Open Access Article
Tilde Martinsen
ab and
Lorraine Brennan
*ab
aUCD School of Agriculture and Food Science, Institute of Food and Health, University College Dublin, Belfield, Dublin 4, Ireland. E-mail: lorraine.brennan@ucd.ie; Tel: +353 1 7166815
bConway Institute, University College Dublin, Dublin 4, Ireland
First published on 22nd December 2025
The field of personalised nutrition is growing and is based on the concept that delivering personalised dietary advice will be more effective than generic healthy eating guidelines for individuals to improve their diet and metabolic health. While there is substantial interest in the field, there is also a need to examine the evidence base. The objective of this review was to examine existing literature on the efficacy of personalised nutrition approaches and to identify research gaps and future needs. A literature search was conducted in PubMed for randomised controlled trials published between 2000 and 2025. Studies investigating the effects of personalised nutrition were included, and relevant papers were identified through the reference lists of existing papers. In total, 24 papers were included, with 12 studies investigating personalised nutrition based on current diet, phenotype, and metabolic biomarkers, five studies examining the effects of genotype-based personalised nutrition, and seven studies exploring approaches based on gut microbiome and machine learning algorithms. Overall, evidence from the included studies indicates that personalised nutrition approaches consistently improved dietary quality and led to significant improvements in metabolic markers, including HbA1c, triglycerides, and insulin sensitivity. However, few studies showed significant between-group differences in weight loss, and most studies did not find significant differences in blood pressure. While the results are promising, there are key challenges and research gaps that remain. Some approaches demonstrated potential for targeted improvements, but further high-quality research is needed to confirm their effectiveness and long-term impact. Future research should prioritise longer-term studies, better stratification of responders and non-responders, and cost-effectiveness evaluations to determine where and for whom personalised nutrition adds the most value.
Tilde Martinsen is a registered dietitian and PhD researcher in Professor Lorraine Brennan's group at the School of Agriculture and Food Science, University College Dublin (Dublin, Ireland). She is part of NUTRIOME, an EU-funded Marie Skłodowska-Curie Actions project, working on data-driven precision nutrition. Her doctoral research uses metabolomics to characterise metabolic responses to foods and dietary patterns, focusing on postprandial metabolism and inter-individual variability. |
Lorraine Brennan is a Full Professor in UCD Dublin. She is the Vice Principal for Research, Innovation and Impact for the College of Health and Agricultural Sciences. She leads a research group at the forefront of the application of metabolomics in nutrition research and the development of Precision Nutrition. She is involved in a number of European Consortiums-MUSAE, PlantIntake and Promed-cog. |
A promising strategy to address this challenge is personalised nutrition, which tailors dietary advice to individual characteristics and needs, such as metabolic profile, genetics, lifestyle and environmental factors.4 Growing evidence indicates substantial inter-individual variability in responses to identical meals.5,6 Studies like The Personalized Nutrition Project and the Predict 1 study have demonstrated that individuals consuming the same food exhibit markedly different postprandial glycaemic and lipid responses.6,7 Consistent with these findings, a recent study reported that seven standardised carbohydrate meals elicited postprandial glycaemic responses that were reproducible within individuals but highly heterogeneous between individuals.5 This variability in dietary responses is determined by a complex interplay of genetic, metabolic, microbiome, circadian, and behavioural factors, including physical activity, sleep, and meal timing.8 Harnessing this variability is a promising approach for delivering personalised dietary advice. Concomitant with this is the more widespread use of omics technologies such as metabolomics and metagenomics.9 Combining these with wearable biosensors and machine learning algorithms is driving a paradigm shift in healthcare, industry and nutritional science.10
However, some criticism exists of the field with a number of key questions remaining. An example is the lack of evidence that adherence to the personalised diets compared to adherence to control diets results in improvements in diet and metabolic health parameters. Furthermore, there is no clear indication on the effect size of personalised dietary advice on the outcome variables. Despite these and other concerns there is growing interest in the area and whether it can be moved into clinical practice. As this field of personalised nutrition continues to evolve, rigorous research through randomised controlled trials remains essential to validate emerging interventions and understand their impact on health outcomes. Thus, the objective of this review is to synthesise existing literature on the efficacy of various personalised nutrition approaches and to identify research gaps and future needs in the field.
