BOSTON, MASSACHUSETTS. Research has shown that a high intake of
the carotenoids lutein and zeaxanthin helps protect against the
development of cataracts. Both lutein and zeaxanthin tend to
accumulate in the macular region of the retina and are also
believed to play a role in the prevention of age-related macular
degeneration. There is evidence that carotenoids including lutein
and zeaxanthin are absorbed better in the presence of fats and
that zeaxanthin is poorly absorbed from cooked vegetables (spinach
and corn). Blood levels of lutein can be increased through
supplementation and zeaxanthin supplements may also be effective.
Researchers at Tuft University now report that chicken egg yolks are an excellent source of bioavailable lutein and zeaxanthin. Their small study involved six men and five women, aged between 46 and 78 years, who had moderately high cholesterol levels. The study participants were fed four different diets for 4.5 weeks with a two-week or longer wash-out period between the different diets. Each diet contained 29-33 per cent of energy as fat. Diet 1 contained 20 per cent of energy as beef tallow; diet 2 contained 20 per cent as corn oil; diet 3 was diet 1 with the daily addition of 1.3 cooked egg yolks providing 300 mg/day of cholesterol; diet 4 was diet 2 with 1.3 cooked egg yolks added per day. Fasting blood samples analyzed at the end of each diet phase showed an increase of 28 per cent and 142 per cent for lutein and zeaxanthin respectively in the diet 3 phase and 50 per cent and 144 per cent respectively at the end of the phase 4 diet. Blood levels of low density cholesterol (LDL) also increased during diets 3 and 4 by 8-11 per cent.
The researchers conclude that the consumption of egg yolks is a
very effective way of raising blood levels of lutein and
zeaxanthin and possibly help prevent macular degeneration. They
caution that eating 1.3 egg yolks per day may increase overall
cholesterol levels by 5 per cent (0.3 mmol/L) and LDL levels by 8-
11 per cent. NOTE: This study was funded in part by the Egg
Nutrition Center.
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