Open Access Article
Mark Pretzel Zumaraga†
ab,
Patrick Borel†
a and
Charles Desmarchelier
*ac
aC2VN, Aix Marseille Univ, INRAE, INSERM, Marseille, France. E-mail: Charles.Desmarchelier@univ-amu.fr
bDepartment of Science and Technology – Food and Nutrition Research Institute, Bicutan, Taguig City, Philippines
cInstitut Universitaire de France (IUF), Paris, France
First published on 18th March 2026
Background and objectives: Lycopene (LYC) is a carotenoid obtained primarily from tomatoes and tomato-based products. LYC displays potent antioxidant properties and its intake and circulating concentrations have been associated with a reduced risk of prostate and breast cancers as well as cardiovascular diseases. Following absorption, it is mainly stored in adipose tissue, which accounts for approximately two-thirds of total body stores, where it may influence processes such as oxidative stress and inflammation. However, the factors determining LYC concentration in adipose tissue remain poorly understood. This study aimed to characterize the interindividual variability of adipose tissue LYC concentration and identify single nucleotide polymorphisms (SNPs) associated with it. Methods: Forty-three healthy adult males (mean age: 32.0 ± 2.0 year; mean BMI: 23.0 ± 0.3 kg m−2) underwent whole-genome genotyping. Periumbilical adipose tissue samples were collected on six occasions (in the fasting state and 8 h after consumption of three different standardized meals), and plasma and adipose tissue LYC concentrations were quantified by HPLC. Forty-three candidate genes potentially involved in LYC metabolism were selected, and the association of 3786 SNPs from these genes with adipose tissue LYC concentration was assessed using partial least squares regression. Results: Adipose tissue LYC concentration showed marked interindividual variability (CV = 55%). Adipose tissue and fasting plasma LYC concentrations were significantly, but moderately, correlated (Pearson's r = 0.37; 95% CI: 0.07–0.61). An internally validated PLS regression model consisting of 17 SNPs in 11 genes—ABCA1, APOB, CD36, ELOVL5, GRAMD1C, INSIG2, IRS1, ISX, PPARG, SOD2, and TCF7L2—explained 55% of the variability in adipose tissue LYC concentration (adjusted R2). Conclusions: Adipose tissue LYC concentration displays high interindividual variability, which can be explained in part by genetic variants in genes involved in carotenoid and lipid metabolism. Clinical trial registry: ClinicalTrials.gov registration number NCT02100774.
The main storage site of LYC in the human body is adipose tissue, which has been estimated to account for approximately 61 and 72% of the total LYC pool in males and females, respectively.10 An in vitro study investigating the subcellular distribution of LYC in adipocytes (3T3-L1 cells) reported the following localization: lipid droplets (32–51%), plasma membrane (32–37%), and nuclear membrane (19–29%).11 Although the majority of dietary LYC occurs in the all-trans conformation,12 cis isomers predominate in circulation and adipose tissue,13 likely due to a combination of enhanced bioavailability, thermodynamic stability, and endogenous isomerization during digestion, absorption and tissue distribution.12 In addition, LYC can undergo enzymatic cleavage by β-carotene oxygenase 2 (BCO2), generating apo-lycopenoids with distinct biological activities.14 Apo-lycopenoids have been found in human blood following chronic consumption of tomato juice,15,16 although at much lower concentrations than cis or trans isomers of LYC. To date, their presence, abundance, and physiological relevance in human adipose tissue remain poorly characterized.17 In a study by Chung et al., carotenoid concentrations were measured in subcutaneous adipose tissue from three anatomical locations (abdomen, buttock, and thigh) in 25 healthy adults (12 males, 13 females; mean age = 31.9 ± 2 years; BMI = 24.5 ± 0.5 kg m−2).13 Although LYC was not the predominant carotenoid in the participants’ diet or serum, it was consistently the most abundant carotenoid in adipose tissue, with the sum of its trans and cis isomers representing 56.1%, 55.8%, and 58.6% of total carotenoids in the abdominal, buttock, and thigh depots, respectively. However, other authors have reported a lower contribution of LYC to total adipose carotenoid concentrations.18 In this tissue, LYC may exert several biological roles. In addition to its well-established and potent antioxidant properties,19 it has been suggested that it also has anti-inflammatory effects.9 This is particularly relevant, as adipose tissue is a key organ in the initiation of metabolic inflammation, which is implicated in the development of various cardiometabolic diseases.9
Despite its physiological relevance, the factors influencing LYC concentration in adipose tissue remain poorly understood.1 LYC in adipose tissue is derived from circulating lipoproteins: in the fasting state, it is primarily associated with LDL (76%), HDL (17%), and VLDL (7%),10 while in the postprandial state, it also circulates in chylomicrons. Nonetheless, correlations between circulating and adipose tissue LYC concentrations are generally weak to moderate. For example, Chung et al. reported Pearson's correlation coefficients of 0.38, 0.33, and 0.27 between serum and abdominal, buttock, and thigh adipose tissue LYC concentrations, respectively.13 Furthermore, our group has shown in rats that carotenoid uptake by adipose tissue is not correlated with the physicochemical properties of the carotenoids,20 suggesting that mechanisms beyond passive diffusion are involved. Supporting this hypothesis, both in vitro and ex vivo studies from our laboratory have demonstrated that CD36 molecule (CD36), an integral membrane protein expressed in many cell types, plays a role in LYC uptake by adipocytes.21 Given the possibility that additional proteins may be involved in LYC transport and metabolism in adipose tissue, we hypothesized that genetic variations in genes encoding these proteins could partly explain interindividual differences in adipose tissue LYC concentrations.
