1
Introduction to Nutraceuticals and Natural Products

Narges Shahgholian

Food Machinery Division, Department of Biosystems Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran

1.1 Introduction

Actually, foods have important bioactive compounds and are the most powerful drugs. According to the old belief of Iranian physicians like Avicenna "Nutrients in small amounts are medicine, in the usual amounts are food and in large quantities are considered toxins for us."

"Focus on prevention rather than cure," which has also been considered in ancient texts, is the key point in the new trend of health considerations. This consciously driven point of view made intense desire to consume dietary supplements, functional food, multifunctional food, etc. Hippocrates (known as the father of medicines) said, "Let food be your medicine and let medicine be your food." (Kalra 2003). There is an ancient Chinese saying, "medicine and food are isogenic."

These foods could delay, manage, or prevent the premature onset of chronic diseases. Research indicates that diets high in fat may increase the risk of cardiovascular disease (CVDs), whereas diets containing plant sterols, omega-3 fatty acids, soluble fibers, or antioxidants may help in preventing these diseases (Shimizu 2003).

What is certain is that food and medicine can have both preventive and curative properties.

Many basic science and clinical researchers focus their research on using naturally occurring chemicals as drugs to treat disease and mitigating chronic inflammation by dietary means, with the goal to prevent the early stages of a pathological condition from progressing into disease (Ullah and Ahmad 2019).

It should be noted that there might be a lot of similar confusing words related to the term "nutraceuticals," such as phytochemicals, pharma foods, medical foods, functional foods, dietary supplements, designer foods, etc. There is a thin dividing line in their interchangeable usage by different people on different occasions. Pharmaceuticals are considered as medications used mainly to treat diseases, while nutraceuticals are the substances that are mostly considered to prevent diseases (Zhao 2007).

The nutraceuticals' revolution is becoming part of the mainstream medical discovery process.

Practitioners are now accepting nutraceuticals as part of the clinical treatment because of more and more scientific medical research.

1.2 Confrontation of Different Definitions of Nutraceuticals

It is better to ask first what "nutraceuticals" are?

The term "nutraceuticals" may be relatively unfamiliar and new, while people have been trusted with their ingredients for hundreds of years. The term "nutraceuticals" was coined by Stephen Defelice MD, founder and chairman of the foundation for innovation in medicine (FIM) Cranford, New Jersy, in 1989 (Brower 1998). According to terminology, "nutraceutical" is a hybrid word composed of "nutrition" (nourishing food) and "pharmaceutical" (component and a medical drug). According to Defelice, "Nutraceuticals are food or part of a food that provide(s) medical or health benefits including the prevention and/or treatment of a disease" (Chauhan et al. 2013). Since then, different definitions of nutraceuticals have been presented.

Health Canada defines a nutraceutical as "a product isolated or purified from foods, that is generally sold in medicinal forms not usually associated with food, is demonstrated to have a physiological benefit or provide protection against chronic disease" (Singh and Orsat 2014).

We come across different definitions of the term "nutraceuticals," each of which defines/interprets it to some extent. Here you can consider some definitions of nutraceuticals (which has nothing to do with the year of its expression):

1. A nutraceutical is something that has both nutritional and medical benefit. To this point, all foods could be considered nutraceuticals (Cao and Sutherland 2018).
2. Nutraceuticals are dietary supplements present in a nonfood matrix that deliver a concentrated form of NBCs from food and used for enhancing health in excess dosages that could be obtained from normal foods (Shahidi 2009; Zeisal 1999).
3. Nutraceuticals are dietary supplements utilized to ameliorate health, delay senescence, prevent diseases, and support the proper functioning of the human body (Sachdeva et al. 2020).
4. A nutraceutical is "a medicinal or nutritional component that includes a food, plant, purified or concentrated naturally occurring material that is used for the improvement of health, by preventing or treating a disease." (Lockwood 2007).
5. Nutraceuticals are food or part of food that provide(s) medical or health benefits including the prevention and/or treatment of a disease, maintaining health and acting against nutritionally induced acute and chronic diseases. Nutraceuticals, on the basis of their natural source, unlike medicine, have no side effects while consumed in certain doses (within their acceptable Recommended Dietary Intakes, thereby promoting optimal health, longevity, and quality of life) (Chauhan et al. 2013).
6. Karla proposed to redefine functional foods and nutraceuticals as the sole item of a meal or diet. While functional foods provides the body with the required amount of nutrients needed for its healthy survival (vitamins, fats, proteins, carbohydrates, etc.), nutraceuticals must not only supplement the diet but should also aid in the prevention and/or treatment of disease and/or disorder. Nutraceuticals are the same as functional foods used with specific-purpose aids in the prevention and/or treatment of disease(s) and/or disorder(s) other than anemia. Thus, functional food for one consumer can act as a nutraceutical for another one (Kalra 2003).
7. Modified in the definition of nutraceuticals: "Nutraceuticals developed from food, dietary substance, traditional herbal or mineral substance or their synthetic derivatives, which are delivered according to the pharmaceutical principles. They are prepared in dosage forms and manufactured under pharmaceutical principles and process controls to ensure the reproducibility and therapeutic efficacy of the product" (Pathak 2009).

What is clear is that most definitions refer to a specific dosage. Pharmaceutical dosage forms mean any forms of pills, tablets, capsules, liquid orals, lotions, delivery systems, as well as dermal preparations. What is certain is that nutraceuticals have gained attention due to nutrition and therapeutic potentials.

To cut a long story short, a general term for nutraceuticals is "food supplements." Another closely related term is "functional foods." It is a difference between nutraceuticals and functional foods. When a bioactive compound is added into a food formulation, it results into a new potential functional food, whereas the equivalent amount of the same substance in a tablet or capsule is considered a nutraceutical (Espín et al. 2007).

1.3 Natural Bioactive Compounds (NBCs)

"Natural bioactive compounds (NBCs)" refer to chemical substances found in nature and represent pharmacologically active agents with distinctive abilities to serve as novel lead compounds or pharmacophores in drug discovery. Some of the most effective drugs in clinical practice are derivatives of natural products (Ullah and Ahmad 2019).

NBCs include pigments (anthocyanins, carotenoids, lycopene, and chlorophyll), herbal polyphenols and flavonoids extract (ginger, garlic, tea, turmeric, etc.), essential oils and omegas, flavors, enzymes, vitamins and minerals, dietary compounds, bioactive peptides and different natural antioxidants. Fruits, vegetables, medicinal plants and other plant-based foods are rich in bioactive phytochemicals that may provide desirable health benefits beyond basic nutrition to decrease or delay the risk of chronic diseases. These compounds have different or similar properties to prevent, delay, or fight against different diseases in our bodies most of them related to inflammation.

NBCs with a broad diversity of chemically active agents and functionalities provide a marvelous collection of molecules for the production of nutraceuticals, functional foods, and food additives.

NBCs have the potential for the treatment and prevention of human diseases. In new researches, NBCs are still more important than ever. It is clear that NBCs are the future in the field of nutraceuticals. Dietary supplements, functional food, multifunctional food, with specific medicinal or health benefit, moreover nutritional effect, fall into this category.

1.3.1 Classification of NBCs (Focusing on a Few Applications)

Nutraceuticals can be classified on the basis of their natural sources (as the products obtained from plants, animals, minerals, or microbial sources), mechanism of action and pharmacological conditions, or as per the chemical constitution of the products.

Bioactive compounds are categorized into the herbal source and dietary supplements. Carbohydrates, proteins, minerals, vitamins, lipids, omegas, fibers, prebiotics and probiotics (synbiotics) and also mushrooms are put in the dietary supplements' group....