Food Factors in Health Promotion and Disease Prevention - ACS

Chapter 1

Food Factors in Health Promotion and Disease Prevention 1

Fereidoon Shahidi and Chi-Tang H o

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Downloaded by 117.253.205.32 on March 7, 2016 | http://pubs.acs.org Publication Date: June 19, 2003 | doi: 10.1021/bk-2003-0851.ch001

1Department of Biochemistry, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X9, Canada 2Department of Food Science, Rutgers, The State University of New Jersey, New Brunswick, NJ 08903-8520

Food factors represent a myriad of different classes of compounds present mainly in plant foods and exert a positive effect in disease prevention and health promotion. The chemicals of interest are present as a mixture and their mechanism of action may be varied and dependent on the presence of other compounds in the "soup" or "cocktail" of extracts under investigation. The compounds involved many function cooperatively and synergistically in exerting their effects on health and disease.

The importance of food factors in health promotion and disease prevention has been an issue of interest since antiquity as evidenced by the Chinese concept of Ying and Yang and the famous saying of Hypocrates "Let food be thy medicine and medicinal be thy food". However, many of the beneficial food factors, at some point, were regarded as "antinutrients" because of their demonstrated effect in lowering nutritive value of food by "protein precipitation" or by toxic effects and growth depression when consumed in relatively large quantities. More recently, the concept of "nutraceuticals", "functional foods", "phytochemicals" and "bioactives" has brought about a better understanding of

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© 2003 American Chemical Society Shahidi et al.; Food Factors in Health Promotion and Disease Prevention ACS Symposium Series; American Chemical Society: Washington, DC, 2003.

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the health promoting activity of many of the minor components of foods as well as certain plant products in the entirety. Thus, effects of food bioactives on gene regulation, signal transduction and modulation of different mechanistic pathways have been studied in relation to their preventive affect on a number of chronic diseases such as cancer, coronary heart disease, diabetes, immune and others. Although the mechanisms of action of bioactives are variai, often antioxidant activity of food components is an issue of interest in supplementing body's ability to neutralize excess free radicals in the elderly and in those suffering from certain diseases and ailments. The food factors of importance to health may be classified into several groups, but not limited to those listed below: >- terpenoids and saponins enzyme inhibitors glucosinolates and their breakdown products >- essential fatty acids, including long-chain omega-3 fatty acids >- phenolics and polyphenols • carotenoids • lignans and related compounds While each plant material may be dominated by the presence of one group of phytochemicals, often several classes of bioactives are present in a certain plant. These compounds/classes of compounds provide a "cocktail" or "soup" that may function in a "cooperative" and "synergistic" manner to exert the beneficial health effects related to the particular material under consideration. Terpenoids and Saponins The terpenoids are a class of secondary plant metabolites that are lipophilic in nature and represent the largest and most diverse class of plant compounds (1,2). The common biosynthetic pathway in their production involves combination of isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate to yield geranyl pyrophosphate which affords monoterpenes (CIO) followed by further combination with more IPP molecules to afford sesquiterpenes (C15), triterpenes (C30) and tetraterpenes (C40). Terpenoids act as allelopathic chemicals and hence have insecticidal activity as well as attraction of insects as pollinators. Some important plant hormones such as abscisic acid and gibberelli acid also belong to the sesquiterpene and diterpene group of compounds, respectively (2). Some important plant terpenoids in food components are myrecene from bay leaves, geraniol from roses and citronella,

Shahidi et al.; Food Factors in Health Promotion and Disease Prevention ACS Symposium Series; American Chemical Society: Washington, DC, 2003.


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and menthol from peppermint, linalool from coriander, pinene and limonene from conifers as well as the widely spread saponins (1,3). Saponins are made of a triterpene or a steroid attached to a sugar moiety and may be distributed in a wide variety of plants. Many types of saponins have teen isolated from soybean seals and these may te divided into two groups; group A and DDMP (2,3-dihy(fro-2,5-dihydroxy-6-methyl-4Hpyran-4-one) saponins. Group A saponins are present only in the soybean hypocotyl, while DDMP saponins are widely distributed in leguminous seeds and are present in both hypocotyl and coltedon. From pharmacological or health point of view, saponins have teen reported to exhibit various effects such as hypolipidemic, antioxidative and HIV infection inhibitory properties. The hypocholesteralenic effect of saponins is quite strong, especially when fed in the presence of cholesterol.