Therefore, the objectives of this study were: (1) to characterize interindividual variability in LYC concentration within subcutaneous white adipose tissue in a sample of 43 healthy adult males, and (2) to identify single nucleotide polymorphisms (SNPs) associated with adipose tissue LYC concentrations using a candidate gene approach.
| Characteristic | Mean (SEM) |
|---|---|
| a Quantified in fasting plasma samples.b Mean of 3 samples collected at least 3 weeks apart. | |
| Age, years | 31.9 (1.9) |
| BMI, kg m−2 | 23.0 (0.3) |
| Plasma total cholesterola, g L−1 | 1.6 (0.1) |
| Plasma LDL-cholesterola, g L−1 | 1.1 (0.1) |
| Plasma HDL-cholesterola, g L−1 | 0.5 (0.01) |
| Plasma triglyceridesa, g L−1 | 0.8 (0.1) |
| Plasma glucosea, mmol L−1 | 4.7 (0.1) |
| Plasma hemoglobina, g dL−1 | 15.0 (0.1) |
| Plasma lycopenea,b, nmol L−1 | 103.6 (12.1) |
Participants were provided with three different test meals, which they consumed in a randomized order, with a washout period of at least three weeks between each meal. All meals had the same basic composition: 70 g of semolina cooked in 200 mL of water, 40 g of white bread, 60 g of hard-boiled egg whites, 50 g of peanut oil, and 330 mL of mineral water. The only difference between the meals was their micronutrient content: the control meal contained no added micronutrients; the vitamin E meal included a capsule containing RRR-α-tocopheryl acetate equivalent to 67 mg (100 IU) of α-tocopherol (Holland & Barrett, Nuneaton, Warwickshire, England); and the tomato puree meal included 100 g of tomato puree, providing 9.7 mg of all-trans LYC as measured by high-performance liquid chromatography (HPLC). Participants were instructed to avoid carotenoid-rich foods (e.g., tomatoes, carrots) for 48 h before each test meal, with a list of such foods provided. On the evening before each test, participants were asked to eat dinner between 7:00 and 8:00 p.m. without alcohol and to refrain from consuming any food or drink other than water until arriving at the Center for Clinical Investigation (La Conception Hospital, Marseille, France) the next morning. At the center, participants consumed one of the three test meals, and blood samples were collected at regular intervals for up to 8 h post-consumption to assess the bioavailability of the meal's micronutrients.22–25,27 Participants were instructed to eat the meal at a consistent pace, consuming half within the first 10 min and the remainder within the next 10 min. No other food was permitted during the following 8 h, although participants were allowed to drink any remaining water provided with the meal.
Postprandial plasma chylomicron LYC concentrations (from 1 to 8 h) following consumption of the tomato puree meal were measured as previously described.23
:
5 in PBS. Lipids, including LYC, were extracted from the remaining 250 µL using 2 mL of trichloromethane/methanol (1/1, v/v) and 0.9 mL PBS. All extractions were performed at room temperature under yellow light to prevent light-induced degradation. The extract was dried and incubated at 37 °C for 1.5 h with 100 µL of 12% ethanolic pyrogallol solution (as an antioxidant) and 1 mL of 5.5% ethanolic potassium hydroxide solution to saponify and quantify total LYC. After cooling, 100 µL of ethanolic apo-8′-carotenal (DSM-Firmenich AG, Kaiseraugst, Switzerland) was added as the internal standard. The mixture was then extracted twice with 3 mL of hexane. The extract was evaporated to dryness under nitrogen and re-dissolved in 100 µL of methanol/dichloromethane (65/35, v/v) for HPLC analysis.
A volume of 90 μL was used for HPLC analysis. The separation was performed using a 10.0 × 4.0 mm Modulo-Cart QS guard column with a 2 μm particle size (Interchim, Montluçon, France), followed by a 250 × 4.6 mm YMC C30 analytical column with a 5 μm particle size (Interchim), maintained at a constant temperature of 35 °C. The mobile phase consisted of HPLC-grade methanol (component A), methyl tert-butyl ether (component B), and water (component C) (Carlo Erba–SDS). A linear gradient was applied, starting with 96% A, 2% B, and 2% C at time 0, transitioning to 18% A, 80% B, and 2% C by 27 min, at a flow rate of 1 mL min−1. The HPLC system consisted of a pump (Waters 2690) associated with a photodiode-array detector (Waters 2996) (Waters). Detection of LYC occurred via UV spectra and retention time coincident with an authentic standard (Sigma-Aldrich, Saint Quentin Fallavier, France), with quantification at 472 nm, considering the sum of all its geometric isomers (cis and trans forms). Peak integration and quantification were carried out using Chromeleon CDS software (version 6.80, Dionex), using an external calibration curve normalized to the internal standard.
