Messelements

Messelements, or meso-elements, is a term used in some nutrition and plant science texts to describe elements that are required by living organisms in amounts intermediate between macronutrients and trace elements. The concept is not universally standardized, and definitions or boundaries vary across fields; in many reviews the classification relies on the traditional division into macroelements and trace elements, with mesoelements treated as an informal or debated third tier. As a result, there are no widely accepted dietary recommendations or official lists of mesoelements applicable across species.

In plants, mesoelements are sometimes discussed using silicon as a frequently cited example of a non-essential or quasi-essential element that can benefit growth and stress tolerance in certain species. Other elements that have been proposed as mesoelements in some contexts include boron and several trace metals, though their essentiality and mid-range requirements are species-dependent. In animals and humans, the mesoelement concept is less established, and most nutrition frameworks do not assign formal roles or numerical intake values to mesoelements; they focus on macroelements such as calcium and potassium and trace elements such as iron and zinc.

Because of the lack of consensus, mesoelement status is primarily of interest in theoretical discussions and comparative biology rather than in standard dietary planning. The term highlights that the boundary between macro- and trace minerals is not always clear-cut and can differ among organisms and environments.