Of the 24 studies included, the sample size varied from 23 to 1607 participants, with an age range of 18 to 80 years. Most studies enrolled generally healthy adults or individuals with overweight, obesity, prediabetes, or metabolic risk factors. Trials were conducted across North America (USA, Canada), Europe (e.g., Denmark, Spain, UK, Ireland, France, Netherlands), Asia (India, Israel), and Australia. Study durations ranged from short-term (2–3 weeks) to longer interventions lasting up to 12 months. Comparator arms typically included standard population-level dietary advice, Mediterranean-style diets, low-fat diets, or general health information. Some used placebo controls (e.g., micronutrient supplementation), while others used non-personalised versions of the same digital tools or dietary programs. Primary outcomes were diverse and included diet quality or adherence scores, weight loss or body composition, glycaemic control (HbA1c, fasting glucose, PPGR), lipid profiles, metabolic biomarkers (e.g., insulin, CRP), and psychosocial outcomes such as health behaviours or perceived control.
| Author, y (country, study) | Methods (RCT, duration) | Population (N, age, health) | Intervention group (approach, delivery) | Control group (approach, delivery) | Outcomes (primary; secondary) | Main results (intervention group (PN), control group (CG), p > 0.05) |
|---|---|---|---|---|---|---|
| Abbreviations: AMED, alternate Mediterranean diet score; ARFS, Australian recommended food score; BMI, body mass index; CG, control group; CRP, C-reactive protein; eNutri, electronic nutrition (app); FI, fasting insulin; FPG, fasting plasma glucose; GA, generic advice; HbA1c, glycated haemoglobin; HDL, high-density lipoprotein; HiP, high personalisation; HMUFA, high-monounsaturated fatty acid diet; HOMA-IR, homeostatic model assessment of insulin resistance; IL-6, interleukin 6; LFHP, low-fat, high-protein, and high-fibre diet; LIR, liver insulin resistance; LDL, low-density lipoprotein; LoP, low personalisation; MEDAS, Mediterranean diet adherence screener; MIR, muscle insulin resistance; MISI, muscle insulin sensitivity index; m-AHEI, modified alternate healthy eating index; NIS, nutrition intake status; PN, personalised nutrition; QoL, quality of life; TAT, total adipose tissue; SF-36, 36-item short form health survey; SPPB, short physical performance battery; TAG, triacylglycerol; TC, total cholesterol; TG, triglycerides; TNFα, tumour necrosis factor alpha; TyG index, triglyceride-glucose index; URI, upper respiratory infection; VAT, visceral adipose tissue. | ||||||
| Aldubayan et al. (2022),11 Denmark | Parallel, double-blinded, 10 weeks | N = 100; 18–65 years, healthy adults with BMI ≥27–<40 kg m−2 | Personalised nutrition based on metabolomics and genotyping, 60% of meals provided, e-health behaviour app with personalised prompts | Generic dietary advice, similar food provided (60%), generic health prompts via app | Fat mass change | No significant difference between PN and CG: fat mass ↓ 2.1 kg (PN) vs. ↓ 2.0 kg (CG), p = 0.77. |
| The Preventomics Study | Weight loss, metabolic markers | Body weight ↓ 3.1 kg (PN) vs. ↓ 3.3 kg (CG), p > 0.05. Both improved insulin resistance and lipid profiles, but differences between groups were not significant. | ||||
| Calderón-Pérez L. et al. (2024),12 Spain | Parallel, single-blinded, three arms, 21 weeks | N = 193; ≥18 years, healthy adults | Personalised nutrition based on omics (genetics, metabolomics, proteomics). Personalised plan: same personalised advice plus behavioural change support. Delivered via a digital tool for tailored grocery selection | Mediterranean diet recommendations via the same digital tool without personalisation | Diet adherence (MEDAS) | All groups: ↑ MEDAS scores, but no significant group differences in MEDAS or conventional clinical markers. |
| Preventomics E-Commerce Study | Biometric, dietary habits, metabolic markers | No significant dietary habit differences between groups, but the PN groups showed selective biomarker improvements (e.g., inflammation, oxidative stress) compared with CG (FDR < 0.05). | ||||
| Celis-Morales et al. (2017),13 seven European countries | Four-arms, 6 months | N = 1607; 18–79 years, mixed health status, 46% overweight or obese | Three levels PN approach: | Standard dietary advice based on European guidelines (L0); also, web based | Dietary intake | PN groups: ↓ red meat (−5.48 g day−1, p = 0.046), ↓ salt (−0.65 g day−1, p = 0.002), ↓ saturated fat (−1.14%↓ energy, p < 0.0001), and ↑ folate (+29.6 µg day−1, p = 0.048), and ↑ healthy eating index (+1.27, p = 0.010). No additional benefit from phenotype or genotype-approach vs. diet only. |
| Food4Me | L1: diet only | Anthropometrics (BMI, WC), blood biomarkers | ||||
| L2: diet + phenotype | ||||||
| L3: diet + phenotype + genotype | ||||||
| - Delivered via website reports | ||||||