Partial least squares (PLS) regression was used to identify combinations of SNPs best explaining the variance in adipose tissue LYC concentration. A two-step approach was applied, combining dimension reduction by univariate filtering followed by PLS regression, as previously described for SNP data.27,28,33–37 The univariate filtering step was based on selecting SNPs showing a Wald test asymptotic p-value <0.05 in either the additive or the dominant genetic model, as obtained from PLINK (v1.07, https://pngu.mgh.harvard.edu/purcell/plink/). A PLS regression model was then built. The X variables included all selected SNPs, anthropometric measurements, and fasting plasma lipid concentrations showing a non-zero correlation (Pearson's r) (e.g., LYC, cholesterol, etc.). The Y variable was adipose tissue LYC concentration. All variables were mean-centered and scaled to unit variance (UV scaling). X variables were ranked according to their variable importance in the projection (VIP) values, which estimate the contribution of each variable to explaining the Y variable in the PLS model. Several PLS regression models were then built using increasing VIP threshold values, as described in detail elsewhere.38 The model that maximized the explained variance (adjusted R2) and was statistically significant according to cross-validation ANOVA39 was selected.
This model was further internally validated using leave-k-out cross-validation,40 regression coefficient stability testing,29 and response permutation testing, as detailed in the SI. For response permutation testing, the explained variance and the explained variance after cross-validation of the original model were compared with the explained variance and the explained variance after cross-validation of 100 models based on data where the order of the Y matrix for the participants (adipose tissue LYC concentration) was randomly permuted, while the X matrix (SNPs and covariates) was kept intact. The SIMCA® Multivariate Data Analytics Solution software (Version 17.0.0.24543, Umetrics, Umeå, Sweden) was used for all PLS regression analyses and internal validation tests.
Adipose tissue LYC concentration was significantly correlated with fasting plasma LYC concentration (r = 0.37). In addition, it was also significantly correlated with fasting plasma total cholesterol (r = 0.31) and HDL-cholesterol concentration (r = 0.39) (Table 2).
| Pearson's r | 95% CI | p-Value | |
|---|---|---|---|
| a For each participant, the baseline-adjusted area under the curve of the postprandial plasma chylomicron lycopene concentration over 8 h following the consumption of the tomato puree test meal,2 an acknowledged marker of carotenoid bioavailability, was calculated.b Parameters were considered significant at 0.05 level. | |||
| Age, years | −0.11 | −0.40, 0.19 | 0.47 |
| BMI, kg m−2 | −0.15 | −0.43, 0.16 | 0.33 |
| Fasting plasma concentration | |||
| Lycopene, nmol L−1 | 0.37 | 0.07, 0.61 | 0.01b |
| Cholesterol, g L−1 | 0.31 | 0.01, 0.56 | 0.04b |
| LDL-cholesterol, g L−1 | 0.15 | −0.19, 0.45 | 0.38 |
| HDL-cholesterol, g L−1 | 0.39 | 0.07, 0.63 | 0.02b |
| Triglycerides, g L−1 | 0.17 | −0.14, 0.45 | 0.27 |
| Postprandial chylomicron lycopene concentrationa | −0.14 | −0.46, 0.22 | 0.45 |
| SNP | Gene | Alleles | Alternate allele frequencya (European population) | Gene region | Unstandardized regression coefficientb | p-Valuec | Variant effect prediction scored |
|---|---|---|---|---|---|---|---|
