Which of the following statements is true about a diet high in phytochemicals?

3 Types of phytochemicals

Phytochemicals have great antioxidant potential and are of great interest due to their beneficial effects on health of human beings, and they give immense health benefits to the consumers. Epidemiological and animal trials suggest that the regular consumption of fruits,and vegetables, and whole grains reduces the risk of various diseases linked with oxidative damage (Cieslik et al., 2006; Scalbert et al., 2005; Kris-Etherton et al., 2002). The natural antioxidants are classified into two categories namely in vitro and in vivo antioxidants. Free radical scavengers act as hydrogen donors, electron donor, peroxide decomposer, singlet oxygen quencher, enzyme inhibitor, synergist, and metal-chelating agents.

Among the phytochemicals mentioned as potentially providing health benefits are polyphenols, flavonoids, isoflavonoids, anthocyanidins, phytoestrogens, terpenoids, carotenoids, limonoids, phytosterols, glucosinolates, and fibers. These antioxidant-rich phytochemicals are explained below in Table 11.1.

Table 11.1. Antioxidant-rich phytochemicals with their food sources and health benefits.

1.4 Use claim of phytochemicals in patents

The phytochemicals are used as functional food, soft drinks, and many other food items, which are having good nutrient value and significant importance, economically. To this Szilbereky et al. (2018) (Fitorex Kft., EP2908664B1) have published a raw material for functional foods in which the seeds of cereals, leguminous plants, soy-beans, rice, wheat, oat, chick pea, or maize have been used. Similarly, Seth (2018) (US20180352834A1) has disclosed a food composition of palmitic acid, linoleic acid, p-coumaric acid, oleic acid, caffeic acid, pantothenic acid, and antioxidative agents including vitamins E, C, B1, or B6. The claimed food composition is applicable for most of the mammals (e.g., dog food).

In India, phytochemicals, as well as medicinal plants, have remained the most abundant source of health care and life improvement since very long. India is the richest source of traditional herbal plants with their prescriptions. In India, Ayurvedic, Unani and Siddha medico-therapeutics are playing a very important role in the society since ancient time. Ayurveda is approximately 5000 years old and predominantly uses phytochemicals in their preparations and formulations. Now in modern era, about 24%–27% drugs are derived from the plant sources. Several synthetic drugs also have been developed as the analogs/prototype of the natural phytochemicals, which serve as lead compounds for these synthetic drugs.

India, being one of the richest plant biodiversity countries in the world, has Western Ghats and Himalayas as the regions rich in plant biodiversity in the country. About 7500 plant species out of 43,000 (that exist in the country) are recorded in various medicines, and ∼1700 species are acknowledged in the Ayurvedic literature. In India, phytochemicals are not limited to medicinal use only, but also they have been used in cosmetics, health and hygiene, fragrance, and food supplements.

The IPR aspect for phytochemicals developed in two schemes: (a) The phytochemicals which are extracted from the natural plants and their use; and (b) Scientifically advanced version of medicinal plants (improved plant varieties) and their extracted phytochemicals. The improvement has been achieved by several private agencies in terms of yield, intrinsic quality, and more resistance or tolerance against pest and diseases. To improve/produce the phytochemicals from the plants, several advanced technologies have been used such as genetic engineering, molecular techniques, etc. Hence, more legal protection has been required for various processes and products of molecular breeding.

2.8 Phytochemical compounds in dates

Phytochemicals are non-nutrient bioactive components that are primarily responsible for scavenging toxic radicals after oxidative stress by generating antioxidants, the main cause of most chronic diseases (Al-Harrasi et al., 2014). Fruit phytochemicals displayed high antioxidant capacities linked to lower incidence of degenerative diseases and lower mortality average in humans (Baliga et al., 2011; Wang et al., 2013). Phenolic acids, flavonoids, tannins, carotenoids, isoflavons, sterols, and lignans are some of date phytochemicals of the fruits that are considered bioactive. Table 1 includes the role of these phytochemicals and their levels in date fruits when it comes to disease prevention.

Table 1. Phytochemicals and the role of date varieties (Gnanamangai et al., 2019).

IV Summary

Numerous bioactive phytochemicals are found in commonly consumed plant foods, including fruits, vegetables, beverages, and spices. Their widespread presence in the diet and apparent low toxicity suggest that phytochemicals have the potential to impact human health and disease risk on the population level. Considering this potential benefit, interest in factors affecting their bioavailability from common dietary sources has grown. When considering bioavailability, dietary phytochemicals can be divided into two distinct classes: water-soluble (phenolics and polyphenols) and lipid-soluble (carotenoids, tocochromanols, and curcuminoids). Significant efforts have been placed on the identification of food factors (macro- and microcomposition, physical form, phytochemical concentration, etc.) and in vivo biological factors (digestion, absorption, metabolism, distribution, and excretion processes) which impact bioavailability in humans and experimental animal models. Such knowledge is critical to improve the bioavailability of health-promoting phytochemicals, and to better understand the mechanisms by which they exert their biological activities at target tissues.