Enzyme Inhibitors There are numerous proteins in higher plants that inhibit enzymes found in plants, animals including humans and microorganisms. These may serve endogenous physiological functions in plant or serve a protective role. There are different classes of enzyme inhibitors amongst which protease inhibitor and amylase inhibitors might be most important Bowman-Birk inhibitors are best known for their health effects, especially against anglogenesis. They are also known to inhibit or prevent the development of chemically-induced cancer of the liver, lung, colon, oral and oesophagus. Lectins from many plant seed extracts are capable of agglutination of erythrocytes and exhibit a wide variety of biological effects. These include possible preferential agglutination of tumor cells, inhibition of tumor growth, inhibition of fungal growth and insecticidal action, among others (4). The unique property of lectins in binding specific sugar residues located on the surface of cells resulting in agglutination is responsible for these effects (5).

Glucosinolates and their Breakdown Products Glucosinolsates are found universally in the family of Brassicaceae in some other angiosperm families (6). Glucosinolates are found in plants along with the enzyme myrosinase which catalyzes their degradation once the plant material is macerated. Although glucosinolates as such are non-toxic, some of their breakdown products may have toxic effects. The biological activity of glucosinolates in most cases is dependent on their hydrolysis and production of certain degradation products. The role of glucosinolates in plants is for defense purposes. The breakdown products of glucosinolates may disturb the fluidity of biomembranes and bind to some enzymes, receptors or other macromolecules


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such as DNA (7). Some major glucosinolates and their respective breakdown products include glucobrassicin giving rise to indole-3-carbinol, gluconasturtin producing phenethyl isothiocyanate, and glucoraphanin affording sulforaphane, among others. Several isothiocyanates have also been shown to inhibit or block tumors induced by chemical carcinogens and 1 -isothiocyanate-4(methylsulfinyl) butane or sulforaphane, isolated from broccoli is a potent inhibitor of mammaiy tumors. Indolyl glucosinolates and their breakdown products, such as indole-3-carbinol play a major role in cancer prevention.


Essential Fatty Acids The essential fatty acids are those that are not produced by the body and need to be acquired from dietary sources. Thus, while saturated and monounsaturated fatty acids may be prepared in the body, polyunsaturated fatty acids containing two or more double bonds have to be obtained from food and possibly supplements. The main polyunsaturated fatty acid groups are parented by linoleic acid (18:2 n-6) and linolenic acid (18:3 n-3). Each of these fatty acids could undergo a series of chain elongation and desaturation to produce other important fatty acids which are important in the body. In particular, production of arachidonic acid (20:4 n-6) from linoleic acid and that of eicosapentaenoic acid (EPA 20:5 n-3) and docosahexaenoic acid (DHA, 20:6 n-3) from linolenic acid is important. Other conditionally essential fatty acids are GLA (gamma-linolenic acid) and CLA (conjugated linoleic acid), among others. The C20 polyunsaturated fatty acids are precursors to eicosanoids and play multifunctional roles in the human body. The importance of long-chain omega-3 fatty acids from marine and algal sources in health and disease has been well explained in the literature (8,9).

Phenolics and Polyphenols Phenolic and polyphenols compounds are found in relatively large quantities and in a variety of chemical forms in plant foods and serve as secondary metabolites that protect plant tissues against injuries, insect and animal attack. They also serve as UV filters, signaling agents and free radical scavengers. These belong to the phenylpropanoid (C -C ) family and are derivatives of cinnamic acid; these are produced from phenylalanine and to a lesser extent in some plants from tyrosine. Benzoic acid derivatives may subsequently be formed from Ce-C compounds via the loss of a two-carbon moiety. Condensation of C - C compounds with malonyl co-enzyme leads to the formation of chalcones which cyclize under acidic conditions to flavonoids and isoflavonoids, among others. Tocopherols and tocotrienols are another group of phenolics found in plants (10). 6

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6 Phenolic acids, phenylpropanoids andflavonoidsmay occur in the free form, but are often glycosylated with different sugars, especially glucose. While the presence of sugar moieties in such compounds is responsible for their specific characteristics, they do not have any significant effect on the biological activity of compounds involved, once ingested. Phenolic acids may also be present in the esterified as well as bound forms. Phenolic compounds have a myriad of health benefits related to cancer prevention, effects on cardiovascular disease by inhibition of cholesterol oxidation and other mechanisms and the process of aging, among others (1112).


