Because our body is balanced ,and each two metals balance each other:

1-calcium and magnesium ,

2-Zinc and copper

3-sodium and potassium .

4-manganese and chromium .

5-vanadium and molybdnum

so the trace elements are available in food and water and soil.

so we should take alln our need from balanced diet

I think this question is not complete. It is not a matter of which one (calcium or magnesium) is crucial, but which one is most needed regarding the body stores and the diet used, plus eventually other interfering factors.

Metalloproteinase ones. All trace elements serving as co-enzymes/co-factors are vital and no particular order of importance.

my dear friends ,this subject is now getting more proud that all diseases and cure vis with deficiency of these minerals ,which connected to soil ,water,plant and finally breached human ,so its crucial nin our life ents in plant and animal nutrition as we seek to explain the adverse effects of deficiencies and toxicities, and avoid suboptimal concentrations that limit the attainment of optimum economic yields of crops and animal productivity and welfare. The term trace element is useful but imprecise because it can refer to any element in the soil-plant-animal system regardless of its role. Originally the term was applied to the many elements found in plants at concentrations that were so small that the then available methods of analysis could only report them as “a trace”, and often before any role could be assigned to them. Now with modern analytical techniques, concentrations as little as ng g-1 can be determined but there is still uncertainty about the optimum concentration of many trace elements in plant tissue and even less information on adequate levels of plant available trace elements in soil. Some trace elements are essential nutrients for plant growth and often also for food and feed quality because the primary route for their intake by humans and animals is plants. These trace elements might better be called micronutrients. Included in this group are boron, chlorine, copper, iron, manganese, molybdenum and zinc. The importance of other trace elements found in plants but, as yet without any recognised function, relates to their role in animal nutrition. Their presence in plants would appear to have allowed animals to use them in their metabolic processes, often in enzyme systems. Among such elements are cobalt, chromium, fluorine, iodine, nickel and selenium. Animals having developed a dependency on these trace elements they too could be described as micronutrients. More elements have been shown to be essential for animals than for plants. Thus it is essential that micronutrients, whether required by plants or animals, are present in sufficient plant-available concentrations in the soil to ensure optimum productivity. A problem with the term trace element is that it might suggest that, even if an element is not essential for plants or animals, it has no adverse effect on either. But some elements can accumulate even as traces to concentrations that are toxic to the plant or to the animal feeding on it. For example, plant growth is adversely affected by excess manganese (Mn) and aluminium (Al) in many soils if they are allowed to become acid, or by nickel (Ni), cobalt (Co) or chromium (Cr) in acid soils derived from minerals in which there is a natural abundance of these elements. In other soils, concentrations of trace elements have increased as a consequence .

Elements such as iron, zinc, and selenium are essential components of enzymes where they attract or subtract molecules and facilitate their conversion to specific end products. Few elements donate or accept electrons in redox reactions, which results in generation and utilization of metabolic energy and have an impact on the structural stability and to import certain biological molecules. Iron is involved in the binding, transporting, and release of oxygen in higher animals. Some of the trace elements control important biological processes by facilitating the binding of molecules to their receptor sites on cell membrane, by alternating the structures or ionic nature of membrane to prevent or allow specific molecules to enter or leave a cell and in inducing gene expression resulting in the formation of protein involved in life processes.

Essential elements for human body

• Four organic basic elements: H, C, N, O
• Quantity elements - Na, Mg, K, Ca, P, S, Cl.
• Essential trace elements - Mn, Fe, Co, Ni, Cu, Zn, Mo, Se, I.
• Function suggested from active handling in humans, but no specific identified biochemical functions - Li, V, Cr, B, F, Si, As.

Please check

Prashanth L, Kattapagari KK, Chitturi RT, Baddam VR, Prasad LK. A review on role of essential trace elements in health and disease. J NTR Univ Health Sci 2015;4:75-85

Dear@Tareq

There are many trace metals in environment. Talking about their utility in our health, IRON seem to be first, CALCIUM is important for bones, MAGNESIUM is important in many ways, ZINC again is useful, COPPER deficiency causes disease. SELENIUM and some research link it to diabetes.

Perhaps many more will be discovered over time with research.

This periodic table pic depicts the metals in our body