Beta-carotene's effects on serum lipoproteins and immunologic indices in humans

Ringer, Thomas V.; DeLoof, Michael J.; Winterrowd, Greg E.; Francom, Steven F.; Gaylor, S K; Ryan, JA; Sanders, Martin; Hughes, Gail

doi:10.1093/ajcn/53.3.688

Cited by 88 publications

(39 citation statements)

References 32 publications

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“…An increase in the percentage NK cells was reported in a non-controlled trial of men aged 35 ± 79 with either oral leukoplakia or Barrets oesophagus, who were supplemented with 30 mg b-carotene daily for 3 months . In contrast, several controlled studies in healthy young or elderly volunteers have reported no effect of supplementation with b-carotene (Ringer et al, 1991;van Poppel et al, 1993;Daudu et al, 1994;Santos et al, 1996), or indeed vitamin E (Meydani et al, 1995), on lymphocyte subsets. The results from the studies of disease groups should be interpreted with care, bearing in mind the dif®culty in controlling these trials adequately.…”

Section: Discussionmentioning

confidence: 88%

“…Therefore, measures that can increase the expression of these molecules may enhance the immune response. In vitro studies indicate that b-carotene may modulate the expression HLA-DR (Rhodes, 1985;Gruner et al, 1986), but varying effects of b-carotene in human supplementation studies on HLA-DR expression have been reported (Ringer et al, 1991).…”

Section: Cd3mentioning

confidence: 99%

“…Some studies have reported stimulation of indices of the immune response (Alexander et al, 1985;Watson et al, 1991), while more have reported no effect in healthy (Ringer et al, 1991;Daudu et al, 1994), or immunocompromised subjects (Silverman et al, 1994). The conversion of b-carotene to vitamin A and retinoids, which are known to have immunostimulatory effects, is one mechanism by which b-carotene may be immunostimulatory (Le Jeune et al, 1996).…”

Section: Cd3mentioning

confidence: 99%

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Low-dose supplementation with lycopene or β-carotene does not enhance cell-mediated immunity in healthy free-living elderly humans

et al. 2001

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Objective: To assess the effects of supplementation with the carotenoids, b-carotene or lycopene, at levels achievable within a diet rich in fruit and vegetables, on immune function in a group of free-living healthy elderly. Design: A double-blind randomized placebo-controlled trial. T cell subsets and the expression of functionally associated cell surface molecules, quanti®ed by¯ow cytometry, and lectin-stimulated lymphocyte proliferation, were compared before and following the treatment period. Subjects: Fifty-eight subjects aged over 65 y were recruited; 52 were included in the ®nal analysis. Interventions: Participants received one placebo, one lycopene (13.3 mg) or one b-carotene (8.2 mg) capsule daily for 12 weeks. Results: No signi®cant differences were observed in any of the parameters examined following either lycopene or b-carotene supplementation. Conclusions: In well-nourished, free-living, healthy elderly individuals, supplementation with relatively low levels of b-carotene or lycopene is not associated with either a bene®cial or detrimental effects on several aspects of cell-mediated immunity. Sponsorship: Financial support was provided by the Commission of the European Communities, speci®c programme AIR2 CT93-0888 DGXII SSMA,`Increased fruit and vegetable consumption within the EC: potential health bene®ts', co-ordinated by Professor S Southon, Institute of Food Research, Norwich, UK.

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Section: Discussionmentioning

confidence: 88%

Section: Cd3mentioning

confidence: 99%

Section: Cd3mentioning

confidence: 99%

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Low-dose supplementation with lycopene or β-carotene does not enhance cell-mediated immunity in healthy free-living elderly humans

et al. 2001

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“…No high-dosage AX or CX supplementation trials with human subjects have been published to date. Ingestion of high daily doses (0,15,45,180, or 300 mg) of b-carotene for 1 month, on the other hand, resulted in fasting b-carotene plasma concentrations ranging from *0.5 to *6.0 lmol/L (Ringer et al 1991). Hence, the carotenoid concentrations used in our cell culture experiments may not reflect normal dietary intake of AX and CX, but might well be achievable upon prolonged consumption of high doses of the carotenoids.…”