| a Alternate allele frequencies were retrieved from dbSNP (https://www.ncbi.nlm.nih.gov/snp/) using the Allele Frequency Aggregator (ALFA) dataset (pooled allele frequency data from dbSNP and the dbGaP) in the European population (10.04.2025). All SNPs were either intronic or intergenic.b Unstandardized regression coefficients represent the mean change in adipose tissue lycopene concentration (nmol per g protein) for each additional copy of the minor allele under the additive model and in the presence of the minor allele under the dominant model.c SNPs are ranked by increasing p-values.d Variant Effect Prediction Score was estimated using RegulomeDB for intron or intergenic SNPs (accessed on 10.04.2025).e For SNPs under the dominant model, participants homozygous for the lesser frequent allele were grouped with heterozygous participants and were compared with participants homozygous for the more frequent allele. Abbreviations: gene names can be found in SI Table S1. | |||||||
| Additive model | |||||||
| rs2205810 | ISX | A > G | G = 0.70 | Intergenic | 106.7 | 0.002 | 0.13 |
| rs4277044 | TCF7L2 | G > A | A = 0.35 | Intron | 106.7 | 0.002 | 0.13 |
| rs1501460 | ABCA1 | T > C | C = 0.44 | Intergenic | −109.0 | 0.004 | 0.59 |
| rs9920375 | LIPC | T > C | C = 0.56 | Intergenic | 78.7 | 0.016 | 0.61 |
| rs12953429 | MC4R | A > G | G = 0.51 | Intergenic | 86.6 | 0.019 | 0.18 |
| rs1422450 | SLC27A6 | T > C | C = 0.60 | Intergenic | 87.1 | 0.025 | 0.15 |
| rs13398058 | IRS1 | G > A | A = 0.61 | Intergenic | 77.1 | 0.025 | 0.13 |
| rs1033772 | TCF7L2 | G > A | A = 0.35 | Intergenic | 82.9 | 0.028 | 0.61 |
| rs4743764 | ABCA1 | T > C | C = 0.42 | Intron | 67.5 | 0.034 | 0.61 |
| rs4276037 | INSIG2 | G > A | A = 0.73 | Intergenic | 69.2 | 0.036 | 0.33 |
| rs2017523 | ISX | G > A | A = 0.33 | Intergenic | 78.1 | 0.036 | 0.41 |
| rs17770539 | INSIG2 | T > C | C = 0.41 | Intergenic | −65.4 | 0.037 | 0.30 |
| rs4684104 | PPARG | A > G | G = 0.57 | Intergenic | 71.0 | 0.044 | 0.61 |
| rs3823037 | SOD2 | T > C | C = 0.40 | Intergenic | 66.7 | 0.049 | 0.22 |
| rs9967057 | MC4R | G > A | A = 0.61 | Intergenic | −74.6 | 0.049 | 0.13 |
| Dominant modele | |||||||
| rs12629751 | PPARG | C > T | T = 0.10 | Intron | 124.9 | 6.68 × 10−4 | 0.18 |
| rs5755436 | ISX | C > T | T = 0.10 | Intergenic | 96.1 | 9.30 × 10−4 | 0.13 |
| rs2817114 | ELOVL5 | T > G | G = 0.11 | Intergenic | 85.3 | 0.002 | 0.61 |
| rs5749894 | ISX | T > C | C = 0.90 | Intergenic | 93.1 | 0.002 | 0.00 |
| rs4682144 | GRAMD1C | A > G | G = 0.32 | Intron | 74.0 | 0.002 | 0.13 |
| rs7575840 | APOB | G > T | T = 0.32 | Intergenic | −71.8 | 0.003 | 0.24 |
| rs10186364 | INSIG2 | A > G | G = 0.84 | Intergenic | 77.1 | 0.004 | 0.61 |
| rs7754295 | SOD2 | C > T | T = 0.06 | Intergenic | 92.9 | 0.004 | 0.61 |
| rs5749872 | ISX | G > A | A = 0.83 | Intergenic | 78.0 | 0.005 | 0.13 |
| rs7558381 | IRS1 | T > C | C = 0.64 | Intergenic | 70.1 | 0.005 | 0.13 |
| rs11196218 | TCF7L2 | G > A | A = 0.28 | Intron | −67.5 | 0.005 | 0.59 |
| rs2056983 | ISX | G > T | T = 0.06 | Intergenic | 86.4 | 0.005 | 0.61 |
| rs6959775 | CD36 | A > G | G = 0.56 | Intergenic | 73.1 | 0.005 | 0.13 |
| rs9607112 | ISX | G > A | A = 0.06 | Intergenic | 81.9 | 0.006 | 0.13 |
| rs5750060 | ISX | T > C | C = 0.17 | Intergenic | 73.2 | 0.006 | 0.61 |
| rs8023369 | LIPC | T > G | G = 0.38 | Intergenic | −68.8 | 0.007 | 0.61 |
| rs7185427 | BCO1 | C > T | T = 0.82 | Intergenic | 74.8 | 0.007 | 0.57 |
| rs11152240 | MC4R | T > C | C = 0.09 | Intergenic | 93.2 | 0.007 | 1.00 |
