Fish is considered as an affordable source of protein, serving a worldwide population as well as a source of nutraceutical. Bioactive components present in our diet play a major therapeutic role against human diseases.
1. Introduction
Traditionally, fish is considered as an affordable source of protein, serving a worldwide population as well as a source of nutraceutical importance
[1]. In addition, about one-half of the total biodiversity is comprised of fish and other marine species, which are also a wonderful source for novel bioactive compounds, implicated in the continuous improvement of human health
[2]. Several bioactive components present in fish such as lipids, proteins, vitamins, minerals, and other fish by-products are considered important due to their therapeutic potentiality. More importantly, the main therapeutic potential of fish consumption has been ascribed with the presence of long-chain omega-3 polyunsaturated fatty acids (PUFAs) in high content. Several reports suggested that, other than long-chain omega-3 PUFAs, various other bioactive components from fish have been found to have a positive effect on human health
[3]. According to the World Health Organization
[4] and American Heart Association
[5], fish should be consumed on a regular basis (i.e., 1–2 servings weekly). It should provide approximately 200–500 mg dose of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which can be easily obtained from fish that contain omega-3, for example, salmon or trout. This will protect against various coronary heart diseases and stroke. On the other hand, the nutritional status of fish and fish products shows that they contain high amounts of other healthy nutrients with countless health benefits
[6].
Recently, it has been seen that, in developed as well as developing countries, lifestyle-related diseases have become a serious issue to the human population. Various epidemiological data and clinical trials have shown that diet is one of the major factors, other than stress and strain in modern life, influencing lifestyle-related diseases, especially in middle-aged and senile people. Imbalance in lifestyle and diet pattern in developed countries has caused a rise in chronic diseases, such as obesity, diabetes, hypertension, and hyperlipidemia, affecting both wellness and well-being
[7].
2. Nutritional Profile of Fish
Fish is one of the supreme and essential foods in the human diet, due to its eminent nutritional value. Proximate analysis of almost all the fish or fish related foods have been studied by researchers. However, minor discrepancies in nutritional composition exist due to their feeding habits, age, sex, season, temperature, adaptation, and hatching
[8]. Further reports and analyses state that fish provide protein of a superior quality with all the essential amino acids, as well as elemental sources of dietary vitamins and minerals, including zinc (marine fish), iron, calcium, phosphorus, iodine, selenium, vitamin A, D, E, several B vitamins (B3, B6, and B12), important amounts of PUFAs and various other micronutrients
[9][10][11]. As it is known that most small fishes are eaten whole (with bone, scales, and fins), they are a rich source of abundantly bioavailable calcium. One such example of small fish is
Amblypharyngodon mola, which is reported to be a rich source of vitamin A, in the form of dihydro-retinol and retinol
[12]. Furthermore, bioavailability of zinc and iron from the other foods in a meal is enhanced by fish
[10]. The chief chemical composition of fish muscles is protein, water, and lipids, which collectively hold around 98% of the total weight. Meanwhile, average proximate compositions as well as micronutrients of fish are presented in
Figure 1 and
Figure 2, respectively.
Figure 1. Average mean proximate composition data * from 62 species of fish
[13].
Figure 2. Average mineral composition (mg) of fish
[8]. *
[11]; **
[14]; ***
[15].
3. Fish as Nutraceuticals
Stephen DeFelice first coined the word “nutraceutical” by combining two words “nutrition” and “pharmaceutical”. He defined nutraceutical as food or a part of food which not only imparts health benefits but also contributes to preventing/treating various diseases
[16][17]. Moreover, in broad terms, nutraceuticals play a vital role in human beings by maintaining their normal physiological functions and well-being. Although fish has always been superior and dominant on other protein nutraceuticals and functional foods, research programs on fish-based nutraceuticals and functional foods have reached a saturation point. Even awareness related to its benefits is lacking and should be underpinned
[18]. Awareness programs only reach the urban population of countries and somehow the rural population is excluded. Moreover, based on a PubMed search using keywords like nutraceuticals and functional foods, a number of research articles were published at a rapid pace since 1995. However, a change in the search of keywords to fish as nutraceuticals/functional food, the rate of publication has been fairly stagnant since 1980 (
Figure 3). This shows the saturation level of this field of study which is a matter of concern.
Figure 3. Graphically represented statistical data * of number of publications in PubMed from 1980 to 2019. * Publications in PubMed when using search bar for searching several keywords/phrases: (1) nutraceuticals (blue); (2) fish as nutraceuticals (orange); (3) functional food (grey); and (4) fish as functional food (yellow). Moving average trend lines show the importance and urgent need for research concerning the development of cheap fish/fish wastes/fish by-products-based nutraceuticals and functional foods.
Fish nutraceuticals can be used to improve health in various ways: it can delay the ageing process, prevent acute and chronic diseases, increase life expectancy, and support the basic structure and functions of the body
[19][20][21]. Urbanization of the population and health awareness among people with either a sedentary lifestyle or stressed lifestyle are the foremost causes of increased growth in the nutraceutical market worldwide
[22]. Recent reports suggested that nutraceuticals provide positive tactics to manage healthcare with remarkable beneficial effects on human health
[23]. A wide range of phytochemicals such as terpenoids, glucosinolates phytosterols, limonoids, anthocyanidin, polyphenols, phytoestrogens, carotenoids, isoflavonoids, flavonoids, etc., have shown numerous therapeutic effects on human well-being, such as anti-inflammatory, antioxidants, antibacterial, anti-allergic, etc.
[24][25][26][27][28][29]. These nutraceuticals alone or in combination with other therapies, not only help in maintaining health and promoting quality of life, but also combat serious medical illnesses of the current era, such as diabetes, cancer, cardiovascular diseases, cholesterol, arthritis, obesity, osteoporosis, etc.
[22][30][31]. Therefore, low-cost nutraceuticals have always been in special demand, particularly among economically vulnerable or reduced income groups. This way fish or fish by-products can also solve the global malnutrition problem and related disorders by providing vital micro and macronutrients, high-density fats, and easily digestible proteins
[32]. These essential nutrients have many more beneficial physiological roles than other proteins
[1].