FROM:
Am J Clin Nutr 1999 (Aug); 70 (2): 247–251
Handelman GJ; Nightingale ZD; Lichtenstein AH;
Schaefer EJ; Blumberg JB
Jean Mayer USDA Human Nutrition Research Center
on Aging at Tufts University,
Boston, MA, USA.
Handelman_lp@hnrc.tufts.edu
BACKGROUND: The food matrix in which carotenoids are
found affects their bioavailability. Lutein and zeaxanthin are
abundant in egg yolks and accumulate in the macular region of the
retina, where they may affect visual function.
OBJECTIVE: We sought to determine
whether plasma lutein and zeaxanthin concentrations are elevated
after dietary supplementation with egg yolk.
DESIGN: Eleven moderately hypercholesterolemic men and
women consumed 2 separate baseline diets, which contained 29-33%
of energy as total fat, with 20% of energy as either beef tallow
or corn oil. These diets were supplemented with cooked chicken
egg yolks (1.3 egg yolks/d for an intake of 10.4 MJ). Each
subject consumed all 4 diets. Each diet was consumed for 4.5 wk,
with a washout period of >/=2 wk between diet phases. At the end
of each diet phase, fasting morning plasma samples were collected
and stored for carotenoid analysis by HPLC. Commercial chicken
egg yolks were analyzed for carotenoids and cholesterol.
RESULTS: Egg yolk supplementation of the beef tallow
diet increased plasma lutein by 28% (P < 0.05) and zeaxanthin by
142% (P < 0.001); supplementation of the corn oil diet increased
plasma lutein by 50% (P < 0.05) and zeaxanthin by 114% (P <
0.001). Changes in plasma lycopene and beta-carotene were
variable, with no consistent trend. Egg yolk supplementation
increased plasma LDL-cholesterol concentrations by 8-11% (P <
0.05).
CONCLUSIONS: Egg yolk is a highly bioavailable source of
lutein and zeaxanthin. The benefit of introducing these
carotenoids into the diet with egg yolk is counterbalanced by
potential LDL-cholesterol elevation from the added dietary
cholesterol.