Impact of micronutrients on human health
As seen in the case of micronutrients, mineral elements like Zn, Fe and Cu are as important as compounds like carbohydrates, fats, protein and vitamins for human development. Micronutrient deficiencies in soils limit crop yields and nutritional quality, which in turn negatively affect human health (Marschner, 2012; Alloway, 2009) Micronutrient intake less than the recommended values can cause slower physiological processes. High consumption of cereal-based foods with low contents of micronutrients is causing health hazards in humans (Imtiaz et al., 2010).
Micronutrient malnutrition, the so-called hidden hunger, affects more than one-half of the world's population, especially women and preschool children in developing countries (Welch and Graham, 2004). Worldwide over 2 billion people suffer from iron (Fe), zinc (Zn) and/or other (multiple) micronutrient deficiencies (WHO, 2016; Black, 2003). The problem is most severe in low and middle-income countries (Muthayya et al., 2013). The physiological impacts of micronutrients are complex, relating to many bodily functions. Even mild to moderate deficiencies of micronutrients can lead to severe health problems.
Selenium: Selenium has important antioxidant, anti-cancer and antiviral properties and its deficiency makes human prone to thyroid dysfunction, cancer, severe viral disease and various inflammatory conditions (Lyons et al., 2004).
Zinc and Iron: Iron deficiency is the prominent cause of anaemia which contributes to compromised physical productivity, cognitive impairment and adverse pregnancy outcomes. Likewise, Zn deficiency has been related to growth failure, decreased immunity leading to increased susceptibility to infection, morbidity and mortality due to diarrheal disease, and the incidence of respiratory tract pneumonia (Etcheverry et al., 2005), impaired growth and development of infants, children and adolescents, as well as impaired maternal health and pregnancy outcome (Martin, 2004).
Trials conducted in several countries indicate that duration and severity of major baby-killers such as diarrhoea and pneumonia can be reduced by 30-50 % by supplying adequate amounts of vitamin A and zinc (Bhargava et al., 2001). In developing countries, zinc deficiency ranks 5th among the leading 10 risk factors. Even on a global scale, taking developed and developing countries together, zinc deficiency ranks 11th out of the 20 leading risk factors. WHO attributes 800,000 deaths worldwide each year to zinc deficiency and over 28 million healthy life years lost. It is estimated that zinc deficiency affects one-third of the world’s population, with estimates ranging from 4 to 73% according to regions, and it is 5th leading risk factor along with the Fe deficiency, the latter is at 6th position globally.