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Historically herbs and spices have enjoyed a rich tradition of use for their flavor-enhancement characteristics and for their medicinal properties. The rising prevalence of chronic diseases worldwide and the corresponding rise in health care costs is propelling interest among researchers and the public for these food related items for multiple health benefits, including a reduction in cancer risk and modification of tumor behavior. A growing body of epidemiological and preclinical evidence points to culinary herbs and spices as minor dietary constituents with multiple anticancer characteristics. This review focuses on the anti-microbial, antioxidant, and anti-tumorigenic properties of herbs and spices, their ability to influence carcinogen bioactivation, and likely anticancer contributions. While culinary herbs and spices present intriguing possibilities for health promotion, more complete information is needed about the actual exposures to dietary components that are needed to bring about a response and the molecular target(s) for specific herbs and spices. Only after this information is obtained will it be possible to define appropriate intervention strategies to achieve maximum benefits from herbs and spices without eliciting ill-consequences.

Evidence is emerging that the intestinal microbiota is intrinsically linked with overall health, including cancer risk. Moreover, its composition is not fixed, but can be influenced by several dietary components. Dietary modifiers, including the consumption of live bacteria (probiotics), nondigestible or limited digestible food constituents such as oligosaccharides (prebiotics) and polyphenols, or both (synbiotics), are recognized modifiers of the numbers and types of microbes and have been reported to reduce colon cancer risk experimentally. Microorganisms also have the ability to generate bioactive compounds from food components. Examples include equol from isoflavones, enterodiol and enterolactone from lignans, and urolithins from ellagic acid, which have also been demonstrated to retard experimentally induced cancers. The gastrointestinal microbiota can also influence both sides of the energy balance equation; namely, as a factor influencing energy utilization from the diet and as a factor that influences host genes that regulate energy expenditure and storage. Because of the link between obesity and cancer incidence and mortality, this complex relationship deserves greater attention. Thus, a complex interrelationship exists between the intestinal microbiota and colon cancer risk which can be modified by dietary components and eating behaviors.

Nutrigenetics and nutrigenomics hold much promise for providing better nutritional advice to the public generally, genetic subgroups and individuals. Because nutrigenetics and nutrigenomics require a deep understanding of nutrition, genetics and biochemistry and ever new ‘omic’ technologies, it is often difficult, even for educated professionals, to appreciate their relevance to the practice of preventive approaches for optimising health, delaying onset of disease and diminishing its severity. This review discusses (i) the basic concepts, technical terms and technology involved in nutrigenetics and nutrigenomics; (ii) how this emerging knowledge can be applied to optimise health, prevent and treat diseases; (iii) how to read, understand and interpret nutrigenetic and nutrigenomic research results, and (iv) how this knowledge may potentially transform nutrition and dietetic practice, and the implications of such a transformation. This is in effect an up-to-date overview of the various aspects of nutrigenetics and nutrigenomics relevant to health practitioners who are seeking a better understanding of this new frontier in nutrition research and its potential application to dietetic practice.

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The Allium genus includes garlic, onions, shallots, leeks, and chives. These vegetables are popular in cuisines worldwide and are valued for their potential medicinal properties. Epidemiological studies, while limited in their abilities to assess Allium consumption, indicate some associations of Allium vegetable consumption with decreased risk of cancer, particularly cancers of the gastrointestinal tract. Limited intervention studies have been conducted to support these associations. The majority of supportive evidence on Allium vegetables cancer preventive effects comes from mechanistic studies. These studies highlight potential mechanisms of individual sulfur-containing compounds and of various preparations and extracts of these vegetables, including decreased bioactivation of carcinogens, antimicrobial activities, and redox modification. Allium vegetables and their components have effects at each stage of carcinogenesis and affect many biological processes that modify cancer risk. This review discusses the cancer preventive effects of Allium vegetables, particularly garlic and onions, and their bioactive sulfur compounds and highlights research gaps.

The discovery of multiple selenoproteins has raised tantalizing questions about their role in maintaining normal cellular function. Unfortunately, many of these remain inadequately investigated. While they have a role in maintaining redox balance, other functions are becoming increasingly recognized. As the roles of these selenoproteins are further characterized, a better understanding of the true physiological significance of this trace element will arise. This knowledge will be essential in defining optimum intakes to achieve cellular homeostasis in order to optimize health, including a reduction in cancer, for diverse populations. Human variation in the response to selenium likely reflects significant interactions between the type and amounts of selenium consumed with the genome and a host of environmental factors including the totality of the diet, as discussed in this review.

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