rs5082 — APOA2 -265T>C

The Saturated Fat Switch: How APOA2 Genotype Determines Your Dietary Risk

Apolipoprotein A-II is the second most abundant protein in HDL particles¹¹ second most abundant protein in HDL particles
After apolipoprotein A-I; ApoA-II accounts for roughly 15-20% of total HDL protein mass, the particles traditionally associated with cardiovascular protection. Yet ApoA-II's role extends well beyond lipid transport — it appears to act as a postprandial satiety signal²² postprandial satiety signal
Released after meals, ApoA-II may communicate fat availability to appetite-regulating centers, particularly in the context of dietary fat intake. The rs5082 variant in the APOA2 promoter region is one of the most robustly replicated gene-diet interactions³³ gene-diet interactions
The modification of a genetic effect by an environmental factor — here, dietary fat intake changes whether the genotype affects body weight in the history of nutrigenetics: the same genotype that has no measurable effect in people eating a modest amount of saturated fat becomes a clinically meaningful obesity risk factor in those eating a high-saturated-fat diet.

The variant is located 265 bases upstream of the APOA2 transcription start site, placing it squarely in the promoter — the region that determines how frequently the gene is switched on. Note on allele nomenclature: the variant is traditionally named "-265T>C" using the APOA2 coding strand, which runs in the reverse direction relative to the reference genome. On the forward (plus) strand reported by 23andMe and other consumer services, the T allele corresponds to A and the C allele corresponds to G. In this profile, all genotypes use forward-strand notation: AA corresponds to the traditional TT, AG to TC, and GG to CC.

The Mechanism

In laboratory reporter assays, the C allele (G in forward-strand notation) reduces the basal transcriptional activity of the APOA2 promoter by approximately 30%⁴⁴ basal transcriptional activity of the APOA2 promoter by approximately 30%
Measured by transfecting cells with reporter constructs containing either the -265T or -265C allele compared to the T allele. Lower transcriptional activity means less ApoA-II protein in circulation. The proposed consequence is a blunted postprandial satiety signal: individuals with the GG genotype may not experience the same dietary fat-induced satiety cues as AA carriers, potentially leading to greater food intake and reduced appetite suppression after fat-rich meals.

In a landmark 2018 epigenomic and metabolomic study⁵⁵ 2018 epigenomic and metabolomic study
Using three populations with stored biosamples from the original 2009 replication study, researchers identified a specific methylation site (cg04436964) located approximately 26 kb from rs5082 that showed significantly higher methylation in GG carriers consuming high saturated fat diets across all three study populations. This methylation was negatively associated with APOA2 mRNA expression — the more methylated, the less ApoA-II produced. The researchers also found downstream metabolomic changes in GG high-SFA consumers: dysregulation of tryptophan/kynurenine and branched-chain amino acid (BCAA) metabolic pathways, implicating altered energy homeostasis and appetite regulation, not just lipid metabolism.

The Evidence

The gene-diet interaction story for rs5082 begins with the 2007 GOLDN study⁶⁶ 2007 GOLDN study
Genetics of Lipid Lowering Drugs and Diet Network; n=1,078, which first reported that CC homozygotes consumed significantly more total energy (9,371 vs 8,456 kJ/day, P=0.005), more fat, and more protein than T allele carriers, and had 1.70-fold higher obesity odds (95%CI 1.02–2.80). Crucially, the obesity association was confined to those consuming high saturated fat.

The pivotal 2009 replication study⁷⁷ 2009 replication study
Cross-sectional and prospective data from three independent U.S. populations analyzed 3,462 individuals from the Framingham Offspring Study (n=1,454), GOLDN (n=1,078), and Boston Puerto Rican Study (n=930), finding consistent results across all three. Among high saturated fat consumers (≥22g/day), GG homozygotes had 6.2% higher BMI on average (range 4.3–7.9%, P<0.05 in each cohort) and 1.84-fold higher odds of obesity (95%CI 1.38–2.47, P<0.0001). In the low-SFA group, there was no association (OR=0.81, P=0.18). This dose-threshold pattern — no effect below 22g/day, clear effect above — is the defining feature of this gene-diet interaction.