| Doets et al. (2019),14 Netherland | Single-blinded, 9 weeks | N = 59; ≥60 years, healthy older adults | Tailored dietary advice based on metabolic, genetic, dietary, and psychological data; online delivery + behavioural support | Generic advice: national guidelines via leaflet | Self-perceived health | No significant group differences (p > 0.05). |
| SPPB, anthropometry, grip strength | Both groups: ↑ physical performance (SPPB) | |||||
| PN: ↓ body fat%, ↓ WC, ∼grip strength | ||||||
| GA: ↑ body fat%, ∼WC, ∼grip strength | ||||||
| Galarregui et al. (2024),19 Spain | Parallel-group, 3 months | N = 127; 50–80 years, healthy older adults with overweight or obesity and ≥1 dysglycemia risk factor | Precision nutrition strategy including a personalised Mediterranean-based diet with individualised functional foods + use of a digital mobile app for guidance, support, and monitoring; in-person dietitian consultations | Generic advice: delivered via online group sessions | Metabolic health score | No significant group differences in metabolic health score (p > 0.05). |
| Body composition, biochemical markers, QoL (SF-36) | Both groups: ↓ triglycerides, ↓ uric acid, ↑ Mediterranean diet adherence, ↓ weight PN: ↓ body fat%, ↓ WC, ↓ HbA1c, ↓ ALT/AST, ↑ QoL (SF-36) | |||||
| CG: ∼body fat%, ∼WC, ∼HbA1c, ∼QoL (SF-36) | ||||||
| Haas et al. (2024),16 Germany | Double-blind, placebo-controlled intervention study, 18 weeks | N = 59; 18–65 years, healthy adults | Individualised supplementation based on dried blood spot analysis of selenium, zinc, and vitamin D levels; delivered as a personalised powder supplement taken daily | Placebo powder (no micronutrients); daily intake | Correction of micronutrient deficits, frequency of URIs, severity and duration of URIs | PN group normalised micronutrients (vitamin D significant). 16 URIs (9 PN, 7 CG). PN had higher URI severity, but no difference in duration. Overall, no effect on URI incidence or severity. |
| Hillesheim E. et al. (2023),20 Ireland | Single-blind, parallel trial, 12 weeks | N = 107; 18–65 years, healthy adults | Personalised nutrition via metabotype framework; dietary advice based on TG, HDL, TC, glucose and personal traits; reports at baseline and week 4 | Population-level advice based on national guidelines; same format reports at weeks 0 and 4 | Dietary quality (AMED score) | Significant improvements in PN group vs. CG (p < 0.05): |
| Metabodiet | Lipid profile, glucose, insulin, blood pressure | PN: ↑ AMED + 12%, ↓ TAG, ↓ TC, ↓ LDL, ↓ TyG index; CG: minor improvements. | ||||
| No significant weight or BP changes. | ||||||
| Hoevenaars et al. (2020),15 France | Parallel trial, 18 weeks (9 weeks run in + 9 weeks intervention) | N = 155; 25–70 years, healthy adults, BMI 20–35 kg m−2 | Personalised nutrition based on metabolic, anthropometric and dietary intake data; delivered via web portal with three dietitian phone calls | No advice (habitual lifestyle) or generic dietary guideline leaflet | Nutrition Intake Status (NIS) | PN group: ↑ fruits, whole grains, nuts, fish, ↓ added salt and sugar-sweetened beverages compared with controls (p < 0.05). |
| LDL cholesterol, other health biomarkers | Within the PN group, LDL cholesterol decreased significantly more in goal-setters for whole grains and nuts than in non-goal setters. No significant between-group differences in health biomarkers overall. | |||||
| Rollo M. E. et al. (2020),17 Australia | 12 weeks | N = 50; mean age 39.2 years, healthy adults | High personalisation (HiP), involving structured video calls plus dietary self-monitoring with text personalised message feedback | Low personalisation (LoP), comprising a web-based personalised nutrition feedback report | Diet quality score (ARFS) | HiP group: ↑ overall diet quality (ARFS +5.6 points), ↑ variety in meat, vegetarian options, and dairy, and ↓ energy from unhealthy foods by 7.2%, ↑ core food intake and ↓ takeaway consumption, with significant changes in 12 dietary variables vs. 1 in the LoP group. |
| Energy intake from healthy and unhealthy foods | ||||||
| Sturgeon K. et al. (2018),22 USA | 12 months | N = 35; 18–55 years, BRCA1/2+ breast cancer survivors, surgically induced menopause before age 45 | Personalised nutrition-based phenotype and biomarkers (subcutaneous adipose tissue, insulin levels and TNF-alpha): | No dietary advice, maintained usual activity | Fasting insulin, inflammatory markers, body composition | PN: ↓ fasting insulin; ↓ SAT; VAT unchanged; ↓ TNFα; IL-6 unchanged. |
| Project HOPE | - Web-based lifestyle modification combining dietary changes and exercise; personalised guidance. | Correlations between biomarkers and body fat | CG: ↑ fasting insulin; no significant changes in other measures. | |||
| Correlation: 10% reduction on TAT associated with 9% decrease in insulin. | ||||||
| Trouwborst I. et al. (2023),21 the Netherlands | Parallel, double-blinded, 12 weeks | N = 242; 40–75 years, adults with overweight or obesity with tissue-specific insulin resistance – either muscle insulin resistance (MIR) or liver insulin resistance (LIR) | PhenoDiet Group B: | PhenoDiet Group A: | Disposition index | No significant difference in disposition index between groups (p = 0.109). |
