Current Nutrition & Food Science - Volume 4, Issue 4, 2008

Tea together with coffee is the most consumed beverage in the world and contains large amounts of catechins, one kind of polyphenols. Experiments in vitro have shown that catechins have various beneficial activities such as chemopreventive one for cardiovascular disease and cancer. Catechins also exhibit cytotoxic effects by damaging the membrane of cells and/or the production of hydrogen peroxide (H2O2). The development of preventive methods for the production of H2O2 in green tea was summarized. Effects of green tea on human health are contradictory in epidemiological studies, possibly due to the difficulty in their uptake into the body and their cytotoxicity. Beverages without sugar are recommended for water intake and mental relaxation, since no noxious side effects of such beverages have been reported in the epidemiological research up to now.

The role of carotenoids in human nutrition has gained increased interest, especially due to their associated health-beneficial effects for a number of chronic diseases, including certain types of cancer and cardiovascular disease. Whereas data is available on the intake and presence of carotenoids in foods, limited information exists on factors influencing their bioavailability, especially for the non-provitamin A carotenoids. However, carotenoid absorption strongly depends on a number of factors which are not entirely understood. These include mainly the release of carotenoids from the food matrix, their incorporation into mixed bile micelles, the transfer of carotenoids from micelles to the mucosa for passive or facilitated absorption (via SR-BI proteins), and the sequestration into chylomicrons. Thus, dietary compounds influencing carotenoid micelle incorporation, e.g. the amount fat present in an ingested meal or components competing for uptake, such as phytosterols and other carotenoids, can have a considerable impact on carotenoid bioavailability. However, the effect of many dietary factors, including dietary fiber, type of fat, or minerals on carotenoid absorption is not well understood. In addition, bioavailability also depends on the carotenoid structure; in general, polar carotenoids are preferably incorporated into mixed micelles and tend to be of higher bioavailability, as may be the case for free vs. esterified xanthophylls, and cis-isomers vs. their trans-form, due to apparent shorter chain-lengths. Whereas their importance as part of a healthy diet warrants an improved understanding of carotenoids, their dietary fate following ingestion, including their stability, efficiency of micelle-incorporation, and pathway of absorption are still marginally understood.

Breast cancer is an important public health problem worldwide and it represents the second leading cause of cancer-related deaths among women in most industrialized countries. Epidemiological studies suggest a much lower incidence of breast cancer in women from countries with high soy phytoestrogen consumption such as China and Japan than the Western world. Phytoestrogens are a group of plant-derived polyphenol compounds that exhibit structural and functional similarities to the human steroid hormone 17β-estradiol. Genistein and daidzein, the main soy phytoestrogens, are two estrogen-mimicking compounds which can bind to estrogen receptors and exert weak estrogenic effects. There are several possible mechanisms by which these phytochemicals may reduce the risk of breast cancer; however their precise mechanisms of action remain to be elucidated. This review will summarize the properties of genistein and daidzein as phytoestrogens, and their chemopreventive effects in breast carcinogenesis including their antioxidant properties, antiinflammatory activities as well as their antiprogression abilities, and their importance in xenobiotic metabolism. Because the use of soy phytoestrogens is increasing, it is important from a public health perspective and a mechanistic understanding to study the potential links existing between soy phytoestrogens and breast cancer prevention.

Polycystic ovarian syndrome (PCOS) is a common endocrine disorder in reproductive age women. PCOS is characterized by the absence of menstruation or irregular and abnormal menstruation, excessive amounts of body hair, excessive body weight, and infertility. Women with PCOS often have multiple ovarian cysts, high levels of androgen hormones, insulin resistance and metabolic syndrome. This review is focused on the dietary approaches and alternative therapies which have been proved to play major roles in the treatment of PCOS. The ideal diet for PCOS is one that promotes weight loss and then weight maintenance. In addition, some of the essential nutrients may improve associated risk factors of PCOS. Among them are chromium, omega 3 fattyacids, antioxidants, phytosterols, magnesium, calcium, potassium and other essential vitamins and minerals. The most important aspect of treatment is managing cardiovascular risks, such as obesity, high blood cholesterol, diabetes and high blood pressure. Early recognition and aggressive lifestyle interventions are the cornerstones of PCOS treatment. Treating individual risk factors might help to reduce overall risk of PCOS. Some of the PCOS risk factors are modifiable. Aggressive medical nutritional therapy may be appropriate in early conditions than advanced stages.

Nowadays, the partial replacement of dietary protein energy (PE) by dietary non-protein energy (NPE, i.e. lipid and carbohydrate) is a common practice in the aquaculture sector. Marine and fresh water fish species is thought to have more protein energy available for growth when NPE is incorporated in the diets. Moreover, lower dietary PE implies less discharge of nitrogen compounds to the aquatic environment. The “sparing-action” of NPE over PE has, however, its limitations. As the NPE content of the diet increases so does the requirement for certain components (e.g. enzymes, hormones, cofactors) involved in the NPE metabolism. In particular, the role of several endogenous (reproduction, life cycle, tissue requirements) and/or exogenous (swimming activity, water temperature and salinity, crowding, fasting) has been shown to affect the mobilization and degree of essentiality of NPE substrates. This mini-review aimed to present an overview of recent work on the influence of swimming activity on the relative importance of the non-protein oxidative fuels in the energy partitioning of fish.

Salt has been used in food preparation since pre-history and is still routinely added in modern food manufacturing processes. Salt may be added at the table or during cooking; however a large amount of dietary salt originates from processed foods (∼60-70% of adult daily dietary salt). Excess salt intake is strongly linked to increases in blood pressure (hypertension) and subsequently pre-disposes individuals to the onset of cardiovascular disease (CVD), a leading cause of death in developed countries. Excess dietary salt intake has also been linked to the development of kidney disease, aggravation of asthma conditions and to the onset of osteoporosis. Results from large numbers of human studies have led to worldwide initiatives being put in place in order to reduce current levels of salt consumption. Hence there is an urgent need to reduce excess dietary salt intake from processed foods in particular. Current daily consumption figures can be as high as ∼10-12g NaCl per day while an intake of 4g salt per day is sufficient. Therefore a target reduction to an intake of 6g per day is the goal for a number of public health agencies worldwide. An incremental reduction in salt content in foods appears to be the best strategy to reduce population blood pressure values. However any reduction in salt content in processed foods must not impact on product safety or sensory quality. In this review various public health aspects of salt intake are considered. Additionally, the technological implications of salt reduction in foods are discussed and the possibilities for replacement of salt by addition of salt replacers, herbs, spices and other food ingredients to maintain product quality are highlighted.

Functional foods have a major role in health enhancement, and therefore, there has been an increase in research aimed at identifying new functional foods and nutraceuticals. The frontier between functional foods and nutraceuticals is tenuous. Functional foods are foods, or dietary components, that may provide a health benefit beyond basic nutrition. Nutraceuticals are, in an abbreviated way, also foods or parts of food that provide health benefits, including the prevention or treatment of disease. Presently many academic, scientific and regulatory organizations are working in an integrated way to establish the scientific basis to support and validate the benefits of foods or food components. It seems that people who consume a wide variety of foods containing these bioactive molecules (like carotenoids, fibers, flavonoids, fatty acids, phytoestrogens, vitamins and minerals, among others) show a reduced risk of developing some diseases and tend to have a better health. For example, the use of antioxidants provides protection against harmful free radicals, usually associated with cardiovascular disease, cancer, diabetes, Alzheimer's disease and age-related functional decline. The present work presents a general overview of functional foods, gives examples of some foods with a recognized functional ability, and finally takes a look at new developments and possible future changes regarding these types of products.

Human milk contains several solid components, water, and wide range of bioactive compounds. Over the evolutionary course of human development, a number of adaptations have resulted in the production of nonnutritive actions associated with breast feeding. In that regard, bioactive compounds in human milk appear not only to compensate for developmental delays in the infants' gastrointestinal tract but also encourage the symbiotic colonization of enteric bacteria that inhibit the growth of bacterial and viral pathogens. Research has also linked these bioactive compounds to certain aspects of the growth and proper development of brain and peripheral nervous system during early infancy. In this review we have summarized what has been learned about the spectrum of nutritive and biological agents in human milk, their physical distribution in human milk over the course of lactation, whether the physical structures and functions of these ingested agents are modified by digestive processes; the precise chemical and cellular loci of their actions, and their short- and long-term biochemical consequences. Although much is still unknown about human milk, and how to optimize infant nutrition substitutes, new information is constantly being discovered. Human milk is and will remain the one standard for infant nutrition by which all infant foods should be compared. It is our species-specific food.