A Systematic Review and Recommendations Around Frameworks for Evaluating Scientific Validity in Nutritional Genomics

Background: There is a significant lack of consistency used to determine the scientific validity of nutrigenetic research. The aims of this study were to examine existing frameworks used for determining scientific validity in nutrition and/or genetics and to determine which framework would be most appropriate to evaluate scientific validity in nutrigenetics in the future.Methods: A systematic review (PROSPERO registration: CRD42021261948) was conducted up until July 2021 using Medline, Embase, and Web of Science, with articles screened in duplicate. Gray literature searches were also conducted (June-July 2021), and reference lists of two relevant review articles were screened. Included articles provided the complete methods for a framework that has been used to evaluate scientific validity in nutrition and/or genetics. Articles were excluded if they provided a framework for evaluating health services/systems more broadly. Citing articles of the included articles were then screened in Google Scholar to determine if the framework had been used in nutrition or genetics, or both; frameworks that had not were excluded. Summary tables were piloted in duplicate and revised accordingly prior to synthesizing all included articles. Frameworks were critically appraised for their applicability to nutrigenetic scientific validity assessment using a predetermined categorization matrix, which included key factors deemed important by an expert panel for assessing scientific validity in nutrigenetics.Results: Upon screening 3,931 articles, a total of 49 articles representing 41 total frameworks, were included in the final analysis (19 used in genetics, 9 used in nutrition, and 13 used in both). Factors deemed important for evaluating nutrigenetic evidence related to study design and quality, generalizability, directness, consistency, precision, confounding, effect size, biological plausibility, publication/funding bias, allele and nutrient dose-response, and summary levels of evidence. Frameworks varied in the components of their scientific validity assessment, with most assessing study quality. Consideration of biological plausibility was more common in frameworks used in genetics. Dose-response effects were rarely considered. Two included frameworks incorporated all but one predetermined key factor important for nutrigenetic scientific validity assessment.Discussion/Conclusions: A single existing framework was highlighted as optimal for the rigorous evaluation of scientific validity in nutritional genomics, and minor modifications are proposed to strengthen it further.Systematic Review Registration:https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=261948, PROSPERO [CRD42021261948].

“Right diet for the right person”: a focus group study of nutritionist-dietitians’ perspectives on nutritional genomics and gene-based nutrition advice

Advances in nutritional genomics are intended to revolutionize nutrition practice. A basic understanding of nutritional genomics among nutritionist-dietitians is critical for such advancements to occur. As a precedent to the development and integration of gene-based nutrition advice, this study aimed to assess hospital-based nutritionist-dietitians’ perceptions of nutritional genomics. A total of ten focus group discussions (FGDs) with sixty-one registered nutritionist-dietitians (RNDs) from hospitals in the National Capital Region (NCR), Philippines, were conducted from October to November 2019. Data were collected using a pretested semistructured discussion guide, and thematic analysis was subsequently performed. Diverging perceptions about nutritional genomics were noted among the FGD participants. Five themes emerged relating to the enablers and barriers of gene-based nutrition advice: training and capacity building, the extent of information to be disclosed, cost, ethical considerations, and government support. Themes related to the desired features of the gene-based nutrition advice included being consent-driven, cost-effective, technology-oriented, and guided by standards. The results of this study suggest that training and continued learning will equip RNDs to provide nutrition advice based on genetic information. However, other factors, such as cost and ethical considerations, are critical dimensions that need to be acknowledged and addressed before integrating gene-based advice into nutrition practice.

