Precision Nutrition, Nutrigenomics & Dietary Supplements

Citation model. Claims grounded in AllNutrition's trust-scored library carry an inline bracketed reference [n] linking to the References section, which lists each source's evidence level and AllNutrition trust score (0–1). Where an AllNutrition query returned an overall evidence_strength and consensus_level, those labels are surfaced in the Evidence Review so readers can calibrate confidence. Only sources actually returned by the tool are cited; no trust scores are invented.

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1. Introduction

A patient hands you a spit-kit report claiming her genes dictate a "high-carb-sensitivity" phenotype and recommending a $300/month personalized supplement stack. A colleague takes eight capsules every morning "for immunity, detox, and longevity." Precision nutrition and the supplement industry sell certainty — a genetic blueprint, a stack of pills — in a field where, as prior modules have established, most dietary effects are modest, contextual, and hard to prove causally.

This module examines the gap between that marketing promise and validated clinical utility. Nutrigenomics and nutrigenetics are real, mechanistically grounded sciences: diet does alter gene expression, and genetic variants do modify individual responses to nutrients. A handful of gene-diet interactions — MTHFR and folate, lactase persistence, CYP1A2 and caffeine, ALDH2 and alcohol — are well characterized and occasionally clinically actionable. But the leap from "genes influence nutrient handling" to "a direct-to-consumer test should personalize your diet" is not supported by current reproducibility or outcomes evidence [10][24]. Meanwhile, dietary supplements occupy a regulatory space (in the U.S., DSHEA) that permits marketing before any proof of efficacy or even purity, producing a landscape where some supplements are rigorously evidence-based (vitamin D in deficiency, B12 in vegans, folic acid periconceptionally) and others are marketed on hope or hype. The physician's task is to know which is which, and to communicate that difference honestly.

2. Learning Objectives

By the end of this module, the learner will be able to:

1. Distinguish nutrigenomics (diet → gene expression) from nutrigenetics (genotype → nutrient response), and explain the biological basis of well-characterized gene-diet interactions (MTHFR/folate, FTO/obesity, lactase persistence, CYP1A2/caffeine, APOE/dietary fat, ALDH2/alcohol).
2. Critically appraise the reproducibility, clinical validity, and clinical utility of direct-to-consumer (DTC) nutrigenetic testing and polygenic "personalized nutrition" products.
3. Describe the promise and current limitations of multi-omics approaches (genomics, metabolomics, microbiomics, machine-learning glycemic-response prediction) to personalized nutrition, and how they relate to microbiome science (Module 26).
4. Explain how DSHEA regulates dietary supplements in the U.S. and the resulting risks of contamination, adulteration, and mislabeling.
5. Identify supplements with established clinical utility in specific populations (vitamin D in deficiency, B12 in vegans/older adults, folic acid periconceptionally, iron in deficiency, omega-3 in hypertriglyceridemia, creatine, fat-soluble vitamins in malabsorption) versus those with weak or absent evidence for disease prevention in the general population (multivitamins, antioxidants, "immune"/"detox" products).
6. Recognize clinically significant supplement-drug interactions and apply a "food-first" counseling framework.

3. Scientific Foundations

3.1 Nutrigenomics versus nutrigenetics

The field of gene-diet interaction splits into two complementary directions. Nutrigenomics studies how nutrients and bioactive food components alter gene expression, through mechanisms such as DNA methylation and histone modification (epigenomics) and downstream transcriptomic change. Nutrigenetics studies the converse: how inherited genetic variation — chiefly single-nucleotide polymorphisms (SNPs) — modifies an individual's absorption, metabolism, and physiological response to nutrients, explaining why two people eating identical diets can have divergent glycemic, lipid, or micronutrient outcomes [1][2]. Together they underpin the aspiration of precision nutrition: replacing uniform dietary guidelines with genotype- and phenotype-informed recommendations [1][2].

3.2 Epigenetics as the mechanistic bridge

Diet alters the epigenome chiefly through one-carbon metabolism: folate, B12, choline, betaine, and methionine supply methyl groups for DNA methylation via S-adenosylmethionine. Methyl-donor-deficient diets produce global DNA hypomethylation linked to genomic instability, while specific loci respond to specific nutrients — high folate intake is associated with reduced methylation at the PPAR-γ locus, and high-fat intake with hypermethylation at the FTO locus [3][4]. Separately, short-chain fatty acids from colonic fiber fermentation (notably butyrate) act as histone-deacetylase inhibitors, promoting regulatory T-cell differentiation and anti-inflammatory gene expression — a direct mechanistic link between fiber intake, the gut microbiome (Module 26), and immune gene regulation [5][4]. Polyphenols such as resveratrol (SIRT1 activation) and EGCG, genistein, and sulforaphane (DNA methyltransferase inhibition) provide further plausible, largely preclinical, links between diet and cancer/metabolism-related gene expression [3][6]. These mechanisms are biologically elegant, but the literature is explicit that epigenetic biomarkers remain resource-intensive, tissue-specific, and "not yet ready for practical application" in routine clinical nutrition [1][3].