| rs16866988 | IRS1 | G > A | A = 0.04 | Intergenic | 100.8 | 0.007 | 0.18 |
| rs7858499 | ABCA1 | T > C | C = 0.20 | Intergenic | 65.4 | 0.008 | 0.61 |
| rs10039077 | SLC27A6 | G > A | A = 0.12 | Intergenic | 81.8 | 0.009 | 0.13 |
| rs134225 | ISX | T > G | G = 0.96 | Intergenic | 99.1 | 0.009 | 0.59 |
| rs1561166 | ABCA1 | T > C | C = 0.09 | Intergenic | 98.8 | 0.009 | 0.13 |
| rs737821 | ISX | C > T | T = 0.73 | Intergenic | −63.2 | 0.009 | 0.61 |
| rs9456400 | SOD2 | A > G | G = 0.14 | Intergenic | 90.7 | 0.009 | 0.18 |
| rs12711901 | INSIG2 | C > T | T = 0.89 | Intergenic | 77.1 | 0.010 | 0.61 |
| rs11057841 | SCARB1 | C > T | T = 0.16 | Intron | 62.0 | 0.011 | 0.13 |
| rs1316328 | IRS1 | A > G | G = 0.12 | Intergenic | 88.8 | 0.011 | 0.61 |
| rs2937359 | ABCA1 | T > C | C = 0.56 | Intergenic | 65.5 | 0.011 | 0.61 |
| rs1152001 | PPARG | G > A | A = 0.79 | Intron | −62.6 | 0.012 | 0.61 |
| rs135159 | ISX | T > C | C = 0.22 | Intergenic | 61.5 | 0.013 | 0.13 |
| rs7022410 | ABCA1 | A > G | G = 0.04 | Intergenic | 81.9 | 0.013 | 0.13 |
| rs2740486 | ABCA1 | T > G | G = 0.47 | Intron | 69.3 | 0.013 | 0.51 |
| rs2120825 | PPARG | T > G | G = 0.10 | Intron | −68.6 | 0.014 | 0.61 |
| rs4694627 | CXCL8 | C > T | T = 0.39 | Intergenic | 61.2 | 0.014 | 0.59 |
| rs7082458 | TCF7L2 | A > G | G = 0.16 | Intron | 63.8 | 0.014 | 0.59 |
| rs4820135 | ISX | C > T | T = 0.21 | Intergenic | −65.9 | 0.015 | 0.26 |
| rs4849726 | INSIG2 | G > A | A = 0.25 | Intergenic | 59.0 | 0.017 | 0.18 |
| rs7573503 | INSIG2 | T > C | C = 0.05 | Intergenic | 90.6 | 0.017 | 0.13 |
| rs5749854 | ISX | A > G | G = 0.15 | Intergenic | 68.3 | 0.018 | 0.24 |
| rs496356 | TCF7L2 | T > C | C = 0.90 | Intergenic | 59.2 | 0.019 | 0.98 |
| rs4564774 | INSIG2 | T > C | C = 0.07 | Intergenic | 82.5 | 0.019 | 0.15 |
| rs6989064 | LPL | C > T | T = 0.56 | Intergenic | 64.3 | 0.022 | 0.61 |
| rs2413241 | ISX | T > C | C = 0.74 | Intergenic | 56.1 | 0.023 | 0.13 |
| rs9382183 | ELOVL5 | A > G | G = 0.89 | Intergenic | 63.4 | 0.024 | 0.59 |
| rs12497191 | PPARG | A > G | G = 0.14 | Intron | 74.8 | 0.024 | 0.22 |
| rs12711897 | INSIG2 | G > A | A = 0.92 | Intergenic | 74.7 | 0.024 | 0.61 |
| rs5755445 | ISX | T > C | C = 0.24 | Intergenic | 56.6 | 0.025 | 0.61 |
| rs1873233 | ISX | T > C | C = 0.20 | Intergenic | 60.4 | 0.027 | 0.13 |
| rs9365050 | SOD2 | G > A | A = 0.73 | Intergenic | 55.9 | 0.027 | 0.13 |
| rs9652472 | LIPC | G > A | A = 0.95 | Intron | 78.0 | 0.027 | 0.57 |
| rs709150 | PPARG | C > G | G = 0.39 | Intron | 60.2 | 0.027 | 0.61 |
| rs4917644 | TCF7L2 | C > T | T = 0.16 | Intron | −54.7 | 0.028 | 0.61 |
| rs608318 | MGLL | G > T | T = 0.86 | Intron | −58.2 | 0.029 | 0.61 |
| rs567384 | MGLL | C > T | T = 0.88 | Intron | 65.4 | 0.030 | 0.04 |
| rs130575 | ISX | A > G | G = 0.14 | Intergenic | 58.9 | 0.031 | 0.18 |
| rs2816376 | ELOVL5 | T > C | C = 0.28 | Intergenic | 52.8 | 0.032 | 0.61 |
| rs3211881 | CD36 | A > G | G = 0.07 | Intron | 58.8 | 0.032 | 0.84 |
| rs5994853 | ISX | A > G | G = 0.20 | Intergenic | −52.5 | 0.033 | 0.13 |
| rs2414555 | LIPC | A > G | G = 0.26 | Intergenic | −52.8 | 0.033 | 0.93 |
| rs7598775 | APOB | G > A | A = 0.09 | Intergenic | 59.8 | 0.034 | 0.55 |
| rs7652615 | MGLL | G > T | T = 0.84 | Intron | −56.4 | 0.035 | 0.52 |
| rs435066 | RPE65 | T > C | C = 0.17 | Intergenic | −54.3 | 0.035 | 0.32 |
| rs6737960 | IRS1 | A > C | C = 0.18 | Intergenic | −55.2 | 0.035 | 0.55 |
| rs9919066 | ABCA1 | C > T | T = 0.09 | Intergenic | −60.8 | 0.036 | 0.00 |
