Adipose tissue 3-carotene

The relationship between serum and tissue concentrations of lutein and zeaxanthin was recently studied by Johnson et al, (2000). Dietary intake of xanthophyll-rich vegetables (for example, spinach and com) resulted in significant increases in lutein concentration in serum, adipose tissue and buccal cells, and this correlated with changes in MP density. However, P-carotene and lycopene are normally the major carotenoids detected in buccal cells (Peng et al, 1994). 

Among 27 prospective and case-control studies, 16 reported inverse associations between some carotenoids and CVDs, taking plasma or serum concentration as carotenoid biomarkers (11 of 16 studies), dietary intake (5 of 16 studies), or adipose tissue level (1 of 16 studies). With regard to the findings from the studies based on CVD risk, only two of seven presented significant inverse associations of carotenoids, particularly lycopene and P-carotene, whereas five studies of nine showed inverse correlations between myocardial infarcts and lycopene and/or P-carotene the others presented no associations. ... 

Lutein and zeaxanthin are the dominant carotenoids in nonretinal eye tissue, and lycopene and p-carotene have been found in the ciliary body, which after the retina and the retinal pigment epithelium (RPE) contains the highest quantity of carotenoids (Bernstein et al. 2001). The orbital adipose tissue also contains measurable quantities of lutein and p-carotene, and possibly other carotenoids as minor constituents (Sires et al. 2001). It is also interesting to note that lutein was recently identified in the vitreous body of human fetuses, 15-28 weeks old (Yakovleva et al. 2007). However, these results may have to be considered with caution, because the vitreous bodies were described as substantially being penetrated with hyaloid blood vessels, which could have contaminated the vitreous with blood. 

In a large trial (37) conducted in eight European countries— European Antioxidant Miocardial Infarction and Breast Cancer (EURAMIC) trial—the fatty acid composition, a-tocopherol, and /3-carotene levels were determined in adipose tissue of patients with acute Ml. The study supported the hypothesis that /3-carotene protects against Ml because it reduces the oxidation of PUFA. The concentration on adipose tissue was considered due to the dietary intake. 

Johnson, E. J., Suier, P. M., Sahyoun, N., Ribaya-Mercado, J., and Russell, R. M. (1995). Relation between p-carotene intake and plasma and adipose tissue concentrations of carotenoids and retinoids. Am, f, Clin. Nutr. 62,598-603. 

Reiser, R. 1949. Peroxidizing and carotene bleaching substances in bacon adipose tissue. J. Am. Oil Chemists Soc. 26, 116. 

Figure 14a. c -Geometrical isomers of carotene related to Pearon s correlation coefficients for serum carotenoids and three adipose tissue carotenoids by diet P-carotene (2), 13 cis P-carotene (52) and 9 cis P-carotene (53). 

Interestingly, among thirteen carotenoids, the abdominal adipose tissue of these subjects had the highest carotenoid concentrations, followed by buttocks adipose tissue, and thigh adipose tissue with the lowest carotenoid concentrations. Especially, their concentrations of a-carotene (1), one trans and total cis type mixtures of P-earotene (2), dX -trans P-carotene (51), 13 cis P-carotene (52), and 5 cis lycopene (59) in the abdominal adipose tissue were signifreantly higher when compared to their eoncentrations in thigh adipose tissue. 

Second, on the adipose tissue carotenoid concentrations, the intake of these carotenoids was significantly correlated with three adipose tissue concentrations of a-carotene (1), P-carotene (2), P-cryptoxanthin (5) and total cis lycopene (60). 

The concentration of a-carotene (1) in the buttock adipose tissue (PCC 0.516 P<0.05) had a more high correlation when compared to the dietary intakes of a-carotene (1) in the thigh adipose tissue (PCC 0.037 P<0.01). 

Third, on the a correlation of the serum carotenoid concentrations with the abdominal adipose tissue, among these carotenoids, serum concentrations of the abdomen versus serum was significantly correlated with the a-carotene (1) [Pearson s correlation coefficient (PCC) 0.518 P<0.05] concentrations in the abdominal adipose tissue (Table 5). 

The subjects taking the dietary carotene intakes of a-carotene (1) and P-carotene (2) over the past year might tend greatly to have the higher serum carotenoid concentrations when compared to three adipose tissue carotenoid concentrations. However, this difference in the correlations with diet was significant only for the thigh adipose tissue. 

From these carotenoid distributions in three adipose tissue sites of the abdominal adipose tissue, buttock adipose tissue and inner thigh adipose tissue, it could suggest that the abdominal adipose tissue could have the highest correlation with a long-term dietary carotenoid intakes and at the same time, serum could be helpful in region of the clinical checkup as an indicator of short-term intake for very popular carotenoids such as a-carotene (1) and P-carotene (2) (Figure 7) [29],... 

P-Carotene (provitamin A) is one of several naturally occurring precursors of vitamin A. Owing to inefficient intestinal conversion, only one-sixth of the dietary intake of 3-carotene is ultimately converted to retinol (Goodman, 1979). Additionally, as the amount of 3-carotene in the diet increases, the conversion to retinol decreases so that systemic vitamin A toxicity is not caused even by massive doses. A variable amount of 3-carotene is also absorbed unchanged from the intestine, enters into circulation, and is stored in adipose tissue. 

The metabolism and pharmacokinetics of the carotenoids are not well understood, and their bioavailabUity is associated with much interindividual and intraindividual variation (281). p-Carotene, a-carotene, cryptoxanthin, lycopene, and lutein are the major carotenoids in human serum, and lycopene and p-carotene are the major carotenoids in other human tissues (282). Small amounts of zeax-anthin, phytofluene, and phytoene are also found in various organs. Various carotenoids tend to be present in similar ratios in human plasma and tissues (282, 283). The carotenoids are safe and even long-term intake of 180 mg of p-carotene per day did not lead to hypervitaminosis. When large amounts of carotenoids are stored in the adipose and other lipid-rich tissues, they may cause reversible yellowing of the... 

Carotenoids are frequently added as colorants to processed foods such as margarines, and when in the form of P-carotene can contribute substantially to the vitamin A activity of diets (Klaui and Bauemfeind, 1981). Some carotenoids may be obtained from animal food products such as egg yolk, milk, and butter, and a small amount from animal tissues where they are deposited mostly in adipose fat. These carotenoids are derived from those animal species that absorb carotenoids and that have yellow fat. However, not all carotenoids that are deposited in animal tissue or those found in the circulation have provitamin A activity. This varies considerably among species and is related first, to their ability to absorb various individual forms of carotenoids, and second, to the chemical alterations that may occur subsequent to absorption. 

In humans, and in mammals in general, it has been shown that the carotenoids ingested in the diet are partly absorbed as such, and deposited in various tissues, such as adipose and plasma, and in the macula, where lutein and zeaxanthin have been found. The highest concentration of carotenoids is found in the plasma, always associated to lipoproteins, and mainly to the low-density fraction (low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL)). The carotenoids most commonly found in the plasma are a-carotene, P-carotene, lycopene, zeaxanthin, lutein, canthaxanthin, and p-cryptoxanthin." ... 

---