Quantitation of vitamin E and a carotenoid pigment in cataractous human lenses, and the effect of a dietary supplement.
The quantitation of tocopherols and carotenoids in lipid extracts of cataractous human lenses was performed in parallel with those of matched samples of plasma, which was also analysed at the same time. Alpha-tocopherol in cataractous lenses from elderly human subjects was present at 4.4 mumoles/kg wet weight, much less than the mean of 33 mumoles/l in plasma from these subjects. The mean ratio of alpha- and gamma-tocopherols was 3.5 in the lenses, and 11.3 in plasma. Lens extracts contained no detectable alpha- or beta-carotene, lycopene, or beta-cryptoxanthin. However, all the lens extracts contained a pigment with the retention time and spectrum of lutein and zeaxanthin. Using the molar extinction coefficient of lutein this was present at ca. 0.03 microM, compared with 0.2 microM in plasma. Seven patients with bilateral cataracts had one of their cataractous lenses removed and analysed, and were then given either an oral placebo, or an oral supplement of ascorbate, alpha-tocopherol and beta-carotene. Three months later, the second cataractous lens, and a blood sample, were analysed. Three of the seven had received the active supplement, as confirmed by substantially raised blood levels of alpha-tocopherol and beta-carotene, and raised aqueous humour levels of vitamin C. However, lens tocopherol levels remained unchanged, and no beta-carotene could be detected in the lenses after supplementation. This preliminary evidence needs to be confirmed in larger studies.
Bates
C J
CJ
MRC Dunn Nutrition Unit, Cambridge, UK.
Chen
S J
SJ
Macdonald
A
A
Holden
R
R
D000368:Aged; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000032:analysis; D002338:Carotenoids / Q000032:analysis*; D002386:Cataract / Q000378:metabolism*; D004032:Diet; D005260:Female; D006801:Humans; D007908:Lens, Crystalline / Q000737:chemistry*; D008297:Male; D012044:Regression Analysis; D014810:Vitamin E / Q000008:administration & dosage* / Q000032:analysis* / Q000097:blood; D019207:beta Carotene / Q000008:administration & dosage* / Q000032:analysis / Q000097:blood
D019207:beta Carotene; D014810:Vitamin E; D002338:Carotenoids; D001205:Ascorbic Acid