| The PERSON study | - MIR: low-fat, high-protein, high-fibre (LFHP) diet | - MIR: HMUFA diet | Fasting insulin, 2 h glucose, insulin, HOMA-IR, Matsuda index, MISI, CRP, TAG, body fat, liver fat, glucose variability, QoL | Greater improvements in PN vs. CG for: fasting insulin, 2 h glucose/insulin, HOMA-IR, Matsuda index, MISI (all p < 0.05). CRP (p = 0.034), TAG (p = 0.028). Similar weight and liver fat reduction in both groups. No significant difference in glycaemic variability or quality of life (p > 0.05). | ||
| - LIR: high-monounsaturated fatty acid (HMUFA) diet | - LIR: LFHP diet | |||||
| Weekly dietary counselling, isocaloric diets, food provision | Same counselling and food support as intervention group | |||||
| Zenun F. et al. (2022),18 UK | Single-blinded, 12 weeks | N = 210; ≥18 years, healthy adults | Personalised nutrition via the eNutri web app; automated, tailored advice based on m-AHEI diet quality score, with feedback on top 3 weakest components, BMI, and physical activity | Generic advice based on UK guidelines; delivered via the same app without personalisation during the intervention | Change in diet quality (m-AHEI) | PN: ↑ diet quality score by +3.5 points (p = 0.003); ↑ nuts and legumes (p = 0.04) and ↓ red/processed meat (p = 0.04); no significant change in BMI or overall, physical activity. |
| EatWellUK | BMI, physical activity | |||||
The Food4Me study examined delivery of personalised advice at different levels: dietary intake alone, dietary intake plus phenotype, and dietary intake plus phenotype and genotype.13 Following the six-month intervention period, all three intervention groups showed greater improvements in dietary intake, including reduced consumption of red meat, salt, and saturated fat, as well as higher Healthy Eating Index scores, compared to those receiving standardised dietary advice. However, incorporating phenotypic or genotypic data did not further enhance the effectiveness of the personalised nutrition approach. In an older adult group (67.7 ± 4.8 years), personalised nutrition tailored using biomarkers, dietary intake and genetic information was compared with generic lifestyle advice.14 After the nine-week intervention the personalised nutrition group showed improvements in body composition and certain aspects of wellbeing, such as motivation and resilience. However, there were no substantial short-term benefits in overall self-perceived health or well-being compared to the control group. Furthermore, an 18-week randomised controlled trial observed that personalised nutrition advice tailored to each participant's dietary intake, anthropometrics and metabolic biomarkers improved adherence to dietary intake for several food groups compared with generic dietary advice or no advice.15 Additionally, within the personalised advice group, participants who set specific goals, such as increasing whole-grain and unsalted-nut intake, achieved a significantly greater reduction in LDL-cholesterol levels than those who did not set such goals.
A total of four studies focused predominantly on dietary intake or nutrient status to deliver the personalisation. Personalised micronutrient supplementation based on blood levels of selenium, zinc, and vitamin D did not improve the incidence or severity of upper respiratory tract infections, compared to a placebo group in an 18-week randomised controlled trial.16 In a 12-week randomised controlled trial, participants were assigned to either a personalised nutrition group receiving dietary feedback, self-monitoring, and dietitian coaching or a control group receiving web-based feedback only.17 Following the study period, the intervention group showed greater improvements in dietary intake compared to the control group including increased consumption of meat, vegetarian alternatives, and dairy, along with reduced intake of energy-dense and nutrient-poor foods. In the EatWellUK study, the effectiveness of personalised nutrition based on dietary intake delivered via a web-based app was compared to standard dietary advice without personalised feedback.18 The intervention led to significant improvements in diet quality over 12 weeks with increased intake of nuts and legumes, and reduced red and processed meat consumption. At follow-up, 64% of participants reported continuing to follow some of the dietary advice, and 31% remained motivated to improve their diet. In a randomised controlled trial, 127 older adults (50–80 years) received either a precision nutrition strategy featuring personalised food products and digital tools or standard dietary advice.19 At three-month follow-up, improvements in metabolic health were observed in both groups. However, the precision nutrition approach demonstrated significantly greater reduction in body weight, BMI, blood pressure, HbA1c, and liver function parameters (ALT and AST) compared with standard advice.