Replication extended across cultures. A 2011 study⁸⁸ 2011 study
In a Spanish Mediterranean population (n=907) and multiethnic Singapore National Health Survey (n=3,605) confirmed the interaction in Mediterranean Europeans, where GG carriers with high SFA intake had 6.8% higher BMI (P=0.018) but no difference with low SFA (P=0.316). In East Asian populations, the GG genotype is rare (<1% in Chinese, ~1.3% in Malays), limiting power but showing directionally consistent trends among Asian Indians, who have higher C allele frequency (~22%). A 2013 analysis⁹⁹ 2013 analysis
Using higher-fat dairy as a specific saturated fat source in the same U.S. populations showed that dairy-derived saturated fat specifically drives the interaction, with a dose-response relationship between higher-fat dairy servings and BMI in GG women.

The most recent evidence comes from the 2025 DIETFITS secondary analysis¹⁰¹⁰ 2025 DIETFITS secondary analysis
609 adults from the DIETFITS randomized trial of healthy low-carbohydrate vs. healthy low-fat diets, followed for 12 months. AA carriers (TT in traditional notation) lost significantly more weight on a low-carbohydrate (and thus higher-saturated-fat) diet than on a low-fat diet at 3, 6, and 12 months — suggesting that the absence of the C allele actually confers an advantage on low-carb approaches. Among GG/AG carriers, the weight-loss advantage of low-carbohydrate diets was present only at 3 months and disappeared by 12 months, consistent with the longer-term saturated fat-driven BMI accumulation in GG homozygotes. The gene-by-SFA interaction on weight loss was statistically significant at 12 months, providing randomized trial evidence — not just observational — for the dietary prescription.

Practical Actions

For GG homozygotes, the key modifiable factor is saturated fat intake. The 22g/day threshold (approximately 10% of calories in a 2,000 kcal diet) is the best-validated cutoff in the literature. Primary sources of saturated fat to reduce: fatty red meat, full-fat dairy (butter, cream, whole milk, hard cheese), tropical oils (coconut, palm), and processed foods containing partially hydrogenated fats. Replacing these with monounsaturated fat sources (olive oil, avocados, nuts) and fish preserves caloric density without activating the genotype-specific obesity pathway.

For those with the heterozygous AG genotype, the effect follows a recessive pattern — meaning a single G allele does not confer meaningful increased risk. The literature consistently treats AA and AG genotypes as equivalent in terms of obesity risk, with the elevated risk appearing specifically in GG homozygotes.

Interactions

The APOA2 rs5082 interaction with saturated fat is one of the best-documented gene-diet interactions in obesity genetics, but it does not operate in isolation. A 2023 lifestyle modification study¹¹¹¹ 2023 lifestyle modification study
Digital health intervention, n>500 found that combined classification using CETP rs9939224 and APOA2 rs5082 genotypes predicted response to lifestyle changes: the worst responders were those with CETP GG × APOA2 AG/GG (on the plus strand), highlighting that lipid-handling pathway variants compound each other. The rs9939609 variant in the FTO gene shares the same phenotypic endpoint (obesity/BMI) through a completely different mechanism (adipocyte thermogenesis rather than satiety signaling); individuals carrying risk alleles at both loci may face compounded difficulties with weight regulation and warrant more aggressive dietary intervention.

APOA2 rs5082 also interacts with the APOA5 gene (rs662799). Both genes encode apolipoproteins that influence postprandial triglyceride-rich lipoprotein metabolism, and studies have identified simultaneous effects of APOA2 and APOA5 variants on plasma lipid responses to dietary fat. The combination of APOA2 GG and APOA5 risk alleles may produce additive impairments in postprandial lipid clearance beyond the individual effects.