Beta-carotene health effects

However, intervention trials investigating the effects of P-carotene and lycopene supplementation on CVD have not reported convincing results (Table 3.1.3). Among the seven studies reviewed herein, four primary prevention trials, namely the Multicenter Skin Cancer Prevention Study, the Beta Carotene and Retinol Efficacy Trial, the ATBC cancer prevention study, " and the Physicians Health Study have shown no association between a supplementation of P-carotene and risk of death from CVD or fatal and non-fatal MI. 

Kim, H.S. and Lee, B.M., Protective effects of antioxidant supplementation on plasma lipid peroxidation in smokers, J. Toxicol. Environ. Health A, 63, 583, 2001. Gaziano, J.M. et al.. Supplementation with beta-carotene in vivo and in vitro does not inhibit low density lipoprotein oxidation. Atherosclerosis, 112, 187, 1995. Sutherland, W.H.F. et al.. Supplementation with tomato juice increases plasma lycopene but does not alter susceptibility to oxidation of low-density lipoproteins from renal transplant recipients, Clin. Nephrol, 52, 30, 1999. 

There is little toxicological data available for extracts of carrots, alfalfa, com oil, palm oil, tomatoes, etc. The JECFA had no objections to their use as food colorants provided that the levels of use did not exceed that normally present in vegetables. A number of toxicity experiments were conducted on Dimaliella algae in view of its increasing importance in the health food area. Twelve studies on D. salina indicated no problems. ( is beta-carotene was absorbed to a lesser extent than trans beta-carotene. Furahashi suggested a no-observed-effect level (NOEL) of 2.5 g kg/day for extracts from D. Hardawil 2 The Joint Expert Committee on Food Additives of the World Health Organization/United Nations (JECFA) did not establish an NOEL or an ADI because of the variation in the composition of the products. 

A case-control study (Ascherio et al., 1994), a cross-sectional study (Bolton-Smith et al., 1996) and three prospective studies the Nurses Health Study (Willett et al., 1993), the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study (Pietinen et al., 1997), and the Zutphen Elderly Study (Oomen et al., 2001), separately assessed the effect of TFAs from hydrogenated vegetable oil and animal fat on the risk of CHD. With the exception of the small Zutpen Elderly Study (Oomen et al., 2001), the studies found that the positive association with the risk of CHD was explained entirely by the intake of TFAs from hydrogenated vegetable oil. 

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. 

Some of the more recent publications about trace elements, trace minerals, or ultratrace elements or minerals, also described as micronutrients, include Micronutrients in Health and Disease Prevention, edited by Adrianne Bendich and C.E. Butterworth Trace Elements in Nutrition of Children, edited by Ranjit Kumar Chandra and Trace Elements, Micronutrients and Free Radicals, edited by Ivor E. Dreosti. The latter reference raises the important question of the undesirable health effects of the chemical agents called free radicals, and their control or eradication by such vitamins as E, C, and beta-carotene. There is a history of the health effects of trace elements going back to Henry A. Schroeder, who in the early 1970s wrote Trace Elements and Man Some Positive and Negative Aspects and also The Poisons Around Us Toxic Metals in Food, Air, and Water. Even further back there was Karl... 

Cook, N.R., Lee, I.M., Manson, J.E., Buring, J.E., and Hennekens, C.H., Effects of beta-carotene supplementation on cancer incidence by baseline characteristics in the Physicians Health Study (United States), Cancer Causes Control, 11,617, 2000. 

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