The remaining three studies delivered personalised dietary advice based on assessment, predominantly of phenotypic and metabolic data. Using a metabotype approach, the Metabodiet study demonstrated that personalised advice improved overall diet quality and led to favourable changes in metabolic health biomarkers, including reduction in total cholesterol, LDL-cholesterol, triacylglycerol and the triglyceride-glucose index, compared with generic advice.20 The metabotype approach classified the intervention group based on four biomarkers (triacylglycerol, high-density lipoprotein-cholesterol, total cholesterol and glucose) and delivered advice based on the metabolic characteristics. In the PERSON study, tailoring diets to tissue-specific insulin-resistance phenotypes significantly improved cardiometabolic health.21 Muscle insulin-resistant individuals exhibited the most significant response to a low-fat, high-protein, high-fibre diet. In contrast, liver insulin-resistant individuals improved most on a high-monounsaturated fat diet. These targeted diets resulted in greater improvements in insulin sensitivity, fasting insulin, 2-hour glucose and insulin, triacylglycerol, and C-reactive protein independent of weight loss. During a 12-month randomised controlled trial, breast cancer survivors in post-surgical menopause received personalised nutrition based on body composition and inflammation markers, while the control group received no dietary advice.22 The intervention resulted in significant reductions in insulin and subcutaneous adipose tissue.
| Author, y (study, country) | Methods (RCT design, duration) | Population (N, age, health) | Intervention group (genotype assessed, delivery) | Control group (approach, delivery type) | Outcomes (primary, secondary) | Main results (intervention group (PN), control group (CG), p > 0.05) |
|---|---|---|---|---|---|---|
| Abbreviations: TPB, theory of planned behaviour; PN, personalised nutrition; CG, control group; BMI, body mass index; RCT, randomised controlled trial; PA, physical activity; FPG, fasting plasma glucose; HbA1c, haemoglobin A1c; BP, blood pressure; T2DM, type 2 diabetes mellitus; MetS, metabolic syndrome; WC, waist circumference; SNP, single nucleotide polymorphism; EPA, eicosapentaenoic acid; DHA, docosahexaenoic acid; RBC, red blood cell; %EPA/DHA, percentage of EPA and DHA in RBCs; GLB, group lifestyle balance; LGx, lifestyle genomics; DNA, deoxyribonucleic acid; y, year; N, number (sample size); FTO, fat mass and obesity-associated gene; rs9939609, SNP in FTO gene; rs7903146, SNP in TCF7L2 gene (linked to T2DM); rs699, SNP in AGT gene (linked to BP); CYP1A2, cytochrome P450 1A2; GSTT1, glutathione S-transferase theta-1; GSTM1, glutathione S-transferase Mu-1; TAS1R2, taste receptor type 1 member 2; ACE, angiotensin-converting enzyme; FADS1, fatty acid desaturase 1; rs174537, SNP in FADS1 gene. | ||||||
| Horne J. R. et al. (2020),23 Canada | Parallel-group, pragmatic, cluster, 12 months | N = 140; ≥18 years, adults with BMI ≥25 kg m−2; predominantly middle-aged, Caucasian females | Genetic-based advice (FTO rs9939609) integrated into Group Lifestyle Balance (GLB + LGx), plus personalised genomics report and dietitian counselling | Standard population-based advice | Theory of planned behaviour: attitudes, subjective norms, perceived behavioural control | PN: ↑ attitudes, ↑ subjective norms, ↑ perceived behavioural control (sustained); ↑ perceptions of family support for PA/nutrition; ↓ fat intake; improved body composition (p < 0.05). CG: short-term improvements only; effects diminished by 12 months. No significant differences in weight or physical activity levels between groups. |
| NOW trial | ||||||
| Karvela M. et al. (2024),24 UK | Open-label, three arms (control, intervention, exploratory), follow-up: 26 weeks | N = 148; mean 59 years, adults with non-diabetic hyperglycaemia | Genotype assessed: SNPs linked to T2DM, obesity, cholesterol, hypertension (e.g. rs7903146, rs699); delivery: dietitian-guided sessions or self-guided app with wearable device | Standard advice, dietitian counselling without DNA personalisation | Change in fasting plasma glucose (FPG) at 6 weeks | No significant difference in FPG at 6 weeks (p = 0.28). At 26 weeks: FPG significantly reduced in PN group (−0.019 mmol L−1, p = 0.01) and exploratory (−0.021 mmol L−1, p = 0.006) vs. CG. HbA1c reduced in PN group (−0.038 mmol mol−1, p = 0.04); no significant change in exploratory (p = 0.4). Small effect on progression to T2DM (p = 0.06). Weight and BMI changes were not statistically significant. |
| ASPIRE-DNA study | FPG, HbA1c, weight, BMI, BP, cholesterol, glucose tolerance, dietary intake | |||||
| McCarthy et al. (2023),25 USA | Two-arm prospective, non-blinded 12 weeks | N = 107; mean age 31, active-duty military personnel at risk for MetS | Genotype-advice, incorporating 80 SNPs across 70 genes linked to metabolic syndrome and vitamin D metabolism. Delivered by dietitians through six weekly sessions (in-person/telehealth) + app | Standardised educational materials on MetS prevention (no counselling) + app | Weight change | No significant weight difference between groups, p = 0.27. |
