Antioxidants plasma concentrations

Bilirubin (normal plasma concentration < 20 iM) is able to scavenge singlet oxygen and peroxyl radicals. It has been proposed that bilirubin bound to human albumin contributes significantly to the non-enzymic antioxidant defences in human plasma (Stocker and Ames, 1987). 

Figure 22.6 How various factors increase the risk of atherosclerosis, thrombosis and myocardial infarction. The diagram provides suggestions as to how various factors increase the risk of development of the trio of cardiovascular problems. The factors include an excessive intake of total fat, which increases activity of clotting factors, especially factor VIII an excessive intake of saturated or trans fatty acids that change the structure of the plasma membrane of cells, such as endothelial cells, which increases the risk of platelet aggregation or susceptibility of the membrane to injury excessive intake of salt - which increases blood pressure, as does smoking and low physical activity a high intake of fat or cholesterol or a low intake of antioxidants, vitamin 6 2 and folic acid, which can lead either to direct chemical damage (e.g. oxidation) to the structure of LDL or an increase in the serum level of LDL, which also increases the risk of chemical damage to LDL. A low intake of folate and vitamin B12 also decreases metabolism of homocysteine, so that the plasma concentration increases, which can damage the endothelial membrane due to formation of thiolactone.

Plasma Concentrations ( utAt) of Endogenous (Nondietary) Phenols and Other Plasma Antioxidants... 

Alcohol consumption Moderate consumption of alcohol (for example, two drinks a day) decreases the risk of coronary heart disease, because there is a positive correlation between moderate alcohol consumption and the plasma concentration of HDLs. However, because of the potential dangers of alcohol abuse, health professionals are reluctant to recommend increased alcohol consumption to their patients. Red wine may provide cardioprotective benefits in addition to those resulting from its alcohol content, for example, red wine contains phenolic compounds that inhibit lipoprotein oxidation (see p. 233). [Note These antioxidants are also present in raisins and grape juice.]... 

Gey, K.F., Moser, U.K., Jordan, P., Stahelin, H.B., Eicholzer, M., Lundin, E. 1993. Increased risk of cardiovascular disease at suboptimal plasma concentrations of essential antioxidants an epidemiological update with special attention to (3-carotene and vitamin C. Am. J. Clin. Nutr. 57, 787S-797S. 

A concern has been raised that phytosterol doses that are effective for cholesterol reduction may impair the absorption and lower blood concentrations of fat-soluble vitamins and antioxidants. A number of studies showed that phytosterols had no effect on plasma concentrations of vitamin D, retinol, or plasma-lipid-standardized alpha-tocopherol. Moreover, the reports of the effect of phytosterols on concentrations of blood carotenoids (lutein, lycopene, and alpha-carotene) are controversial. There seems to be general agreement that phytosterol doses >1 g/d significantly decrease LDL-C standardized beta-carotene concentrations however, it remains to be determined whether a reported 15-20% reduction in beta-carotene due to phytosterol supplementation is associated with adverse health effects. Noakes et al. found that consumption of one or more carotenoid-rich vegetable or fruit servings a day was sufficient to prevent lowering of plasma carotenoid concentrations in 46 subjects with hypercholesterolemia treated with 2.3 g of either sterol or stanol esters. 

The bioavailability of lycopene in tomato-based foods vs. that in fresh tomatoes increases even further when lycopene is consumed with oil. In studies by Stahl and Sies (1992, 1996), ingestion of tomato juice cooked in an oil medium resulted in a two- to threefold increase in lycopene serum concentrations 1 day after ingestion. An equivalent consumption of unprocessed tomato juice caused no rise in lycopene plasma concentration. This indicates that thermal pretreatment and an oil medium were beneficial for extracting lycopene into the lipophilic phase. Solubilization of lycopene in a lipophilic matrix is expected to considerably enhance its availability and its bioactivity. This is likely to boost its effectiveness as an antioxidant. However, this higher reactivity also renders lycopene more vulnerable to the detrimental effects of factors such as air, temperature and interactions with other components of the food. 

If the prevention of oxidative DNA damage plays an important role in the cancer chemopreventive effects of dietary antioxidants, then one would expect to see an inverse relationship between antioxidant intake and biomarkers of oxidative DNA damage. Lymphocyte ascorbate concentrations were inversely associated with lymphocyte 8-oxodG concentrations in 105 men and women (r=-0.28)." However, plasma concentrations of a-tocopherol and carotenoids were positively correlated with lymphocyte concentrations of 8-oxodG in a study of 52 healthy women (r=0.29 to... 

---