3.3 Well-characterized gene-diet interactions

A small number of gene-nutrient interactions have relatively strong, reproducible human evidence and some clinical relevance:

• MTHFR (C677T, A1298C) and folate. C677T can reduce methylenetetrahydrofolate reductase activity by up to ~75%, elevating homocysteine and modifying folate requirements; it is implicated in neural tube defect risk, late-onset Alzheimer's disease (particularly with APOE ε4 co-carriage), and gestational-diabetes risk modification [7][8][9]. Genotype-specific folate dosing (e.g., 800–1200 µg/day rather than standard 400 µg/day for reduced-activity carriers) has been proposed but is not yet standard practice [10].
• FTO and obesity. The FTO rs9939609 risk allele is the most consistently replicated common obesity variant (+0.9 kg/m² BMI, +1.4 cm waist circumference on average) via increased ghrelin, impaired leptin signaling, and reduced satiety [11]. Its effect is modifiable: physical activity attenuates FTO-associated obesity risk by roughly 30% [12], and lower-refined-carbohydrate diets blunt the genotype's effect, an interaction that appears stronger in some Asian cohorts [13][14]. A meta-analysis of caloric-restriction trials found FTO carriers had higher baseline triglycerides than non-carriers but otherwise similar responses to weight loss, at low-to-very-low certainty [11].
• Lactase persistence/non-persistence. Non-persistence — enzymatic decline after weaning — is the ancestral state; the −13910*T polymorphism (and independent regional variants) confers lifelong persistence and emerged under strong selection ~7,500 years ago in dairying populations [15][16]. This is among the most robust, actionable gene-diet interactions in nutrition, though management (fermented dairy, enzyme replacement, microbiome adaptation) is behavioral, and a lactose breath test is simpler than genetic testing [15][16].
• CYP1A2 and caffeine. CYP1A2 polymorphisms determine hepatic caffeine clearance; "slow metabolizers" sustain prolonged plasma exposure and are more prone to palpitations, anxiety, and insomnia, with activity further modulated by smoking (induction) and by sex hormones, inflammation, and hypertension (reduction) [17][18]. High caffeine doses (5–9 mg/kg) raise blood pressure and reduce peripheral perfusion regardless of genotype [19].
• APOE and dietary fat/cardiovascular risk. The three common isoforms (ε2, ε3, ε4) modulate lipid response to dietary fat. APOE4 carriers show heightened LDL-cholesterol rises with saturated fat and increased vascular inflammation independent of plaque burden, and ε4 is simultaneously the strongest common genetic risk factor for late-onset Alzheimer's disease; APOE2 can promote hyperlipidemia on Western-pattern diets [20][21]. A systematic review confirms APOE, CETP, and APOB as among the most consistently replicated lipid-response gene-diet interactions, with PUFA the most reliably implicated dietary component [20].
• ALDH2 deficiency and alcohol. A common East Asian variant impairs conversion of acetaldehyde (a genotoxic alcohol metabolite) to acetate, causing the "flush reaction" and, with continued drinking, markedly elevated esophageal/colorectal cancer, liver disease, and cardiomyopathy risk [22][23]. Here the genetic signal directly informs a clinical message: there is no biologically "safe" alcohol threshold for ALDH2-deficient individuals with respect to cancer risk [22].