| rs579902 | TCF7L2 | A > G | G = 0.25 | Intergenic | −52.4 | 0.037 | 0.59 |
| rs1247683 | CXCL8 | C > T | T = 0.97 | Intergenic | 79.8 | 0.037 | 0.61 |
| rs6744750 | APOB | T > C | C = 0.23 | Intergenic | 51.8 | 0.037 | 0.59 |
| rs16866708 | IRS1 | A > G | G = 0.14 | Intergenic | −55.5 | 0.038 | 0.45 |
| rs2842994 | SOD2 | G > A | A = 0.16 | Intergenic | 52.5 | 0.039 | 0.61 |
| rs739066 | ISX | C > T | T = 0.78 | Intergenic | 50.3 | 0.042 | 0.61 |
| rs2915775 | PNLIP | T > C | C = 0.83 | Intron | 57.4 | 0.042 | 0.89 |
| rs3124016 | ABCA1 | A > G | G = 0.74 | Intergenic | 50.8 | 0.042 | 0.11 |
| rs2396261 | IRS1 | C > T | T = 0.76 | Intergenic | −54.9 | 0.042 | 0.18 |
| rs12587408 | RDH12 | C > A | A = 0.16 | Intergenic | −57.2 | 0.043 | 0.50 |
| rs4149290 | ABCA1 | T > C | C = 0.11 | Intron | −64.0 | 0.043 | 0.59 |
| rs17186765 | BCO1 | C > T | T = 0.12 | Intergenic | −59.0 | 0.043 | 0.18 |
| rs10933143 | IRS1 | G > A | A = 0.26 | Intergenic | 49.6 | 0.045 | 0.61 |
| rs6567169 | MC4R | T > C | C = 0.62 | Intergenic | 49.3 | 0.048 | 0.18 |
| rs1361325 | SOD2 | C > T | T = 0.22 | Intergenic | 51.7 | 0.049 | 0.22 |
| rs980069 | TCF7L2 | G > A | A = 0.27 | Intergenic | −48.5 | 0.049 | 0.57 |
| rs1339326 | SOD2 | A > C | C = 0.87 | Intergenic | 65.5 | 0.050 | 0.13 |
| Genea | SNP | VIP valueb | Regression coefficientc |
|---|---|---|---|
| a Gene names can be found in SI Table S1.b Variables were ranked according to their variable importance in the projection (VIP) value, which estimates the contribution of each SNP in the projection used in the PLS regression model.c Regression coefficients are for untransformed variables and represent the mean change in adipose tissue lycopene concentration (nmol per g protein) for each additional copy of the minor allele under the additive model and in the presence of the minor allele under the dominant model. | |||
| PPARG | rs12629751 | 1.37 | 54.98 |
| ISX | rs5755436 | 1.34 | 42.31 |
| ELOVL5 | rs2817114 | 1.27 | 37.54 |
| ISX | rs5749894 | 1.24 | 40.99 |
| GRAMD1C | rs4682144 | 1.24 | −32.58 |
| ISX | rs205810 | 1.23 | 23.49 |
| TCF7L2 | rs4277044 | 1.23 | 23.48 |
| APOB | rs7575840 | 1.23 | −31.63 |
| INSIG2 | rs10186364 | 1.18 | 33.96 |
| ABCA1 | rs1501460 | 1.18 | −23.99 |
| SOD2 | rs7754295 | 1.17 | 40.91 |
| ISX | rs5749872 | 1.16 | 34.36 |
| IRS1 | rs7558381 | 1.16 | −30.84 |
| TCF7L2 | rs11196218 | 1.15 | −29.71 |
| ISX | rs2056983 | 1.15 | 38.03 |
| CD36 | rs6959775 | 1.15 | −32.17 |
| ISX | rs9607112 | 1.14 | 36.04 |
![]() | (1) |
In this group of healthy adult males, adipose tissue LYC concentration exhibited a CV of 55%, which is relatively high given the homogeneous characteristics of this healthy male cohort. This implies that variability may be even greater in the general population. Still, this estimate falls within the range reported in previous studies (Table 5). Adipose tissue LYC concentration was only modestly correlated with fasting plasma LYC concentration (r = 0.37), in agreement with earlier reports.13,18,43 In addition, positive associations with plasma total cholesterol (r = 0.31) and HDL-cholesterol concentrations (r = 0.39) are consistent with the role of lipoproteins in LYC transport and tissue delivery. Altogether, these findings suggest that interindividual differences in adipose tissue LYC concentration reflect both systemic factors related to lipoprotein metabolism and tissue-specific mechanisms of cellular uptake and storage.
