**2. Plant metabolites**

In addition to nutritional value, consumption of fruits and vegetables also provide health benefits to humans due to the nature of their secondary metabolites [1]. Plants of all kinds, including fruits and vegetables, possess two types of metabolites with distinct roles known as primary and secondary metabolites as shown in **Figure 1**. Primary metabolites, generally possessed by all plants, are metabolites that contribute to the plants' growth [2]. Primary plant metabolites include carbohydrates, lipids, proteins, and nucleic acids. Secondary metabolites, sometimes found in specific plants or plants parts, are for the performance of protection

**Figure 1.** Plant metabolites and their different roles in plants.

functions from threats that emanate mainly from external factors [3]. Secondary plant metabolites include alkaloids, phenolic compounds, sterols, steroids, essential oils and lignins, and are commonly known or referred to as phytochemicals.