Section: Discussionmentioning

confidence: 99%

Comparison of tetrahydrofuran, fetal calf serum, and Tween 40 for the delivery of astaxanthin and canthaxanthin to HepG2 cells

et al. 2010

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The present investigation aimed to compare fetal calf serum (FCS) and Tween 40 with the commonly employed tetrahydrofuran (THF) with respect to cytotoxicity, stability of the solubilized carotenoids, and uptake and accumulation of the xanthophylls astaxanthin (AX) and canthaxanthin (CX) in cultured human liver cells (HepG2). Incubation of HepG2 cells for 24 h with THF (C1.25%) or FCS (C11.25%) with or without AX (C25 lmol/L) or CX (C25 lmol/L) did not affect cell viability. Tween 40 (0.25-1.25% in medium) reduced cell viability by 75-99%. The stabilities of AX and CX in cell-free RPMI 1640 medium for B24 h were higher when delivered with THF instead of FCS. The doseand time-dependent accumulations of AX and CX (1-10 lmol/L) in HepG2 cells were higher when carotenoids were delivered with FCS compared to THF. In conclusion, FCS and THF, but not Tween 40, were suitable solvent systems for the delivery of AX and CX to HepG2 cells. In our experiments FCS was superior with regard to the uptake and accumulation of both carotenoids.

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“…In contrast to vitamin A, several studies have reported no effect of beta-carotene on serum lipids (Nierenberg et al, 1991;Ringer et al, 1991;Hughes et al, 1994;Van Poppel et al, 1994;Ribaya-Mercado et al, 1995). In a large randomized trial in which a combination of antioxidants (vitamin C, vitamin E and beta-carotene) was compared to placebo, small but significant differences in both total cholesterol and triglycerides were observed at trial end.…”

Section: Introductionmentioning

confidence: 99%

Changes in cholesterol and triglyceride concentrations in the Vanguard population of the Carotene and Retinol Efficacy Trial (CARET)

et al. 2005

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Background: The Beta-Carotene and Retinol Efficacy Trial (CARET) was terminated 21 months ahead of schedule due to an excess of lung cancers. Deaths from cardiovascular disease also increased (relative risk ¼ 1.26 (95% confidence interval (CI) 0.99-1.61)) in the group assigned to a combination of 30 mg beta-carotene and 25 000 IU retinyl palmitate (vitamin A) daily. The basis for increased cardiovascular mortality is unexplained. Design: We analyzed data on serum lipids, available for 1474 CARET Vanguard participants who were enrolled in the two CARET pilot studies and transitioned to the Vanguard study. Total cholesterol and triglycerides were measured 2 months prior to, 4 and 12 months following randomization, and annually thereafter for up to 7 y. Intervention: In the asbestos-exposed pilot (N ¼ 816), participants were assigned to beta-carotene and retinol or to placebo; in the smokers pilot (N ¼ 1029), participants were assigned to beta-carotene, retinol, a combination, or placebo. Results: Serum cholesterol showed a decline over time in both arms; serum triglycerides had a continuous decline over time in the placebo arm, but an initial increase that persisted in the active arm. Both serum cholesterol concentrations (Po0.0003) and serum triglycerides (Po0.0001) were significantly higher in the participants receiving vitamin A and/or a combination of vitamin A and beta-carotene (n ¼ 863) as compared to the placebo group (n ¼ 611). Those in this active intervention group had an average cholesterol concentration 5.3 mg/dl (0.137 mmol/l) higher than those in the placebo arm. Conclusion: The differences in cholesterol and triglyceride concentrations between the groups following randomization may account in part for the unexpected excess in cardiovascular deaths seen in the active intervention arm of CARET.

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Beta-carotene's effects on serum lipoproteins and immunologic indices in humans

Cited by 88 publications

References 32 publications

Low-dose supplementation with lycopene or β-carotene does not enhance cell-mediated immunity in healthy free-living elderly humans

Low-dose supplementation with lycopene or β-carotene does not enhance cell-mediated immunity in healthy free-living elderly humans

Comparison of tetrahydrofuran, fetal calf serum, and Tween 40 for the delivery of astaxanthin and canthaxanthin to HepG2 cells

Changes in cholesterol and triglyceride concentrations in the Vanguard population of the Carotene and Retinol Efficacy Trial (CARET)

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