| Body composition, BP, serum biomarkers, MetS criteria, app adherence | MetS prevalence ↓ (27% → 17.8%, p = 0.05); WC ↓ more in intervention males (p = 0.015); other outcomes no significant difference. | |||||
| Nielsen D. E. and El-Sohemy A. (2014),26 Canada | Double-blinded, parallel group, 12 months | N = 138; 20–35 years, healthy adults | Genotype-advice based on: CYP1A2, GSTT1, GSTM1, TAS1R2, ACE; delivery: via email | General dietary recommendations with no genetic info; email delivery | Changes in dietary intake of caffeine, vitamin C, added sugars, sodium | At 12 months, sodium intake was significantly reduced in the ACE risk genotype group (−287.3 mg day−1 vs. control 129.8 mg day−1, p = 0.008). No significant changes in other nutrients or among non-risk genotypes (p > 0.05). |
| Roke K. et al. (2017),27 Canada | Parallel-arm, 12 weeks | N = 57; females 18–25 years, healthy, not using omega-3 supplements | FADS1 (rs174537); received personal genetic info + general omega-3 dietary info | Non-genotype-based advice | Dietary EPA + DHA intake | Both groups ↑ EPA + DHA intake (p = 1 × 10−4); no significant difference between groups (p > 0.05); PN group ↑ awareness and perceived usefulness. |
| RBC %EPA/DHA, omega-3 awareness | ||||||
In a randomised controlled trial of 138 participants, precision nutrition advice, based on genetic risk variants associated with metabolic syndrome and vitamin D metabolism, did not result in greater weight loss compared to standardised dietary advice.25 Waist circumference decreased more in males in the intervention group, but no other anthropometric or metabolic markers showed significant changes. In a randomised controlled trial, participants who received DNA-based personalised nutrition advice did not exhibit significant dietary changes at 3 months compared to those given standard dietary advice.26 However, at 12 months, individuals carrying the risk allele of the angiotensin-converting enzyme gene who were advised to limit sodium intake to ≤1500 mg day−1 showed a significant reduction in sodium consumption. No significant genotype-specific effects were observed for caffeine. A 12-week randomised controlled trial investigated whether providing females with their personal FADS1 genetic information would influence omega-3 fatty acid intake and blood levels.27 The control group received general written information about omega-3 fatty acids recommendations. Both groups significantly increased their intake of EPA and DHA; however, receiving genetic information did not lead to greater changes compared to the control group.
| Author, y (study, country) | Methods (RCT design, duration) | Population (N, age, health) | Intervention group (approach, delivery) | Control group (approach, delivery) | Outcomes (primary, secondary) | Main results (intervention group (PN), control group (CG), p > 0.05) |
|---|---|---|---|---|---|---|
| Abbreviations: BMI, body mass index; BP, blood pressure; CG, control group; CGM, continuous glucose monitoring; CRP, C-reactive protein; FLI, fatty liver index; HbA1c, haemoglobin A1c; LDL-C, low-density lipoprotein cholesterol; MAGE, mean amplitude of glycaemic excursions; N, number of participants; OGTT, oral glucose tolerance test; PN, personalised nutrition; PPGR, postprandial glucose response; RCT, randomised controlled trial; T2D, type 2 diabetes; TGs, triglycerides. | ||||||
| Ben-Yacov et al. (2023),28 Israel | Single-blind; 6-month intervention + 6-month follow-up | N = 225; 18–65 years, adults with prediabetes | Personalised PPGR diet using machine learning algorithm (integrated clinical and gut microbiome features); delivered via app + dietitian support | Mediterranean diet based on standard guidelines; delivered via menu + dietitian support | Change in CGM-measured time with glucose >140 mg dL−1 and HbA1 | PN showed greater improvements: |
| OGTT, lipids, fructosamine, weight, FLI, others | Time >140 mg dL−1 decreased by −1.3 h day−1 in PN vs. −0.3 h day−1 in CG, (p < 0.001), HbA1c decreased by −0.16% in PN vs. −0.08% in CG, (p = 0.007). | |||||
| No significant difference in OGTT (p = 0.8). Other secondary outcomes, including triglycerides, HDL, and FLI favoured PN (all p < 0.05). | ||||||
| Bermingham K. M. et al. (2024),32 USA | Parallel group, 18 weeks | N = 347; 41–70 years, generally healthy adults with overweight or obesity | Personalised dietary program using postprandial glucose, triglycerides, microbiome, and health history; delivered via ZOE mobile app | Standard care dietary advice; delivered via leaflet, video, online resources | LDL-C and triglycerides | In the PN group, triglycerides were significantly reduced (p = 0.016), with no significant between-group difference in LDL-C (p = 0.521). |
| The ZOE METHOD study | Weight, waist circumference, HbA1c, diet quality, microbiome composition | Improvements in secondary outcomes (e.g., weight, WC, HbA1c, diet quality) were greater in PN than CG. No significant between groups differences for insulin, fasting glucose or BP: p > 0.05. | ||||
