Carotenoid bioavailability

The absorption and transport processes of many of the phytochemicals present in food are complex and not fully understood, and prediction of their bioavailability is problematic. This is particularly true of the lipid-soluble phytochemicals. In this chapter the measurement of carotenoid bioavailability will be discussed. The carotenoids serve as an excellent example of where too little understanding of food structure, the complexity of their behaviour in foods and human tissues, and the nature and cause of widely different individual response to similar intakes, can lead to misinterpretation of study results and confusion in our understanding of the relevance of these (and other) compounds to human health. 

Factors affecting carotenoid bioavailability food sources and intakes... 

VAN HET HOF K H, DE BOER B C, TIJBURG L B, LUCIUS B R, ZIJP I, WEST C E, HAUTVAST J G and WESTRATE J A (2000) Carotenoid bioavailability in humans from tomatoes processed in different ways determined from the carotenoid response in the triglyceride-rich lipoprotein fraction of plasma after a single consumption and in plasma after 4 days of consumption. JNutr 130(5) 1189-96. 

FIGURE 3.2.1 In vitro digestion/Caco-2 cell model combination approach to assess carotenoid bioavailability. LCM = large chylomicrons. SCM = small chylomicrons. VLDL = very low density lipoproteins. 

A number of factors described as influencing carotenoid bioavailability were regrouped under the SLAMENGFll mnemonic. Species of carotenoid. Linkages at molecular level. Amount of carotenoids consumed in a meal. Matrix in which the carotenoid is incorporated. Effectors of absorption and bioconversion. Nutrient status of the host. Genetic factors. Host-related factors, and Interactions among these variables. Only the factors that affect the micellarization of the compound in the gut are discussed and summarized in Table 3.2.1. 

For carotenoids, the type of matrix varies from relatively simple matrices in which the free carotenoid is dissolved in oil or encapsulated in supplements to more complex matrices in which the carotenoid is within plant foods. It is clear that the efficiency of the process by which the compound becomes more accessible in the gastrointestinal tract is inversely related to the degree of complexity of the food matrix. Carotenoid bioavailability is indeed far greater in oil or from supplements than from foods and usually the pure carotenoid solubilized in oil or in water-soluble beadlets is employed as a reference to calculate the relative bioavailability of the carotenoid from other foods. ... 

Garrett, D.A., Failla, M.L., and Samara, R.J., Development of an in vitro digestion method to assess carotenoid bioavailability from meals, J. Agric. Food Chem., 47, 4301, 1999. 

Liu, C.S., Glahn, R.P., and Liu R.H., Assessment of carotenoid bioavailability of whole foods using a Caco-2 cell culture model coupled with an in vitro digestion, J. Agric. Food Chem., 52, 4330, 2004. 

D. A. Garrett, M. L. Failla, and R. J. Sarama, Estimation of carotenoid bioavailability from fresh stir-fried vegetables using ab in vitro digestion/Caco-2 cell culture model, J. Nutr. Biochem. 11 (2000) 574—580. 

Xanthophyll esters are common in fruits and vegetables. Few data exist regarding the effect of carotenoid esterification on carotenoid bioavailability. Xanthophyll esters are readily broken in the human intestine (West and Castenmiller 1998 Breithaupt and others 2003 Faulks and Southon 2005). Chitchumroonchokchai and Failla (2006) demonstrated that hydrolysis of zeaxanthin esters increases zeaxanthin bioavailability. Wingerath and others (1995) did not find (3-cryptoxanthin esters in chylomicrons from humans fed with tangerine juice. Herbst and others (1997) demonstrated that lutein diesters are more bioavailable than free lutein. However, the question of whether the free or the esterified form is more bioavailable to humans is still an ongoing discussion. 

There is no solid evidence that relates human aging and reduction of carotenoid absorption. In some studies, old people have shown a lower (3-carotene absorption than that of young people (Madani and others 1989), whereas the opposite has also been reported by other studies (Sugarman and others 1991). The absorption of lipid-soluble substances, including carotenoids, is affected by any disease related to the digestion and absorption of fats (West and Castenmiller 1998). Inadequate production of lipase and bile as well as an inadequate neutralization of the chyme in the duodenum affect carotenoid bioavailability (Guyton and Hall 2001). 

Brown MJ, Ferruzzi MG, Nguyen ML, Cooper DA, Eldridge AL, Schwartz SJ and White WS. 2004. Carotenoid bioavailability is higher from salads ingested with full-fat than with fat-reduced salad dressings as measured with electrochemical detection. Am J Clin Nutr 80 396-403. 

Faulks RM and Southon S. 2005. Challenges to understanding and measuring carotenoid bioavailability. Biochim Biophys Acta 1740 95—100. 

West CE and Castenmiller JJM. 1998. Quantification of the SLAMENGHI factor for carotenoid bioavailability and bioconversion. Int J Vit Nutr Res 68 371-377. 

Yeum KJ and Russell RM (2002) Carotenoid bioavailability and bioconversion. Annual Reviews of Nutrition 22,483-504. 

Brown, E.D. et al.. Vegetable concentrates interact with canthaxanthin to affect carotenoid bioavailability and superoxide dismutase activity but not immune response in rats, Nutr. Res.,... 

It is also recognized that co-ingested dietary fat improves carotenoid bioavailability (Dimitrov et al. 1988 Prince and Frisoli, 1993 Reddy etal. 1995 Jayarajan et al. 1980). Because of their hydrophobic nature the carotenoids are constrained to the hydrophobic domains of plant tissues where they may be present as part of the photosynthetic mechanism in leaf chloroplasts (CogdeU 1988), as semicrystalline bodies in fruit and roots (Thelander et al. 1985) or dissolved in lipid droplets within plastids in ripe fruit (de Pee et al. 1998). Absorption studies would indicate that carotenoid present as semicrystalline bodies is most difficult to absorb, followed by carotenoids in leaves, with fruit carotenoids dispersed in oil droplets being most easily absorbed. 

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