Food-based approaches to meeting vitamin and mineral needs - Iron and Zinc

Reference from the joint report of FAO/WHO expert consultation on Human Vitamins and Minerals verbatim. (Chapter 2)

Minerals such as iron and zinc are low in cereal and tuber-based diets, but the addition of legumes can slightly improve the iron content of those diets. However, the bio-availability of this non-heme iron source is low.

Therefore, it is not possible to meet the recommended levels of iron and zinc in the staple-based diets through a food-based approach unless some meat, poultry, or fish is included. For example adding a small portion (50 g) of meat, poultry, or fish will increase the total iron content as well as the amount of bio-available iron.

Adequacy of Zinc Intakes in Relation to Requirement Estimates

Reference from the joint report of FAO/WHO expert consultation of Human Vitamins and Minerals verbatim.

32. AO/IAEA/WHO. 1996. Trace elements in Human nutrition and health. Geneva, World Health Organization.

43. Gibson, R.S. & Ferguson, E.L. 1998. Assessment of dietary zinc in a population. Am. J. Clin. Nutr., 68(suppl.): 430S-434S

The risk for inadequate zinc intakes in children has been evaluated by using the suggested estimates of zinc requirements (32) and by using data available on food composition and dietary intake in different parts of the world (43).

Upper Limits of Zinc Intake

Reference from the joint report of FAO/WHO expert consultation on Human Vitamins and Minerals verbatim.

Only a few occurrences of acute zinc poisoning have been reported. The toxicity signs are nausea, vomiting, diarrhoea, fever, and lethargy and have been observed after ingestion of 4-8 g (60-120 mmol) zinc. Long-term zinc intakes higher than the requirements could, however, interact with the metabolism of other trace elements. Copper seems to be especially sensitive to high zinc doses.

Inter-individual Variations in Zinc Requirements and Recommended Nutrient Intakes

Reference from the joint report of FAO/WHO expert consultation on Human Vitamins and Minerals verbatim.

Zinc Requirements

Reference from the joint report of FAO/WHO expert consultation on Human Vitamin and Minerals verbatim.

Populations at Risk for Zinc Deficiency

Reference from the joint report of FAO/WHO expert consultation on Human Vitamins and Minerals verbatim.

32. AO/IAEA/WHO. 1996. Trace elements in Human nutrition and health. Geneva, World

Health Organization.

29. Simmer, K., Khanum, S., Carlsson, L. & Thompson, R.P.H. 1988. Nutritional rehabilitation in Bangladesh – the importance of zinc. Am. J. Clin. Nutr., 47: 1036-40.

13. Brown, K., Peerson, J.M. & Allen, L.H. 1998. Effects of zinc supplementation on children’s growth. In: Role of trace elements for health promotion and disease prevention. Sandström, B., Walter, P., eds. Bibliotheca Nutritio et Dieta, Basel: Karger; 54: 76-83.

Dietary Sources and Availability of Zinc

Reference from the joint report of FAO/WHO expert consultation on Human Vitamins and Minerals verbatim.

19. Sian, L., Mingyan, X., Miller, L.V., Tong, L., Krebs, N.F. & Hambidge, K.M. 1996. Zinc absorption and intestinal losses of endogenous zinc in young Chinese women with marginal zinc intakes. Am. J. Clin. Nutr., 63: 348-53.

23. Knudsen, E., Jensen, M., Solgaard, P., Sørensen, S.S. & Sandström, B. 1995. Zinc absorption estimated by fecal monitoring of zinc stable isotopes validated by comparison with whole-body retention of zinc radioisotopes in Humans. J. Nutr., 125: 1274-1282.

25. Hunt, J.R., Gallagher, S.K., Johnson, L.K. & Lykken, G.I. 1995. High- versus low-meat diets: effects on zinc absorption, iron status, and calcium, copper, iron, magnesium, manganese, nitrogen, phosphorus, and zinc balance in postmenopausal women. Am. J. Clin. Nutr., 62: 621-32.

32. AO/IAEA/WHO. 1996. Trace elements in Human nutrition and health. Geneva, World

Health Organization.

20. Sandström, B. 1989. Dietary pattern and zinc supply. In: Zinc in Human biology. Mills C.F. ed. p. 350-363. Devon , U.K., Springer-Verlag.

Zinc Metabolism and Homeostasis

Reference from the joint report of FAO/WHO expert consultation on Human Vitamins and Minerals verbatim.

3. Sandström, B. 1997. Bio-availability of zinc. Eur. J. Clin. Nutr., 51(suppl. 1): S17-S19

Zinc absorption is concentration dependent and occurs throughout the small intestine. Under normal physiologic conditions, transport processes of uptake are not saturated. Zinc administered in aqueous solutions to fasting subjects is absorbed efficiently (60–70 percent), whereas absorption from solid diets is less efficient and varies depending on zinc content and diet composition (3).

Role of Zinc in Human Metabolic Processes

Reference from the joint report of FAO/WHO expert consultation on Human Vitamin and Minerals verbatim. 

Zinc is present in all body tissues and fluids. The total body zinc content has been estimated to be 30 mmol (2 g). Skeletal muscle accounts for approximately 60 percent of the total body content and bone mass, with a zinc concentration of 1.5–3 μmol/g (100-200 μg/g), for approximately 30 percent.