| Kallapura et al. (2024),33 India | Prospective, open-label, parallel group study, with two arms, 3 months | N = 30; 42–65 years, adults with type 2 diabetes and or/and hyperlipidaemia | A microbiome-based targeted personalised diet; in-person + remote guidance. | Diabetic nutritional guidance | HbA1c | PN group: HbA1c ↓ from 8.30% to 6.67% (p < 0.001); CRP ↓ 20%; BP ↓ (significant only in subgroup); and gut diversity increased. CG: HbA1c ↓ from 8.24% to 7.32% (p = 0.15); less change in CRP/BP. Lipids changes were not significant in either group (p > 0.05). |
| CRP, BP, lipid profile, microbiota changes | ||||||
| Kharmats A. Y. et al. (2023),29 USA | 6 months | N = 156; 18–80 years, adults with BMI ≥27 kg m−2 and prediabetes or moderately controlled T2D | Personalised diet guided by a machine learning algorithm, with mobile app feedback including meal scores based on predicted PPGR | Standardised low-fat diet, (<25% energy from fat), same app without PPGR-based personalisation | Glycaemic variability (MAGE) | No significant difference between PN and CG (p > 0.92). Both groups had reductions in MAGE and HbA1c, but no between-group differences. |
| HbA1c, other CGM metrics | ||||||
| Popp C. et al. (2022),30 USA | Parallel-group, 6 months | N = 269; 18–80 years; BMI: 27–50 kg m−2; prediabetes or moderately controlled T2D | Personalised diet tailored to predict and minimise PPGR using a machine learning algorithm (clinical data, anthropometrics, gut microbiome); delivered via mobile app + counselling | Standardised low-fat diet (<25% of energy from fat); same app and counselling without PPGR personalisation | % Weight loss | No significant difference in % weight loss between PN (−3.26%) and CG (−4.31%); p = 0.16. |
| The Personal Diet Study | Changes in body composition, resting energy expenditure, adaptive thermogenesis | No group differences in body composition or thermogenesis; REE increased more in CG (+92.3 kcal d−1; p = 0.05). | ||||
| Rein M. et al. (2022),31 Israel | Crossover trial; 2-week crossover + 6-month single-arm follow-up | N = 23 (short-term), N = 16 (6-month); mean age 53.5 ± 8.9; newly diagnosed T2M, no diabetes medications | Personalised postprandial-targeting diet using a machine learning algorithm predicting individual glycaemic responses based on clinical and microbiome data; menus delivered digitally, meals self-prepared | Mediterranean diet, based on standard guidelines for T2M; menus delivered digitally, meals self-prepared | Blood fructosamine (short-term), HbA1c (6-month) | PN significantly outperformed CG in lower mean glucose, PPGR, and fructosamine (all p < 0.001). |
| CGM-based metrics (mean glucose, time > 140 mg dL−1), fasting glucose, insulin, HOMA-IR, lipids, body composition, microbiome | In a 6-month single arm follow-up, PN led to reductions in HbA1c (−0.39%, p < 0.001), FPG (p = 0.02), and triglycerides (p < 0.001) and 61% achieved diabetes remission. | |||||
| Zeevi D. et al. (2015),7 Israel | Blinded, two-arm crossover; 1-week profiling + 2 × 1-week intervention | N = 26; 18–70 years; non-diabetic adults, some prediabetes | Personalised diets based on an algorithm predicting PPGR. Delivered via pre-designed meals tailored to individual glycaemic profiles | Control group received expert selected diets based on measured PPGRs (profiling week) to elicit lower vs. higher PPGR. | PPGR, variability in glucose response, gut microbiota composition | PN (algorithm) significantly reduced PPGR on the lower predicted diet compared to higher predicted diet in 10/12 participants (p < 0.05); expert arm showed a comparable within participant difference (8/14, p < 0.05); overall, glucose variability improved (p < 0.05) and gut microbiota changes were observed. |
| The Personalized Nutrition Project | ||||||
In the ZOE METHODS study, participants were randomised to receive either a personalised dietary program, integrating individual postprandial glycaemic and lipemic responses, microbiome composition, dietary intake and health history delivered via an app, or standard dietary advice over 18 weeks.32 Following the intervention, the personalised nutrition group exhibited a significant reduction in triglyceride levels, whereas changes in low-density lipoprotein cholesterol were not significant. The personalised program also led to greater reduction in weight, waist circumference, HbA1c and greater improvement in diet quality compared with standard dietary advice, whereas blood pressure and fasting glucose did not differ between groups. In a randomised controlled trial, adults with type 2 diabetes and hyperlipidaemia received either a microbiota-based personalised dietary intervention or standard diabetic dietary advice.33 The personalised group showed a significant reduction in HbA1c levels. However, only within group comparisons were reported. No significant between group differences were observed for LDL, HDL or triglyceride levels.