Genome-wise engineering of ruminant nutrition- nutrigenomics: applications, challenges, and future perspectives – a review

Use of genomic information in ruminant production systems can help relieve concerns related to food security and sustainability of production. Nutritional genomics (i.e., Nutrigenomics) is a field of research that is interested in all types of reciprocal interactions between nutrients and genomes of organisms, i.e., variable patterns of gene expression and effect of genetic variations on the nutritional environment. Devising a revolutionizing analytical approach to traditional ruminant nutrition research, the relatively novel area of ruminant nutrigenomics has several studies concerning different aspects of animal production systems. This paper aims to review the current nutrigenomics research in the frame of how nutrition of ruminants can be modified accounting for individual genetic backgrounds and gene/diet relationships behind productivity, quality, efficiency, disease resistance, fertility, and GHG emissions. Furthermore, current challenges facing ruminant nutrigenomics are evaluated and future directions for the novel area are strongly argued by this review.

Strengthening the Reporting of Nutritional Genomics Research to Inform Knowledge Translation in Personalized Nutrition

The ultimate goal of researching nutrigenetic interactions is to be able to provide individuals with genetically-tailored nutrition advice (when evidence is sufficient) in an effort to optimize health outcomes. Accordingly, original research often discusses the potential for the results to inform genetically-tailored nutrition advice. Despite this, many studies do not report their methods, results, and discussion in a manner that is conducive to knowledge translation. With several consumer nutritional genomics companies now offering genetic testing for personalized nutrition, proper reporting of nutritional genomics research for knowledge translation is of vital importance. Common reporting errors relate to SNP and genotype reporting, results lacking detail, consideration of linkage disequilibrium, mechanisms of action/functional SNPs, details of dietary intake, and sample reporting. Because of this, knowledge translation professionals may be unable or challenged in their attempt to use the findings from such research to inform clinical practice in nutritional genomics and personalized nutrition. The present article provides an overview of the issues at hand. It further pre­sents a checklist as well as table and figure templates for researchers to use when reporting the results of original research in nutritional genomics to inform knowledge translation.

Bulk Segregant Approaches to Nutritional Genomics in Plasmodium falciparum

Nutrient acquisition/metabolism pathways provide potent targets for drug design. We conducted crosses between African (NF54) and Asian (NHP4026) malaria parasites, and compared genome-wide allele frequency changes in independent progeny populations grown in human serum or AlbuMAX, a commercial bovine serum formulation. We detected three QTLs linked with differential growth that contained strong candidate genes: aspartate transaminase AST (chromosome 2), cysteine protease ATG4 (chr. 13) and EBA-140 (chr. 14). Alleles inherited from NF54 (chr. 2 and 14) and from NHP4026 (chr. 13) were positively selected in AlbuMAX, while the same alleles were selected against in serum. Selection driving differential growth was strong (s = 0.10 – 0.23 per 48-hour lifecycle) and observed in all biological replicates. These results demonstrate the effectiveness of bulk segregant approaches for revealing nutritional polymorphisms in Plasmodium falciparum. This approach will allow systematic dissection of nutrient acquisition/metabolism pathways that are potential targets for intervention against P. falciparum.

Genotype-guided dietary supplementation in precision nutrition

Achieving adequate micronutrient status, while avoiding deficiencies, represents a challenge for people globally. Consequently, many individuals resort to oral nutrient supplementation (ONS) in order to correct suboptimal dietary intakes. Advances in the fields of nutrigenetics and nutritional genomics have identified differences in response to micronutrient supplementation according to genetic makeup, adding dietary supplement use to the clinician’s toolkit in the precision nutrition era. This review focuses on published evidence linking genetic variants to the responses associated with some of the most popular dietary supplements. With an increasing number of health professionals becoming involved in the prescription of ONS, identifying and matching individuals to the appropriate dietary supplement according to their genotype is important for achieving optimal health benefits and micronutrient equilibrium, while reducing the adverse events and financial costs often associated with excessive ONS.

