Manganese: From Soil to Human Health-A Comprehensive Overview of Its Biological and Environmental Significance

Abstract

Background: Manganese is an essential micronutrient that plays a pivotal role in environmental systems, plant physiology, and human health. This review comprehensively examines the manganese cycle in the environment, its absorption and transport mechanisms in plants, and the implications of manganese exposure to human health. Objectives: The objectives of this review are to (i) analyze the environmental cycling of manganese and its bioavailability, (ii) evaluate the role of manganese in plant metabolism and disease resistance, and (iii) assess the impact of manganese toxicity and deficiency on human health. Conclusion: This review highlights that while manganese is crucial for photosynthesis, enzyme activation, and resistance to plant diseases, both its deficiency and toxicity can have severe consequences. In plants, manganese deficiency can lead to impaired growth and reduced crop yields, while toxicity, particularly in acidic soils, can inhibit photosynthesis and stunt development. In humans, manganese is necessary for various physiological processes, but overexposure, especially in occupational settings, can result in neurodegenerative conditions such as manganism. The conclusion emphasizes the importance of managing manganese levels in agriculture and industry to optimize its benefits while minimizing health risks. A multidisciplinary approach is advocated to enhance agricultural productivity and ensure public health safety.

Keywords: Mn cycling in environment; Mn metabolism; food chain; human nutrition; manganese; water quality.

Figure 1

Cycle of manganese in the environment [16].

Figure 2

(a) Typical interveinal necrosis caused by manganese deficiency in barley [49]; (b) Manganese deficiency in peanuts [50].

Figure 3

Brown spots and yellowing of leaves due to Mn toxicity in cantaloupe (Cucumis melo) [63].

Figure 4

The pathways of human manganese exposure [97].