Most of the included studies used an integrated approach, combining several individual-level factors, such as metabolomics, genotyping and phenotyping, to provide personalised dietary advice. While the majority of these studies reported significant improvements when compared with generic approaches, there is a need to understand which information contributed to the improved outcomes. To address the added benefits of each personalised component, future studies should consider incorporating more nuanced and stratified control groups. Many studies combined multiple data types, opening questions about the cost-effectiveness of the approach. The original Food4Me study demonstrated that personalisation based solely on diet was as effective as the approaches incorporating phenotype and genotype.13 Furthermore, an approach using metabotyping based on common clinical biomarkers demonstrated a clear benefit on diet quality and metabolic health markers, making it attractive from a cost-effectiveness viewpoint.20 These findings support the need for the development of simpler, phenotype-driven approaches combined with support by dietitians or nutritionists, as an effective strategy in changing diet and improving metabolic marker outcomes.
Current evidence suggests that genotype-based nutrition interventions, when delivered in isolation, have a limited and inconsistent effect on clinical and behavioural outcomes, such as weight loss, dietary intake or metabolic markers.25,26 While genetic information may prompt short-term interest or modest dietary adjustments, sustained change appears to require structured support. For instance, studies that included behavioural factors, such as those informed by the Theory of Planned Behaviour or incorporating regular counselling, consistently demonstrated greater improvements in engagement, self-efficacy and longer-term adherence.23,24 For example, in one of the studies, participants in the personalised nutrition group who set specific goals, such as increasing whole-grain and unsalted-nut intake, achieved significantly greater reduction in LDL-cholesterol underscoring the added value of structured goal-settings.15 Moreover, the reviewed trials also indicate that increasing the complexity or breadth of genetic information does not necessarily enhance efficacy, underscoring the importance of targeting gene–diet interactions that are relevant to individual risk profiles. Overall, results indicate that genotype alone is not an effective approach for delivery of personalised nutrition. However, its impact is significantly enhanced when integrated into broader, behaviourally informed personalised nutrition frameworks.
The review provides emerging evidence for the effectiveness of machine learning driven personalised nutrition approaches in improving glycaemic outcomes. Overall, four out of five studies reviewed that specifically targeted glycaemic measures demonstrated significant improvements, including reductions in HbA1c, postprandial glucose, and CGM-derived metrics.7,28,31,32 This consistency across varied populations and study designs strengthens confidence in the clinical relevance of this approach. The one study that did not report superior glycaemic outcomes compared to a standard dietary intervention still observed within-group improvements,29 suggesting that factors such as algorithm accuracy, intervention duration, individual variability and the choice of the control group may influence effectiveness. The findings underscore the potential of algorithm-based personalisation to support glycaemic control in individuals at metabolic risk. However, a key question emerging from these studies is which specific input features are most influential in driving improvements in clinical parameters. Identifying the most predictive inputs and understanding their underlying mechanisms could inform algorithm refinement and enable more precise, targeted dietary interventions. Furthermore, there is a need to demonstrate that these machine learning-based algorithms are delivering more than low carbohydrate dietary advice and that individuals receive different patterns of dietary advice. The suitability of these diets for long-term adherence is also lacking.
To realise the clinical potential and public health value of personalised nutrition, future research must prioritise rigorous, long-term randomised controlled trials. These studies should assess whether personalised approaches offer advantages over optimised generic diets, such as the Mediterranean or DASH diets, in improving cardiometabolic outcomes. Moreover, future trials must control for intensity of behavioural support and blinding, as unbalanced study designs risk overestimating personalised nutrition benefits due to placebo or engagement effects. A key concern previously raised is that many existing algorithms provide similar advice across individuals, often recommending lower carbohydrate or higher fibre diets, regardless of complex input variables like genotype or microbiome profile,35 which raises questions about the distinctiveness and reproducibility of personalised nutrition advice. As such, within-subject repeatability testing and comparative effectiveness studies are crucial to validate whether personalised recommendations truly differ between individuals and meaningfully impact outcomes. Most personalised nutritional trials to date lack demographic diversity, with participants skewing towards European and North American ancestry, higher socioeconomic status, and lower comorbidity profiles. Diverse recruitment, across age, ethnicity, gender, health status, and socioeconomic backgrounds, will be critical for identifying differential responses and ensuring real-world applicability. Consistent with our findings, a previous systematic review reported that interventions relying solely on genotype data produced inconsistent results.36 This highlights the need for future models to focus on mechanistic insights derived from systems biology and to investigate which combinations of clinical, behavioural, and biological inputs most effectively predict dietary responses. As machine learning algorithms become more central to personalised nutrition, transparency is paramount. The “black box” nature of machine learning models obscures which variables drive dietary recommendations, limiting understanding of key predictive features. Developing interpretable models with clear and reproducible decision pathways will be essential for the broader implementation of personalised nutrition, including its integration into both clinical practice and public health strategies.
Supplementary information is available. See DOI: https://doi.org/10.1039/d5fo02969d.
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