Carotenoids Carotenoids are among the most widely distributed class of compounds in nature, particularly among organisms that are exposed to light They possess a C4o-backbone and may be acyclic or have a cyclic end-group. In food, dietary carotenoids have been mostly studied for their protective effect against a variety of degenerative diseases, such as cancer (13), cardiovascular disease (14), and age-related macular degeneration (15). The mechanisms of cancer chemopreventive action of carotenoids are varied and include upregulation of the gene expression and gap junction proteins. The anti-inflammatory properties, anti-tumor promoting property and induction of the phase 2 detoxification enzymes are among mechanisms by which carotenoids function. Thus formulation of mixtures, as nutraceuticals, which could closely resemble those present in the healthy individuals who consume a diet rich infruitsand vegetables might prove beneficial.

Lignans and Related Compounds Lignans are present in higher plants including cereals, legumes, oilseeds, fruits and vegetables. Lignans are a group of diphenolic compounds formed by the union of two cinnamic acid residues and comprised of a dibenzylbutane backbone (13). The lignan, seeoisolariciresorsinol diglycoside (SDG) is found in a relatively large amount inflaxseed(16). Flax lignans act as natural anticancer agents. Thus the total number of aberrant crypts and reductions in early risk markers for mammary tumors and tumors size were demonstrated in rats fed a high-fat diet supplemented with flaxseed. Other Food Factors There are many other food factors that are of interest with different biological activities and potential beneficial health effects. These include


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biopeptides, carbohydrates, çyanogenic glycosides, tetrahydro-e-carboline derivatives as well as sulfur-containing compounds from garlic, among others. In addition, pre- and probiotics are of interest in view of their effects on health and disease prevention.

References 1.


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Brielmann, H.L., Jr. In Natural Products from Plants. P.B. Kaufman, L.J. Cseke, S. Warber, J.A. Duke and H.L. Brielmann, Eds. CRC Press: Boca Raton, FL. 1999, pp. 1-36. Harborne, J.B. In Chemicals from Plants: Perspectives on Plant Secondary Metabolites. N.J. Walton and D.E. Brown, Eds. Imperial College Press: London, UK. 1999, pp. 45-59. Gershenzon, J.; Kreis, W. In Biochemistry of Plant Secondary Metabolism. Annual Plant Reviews, Volume 2. M . Wink, Ed. Sheffield Academic Press: Sheffield, UK. 1999, 222-299. Liener, I.E. In Herbivors: Their Interaction with Secondary Metabolites. Volume 1. The Chemical Participants. G.A. Rosenthal andM . R .Berenbaum, Eds. Academic Press: San Diego, CA. 1991, pp. 327-353. Harborne, J.B. In Secondary Plant Products: Antinutritional and Beneficial Actions in Animal Feeding. J.C. Caygill and I. MuellerHarvey, Eds. Nottingham University Press: Nottingham, UK. 1999, pp. 7-16. Shahidi, F.; Daun, J.K.; DeClercq, D.R. In Antinutrients and Phytochemicals in Food. ACS Symposium Series 662. F. Shahidi, American Chemical Society: Washington, D.C. 1997, pp. 31-43. Selmar, D. In Biochemistry of Plant Secondary Metabolism, Annual Plant Reviews, Volume 2, M . Wink, Ed. Sheffield Academic Press: Sheffield, UK. 1999, pp. 79-150. Shahidi, F.; Finley, J.W. Omega-3 Fatty Acids: Chemistry, Nutrition and Health Effects. ACS Symposium Series 788. American Chemical Society: Washington D.C. Shahidi, F.; Kim, S-K. In Bioactive Compounds in Foods: Effects of Processing and Storage. ACS Symposium Series 816. T-C. Lee and C-T. Ho, Eds. American Chemical Society: Washington, D.C. 2002, pp. 1-13. Shahidi, F. Nahrung 2000, 40, 158-163.


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Shahidi, F. Natural Antioxidants: Chemistry, Health Effects and Applications. AOCS Press: Champaign,IL,1997, pp. 1-414. Shahidi, F.; Ho, C-T. Phytochemicals and Phytopharmaceuticals. AOCS Press: Champaign, IL. 2000, pp. 1-431. Ziegler, R.G. Am. J. Clin. Nutr. 1991, 53 (Supp.), 251S-259S. Morris, D.L.; Kritchevsky, S.B.; Davis, L.E. J. Am. Med. Assoc. 272, 1439-1441. Bernstein, P.S.; Khachik, F.; Carvalho, L.S.; Muir, G.J.; Zhao, D.Y.; Katz, N.B. Exp. Eye Res. 2001, 72, 215-223. Rickard, S.E.; Thompson, L.V. In Antinutrients and Phytochemicals Food. ACS Symposium Series 662. Shahidi, F., Ed. American Chemical Society: Washington, D.C. 1997, pp. 273-293.


Food Factors in Health Promotion and Disease Prevention - ACS

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