| Population characteristics | Mean | SD | %CVa | Ref. |
|---|---|---|---|---|
| a The value of %CV was calculated, when SD or SEM was reported.b Femoral and gluteal adipose tissue LYC concentration were also measured.c The value provided included participants of both sexes. | ||||
| 213 healthy participants; gluteal adipose tissue | 43 | |||
| 91 males; age: 52.5 ± 1.0 year; BMI: 25.7 ± 0.3 kg m−2 | 0.3 μg g−1 fatty acid | 0.2 | 67 | |
| 122 females; age: 61.3 ± 0.6 years; BMI: 25.8 ± 0.4 kg m−2 | 0.4 μg g−1 fatty acid | 0.3 | 75 | |
| 458 healthy participants; gluteal adipose tissue | 18 | |||
| 347 males; age: 56 ± 0.6 years; BMI: 25.5 ± 0.2 kg m−2 | 0.17 μg g−1 tissueb | 0.19 | 112 | |
| 111 females; age: 59 ± 0.9 years; BMI: 26.2 ± 0.4 kg m−2 | 0.28 μg g−1 tissuec | 0.21 | 75 | |
| 25 healthy adults; abdominal adipose tissueb | 3.3 µmol mg−1 tissuec | 2.2 | 67 | 13 |
| 13 males; age: 32.2 ± 2.7 years; BMI: 23.9 ± 0.5 kg m−2 | ||||
| 12 females; age: 31.6 ± 2.9 years; BMI: 24.5 ± 2.0 kg m−2 | ||||
Since these processes involve proteins, and therefore genes, we sought to identify single nucleotide polymorphisms (SNPs) associated with adipose tissue LYC concentration using a candidate gene approach. With a two-step strategy, i.e., univariate filtering followed by PLS regression, we identified a combination of 17 SNPs located in or near 11 genes associated with this trait. Notably, non-genetic covariates such as plasma LYC and cholesterol concentrations were not retained in the final PLS model, suggesting that the selected SNPs accounted for part of the variability shared with these circulating measures. Among them, the SNP showing the strongest effect in the final PLS model (Table 5), based on its VIP value, was rs12629751 in PPARG. This gene encodes peroxisome proliferator-activated receptor gamma (PPARγ), a nuclear receptor that acts as a lipid-sensing transcription factor. It is highly expressed in adipose tissue, where it regulates adiposity by coordinating adipocyte differentiation and lipid metabolism.45 PPARγ influences these processes through the regulation of multiple genes and pathways,46 including scavenger receptor class B type 1 (SCARB1)47 and CD36.48 Scavenger receptor class B type 1 (SR-B1), which is encoded by SCARB1, and CD36 both encode membrane proteins involved in lipid transport, including lipophilic micronutrients,49 and are expressed in several tissues such as adipocytes, hepatocytes, and enterocytes. In enterocytes, SR-B1 mediates the apical uptake of LYC,50 while CD36 has been shown to participate in LYC uptake by adipocytes (3T3-L1 cells), and reduced carotenoid uptake in adipose tissue explants from CD36−/− mice further supports its role in this process.21 Therefore, PPARγ could affect LYC accumulation in adipocytes both indirectly, through its broader regulation of lipid metabolism, and directly, by modulating CD36 and SCARB1 expression and potentially facilitating LYC uptake into these cells. Notably, a SNP in CD36, rs6959775, was also retained in the final PLS regression model. Interestingly, this SNP in PPARG was also the strongest genetic determinant of adipose tissue retinol concentration in the same group of participants.37 Moreover, other PPARG variants, not in LD with rs12629751, were associated with adipose tissue concentrations of α-tocopherol,28 lutein, and zeaxanthin36 in this cohort. Altogether, these findings highlight the pivotal role of PPARG in the regulation of lipophilic micronutrient concentrations in adipose tissue.
We also identified six SNPs in ISX (rs5755436, rs5749894, rs205810, rs5749872, rs2056983, rs9607112) associated with adipose tissue LYC concentration. ISX encodes intestine-specific homeobox, a transcription factor restricted to the intestine that represses two key genes involved in intestinal carotenoid metabolism and transport: BCO1 and SCARB1.51 BCO1 is one of two enzymes capable of cleaving LYC, the other being BCO2. Although BCO2 has recently been established as the main enzyme responsible for LYC cleavage,14 several SNPs in BCO1 have previously been associated with fasting plasma/serum LYC concentration52 and LYC bioavailability.53,54 Taken together, these observations suggest that genetic variations in ISX could modulate LYC bioavailability and, consequently, its deposition in tissues such as adipose tissue. Supporting this hypothesis, we also identified rs2056983 in ISX as being associated with LYC bioavailability—estimated by the 0–8 h area under the curve of postprandial chylomicron LYC concentration—following the consumption of the tomato puree meal in the same cohort.23
Adipose tissue LYC concentration was also associated with rs2817114 in ELOVL5, which encodes an enzyme that catalyzes the elongation of eicosapentaenoic acid (EPA) to docosapentaenoic acid and subsequently to docosahexaenoic acid (DHA). Although carotenoids are not substrates of enzymes in the omega-3 biosynthetic pathway, several interactions between omega-3s and carotenoids have been reported. We previously showed that SNPs in ELOVL2 and ELOVL5 are associated with the bioavailability of LYC, β-carotene, lutein, and phytofluene.22–24,27 In vitro studies using Caco-2 cells have demonstrated that EPA inhibits β-carotene absorption, at least partly through activation of the PPARα receptor,55 and that both EPA and DHA reduce the expression of SR-B1.55,56 Notably, rs2817114 was also associated with adipose tissue concentrations of lutein and zeaxanthin in the same cohort.36 This association may reflect indirect effects of ELOVL5 variants on LYC bioavailability, as well as downstream effects on SR-B1 expression mediated by long-chain omega-3 fatty acids.