Statistical and Machine-Learning Analyses in Nutritional Genomics Studies

Nutritional compounds may have an influence on different OMICs levels, including genomics, epigenomics, transcriptomics, proteomics, metabolomics, and metagenomics. The integration of OMICs data is challenging but may provide new knowledge to explain the mechanisms involved in the metabolism of nutrients and diseases. Traditional statistical analyses play an important role in description and data association; however, these statistical procedures are not sufficiently enough powered to interpret the large integrated multiple OMICs (multi-OMICS) datasets. Machine learning (ML) approaches can play a major role in the interpretation of multi-OMICS in nutrition research. Specifically, ML can be used for data mining, sample clustering, and classification to produce predictive models and algorithms for integration of multi-OMICs in response to dietary intake. The objective of this review was to investigate the strategies used for the analysis of multi-OMICs data in nutrition studies. Sixteen recent studies aimed to understand the association between dietary intake and multi-OMICs data are summarized. Multivariate analysis in multi-OMICs nutrition studies is used more commonly for analyses. Overall, as nutrition research incorporated multi-OMICs data, the use of novel approaches of analysis such as ML needs to complement the traditional statistical analyses to fully explain the impact of nutrition on health and disease.

Bulk Segregant Approaches to Nutritional Genomics in Plasmodium falciparum

Nutrient acquisition/metabolism pathways provide potent targets for drug design. We conducted crosses between African (NF54) and Asian (NHP4026) malaria parasites, and compared genome-wide allele frequency changes in independent progeny populations grown in human serum or AlbuMAX, a commercial bovine serum formulation. We detected three QTLs linked with differential growth that contained strong candidate genes: aspartate transaminase AST (chromosome 2), cysteine protease ATG4 (chr. 13) and EBA-140 (chr. 14). Alleles inherited from NF54 (chr. 2 and 14) and from NHP4026 (chr. 13) were positively selected in AlbuMAX, while the same alleles were selected against in serum. Selection driving differential growth was strong (s = 0.10 – 0.23 per 48-hour lifecycle) and observed in all biological replicates. These results demonstrate the effectiveness of bulk segregant approaches for revealing nutritional polymorphisms in Plasmodium falciparum. This approach will allow systematic dissection of nutrient acquisition/metabolism pathways that are potential targets for intervention against P. falciparum.

Nutrigenetics and nutrigenomics: ready for clinical use or still a way to go?

Nutritional Genomics or nutrigenetics/nutrigenomics is an emerging area of research aiming to delineate the interplay between nutrients intake and the reciprocal pathologies with the human genome. Coupled with other omics disciplines, such as metabolomics, proteomics and transcriptomics, nutrigenomics aspires to individualize nutrition, reminiscent of pharmacogenomics and the individualization of drug use. Here, we provide an overview of a session focused on nutrigenomics, organized in conjunction with the Panhellenic Bioscientists Association during the First Greek National Personalised Medicine Conference in Athens, Greece on 15 December 2019.

Nutrition and Genetics in NAFLD: The Perfect Binomium

Nonalcoholic fatty liver disease (NAFLD) represents a global healthcare burden since it is epidemiologically related to obesity, type 2 diabetes (T2D) and Metabolic Syndrome (MetS). It embraces a wide spectrum of hepatic injuries, which include simple steatosis, nonalcoholic steatohepatitis (NASH), fibrosis, cirrhosis and hepatocellular carcinoma (HCC). The susceptibility to develop NAFLD is highly variable and it is influenced by several cues including environmental (i.e., dietary habits and physical activity) and inherited (i.e., genetic/epigenetic) risk factors. Nonetheless, even intestinal microbiota and its by-products play a crucial role in NAFLD pathophysiology. The interaction of dietary exposure with the genome is referred to as ‘nutritional genomics,’ which encompasses both ‘nutrigenetics’ and ‘nutriepigenomics.’ It is focused on revealing the biological mechanisms that entail both the acute and persistent genome-nutrient interactions that influence health and it may represent a promising field of study to improve both clinical and health nutrition practices. Thus, the premise of this review is to discuss the relevance of personalized nutritional advices as a novel therapeutic approach in NAFLD tailored management.