Phytochemicals and gastrointestinal health

Buddington and Y. Kimura, Mississippi State University, USA and Y. Nagata, Otsuka Pharmaceutical Co. Ltd, Japan 

As could be predicted, the magnitude and patterns of responses to phytochemicals vary among individuals and between animals with different evolutionary diets. 

No other organ system has the same level of exposure and diversity of responses to phytochemicals. Because virtually all characteristics of the GIT are influenced by phytochemicals, there are many opportunities to improve health and nutritional status. Our objective in preparing this contribution was to provide readers with insights into the known and potential interactions 

The mucosa of the GIT represents an interface between the external and internal environments. The expansive surface area is necessary for the efficient hydrolysis of foodstuffs and the absorption of energy and nutrients. The mucosa also influences the systemic availability of non-nutrient compounds in the diet, both beneficial and detrimental. Digestion and absorption of glucosinolates are critical determinants of health benefits (see Chapter 4) Similarly, the bioavailability and health benefits of phytoestrogens, such as genistein (see Chapters 5 and 10) are at least partly dependent on the carrier-mediated processes of absorption associated with the GIT (Oitate et al, 2001). Moreover, the metabolic activities of the mucosa can influence the systemic concentrations and forms of dietary phytochemicals, as exemplified by research with soy isoflavones (Andlauer et al., 2000). 

The different types or classes of phytochemicals can have multiple influences on the GIT (Kitts, 1994). For example, caffeine stimulates the motor, hormonal and secretory functions (Boekmaefa/., 1999). Although many phytochemicals reduce nutrient quality or availability, traditional herbal medicines have exploited some of these characteristics to improve health. Moreover, some of the systemic responses attributed to certain phytochemicals (beneficial or detrimental) can be explained by their influences on the GIT (Carbonaro et al., 2001). To date, the most of the information about phytochemicals is focused on the reductions in the functional capacities of the GIT (the bad), or the toxic properties (the ugly). There are also numerous examples of phytochemicals that can be used to obtain desirable GIT characteristics (the 

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The above scientific information on rice bran phytochemicals indicates that a multitude of mechanisms are operating at the cellular level to bring about specific health effects. Several health benefits of rice bran appear to be the result of the synergistic function of the many phytochemicals, antioxidants, vitamins and minerals which operates through a specific immune response. Their role in the biochemical mechanisms at the cellular level which result in major health effects is shown in Fig. 17.1. A short overview summarizing the effect of the various phytochemicals on major health issues such as cancer, immune function, cardiovascular disease, diabetes, altered liver function and gastrointestinal and colon disease will be given below. 

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