed for a total period of 52 weeks. 

One study showed that, in full-term infants, manganese is absorbed from breast milk and cow s milk formulas that were either unsupplemented or supplemented with iron, copper, zinc, and iodine (Domer et al. 1989). Manganese intake was greater in the formula-fed infants than in the breast-fed infants due to the higher manganese content of the formula. However, breast-fed infants retained more of their daily intake of... 

The average adult contains 2 g of zinc and requires a daily intake of 15 to 20 mg, only half of which is absorbed, to maintain this level. Although food in many technologically advanced societies contains sufficient zinc to afford this balance, zinc deficiencies occur in certain populations where there is either an unbalanced diet or food that inhibits zinc absorption. An especially interesting example of the latter phenomenon is found in certain villages in the Middle East... 

The normative daily zinc requirement of people with moderate bioavailability may be < 6.0 and < 8.0 mg, taking the average over a week (Anonymous 1996). This daily intake corresponds to a zinc level of 90 pg kg body weight and a zinc concentration of 20 mg kg DM consumed (Anke et al. 1999c, Rbhrig et al. 1998). 

Overexposure to zinc by food, water, and air commonly poses no risk to the general population. Long-term administration of zinc (100-150 mg per day) to patients to promote wound healing is usually well tolerated, but anemia may be induced in case of low copper status. This effect is readily reversible, however. Using a safety factor of 10 this means that an additional zinc intake of 10-15 mg per day does not constitute a health hazard (US ERA 1980). The provisional maximum tolerable daily intake for man has been estimated at 0.3 to 1.0 mg Znkg body weight (WHO 1983). 

Sharrett AR, Carter AP, Orheim RM and Feinlieb M (1982a) Daily intake of lead, cadmium, copper, and zinc from drinking water the Seattle study of trace metal exposure. Environ Res 28 456-475. 

Hunt CD and Meacham SL (2001) Aluminum, boron, calcium, copper, iron, magnesium, manganese, molybdenum, phosphorus, potassium, sodium, and zinc concentrations in common Western foods and estimated daily intakes by infants toddlers and male and female adolescents, adults, and seniors in the United States. J Am Diet Assoc 101 1058-1060. 

The mean daily intake of zinc in different regions of the world is between 5 and 22 mg [20]. The foodstuffs rich in proteins usually contain sufficiently high zinc concentrations (10-50 mg kg fresh weight). In contrast to this, fruits and vegetables contain only low zinc concentrations (6 and 2 mg kg respectively). 

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