Phytochemicals, polyphenols, bioactive compounds, phytonutrients, and nutraceuticals
These are terms you've heard a lot. All of these words are used interchangeably in most cases. All these terms refer to the substances that are related to plants and produced by plants and can affect health. Personally, it's a field I'm very interested in, so I tend to look for various materials. It's already a complex and difficult concept, but these interchangeable terms make my head feel even more dizzy.
I just stumbled across an excellent article that points out the importance of harmonizing  terminology and naming for plant-derived components in nutrition and related research. The paper emphasizes the need for international efforts and collaboration to achieve this. As an individual who frequently encounters these terms, I find the efforts towards standardization and naming convention quite welcome.
When we have a clear understanding of the terms and their meanings, we can navigate through the vast ocean of information more effectively and it allows us to filter and identify the relevant information that relates with our interests and needs.


Lets look into each term in a bit more detail,

1. Phytochemicals

Phytochemicals, derived from the Greek word "phyton" meaning plant, are compounds that are naturally present in plants or derived from plants. They are considered plant metabolites, meaning they are produced by plants during their metabolic processes. Phytochemicals can be classified into various subgroups based on their chemical structures;  phenols, polyphenols and tannins, sulfur-containing compounds (ex. sulforaphane), terpenes, alkaloids (ex. caffeine), acetylene and psoralen, and carotenoids (ex. lycopene, lutein). 

2. Polyphenols:

Polyphenols are a specific subgroup of phytochemicals that contain one or more phenolic rings in their chemical structure. It is important to note that the term "polyphenols" is primarily a concept based on chemical structure and does not directly imply biological efficacy or a specific relationship with health.

3. Bioactive compound:

The term "bioactive compound" refers to a substance that has physiological activity or effects on living organisms. While it is commonly associated with compounds found in plants, the term itself is not limited to plant-derived substances. In fact, bioactive compounds can include a wide range of substances originating from various sources, including animals, bacteria, the environment, and even synthetic compounds.

4. Phytonutrient: 

Phytonutrients, as the name suggests, are nutrients that are derived from plants. They are different from traditional nutrients in the sense that they may not be essential for basic growth and life support like vitamins and minerals. However, phytonutrients are believed to offer numerous health benefits and contribute to overall wellness. Unlike traditional nutrients, phytonutrients are not considered essential in the same way.

5.  Nutraceutical :

The term "nutraceutical" is a combination of the words "nutritional" and "pharmaceutical." It is a term used in a specific and narrow sense within the area of dietary and health-related products. Nutraceuticals refer to products that contain dietary ingredients or supplements that are believed to have beneficial effects on health.
The five categories mentioned earlier have distinct meanings and differ in terms of their origin, chemical structure, and intended use. With all these considerations, these concepts do have overlapping areas, but each of them exists independently and carries its distinct meaning and role. This diagram explains the relationship between theses concepts very clearly.
Diagram showing the relationship between 5 concepts
Polyphenols are a specific type of phytochemical, which means all polyphenols are phytochemicals, but not all phytochemicals are polyphenols. While phytochemicals are primarily associated with plant-based sources, bioactive compounds can originate from various sources including plants, animals, bacteria, and even synthetic compounds. Some phytonutrients are polyphenols, but by definition, all phytonutrients can be considered bioactive compounds.
This understanding will certainly make it easier process other concepts within this big frame. For example, lets talk about the concept of antioxidant. They are a type of bioactive compound that help reduce oxidative stress in our body. This can include a variety of compounds such as polyphenols, flavonoids, and vitamins C and E. These compounds can all be phytochemicals and therefore classified as phytonutrients. Well this is the way I will process the concept from now.
I enjoyed and benefited so much from this not too long article. It will surely guide me better in assessing the information I come across whether they are credible, reliable, and applicable to whatever context they are.