3.4 The disappointing reproducibility of direct-to-consumer nutrigenetic testing

Despite these legitimate mechanisms, the DTC nutrigenetic testing industry has expanded far faster than its evidence base. A scoping review of 104 DTC companies found a 43% increase in companies and 63% increase in genes marketed for nutrition advice since 2019, yet found striking inconsistency: of 48 genes variously linked to sodium sensitivity across companies, only five appeared on four or more panels [10]. Monogenic traits (lactose intolerance) show much better cross-company agreement than polygenic traits (obesity, cardiometabolic risk), where FTO, PPARG, and TCF7L2 dominate marketing despite unclear individual clinical relevance [10]. Most underlying gene-diet association studies derive from European or North American cohorts and frequently fail to replicate in African, South Asian, Middle Eastern, or Latin American populations, and proprietary, non-transparent algorithms further block independent validation [10][24]. A systematic review and meta-analysis of RCTs testing genotype-guided "personalized nutrition" for cardiometabolic outcomes found greater body-weight and body-fat loss than standard advice, but no significant improvement in BMI, waist circumference, lipids, or glycemic markers — concluding that routine clinical implementation is not yet supported [25]. The honest summary is that nutrigenetic testing for monogenic traits (lactase persistence, caffeine/alcohol metabolism) has real utility, while polygenic DTC "personalized diet" products currently outrun the evidence [10][24][25].

3.5 Multi-omics and the promise (and limits) of personalized nutrition

Beyond single-gene nutrigenetics, multi-omics approaches integrate genomics, metabolomics, and microbiomics (see Module 26) with continuous physiological monitoring to predict individual responses to food — most visibly, postprandial glucose and triglyceride excursions. Research demonstrates substantial heterogeneity in postprandial glucose/triglyceride curve shape and magnitude in response to identical meals; carbohydrate content and baseline glucose most strongly predict the magnitude of glycemic excursions, while fat content and baseline glucose more strongly predict timing [26][27]. Algorithm-guided recommendations derived from gut-microbiome composition have reduced postprandial glucose spikes more effectively than standardized advice in some studies, and machine-learning "digital twin" interventions have produced greater HbA1c and weight reductions than usual care in small trials [28][29][30]. However, AllNutrition's returned evidence has not surfaced the specific historical benchmark studies often invoked in this space (e.g., the original 2015 Israeli glycemic-prediction cohort or the PREDICT trial series), and flags real translational barriers: overfitting, small non-diverse training cohorts, and the need for external validation before clinical adoption [28][29][30]. The calibration point for learners: algorithm-predicted individual glycemic response is well-supported as a concept, but claims about specific named studies should be sourced independently rather than assumed.

4. Clinical Relevance

Patients increasingly arrive having already spent money on genetic testing or supplement stacks, and physicians are expected to interpret both. Miscalibrated responses cause harm in both directions: dismissing genetics wholesale ignores real, occasionally actionable interactions (lactase status, ALDH2, MTHFR-informed folate dosing in pregnancy planning); uncritically endorsing DTC polygenic reports or "immune support" supplement stacks wastes patient resources, can create false reassurance, and — via unregulated, sometimes contaminated products — can cause direct harm from adulterants, drug interactions, or nutrient toxicity [31][32][33]. The clinician's job is to separate the genuinely actionable from the merely marketable, and to default to "food first," reserving supplementation for documented deficiency, defined high-risk states, or specific evidence-based indications.

5. Evidence Review

Established (high confidence):

• Lactase persistence/non-persistence has a clear, well-replicated genetic basis and direct clinical correlate (dairy tolerance). AllNutrition evidence_strength: moderate, consensus_level: moderate [15][16].
• CYP1A2 genotype governs caffeine clearance and modifies cardiovascular/CNS caffeine sensitivity. evidence_strength: strong, consensus: mixed [17][19][18].
• ALDH2 deficiency substantially raises acetaldehyde-mediated cancer and liver-disease risk with alcohol exposure. evidence_strength: moderate, consensus: moderate [22][23].
• Vitamin D supplementation reduces falls, hip fractures, and mortality specifically in deficient older adults, but not in replete adults; high bolus doses (>40–60 ng/mL) may paradoxically raise fall/fracture risk via FGF-23 induction. evidence_strength: strong, consensus: moderate [34][35][36][37].
• B12 deficiency is common and clinically significant in unsupplemented vegans and older adults (10–15% >65, up to 35% in centenarians, chiefly age-related malabsorption); oral supplementation reliably corrects status [38][39][40].
• Periconceptional folic acid (400 µg/day, initiated pre-conception) reduces neural tube defect risk; timing is critical given neural tube closure at 21–28 days gestation, often before pregnancy is recognized [41][42].
• Creatine monohydrate (3–5 g/day maintenance) has one of the strongest safety/efficacy profiles of any supplement, with an excellent safety record across >26,000 trial participants [43][44][45].
• Iron supplementation (oral or IV) is highly effective for confirmed iron-deficiency anemia; supplementing without confirmed deficiency risks iron overload given the absence of a physiological excretion pathway [46][47][48].
• Multivitamins do not reduce all-cause mortality or cardiovascular events in generally healthy, well-nourished adults (~390,000-participant cohort, up to 27 years follow-up) [49][50].
• U.S. supplements are regulated under DSHEA as foods, without premarket approval; reviews document 9–15% of sports supplements contaminated with undeclared substances, with kratom, herbal/botanical, and weight-loss products the highest-risk categories for hepatotoxicity and death [31][32][33].

