LETTER TO THE EDITOR
The role of lutein in the prevention of atherosclerosis
Alexandra Alves-Rodrigues, PhD* and
Boban Thomas, MD*
* Kemin Foods Europe, Av. Visconde Valmor, 66, 5° andar, 1050-242, Lisbon, Portugal
alexandra.rodrigues{at}kemin.pt
McQuillan et al. (1) reported the findings of the Carotid Ultrasound Disease Assessment Study (CUDAS). They concluded that the evidence for the use of supplemental vitamin antioxidant to prevent atherosclerosis was limited, and this opinion was echoed by Lonn (2) in an accompanying editorial. These findings are consistent with another study where the evidence for a combination of antioxidants (vitamin E, vitamin C, beta-carotene, and selenium) in the prevention of coronary disease was rather tenuous (3). Unfortunately, numerous compounds labeled as antioxidant vitamins are grouped together, and often the results are extrapolated from one compound to another, implying that they all would yield similar results. This can be misleading, given the favorable results noted in another study investigating the xanthophyl carotenoid lutein (4). The Los Angeles Atherosclerosis Study investigated the progression of intima-media thickness of the common carotid artery. Over an 18-month period, subjects with the highest serum lutein level (0.42 µmol/l) had 80% less arterial wall thickening relative to those at the lowest quintile of serum lutein (0.15 µmol/l). No such relationship was observed with serum beta-carotene. Buttressing these findings were the animal experiments reported in the same study, where lutein supplementation reduced the size of atherosclerotic lesions in susceptible mice by 45% and inhibited low-density lipoprotein (LDL) oxidation in a dose-dependent manner up to almost 80%.
Moreover, complementary in vitro studies revealed that attraction of monocytes to oxidatively damaged human endothelial and smooth muscle cells was dose-dependently inhibited in cells incubated with lutein, with the inhibition of attraction up to eight-fold more than cells incubated with LDL alone. Taken together, these elegant findings suggest an important role for lutein in the prevention of atherosclerosis (4).
We believe that the findings, and probably the interpretation, of CUDAS could have been different had the investigators had the opportunity to determine the levels of lutein in their cohort. Moreover, it is well established that the bioavailability of lutein from the diet is higher than that of beta-carotene (5–7). Conversion of beta-carotene to retinol may be responsible for its low plasma levels compared with those of lutein. In the Atherosclerosis Risk in Communities (ARIC) study (8) it was also found that there is a possible beneficial effect of a lutein-rich diet, which is acknowledged by the CUDAS investigators.
Given the considerable interest in the prevention of early atherosclerosis with antioxidants, it is important to ferret out those that may have beneficial actions and those that do not. Grouping together various agents under a broad category can be misleading. Although statins have often been discussed as a class, the experience with cerivastatin (9) should reinforce the contention that all compounds within the same pharmacologic class are not equivalent—some may be beneficial while others may be harmful or relatively ineffective. Similarly, there are various antioxidants and carotenoids, and although some may not play a role in early protection against atherosclerosis, others, like lutein, may indeed have a protective role.
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1. McQuillan BM, Hung J, Beilby JP, Nidorf M, Thompson PL. Antioxidant vitamins and the risk of carotid atherosclerosis. The Perth Carotid Ultrasound Disease Assessment Study (CUDAS). J Am Coll Cardiol. 2001;38:1788–1794[Abstract/Free Full Text]
2. Lonn E. Do antioxidant vitamins protect against atherosclerosis? The proof is still lacking. J Am Coll Cardiol. 2001;38:1795–1798[Free Full Text]
3. Brown BG, Zhao XQ, Chait A, et al. Simvastatin and niacin, antioxidant vitamins, or the combination for the prevention of coronary disease. N Engl J Med. 2001;345:1583–1592[Abstract/Free Full Text]
4. Dwyer JH, Navab M, Dwyer KM, et al. Oxygenated carotenoid lutein and progression of early atherosclerosis: the Los Angeles Atherosclerosis Study. Circulation. 2001;103:2922–2927[Abstract/Free Full Text]
5. van het Hof KH, Brouwer IA, West CE, et al. Bioavailability of lutein from vegetables is 5 times higher than that of beta-carotene. [see comments]Am J Clin Nutr. 1999;70:261–268[Abstract/Free Full Text]
6. Castenmiller JJ, West CE, Linssen JP, van het Hof KH, Voragen AG. The food matrix of spinach is a limiting factor in determining the bioavailability of beta-carotene and to a lesser extent of lutein in humans. J Nutr. 1999;129:349–355[Abstract/Free Full Text]
7. Gartner C, Stahl W, Sies H. Preferential increase in chylomicron levels of the xanthophylls lutein and zeaxanthin compared to beta-carotene in the human. Int J Vitam Nutr Res. 1996;66:119–125[Medline]
8. Kritchevsky SB, Shimakawa T, Tell GS, et al. Dietary antioxidants and carotid artery wall thickness. The ARIC study. Atherosclerosis Risk in Communities study. Circulation. 1995;92:2142–2150[Abstract/Free Full Text]
9. Fleck F. Bayer faces Swiss criminal probe over cerivastatin. BMJ. 2002;324:130[Free Full Text]
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