Nutritional Deficiencies
Zinc -
updated: 18 December 2008
Use of national food balance data to estimate the adequacy of zinc in national food supplies: methodology and regional estimates
Public Health Nutr. 2005 Oct;8(7):812-9
Wuehler SE, Peerson JM, Brown KH.
OBJECTIVES: Adequate zinc nutriture is critically important for human health, but the development of programmes to control zinc deficiency is limited by the lack of reliable information on population zinc status. The present analyses were conducted to: (1) estimate the absorbable zinc content of national food supplies; (2) compare this information with theoretical population requirements for zinc; and (3) use these results to predict national risks of inadequate zinc intake. SETTING AND DESIGN: National food balance data were obtained for 176 countries from the Food and Agriculture Organization of the United Nations. The amount of absorbable zinc in these foods was estimated from food composition data, and zinc absorption was predicted using a model developed by the International Zinc Nutrition Consultative Group (IZiNCG). Demographic data were obtained from United Nations estimates, and age- and sex-specific physiological requirements for absorbable zinc were estimated using IZiNCG recommendations. RESULTS AND CONCLUSIONS: The mean per capita absorbable zinc content of national food supplies ranged from 2.98-3.01 mg day(-1) in Western Europe and USA & Canada to 2.09 mg day(-1) in Southeast Asia. The estimated percentage of individuals at risk of inadequate zinc intake ranged from 9.3-9.5% in the regions of North Africa & Eastern Mediterranean and USA & Canada to 33.1% in Southeast Asia. Overall, approximately 20.5% of the world's population is estimated to be at risk of inadequate zinc intake. Data on the absorbable zinc content of national food supplies can be used to determine whether further assessments of population zinc status and development of intervention programmes are warranted.
Publication Types:
Online - Abstract
Zinc: requirements, bioavailabilities and recommended dietary allowances
Prog Clin Biol Res. 1983;129:147-69.
Smith JC Jr, Morris ER, Ellis R.
This review has approached zinc requirements, bioavailabilities and recommended dietary allowances from a historical view. For example, a requirement for zinc was first demonstrated for the microorganism Aspergillus niger more than a century ago, although zinc has been recognized as a dietary nutrient for humans only within the last decade. Dietary requirement was defined as that quantity of zinc which must be provided daily in order to meet the metabolic requirement. The degree of bioavailability determines the total dietary zinc which must be consumed by humans to remain in metabolic equilibrium. In regard to recommended dietary allowances (RDA), they are recommended average daily intakes of nutrients that population groups should consume. RDA are not synonymous with requirements. Metabolic requirements (the quantity that must be provided to the circulating blood daily) have been determined previously using radio-isotope studies and have indicated a calculated need of approximately 6 mg for an adult per day. More recently a similar amount (4-6 mg) has been found to be required daily (intravenously) in order to maintain plasma zinc concentrations and daily urinary zinc excretion within normal range in hospitalized subjects. Average zinc intakes of large segments of the U.S. population are receiving levels approaching one-half or less the RDA with no apparent deleterious effects. These subjects include pregnant and lactating women. In addition, the zinc content of breast milk is lower than previous studies indicated. Thus, it appears that the majority of breast-fed infants are receiving no more than 70% of the recommended intake, with a recent study indicating less than 50%. Factors reported to affect bioavailability of zinc from foods are discussed. These include fiber and phytate. It was concluded that no definite conclusion can be reached regarding the overall effect of food fiber on zinc balance. Many of the studies were of short duration, with the longest being 32 days. It is probable that different sources of food fiber may have different effects on zinc balance. The apparent discrepancy in the literature regarding the effect of soy protein on zinc requirement was cited. Lastly, the phytate:zinc molar ratio concept was designed to test it as a predictor of zinc bioavailability to humans. The concept must be expanded to recognize the relevance of the total daily dietary zinc intake. Specifically, impairment of absorption of zinc by phytate would be more critical if the total dietary intake was low since the metabolic requirements might not be met
Publication Types:
Online - Abstract
Zinc deficiency in the elderly
Nippon Ronen Igakkai Zasshi. 2007 Nov;44(6):677-89
Miyata S.
Zinc is one of the essential trace elements which usually contain 1.4-2.3g in the human body. Zinc is present in muscle (60%), bone (30%) and other organs (10%) such as liver, kidney, pancreas, brain, skin, prostate etc. Daily zinc requirement of an adult is 15mg and normal range of serum zinc concentration is 84-159microg/dl. Zinc absorption in the elderly is significantly lower than that of the younger. Zinc deficiency is common in the elderly, especially those aged over 75. The symptoms of dermatitis, diarrhea etc. Immunocompetence and wound healing are disturbed in those with zinc deficiency and zinc supplementation is necessary as a nutrient for a good quality of life in the elderly.
Publication Types:
Online - Abstract
Publication Types:
Publication Types:
|