Probable:

• FTO genotype meaningfully influences obesity risk, attenuated by physical activity (~30%) and lower-glycemic diets, though genotype-tailored-diet trial evidence remains low-to-very-low certainty [11][13][12].
• APOE genotype (particularly ε4) modifies LDL response to saturated fat and cardiovascular/inflammatory risk, plausibly justifying stricter saturated-fat limits in known ε4 carriers [20][21].
• Multivitamin-mineral supplementation modestly slows age-related cognitive decline (COSMOS meta-analysis: effect equivalent to ~2 years of cognitive aging) despite no mortality/cardiovascular benefit [51][50].
• Omega-3s reliably lower triglycerides; high-dose purified EPA (4 g/day) reduced major cardiovascular events by ~25% in one landmark trial, while lower-dose EPA+DHA shows inconsistent benefit against modern background therapy and higher doses raise atrial fibrillation risk [52][53][54].
• MTHFR genotype modifies folate requirements and homocysteine-mediated disease risk, though genotype-guided dosing is not yet standard practice [7][8][9].

Emerging:

• Multi-omics/AI-driven prediction of postprandial glycemic/lipid responses shows promise in small trials but requires external validation and standardized protocols before clinical translation [26][28][29][30].
• Epigenetic biomarkers as tools for personalizing nutrition counseling — mechanistically compelling but not yet clinically actionable [1][3].
• Genotype-informed dosing (e.g., higher folate targets for reduced-activity MTHFR carriers) is biologically plausible but lacks outcome-based RCT validation [10][7].

Controversial:

• Whether DTC polygenic nutrigenetic testing has enough clinical validity to justify routine use outside monogenic-trait contexts; reviews highlight panel inconsistency, poor cross-population replication, and proprietary opacity as unresolved barriers [10][24][25].
• Whether antioxidant supplementation is net-beneficial or net-harmful: dietary antioxidant intake shows a favorable, plateauing dose-response for cardiovascular outcomes, while high-dose isolated antioxidant supplements show harm signals in specific populations. evidence_strength: moderate, consensus: moderate [55][56][57].

Unsupported / overstated:

• High-dose beta-carotene in smokers: two major trials (ATBC, CARET) found 16–28% increased lung cancer incidence and mortality — supplement harm contradicting the "more antioxidants must be protective" assumption [55].
• Generic "immune support" and "detox" products for nutritionally replete individuals: no measurable benefit beyond correcting a documented deficiency, and no evidence basis for "detox" given intrinsic liver/kidney/GI detoxification capacity [58][59].
• Routine multivitamin use for cardiovascular, cancer, or mortality prevention in the general healthy adult population [49][50][59].

6. Practical Clinical Applications

When genetic/nutrigenetic information is worth acting on:

• Confirmed lactase non-persistence → recommend fermented dairy, lactase enzyme supplementation, or gradual reintroduction rather than blanket avoidance (which risks calcium/vitamin D shortfall) [15][16].
• Documented caffeine sensitivity/CYP1A2 slow-metabolizer phenotype → counsel lower, earlier-day caffeine intake, particularly in anxiety, insomnia, or arrhythmia-prone patients [17][18].
• ALDH2 deficiency/flush reaction → counsel that there is no cancer-safe alcohol threshold; raise esophageal/colorectal cancer screening awareness [22].
• MTHFR variant identified via family history of NTDs/recurrent pregnancy loss → ensure adequate periconceptional folate (specialist-guided dosing) rather than ordering broad panels [7][9].
• Generally avoid endorsing broad DTC polygenic "personalized nutrition" panels for weight, macronutrient tolerance, or general wellness outside research; evidence does not support meaningful outcome improvement over standard counseling [10][24][25].

