Supplements to benefit eye health

Safety and Bioavailability of Carotenoids

By Michael J. Tolentino, MD, and Andrew J. Tolentino

As you know, lutein (L), zeaxanthin (Z), and meso-zeaxanthin (M) are carotenoids that accumula

te as pigment in the center part of the retina called the macula. Macular pigment (MP) protects against macular degeneration, enhances visual performance, filters high-energy blue light, and potently neutralizes free radicals. Accumulation of macular pigment, while important for vision, requires dietary intake to initiate and maintain adequate levels, so understanding bioavailability and safety of these carotenoids is crucial.

Dietary Sources
Human breast milk contains high levels of lutein and zeaxanthin. Compared with infant formula, carotenoids in breast milk are four times more bioavailable.¹ The presence and increased bioavailability of breast milk carotenoids reinforces the safety and necessity of these pigments in our diet. The increased absorption of breast milk carotenoids gives us clues on optimizing bioavailability in adults who need macular pigment replenishment to prevent macular degeneration and age-related visual impairment.

Variability in macular pigment levels is related to inter-individual differences in carotenoid absorption. Food preparation, bioavailability in food, and competition with other nutrients determine absorption. For example:

• Food preparation. Foods high in carotenoids include green leafy vegetables, eggs, orange juice, and broccoli. Cooking or grinding carotenoid-rich foods increases absorption, as does ingestion with fat.²
• Bioavailability. Eggs have carotenoids embedded in the yolks; the lipid matrix provides greater bioavailability than green leafy vegetables.³ Carotenoids are fat-soluble, and for absorption require transfer to blood high-density lipoproteins (HDLs).
• Competition. Beta-carotene consumption diminishes absorption of carotenoids through upregulation of beta-carotene oxygenase 1 (BCO1), which inhibits absorption of carotenoids.²

The Need for Supplementation
Taken in context, the most efficient means of absorbing carotenoids and upregulating macular pigment is to consume carotenoids in a similar fashion to neonates: In lieu of human breast milk, a carotenoid supplement solubilized in fat and taken with milk on an empty stomach so as to not to activate BCO1 will optimize absorption. It is important that the carotenoid formulation is not desiccated and is solubilized in fat; otherwise, carotenoid transfer to HDL and transport to the macula will not occur. This is the recommended strategy for optimizing bioavailability and upregulating macular pigment.

Reference(s):

1. Bettler J, Zimmer JP, Neuringer M, DeRusso PA. Serum lutein concentrations in healthy term infants fed human milk or infant formula with lutein. Eur J Nutr. 2010;49(1):45-51.
2. Mares, J. Lutein and zeaxanthin isomers in eye health and disease. Annu Rev Nutr. 2016;36:571-602.
3. Chung HY, Rasmussen HM, Johnson, EJ. Lutein bioavailability is higher from lutein-enriched eggs than from supplements and spinach in men. J Nutr. 2004;134:1887-1893.