A SNP in GRAMD1C, rs4682144, was also associated with adipose tissue LYC concentration. GRAMD1C encodes Aster-C, a member of the Aster protein family recently implicated in the non-vesicular transfer of cholesterol between the plasma membrane, endoplasmic reticulum, and mitochondria.57 Given the chemical similarities between cholesterol and carotenoids, Aster proteins have been hypothesized to mediate carotenoid intracellular transport, a role confirmed in 2022 for Aster-B (encoded by GRAMD1B).58 More recently, studies in mice demonstrated that Aster-C, which is highly expressed in enterocytes, influences zeaxanthin bioavailability.59 Our findings therefore add to growing evidence linking Aster proteins to carotenoid metabolism. Although the mechanism underlying the association of rs4682144 with adipose tissue LYC concentration remains unclear, GRAMD1C (ASTER-C) is more highly expressed in small intestine and liver than in adipose tissue according to the Human Protein Atlas. It is therefore plausible that this variant—or another in LD—modulates GRAMD1C expression or activity in these tissues, thereby influencing LYC bioavailability and ultimately its deposition in adipose tissue.
Another SNP of interest associated with adipose tissue LYC concentration was rs7754295 in SOD2. SOD2 encodes superoxide dismutase 2, a mitochondrial enzyme that converts superoxide radicals into hydrogen peroxide, thereby protecting cells against oxidative stress. Observational studies have consistently reported inverse correlations between oxidative stress biomarkers and circulating carotenoid concentrations, including LYC.60 Although several intervention trials have reported reductions in oxidative stress biomarkers following carotenoid supplementation or consumption of carotenoid-rich foods (including tomatoes and tomato products) in participants with chronic diseases, results from similar trials conducted in healthy individuals remain inconclusive.60 Therefore, the causal direction of this relationship remains uncertain. Since LYC exhibits strong antioxidant activity in vitro,3 a plausible explanation for the observed association is that reduced SOD2 activity could increase oxidative stress, resulting in greater utilization of antioxidants such as LYC and consequently lower tissue concentrations. Notably, this variant has also been suggested to act as an expression quantitative trait locus (eQTL), potentially influencing SOD2 expression.61
This study has several limitations. First, we did not assess dietary LYC intake, as no dietary survey was conducted. Because humans cannot synthesize carotenoids, all adipose tissue LYC originates from the diet, and it is reasonable to assume that intake influences adipose tissue concentrations. However, correlations between dietary intake and adipose tissue LYC are generally modest. El-Sohemy et al. reported Spearman's ρ = 0.26 in males and 0.14 in females,18 while Chung et al. found r values of 0.41 (abdomen), 0.24 (buttocks), and 0.06 (thigh).13 Our regression model included fasting circulating LYC concentrations, which can serve as a proxy for dietary LYC intake. Nevertheless, incorporating dietary LYC intake might have further enhanced the model's explanatory power. Second, our HPLC method did not allow full chromatographic resolution of LYC isomers, so we quantified LYC as the sum of all isomers. While dietary LYC is predominantly in the all-trans form, cis-isomers are more abundant in blood and tissues,10 including adipose tissue,13 due to higher bioavailability, greater thermodynamic stability at elevated temperatures, and endogenous isomerization.10 Given that cis-isomers may exhibit stronger antioxidant activity than all-trans LYC62 while sharing some of its biological functions,63 future studies should investigate their determinants in adipose tissue. Third, we acknowledge that different fat depots, especially visceral fat, may exhibit distinct concentrations of LYC or genetic associations with LYC concentration. Future studies could explore these differences to provide further insights into the functional roles of LYC in different adipose depots. Fourth, our sample included only 43 Caucasian adult males. Given the relatively small sample size, the associations identified in this exploratory study require confirmation in larger, independent cohorts. In addition, these findings cannot currently be generalized to other populations, including females and individuals from different ethnic backgrounds. Females have been reported to display higher adipose tissue LYC concentrations than males,13,18,43 raising the possibility of sex-related differences in LYC metabolism, potentially linked to differential expression of related proteins. Finally, our candidate gene approach may have missed important genes not previously implicated in adipose tissue LYC concentration. In addition, several SNPs in the selected genes were not included in the PLS regression because they were absent from the BeadChips or excluded during quality control (see Methods). Taken together, these limitations indicate that the present work should be considered exploratory and that the reported genetic associations should be interpreted as hypothesis-generating pending replication in larger and more diverse populations.
To conclude, this work represents the first step toward identifying genetic determinants of LYC concentration in human adipose tissue, its major storage site. The results suggest that some individuals may have a reduced capacity to accumulate LYC, which could influence their ability to benefit from its proposed health effects, including antioxidant protection and potential roles in cardiometabolic and cancer prevention. As with other fat-soluble micronutrients,28,36,37 genetic variation may therefore contribute to interindividual differences in tissue status and related disease risk. Future studies should aim to replicate these findings in larger and more diverse populations, to clarify the mechanisms involved, and ultimately to determine whether genetic information could be used to identify individuals who might benefit from tailored dietary advice or LYC supplementation.
| HPLC | High-performance liquid chromatography |
| LD | Linkage disequilibrium |
| LYC | Lycopene |
| PBS | Phosphate-buffered saline |
| PLS | Partial least squares |
| SNP | Single nucleotide polymorphism |
| VIP | Variable importance in the projection |
Supplementary information (SI) is available. See DOI: https://doi.org/10.1039/d5fo05171a.
Footnote |
| † Co-first authors. |
| This journal is © The Royal Society of Chemistry 2026 |