When supplementation helps (evidence-based indications): vitamin D for confirmed deficiency (target 20–40 ng/mL, daily rather than high-dose bolus dosing) [34][36][37]; B12 for vegans/vegetarians and adults >65 (atrophic gastritis, metformin, acid-suppressant use) [38][39][40]; folic acid (400 µg/day) for all persons capable of pregnancy, started ≥1 month pre-conception [41][42]; iron for confirmed iron-deficiency anemia only, guided by ferritin/hemoglobin — oral first-line, IV for intolerance or heart failure with iron deficiency [46][47][48]; omega-3 (high-dose purified EPA) for confirmed hypertriglyceridemia in high cardiovascular-risk patients on statin therapy [52][53]; creatine monohydrate (3–5 g/day) for resistance-training adults, older adults, and plant-based eaters with low baseline stores [43][44][45]; and fat-soluble vitamins (A, D, E, K) in malabsorption syndromes (celiac disease, chronic pancreatitis, short bowel syndrome, post-bariatric surgery), guided by laboratory monitoring, not blind dosing, given real toxicity risk [60][61][62][63].

When supplementation does not help or may harm: multivitamins for cardiovascular, cancer, or mortality prevention in generally healthy adults — no benefit in large cohorts [49][50]; high-dose beta-carotene in current or former smokers — demonstrated harm [55]; generic "immune support" or "detox" products in nutritionally replete individuals — no demonstrated benefit [58][59]; and any unregulated product lacking third-party verification (USP, NSF Certified for Sport, independent lab testing), particularly weight-loss, muscle-building, and herbal/botanical categories, which carry the highest documented adulteration rates [31][32][33].

Supplement-drug interaction checklist: vitamin K ↔ warfarin (counsel consistency, not avoidance, since sudden changes destabilize INR) [50]; St John's wort ↔ warfarin/DOACs (potent CYP3A4/P-glycoprotein induction reduces drug exposure — generally avoid co-use) [65]; calcium/iron ↔ levothyroxine (separate dosing ≥4 hours; high dairy intake is linked to nearly 7-fold higher odds of needing dose escalation) [50][64][66]; grapefruit juice ↔ CYP3A4 substrates (calcium channel blockers, some statins, sedatives — furanocoumarins cause prolonged intestinal enzyme inhibition, so timing separation is often insufficient); omega-3/fish oil ↔ antiplatelets/anticoagulants (theoretical additive bleeding risk at high doses, warranting perioperative caution).

"Food-first" counseling principle: whole foods generally outperform isolated supplements for the same nutrient because of the food matrix effect — intact cell walls, protein-starch assemblies, and co-occurring phytochemicals slow digestion, blunt glycemic response, enhance absorption of accompanying minerals, and preserve fiber/phytochemical co-benefits lost during isolation or fortification [67][68][69]. Supplement use should be framed to patients as filling a specific, ideally lab-confirmed gap, not as a substitute for dietary quality.

7. Clinical Pearls

• Order a lactose breath test or take a dietary history before recommending a nutrigenetic panel for dairy intolerance — it's cheaper, faster, and equally actionable.
• "No safe amount of alcohol" is not a generic slogan for ALDH2-deficient patients — it is a specific, mechanistically grounded, cancer-risk-based recommendation.
• A DTC report claiming to personalize your patient's diet from 20+ genes is, for most polygenic traits, working from panels that don't even agree with each other company-to-company.
• Vitamin D bolus dosing (large monthly/annual doses) is not simply a convenience upgrade from daily dosing — it can paradoxically raise fall and fracture risk via FGF-23 induction.
• "Immune support" and "detox" are marketing categories, not clinical indications; ask what deficiency, specifically, the product claims to correct.
• Multivitamins are a reasonable choice for a documented gap-filling role (malabsorption, restrictive diet, alcohol use disorder) — not a wellness or longevity intervention for the general healthy adult.
• Beta-carotene supplementation in smokers is a rare, well-documented example of a "protective" nutrient causing net harm in trial data — a useful teaching case against extrapolating antioxidant epidemiology to supplement pills.

8. Common Misconceptions

• "My genes explain why diets don't work for me." Outside of well-characterized monogenic interactions (lactase persistence, ALDH2, CYP1A2), most polygenic "personalized diet" claims exceed current evidence; energy balance and dietary pattern remain the dominant levers for most patients [10][25].
• "Natural supplements are inherently safe because they're not drugs." DSHEA's no-premarket-approval framework means safety is largely established after marketing, and 9–15% of tested sports/weight-loss/herbal products contain undeclared, sometimes dangerous, adulterants [31][32][33].
• "More antioxidants are always better." High-dose antioxidant supplementation has shown clear harm in specific contexts (beta-carotene in smokers; possible blunting of exercise-training adaptation with high-dose vitamin E/C), while dietary antioxidant intake shows a plateauing, not linear, benefit curve [55][57].
• "A multivitamin is a reasonable insurance policy for everyone." Large, long-term cohort data show no mortality or cardiovascular benefit in well-nourished adults; the strongest documented benefit (modest cognitive slowing) is specific to older adults and does not generalize as a rationale for universal use [49][51][50].
• "If it's a vitamin, more can't hurt." Fat-soluble vitamins (A, D, E, K) accumulate and carry real toxicity risk, especially in malabsorption patients receiving well-intentioned but unmonitored high-dose repletion [60][62].

