This is the final part of the three-part note on the basics of nutrition. This week, we’re looking at minerals within the category of micronutrients. Micronutrients are, as the name suggests, those needed by the body in smaller quantities.
As we did last week, we’ll be using the US Recommended Daily (or Dietary) Allowances (RDAs), for nutrients (Ref 1). These are established for each vitamin and mineral by the Food and Nutritional Board of the National Academy of Sciences and the Food and Drug Administration (FDA). Where the RDA column in the table has (AI) – this means “Adequate Intake”.
Recommended amounts differ for males and females and people of different ages. I have taken the higher of the recommendation for either males or females in the 19-65 age group. This is usually the figure for males. Pregnant women have even higher RDAs for certain nutrients and older or younger people sometimes have additional needs. However, the RDA for males or females aged 19-65 will cover the vast majority of the population and will serve well as an indication of the minimum amount of each nutrient that we require on a daily basis. The RDAs for males and females are invariably the same and any differences are small.
There are two categories of minerals – macro minerals are both present in the body and needed by the body in larger amounts than the trace minerals (where only a trace is needed). The macro minerals are calcium; chloride; magnesium; phosphorus; potassium; sodium and sulphur. The trace minerals are chromium; copper; fluoride (Ref 2); iodine; iron; manganese; molybdenum; selenium and zinc.
The word mineral literally means “mined from the earth.” There are four types of minerals:
- Metallic elements that are present in large quantities in the body and in what we eat (like calcium, magnesium and potassium);
- Non metallic elements that are present in large quantities in the body and in what we eat (like carbon, phosphorus and sulphur). Please note that only phosphorus is included in our review of minerals, as this is the only element of these three that we need to consume in food;
- Metallic elements present in very small quantities in the body and in what we eat (like chromium, copper, iron and zinc);
- Non metallic elements present in very small quantities in the body and in what we eat (like iodine and selenium).
These are all utterly vital for our health and well-being. Let us now look at minerals in the same way that we looked at vitamins: