Nutritional phenolics and cardiovascular disease

E Virgili and C. Scaccini, National Institute for Food and Nutrition Research, Italy, L. Packer, University of California, USA, and G. Rimbach, University of Reading, UK 

A number of subtle dysfunctions occur at the cellular and molecular levels in the early stages of disease progression associated with the loss of cellular homeostatic functions of endothelial cells, smooth muscle cells and macrophages which constitute the major cell types in the atheroma environment. These events include the modification of the pattern of gene expression, cell proliferation and apoptosis. 

In the last few decades, several epidemiological studies have shown that a dietary intake of foods rich in natural antioxidants correlates with reduced risk of coronary heart disease particularly, a negative association between consumption of polyphenol-rich foods and cardiovascular diseases has been demonstrated. This association has been partially explained on the basis of the fact that polyphenols interrupt lipid peroxidation induced by reactive oxygen species (ROS). A large body of studies has shown that oxidative modification of the low-density fraction of lipoprotein (LDL) is implicated 

At cellular level each stage of atheroma development is accompanied by the expression of specific glycoproteins by endothelial cells which mediate the adhesion of monocytes and T-lymphocytes. Their recruitment and migration is triggered by various cytokines released by leukocytes and possibly by smooth muscle cells. Atheroma development continues with the activation of macrophages, which accumulate lipids and become, together with lymphocytes, so-called fatty streaks. The continuous influx, differentiation and proliferation finally leads to more advanced lesion and to the formation of the fibrous plaque.  

It is accepted that oxidation of LDL is a key event in endothelial injury and dysfunction. Oxidised LDL (oxLDL) may directly injure the endothelium and trigger the expression of migration and adhesion molecules. Monocytes and lymphocytes interact with oxLDL and the phagocytosis which follows leads to the formation of foam cells, which in turn are associated with the alteration of the expression pattern of growth regulatory molecules, cytokines and pro-inflammatory signals. The proposed role of oxLDL in atherogenesis, based on studies in vitro, is shown in Fig. 2.1. 

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Johnson, L Williamson, G. 2003. Nutritional phenolics and cardiovascular disease. In Phytochemical Functional Foods (Johnson, L Williamson, G., Eds.). CRC Press, Cambridge, England, pp. 5-17. 

Various excellent reviews are available on phenolic compounds, their chemistry and analysis, content in foods and nutritional significance (Bravo, 1998 Dykes and Rooney, 2006 Manach et al., 2004 Naczk and Shahidi, 2006 Robbins, 2003). From a nutritional perspective, phenolic compoimds (especially tannins) are regarded as antinutritional factors due to their ability to form complexes with dietary proteins and minerals and digestive enzymes (Bravo, 1998). However, lately there has been increasing focus on the positive aspects of phenolics due to their ability to act as antioxidants which may offer potential health benefits such as prevention of diseases such as cancer and cardiovascular disease. 

Proanthocyanidins (PAs) are oligomeric and polymeric flavan-3-ols, better known as condensed tannins. They are ubiquitous and one of the most abundant groups of natural phenols (Porter, 1988). PAs affect the texture, color, and taste of many common foods including cereals, fruits, vegetables, and wines. PAs in foods are also of interest in nutrition and medicine because of their potent antioxidant capacities and beneficial effects on human health in reducing the risk of chronic diseases, such as cardiovascular diseases and cancers (Santos-Buelga and Scalbert, 2000 Prior and Gu, 2005). 

In addition to the above discussed nutrients, diverse amoimt of phenolic molecules has been identified from seaweed and is classified imder different groups of phytochemicals. Those molecules virtually do not play the roles of nutrients and proven to have different bioactive properties associated with enhancing physical fitness to refrain from diseases or to exert therapeutic effects against certain illnesses. However, the medicinal effects of such molecules are not discussed in this chapter. Non-communicable diseases such as diabetes, obesity, and cardiovascular dieses have a strong relationship with dietary habits and nutritional profiles of the food. Therefore, next few sections of this chapter address the nutrition-related several health effects of seaweed fiber, other than previously mentioned, and its contribution to enhance digestive health. 

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