9. Summary

Nutrigenomics and nutrigenetics describe genuine, mechanistically grounded biology: diet shapes gene expression through epigenetic mechanisms, and inherited variation modifies nutrient handling in ways that are sometimes clinically important — lactase persistence, CYP1A2-mediated caffeine sensitivity, ALDH2-mediated alcohol/cancer risk, MTHFR-modified folate needs, APOE-modified lipid response to fat, and exercise/diet-modifiable FTO obesity risk. What the evidence does not support is the leap from these narrow, well-replicated interactions to broad, proprietary DTC polygenic "personalized nutrition" products, whose panels disagree across companies, rest on non-diverse cohorts, and have not outperformed standard counseling on hard outcomes in RCTs. Multi-omics and machine-learning approaches to predicting postprandial responses are a promising research frontier, continuous with the microbiome science of Module 26, but remain pre-clinical in maturity. On the supplement side, DSHEA's post-market regulatory model means efficacy and purity are not guaranteed before a product reaches shelves, producing real, documented contamination and adulteration rates. Clinicians should confidently recommend a short, well-evidenced list of supplements for specific, ideally lab-confirmed indications — vitamin D in deficiency, B12 in vegans and older adults, folic acid periconceptionally, iron in confirmed deficiency, omega-3 in hypertriglyceridemia, creatine, and fat-soluble vitamins in malabsorption — while steering patients away from multivitamins, high-dose antioxidants, and "immune"/"detox" products marketed for prevention absent deficiency. The unifying principle is "food first": whole-food nutrient matrices generally outperform isolated supplement forms, and precision-nutrition tools should augment, not replace, that foundation.

10. References

Numbered in order of first citation in the text above; evidence level and AllNutrition trust score (0–1) as returned by the tool are shown so readers can also rank sources by strength.