2.5 Essential Phytochemicals

Phytochemicals are precious for human nutrition. Indoles, isothiocyanates, and sulforaphane from vegetables, such as broccoli, alylic sulfides from onions and garlic and isoflavonoids from soybeans are known as plant phytochemicals. These are present in high concentration in raw foods but intensities are reduced during processing and handling (Wang and Murphy, 1996). Enhanced amount of phytochemicals in foods can resolve this difficulty. Two genes IFS1/IFS2, encoding for isoflavone synthase in soybean are revealed and expressed in Arabidopsis thaliana, to activate the synthesis of isoflavonoid genistin (Jung et al., 2000).

Defining Bioactive Phytochemicals

Phytochemical is a broad term meaning plant (phyto) chemical referring to a wide variety of compounds that occur naturally in plants. The term bioactive also has broad meaning. Guaadaoui et al. (2014) defined bioactive compounds as those that have the ability to interact with one or more component(s) of a living tissue presenting a wide range of probable effects. Generally, phytochemicals have been classified into six major categories based on their chemical structures and characteristics. These categories include carbohydrate, lipids, phenolics, terpenoids and alkaloids, and other nitrogen-containing compounds (Figure 1; Harborne and Baxter, 1993; Campos-Vega and Oomah, 2013). Within each category, further division based on biogenesis or biosynthetic origin gives rise to different subcategories.

In recent years the term ‘phytochemical’ has been used to distinguish plant chemicals that do not meet the classical definition of ‘essential nutrients.’ Some phytochemicals produce activity in biological systems, including humans; hence, the term ‘bioactive phytochemicals.’ Liu (2013) has defined phytochemicals as bioactive nonnutrient compounds in fruits, vegetables, grains, and other plant foods that have been linked to reductions in the risk of major noncommunicable chronic diseases. In this review, nonnutrient compounds derived from plants that have biological activity in humans are considered to be bioactive phytochemicals. These include phenolic compounds, terpenoid compounds, and alkaloids. More than 5000 individual dietary phytochemicals have been identified in plant foods (i.e., fruits, vegetables, whole grains, legumes, and nuts) with varying content and composition. However, a large percentage of these compounds still remain unknown with respect to chemical structure and/or the biological role in humans (Liu, 2013).

Cytochrome P450

Phytochemicals are largely metabolized by the same enzymes that metabolize food and drugs. First described and discovered in the 1950s by Julius Axelrod, cytochrome P450 (CYP450) are a set of enzymes capable of promoting excretion of xenobiotics through hydroxylation reactions using a heme molecule as a cofactor (Axelrod, 1955; Berg et al., 1976). Phytochemicals interact with CYP450 as substances to be metabolized, and select phytochemicals are also capable of inducing and/or inhibiting specific or multiple CYP enzymes. Naturally, the abundance of specific CYP enzymes varies by ethnicity and also by individuals. Therefore, effectiveness of medications for different patients and interactions between medications also vary across individuals. Ingestion of phytochemicals from TCMs should be used with caution, especially when patients are concurrently using western therapeutics because induction and/or inhibition of enzymes can lead to a decreased or increased dose of the phytochemical or western medication. Toxic effects are especially of concern for medications or phytochemicals with a narrow therapeutic index or high toxicity profiles, such as warfarin or ginkgo nuts, respectively. As the usage of herbal compounds becomes more prevalent, even in the United States, it is important for prescribers to be aware of possible cytochrome interactions that common herbal decoctions can cause.

12.5.1 Diet and Nutrition’s Impact at the Molecular Level

The phytochemicals impart a plant with color, aroma, and flavor and a protection from infection and predators. The phytochemicals may stimulate the immune system, slow the growth rate of cancer cells, and prevent DNA damage that can lead to cancer and other diseases as described in the following section suggesting that many phytochemicals are antioxidants protecting the cells of the body from oxidative damage from water, food, and the air. Eating a balanced diet which includes whole grains, legumes, nuts, seeds, and a variety of colorful fruits and vegetables provides the body with phytochemicals [8].

4.3.5 Phytochemicals

Phytochemicals are non-nutritive components present in a plant-based diet (‘phyto’ is from the Greek word meaning plant) that exert protective or disease-preventing effects. They have been associated with protection from and/or treatment of chronic diseases such as heart disease, cancer, hypertension, diabetes and other medical conditions (Surh, 2003). A range of different phytochemicals, including tocols, folate, sterols, phenolic acids and alkylresorcinols, are found in barley in small amounts (Table 4.8). The folate content in the barley grain is higher than that observed for wheat and oats (Andersson et al., 2008). Andersson et al. (2008) showed that the levels of phytochemicals in barley can be manipulated by breeding and that the contents of single phytochemicals may easily be adjusted by careful selection of a genotype.

Table 4.8. Phytochemical content of barley (%w/w)

Source: Andersson et al. (2008).

6.5 Conclusion

Phytochemicals are found in plants and their consumption generally provides beneficial health effects. Preclinical, clinical, and epidemiological research suggests that phytochemicals may be effective in treating various diseases owing to their antioxidant and antiinflammatory activities. On the other hand, consumption of certain phytochemicals may cause some acute and chronic toxic effects and may even cause the development of cancer. It is obvious that the number of phytonutrients taken, the individual’s age and gender, and the conditions, as well as exposure levels, are important in the occurrence of potential risks. The daily consumption of specific phytonutrients may easily reach high levels when high doses of related compounds containing dietary supplements are taken simultaneously. Consumers need to know the right phytonutrient dose they should take in either foods or dietary supplements. Consequently, the safety assessment of phytopharmaceutical preparations should be very well established before use.