Historically, spices have shaped many events throughout the world. Many voyagers, including the legendary Christopher Columbus, explored the seas in search of treasured spices. These valued commodities contribute not only flavors but also serve as colorants and preservatives in a wide variety of cultures. Today, spices are increasingly revered not only for their culinary properties but also for their potential health benefits. Although the health attributes associated with spice use may arise from their antioxidant properties, their biological effects may arise from their ability to induce changes in a number of cellular processes, including those involved with drug metabolism, cell division, apoptosis, differentiation, and immunocompetence.
The complexity of understanding the biological response to spices first surfaces in the criteria used to distinguish what constitutes a culinary spice and how they differ from culinary herbs. These terms are often used interchangeably in the scientific and lay literature. The U.S. Food and Drug Administration (FDA) defines a spice as an “aromatic vegetable substance, in the whole, broken, or ground form,” whose significant function in food is “seasoning rather than nutrition” and from which “no portion of any volatile oil or other flavoring principle has been removed” (Food and Drug Administration 2007:205-208). While this is a viable definition, it does not consider the biological consequences of consuming these items and how they differ from herbs. The U.S. National Arboretum offers an alternative definition and describes spices as “flavorings (often of tropical origin) that are dried and culinary herbs that are fresh or dried leaves from plants which can be used for flavoring purposes in food preparation” (United States National Arboretum 2002). We must remember that the quantity of an item consumed does not dictate its importance. Thus, to avoid the health significance in any definition would appear flawed. In this chapter, we use the terms “herbs” and “spices” interchangeably and assume that both have properties that extend beyond simply providing flavor and color.
There is little doubt that nutrition and health are intimately linked (Kennedy 2008). For generations, people have alleged that foods provide greater benefits than simply supplying energy. Beliefs in the medicinal properties of foods have surfaced in many early writings of man. Hippocrates is frequently quoted as having said “Let food be thy medicine and medicine be thy food.” Epidemiological, preclinical, and clinical studies continue to provide fundamental insights into the dynamic relationships between nutrients—defined here as any substance in the diet that brings about a physiological effect—and health. Today, claims about the ability of foods, including spices, to lower disease risk or to enhance the quality of life continue to captivate our lives (Kaefer and Milner 2008; Kochhar 2008; Krishnaswamy 2008; Iyer et al. 2009). Three types of biomarkers— exposure, effect, and susceptibility—are needed to evaluate the effects of spices in cancer prevention and therapy (Figure 17.1). Additional information about the amounts of specific spices required to bring about a response (effect) and the interactions of spices with other constituents of the diet, microbes in the gastrointestinal tract, environmental exposures, and human genetics (susceptibility factors) will be needed to unravel the true benefits of adding spices to the diet.
FIGURE 17.1(See color insert.) Three types of biomarkers (exposure, effect, and susceptibility) are needed to assess the benefits or risk of spices.
Spices may be a key to determining the balance between pro- and anticancer factors that regulate risk and tumor behavior (Figure 17.2). About 75% of U.S. households use dietary approaches to reduce their risk of diseases, including cancer (Sloan 2005). Americans between the ages of 36 and 55 are increasingly interested in adopting healthy eating behaviors and are gravitating toward ethnic cuisines based on perceived health benefits (Uhl 2000). Many of these ethnic foods are loaded with unique and flavorful spices; however, while dietary guidelines in several countries tend to support the incorporation of spices into diets, quantifiable recommendations for specific amounts have not yet been forthcoming (Tapsell et al. 2006).
FIGURE 17.2Multiple factors may influence the need for spices for reducing the risk of cancer or changing the biological behavior of cancerous cells.
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