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3. Interactions between nutrition and the epigenome: how can it be harnessed for public health? Future Science OA (2026). Review — trust 0.715.
4. Nutritional regulation of cardiac metabolism and function: molecular and epigenetic mechanisms. Nutrients (2025). Review — trust 0.695.
5. Coevolution of Human Diet and Gut Microbiome: Implications for Nutrigenomics. International Journal of Microbiology (2026). Review — trust 0.708.
6. The nutrigenomic-epigenetic axis in cancer: from dietary bioactives to precision oncology. Nutrition & Metabolism (2026). Review — trust 0.637.
7. The Roles Of Folate MTHFR Genetics Vitamin B12 In Pregnancy Outcomes. Frontiers in Nutrition (2026). Review — trust 0.715.
8. Role of Folate Metabolism in Neurodegenerative Diseases. Current Nutrition Reports (2026). Review — trust 0.695.
9. MTHFR variants modify the association between pre-pregnancy BMI and postpartum abnormal glucose tolerance in GDM. BMC Endocrine Disorders (2026). Observational — trust 0.752.
10. A scoping review of direct-to-consumer nutrigenetic testing: Mapping genes and associated nutrition recommendations. Advances in Nutrition (2026). Review — trust 0.875.
11. Genetic influences on obesity: the role of FTO and the promise of precision nutrition. Nutrition Research Reviews (2026). Review — trust 0.75.
12. The interplay between genetic and lifestyle obesity-related risk factors in diabetes mellitus. Frontiers in Endocrinology (2026). Observational — trust 0.6.
13. The diet–gene interaction: FTO rs9939609 and its role in obesity and metabolic syndrome among Asian populations. Egyptian Journal of Medical Human Genetics (2026). Review — trust 0.708.
14. Fat mass- and obesity-associated genotype, dietary intakes and anthropometric measures in European adults: the Food4Me study. British Journal of Nutrition (2016). Observational — trust 0.577.
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16. Exploring the dairy milk matrix beyond isolated nutrients — a narrative review. Critical Reviews in Food Science and Nutrition (2026). Review — trust 0.525.
17. Bioactive Compounds in Coffee: Metabolism, Bioavailability and Health Effects. Molecules (2026). Review — trust 0.705.
18. Dietary caffeine to assess CYP1A2 activity, tailor clozapine doses, and predict treatment response. Molecular Psychiatry (2026). Observational — trust 0.802.
19. Effects of different caffeine doses on fat oxidation and cardiovascular response during exercise. JISSN (2026). RCT — trust 0.802.
20. One Diet Does Not Fit All: A Systematic Review and Meta-Analysis of Gene–Diet Interactions Affecting Blood Lipid Profiles. Current Issues in Molecular Biology (2026). Systematic review — trust 0.762.
21. Aortic Single-Cell Transcriptome Analysis Reveals ApoE-Isoform-Specific Influences on Vascular Disease. Cells (2026). Observational — trust 0.725.
22. Rethinking ethanol consumption and colorectal carcinogenesis: an insight from diet and gut microbiota. Frontiers in Cellular and Infection Microbiology (2026). Review — trust 0.775.
23. The aftermath of alcohol misuse: linking cellular damage, suboptimal micronutrient nutrition, and organ dysfunction. Pharmacology and Therapeutics (2026). Review — trust 0.765.
24. Molecular basis of precision nutrition: food components, microbiome-derived metabolites, and multi-omics modeling. Food Chemistry: Molecular Sciences (2026). Review — trust 0.695.
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26. Within-person modeling of postprandial glucose using multimodal wearable data. Frontiers in Digital Health (2026). Observational — trust 0.6.
27. Heterogeneity in postprandial glucose-insulin and triacylglycerol dynamics and associations with plasma metabolome and body composition in obesity. American Journal of Physiology-Endocrinology and Metabolism (2026). Observational — trust 0.662.
28. Precision nutrition through diet-gut microbiome interactions: emerging insights driven by artificial intelligence. Gut Microbes Reports (2026). Review — trust 0.677.
29. The Nutri-Exposome Intelligence Framework: Integrating Multi-Omics, Machine Learning, and Digital Nutrition for Precision Chronic Disease Prevention. Nutrients (2026). Review — trust 0.9.
30. Machine Learning and Artificial Intelligence in Nutrition Research: Analytical Methods, Applications, and Key Considerations. The Journal of Nutrition (2026). Review — trust 0.765.
31. Systematic review of undeclared prohibited substances and pharmacological adulterants in dietary supplements: prevalence, detection, and risks in sport. Frontiers in Sports and Active Living (2026). Systematic review — trust 0.842.
32. Insights into dietary supplements as popular product supporting the diet. Naunyn-Schmiedeberg's Archives of Pharmacology (2025). Review — trust 0.733.
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34. Consensus statement on vitamin D role in metabolic health. Metabolism (2025). Observational — trust 0.757.
35. VITamin D and OmegA-3 TriaL (VITAL): Effects of Vitamin D Supplements on Risk of Falls in the US Population. Journal of Clinical Endocrinology & Metabolism (2020). RCT — trust 0.765.
36. Impact of Vitamin D and Calcium on Falls and Fractures in Older Adults. Endocrine Practice (2025). Review — trust 0.742.
37. Revisiting the Role of Vitamin D in Fracture Prevention in the Era of Mega-Trials. Endocrinology and Metabolism (2026). Review — trust 0.733.
