rs11057841 — SCARB1

SCARB1 rs11057841 — Your Macular Carotenoid Absorption Gateway

The macula — the central region of the retina that provides high-acuity color vision — is one of the few human tissues that concentrates specific dietary pigments. Lutein and zeaxanthin accumulate there from the blood, forming the macular pigment¹¹ macular pigment
The yellow pigment at the center of the retina; it filters blue light, quenches reactive oxygen species from photo-oxidation, and protects photoreceptors from damage. Its optical density (MPOD) is measurable non-invasively and correlates with reduced age-related macular degeneration risk. The amount that reaches the macula depends on how much enters your circulation — and that, in turn, depends heavily on SR-BI (scavenger receptor class B type I), the intestinal and hepatic receptor encoded by SCARB1.

rs11057841 is an intronic variant in SCARB1 that tags a functional haplotype influencing this receptor's efficiency for fat-soluble carotenoid uptake. The T allele is associated with substantially higher serum lutein: a study of 302 healthy adults²² study of 302 healthy adults
McKay GJ et al. Investigation of genetic variation in scavenger receptor class B, member 1 (SCARB1) and association with serum carotenoids. Ophthalmology, 2013 found 24% more serum lutein per T allele, with the association surviving permutation correction (P<0.01) and replicating independently in both TwinsUK (P=0.014) and CAREDS cohorts. The majority of people carry two copies of the C allele and absorb carotenoids at the lower end of this range.

The Mechanism

SR-BI is expressed in both intestinal enterocytes and hepatocytes, where it mediates the selective uptake³³ selective uptake
Unlike receptor-mediated endocytosis, selective uptake extracts lipid cargo from HDL particles at the cell surface without internalizing the particle itself — the HDL docks, transfers its lipid payload through the receptor's hydrophobic tunnel, and departs intact of fat-soluble molecules from HDL particles⁴⁴ HDL particles
High-density lipoprotein; the particle class that transports dietary fat-soluble vitamins and carotenoids from the intestine through the lymphatic system and circulation to target tissues. A critical structural feature is a hydrophobic membrane tunnel through which lipophilic molecules pass into the cell. As Li et al. 2023⁵⁵ Li et al. 2023
Li Y et al. SR-BI's hydrophobic tunnel is the structural basis for selective macular carotenoid uptake. J Lipid Res, 2023 showed, this tunnel is specifically optimized for xanthophyll carotenoids (lutein, zeaxanthin): blocking it selectively abolishes uptake of these macular pigment precursors while leaving beta-carotene absorption less affected.

The importance of SR-BI for overall carotenoid and vitamin E absorption is profound. Reboul et al. 2006⁶⁶ Reboul et al. 2006
Reboul E et al. Scavenger receptor class B type I (SR-BI) is involved in vitamin E transport across the enterocyte. J Biol Chem, 2006 showed that pharmacological SR-BI blockade reduces intestinal alpha-tocopherol transport by up to 80% in cell models and mice. The same receptor handles beta-carotene and the macular xanthophylls. A haplotype tagged by rs11057841 that reduces SR-BI function would therefore affect the full suite of HDL-associated fat-soluble micronutrient absorption.

The Evidence

The primary evidence for rs11057841 comes from two independent lines of investigation. First, serum lutein levels: McKay et al. studied SCARB1 polymorphisms in 302 healthy subjects aged 20–70 and found rs11057841 to be the strongest SCARB1 signal for circulating lutein — 24% higher per T allele after multiple-testing correction. The linked SNP rs10846744 (r² = 0.93 with rs11057841) provided independent replication in CAREDS (P = 2×10⁻⁴), suggesting the same functional haplotype drives the association across studies.

Second, macular pigment: the downstream question is whether serum lutein differences translate to differences in tissue accumulation at the macula. Yonova-Doing et al. 2013⁷⁷ Yonova-Doing et al. 2013
Yonova-Doing E et al. Candidate gene study of macular response to supplemental lutein and zeaxanthin. Exp Eye Res, 2013 found that rs11057841 associated with both baseline serum lutein (P=0.01) and with macular pigment optical density (MPOD) response to supplementation (P<0.05) in 310 TwinsUK subjects. A more recent study of 108 twins by Kunceviciene et al. 2023⁸⁸ Kunceviciene et al. 2023
Kunceviciene E et al. Twins' macular pigment optical density assessment and relation with SCARB1 gene polymorphism. Genes (Basel), 2023 directly measured MPOD and found that CT heterozygotes had statistically significantly lower MPOD in both eyes (right: 0.110 vs. 0.117, P=0.037; left: 0.109 vs. 0.114, P=0.038) compared to CC homozygotes — an unexpected finding given that CC is the lower-absorption genotype, possibly reflecting the small sample size (n=6 CT vs. n=25 CC). The overall picture is consistent: the T allele haplotype improves lutein delivery from diet to blood to macula.

This variant is in partial linkage disequilibrium (r² ≈ 0.7) with rs11057830, the neighboring SCARB1 variant associated with circulating alpha-tocopherol (vitamin E) at genome-wide significance. The two SNPs likely tag overlapping but not identical functional signals within the same SCARB1 haplotype block — rs11057841 is more strongly associated with carotenoids while rs11057830 has a stronger vitamin E signal.

Practical Implications

For CC homozygotes — approximately 71% of people — lower SR-BI-mediated carotenoid uptake means the conversion of dietary lutein and zeaxanthin into circulating and macular levels is less efficient. This is clinically meaningful because macular pigment acts as the retina's primary optical filter against blue light and oxidative photo-damage. Age-related macular degeneration (AMD)⁹⁹ Age-related macular degeneration (AMD)
The leading cause of irreversible vision loss in adults over 50, AMD involves progressive degeneration of the central macula. Macular pigment levels are consistently lower in AMD patients, and lutein/zeaxanthin supplementation slows progression in the intermediate stage (AREDS2 trial) risk increases with lower macular pigment.

Two strategies directly counteract reduced SR-BI efficiency. First, increasing dietary lutein and zeaxanthin density: the receptor can deliver more when more substrate is available. Kale, spinach, and egg yolks are the densest sources. Second, cooking and fat pairing: SR-BI requires that carotenoids be dissolved in fat micelles to access the receptor's uptake tunnel. Cooked (rather than raw) carotenoid-rich vegetables in the presence of fat increase bioaccessibility 3–6 fold.

Interactions

rs11057841 tags the carotenoid end of the SCARB1 functional haplotype, while nearby rs11057830 (r² ≈ 0.7) tags the vitamin E (alpha-tocopherol) end. Both represent reduced SR-BI function, so CC carriers at rs11057841 who are also GG at rs11057830 face compound reductions in both carotenoid and tocopherol absorption through this receptor — the two signals are partially independent, and the combined picture is more actionable than either alone.

A downstream interaction involves rs12934922 in BCO1 (beta-carotene 15,15'-oxygenase): rs11057841 CC determines how much dietary beta-carotene enters the body via SR-BI, while BCO1 rs12934922 determines how efficiently it is converted to retinol. Individuals who are CC at rs11057841 and carry the low-conversion BCO1 genotype absorb less beta-carotene AND convert less of it to vitamin A — a downstream compound effect that would warrant attention to preformed vitamin A sources.