38. The importance of vitamin B12 for individuals choosing plant-based diets. European Journal of Nutrition (2022). Review — trust 0.692.
39. Position of the Academy of Nutrition and Dietetics: Vegetarian Diets. Journal of the Academy of Nutrition and Dietetics (2016). Guideline — trust 0.74.
40. Examining the Clinical Usefulness of Urine Methylmalonic Acid for Diagnosis of Vitamin B-12 Deficiency in Older Adults. Clinical Interventions in Aging (2026). Observational — trust 0.752.
41. Awareness and Use of Folic Acid Among Pregnant Women in Western Ukraine: A Pilot Study. International Journal of Environmental Research and Public Health (2026). Observational — trust 0.752.
42. Prior Pregnancies Deplete Maternal Folate Status and Increase Risks of Neural Tube Defects in Addis Ababa, Ethiopia. The Journal of Nutrition (2026). Observational — trust 0.6.
43. The emerging and evolving evidence supporting creatine as an ergogenic aid: history and applications. JISSN (2026). Review — trust 0.778.
44. Creatine monohydrate for lean mass, strength, and bone density in postmenopausal women: a systematic review and meta-analysis. JISSN (2026). Systematic review — trust 0.857.
45. Evaluating the Safety of Creatine Monohydrate in Adolescents: A Systematic Review. Cureus (2026). Systematic review — trust 0.65.
46. Iron Deficiency in Cardiovascular Disease — Diagnosis, Clinical Implications, and Future Directions. Circulation Journal (2025). Review — trust 0.715.
47. Bovine Lactoferrin Compared With Ferrous sulfate for Treating Iron-Deficiency Anemia in Bangladeshi Women — a Randomized Controlled Trial. The Journal of Nutrition (2026). RCT — trust 0.812.
48. Iron deficiency in non-pregnant women with normal hemoglobin: a cross-sectional analysis. Frontiers in Medicine (2026). Observational — trust 0.752.
49. Multivitamin Use and Mortality Risk in 3 Prospective US Cohorts. JAMA Network Open (2024). Observational — trust 0.762.
50. Multivitamins in Adult Medical Practice: Evidence, Risks, and Pragmatic Prescribing. Cureus (2026). Review — trust 0.66.
51. Effect of multivitamin-mineral supplementation versus placebo on cognitive function: results from COSMOS. American Journal of Clinical Nutrition (2024). RCT/meta-analysis — trust 0.842.
52. Effect of Omega-3 Supplementation vs. Placebo on Blood Lipid Levels in Patients with Ischemic Heart Disease: A Systematic Review and Meta-Analysis. Research Square (2025). Systematic review — trust 0.762.
53. Meta Analysis of DHA and EPA Supplementation on Cardiovascular Outcomes and Atrial Fibrillation Risk. Pharmacology Research & Perspectives (2026). Systematic review — trust 0.827.
54. The Role of Omega-3 and Omega-6 Polyunsaturated Fatty Acid Supplementation in Human Health. Foods (2025). Review — trust 0.695.
55. From carotenoid intake to carotenoid blood and tissue concentrations — implications for dietary intake recommendations. Nutrition Reviews (2020). Review — trust 0.733.
56. Targeted Supplementation and Nutritional Strategies for Healthy Aging: A Review of Physiological and Molecular Benefits. Current Nutrition Reports (2026). Review — trust 0.833.
57. International Society of Sports Nutrition position stand: effects of dietary antioxidants on exercise and sports performance. JISSN (2026). Guideline — trust 0.907.
58. Between Deficiency and Excess: The Dual Role of Selected Dietary Supplements in Immune Health. Cureus (2026). Review — trust 0.695.
59. A to Z of Health: An Evidence-Based Narrative Review of Multivitamin-Multimineral and Nutraceutical Supplementation. Cureus (2026). Review — trust 0.637.
60. ESPEN practical guideline on clinical nutrition in acute and chronic pancreatitis. Clinical Nutrition (2024). Guideline — trust 0.9.
61. Dietary Therapies for Gastrointestinal Disorders. Nutrients (2026). Review — trust 0.775.
62. Rethinking Vitamin A Deficiency: Its Causes, Ophthalmologic Presentation, and Management Gaps. Nutrients (2026). Observational — trust 0.688.
63. Optimizing Perioperative Nutrition in Elective Gastrointestinal Surgery: An ERAS-Focused Narrative Review. Nutrients (2026). Review — trust 0.695.
64. Dose adjustment of oral thyroxine in patients consuming dairy products: A cohort retrospective study. Wiadomości Lekarskie (2026). Observational — trust 0.715.
65. Bioactive Natural Products in Cardiovascular Disease: Focus on Thrombotic Events. Phytotherapy Research (2026). Review — trust 0.588.
66. Diet plays a supportive role in managing thyroid disorders – but a critical one! European Thyroid Journal (2026). Review — trust 0.833.
67. Functions and metabolic effects of cereal dietary fiber components: implications for whole-grain foods. Food Bioscience (2026). Review — trust 0.825.
68. Food Matrix Effects on Plant-Derived Bioactive Compounds and Micronutrients: Implications for Functional Food Development. International Journal of Molecular Sciences (2026). Review — trust 0.875.
69. Traditional Food Systems as Nutrient Optimization Architectures: Mechanisms of Bioavailability and Dietary Resilience. Nutrients (2026). Review — trust 0.665.

Supporting sources also surfaced but not directly cited above: Precision nutrition and chronic disease — integrating genomics, microbiome, and digital health (Clinical Nutrition ESPEN, review, trust 0.6); Effects of calcium and vitamin D supplementation on cardiovascular disease outcomes (Trends in Cardiovascular Medicine, review, trust 0.69); Possible Interaction Between Hibiscus and Warfarin Resulting in Severe INR Elevation (Cureus, case report, trust 0.562).