Nutritional Genomics

Advances in molecular biology, emergence of novel techniques and huge amount of information generated in the post-Human Genome Project era have fostered the emergence of new disciplines in the field of nutritional research: Nutrigenomics deals with the effect of diet on gene expression whereas nutrigenetics refers to the impact of inherited traits on the response to a specific dietary pattern, functional food or supplement. Understanding the role of micronutrient supplementation with specific genetic backgrounds may provide an important contribution to a new optimum health strategy based on individualized nutritional treatment and may provide the strategies for the development of safer and more effective dietary interventions. This overview of the various aspects of supplementation of micronutrients in the era of nutrigenetics and nutrigenomics may provide a better understanding of novel nutritional research approach and provide an additional insight that can be applied to the daily dietary practice.

Nutritional genomics has potential to be used in both the clinical and public health practice settings.  This emerging field includes the development of diet plans matched to an individual’s genetically determined abilities to use the nutrients in specific foods.  Developing educational tools to make dietetic students aware of nutritional genomics and its practical applications is a critical step in increasing the competency of future dietitians and allowing them to bring healthcare to clients at a more personalized level.  Teaching modules were developed to be incorporated into two nutrition courses at the University of Delaware – NTDT 103 (Introduction to Nutrition Professions) and NTDT 401 (Micronutrients) – with the expectation that the students’ level of knowledge and interest in nutritional genomics would increase after being taught the lesson in each class.  The effectiveness of the modules was evaluated with the use of pre-surveys and post-surveys, which were approved by the Human Subjects Review Board at the University of Delaware.  Minitab® 15 Statistical Software was used to compare the pre-survey and post-survey results of each student.  Overall, students in both courses became more interested in nutrigenomics after the lesson, and the number of students who answered nutritional genomics-related questions correctly increased.  In addition, 79% of the students in NTDT 103 and 70% of the students in NTDT 401 said the lecture helped them understand the concept of nutrigenomics, and 74% of those in NTDT 103 said the lecture taught them valuable information on possible future job opportunities involving nutrigenomics.  Given that the current education on nutritional genomics that is available to undergraduate dietetics students at the University of Delaware is limited, the modules developed for NTDT 103 and NTDT 401 are effective in teaching students about this cutting-edge field.

"The proximate, functional properties, In-vitro multi enzyme
protein digestibility and amino acid composition of velvet
tamarind (Dalium guineense) pulps were evaluated. The ash,
moisture, crude fat, crude fibre, crude protein and carbohydrate of
the velvet tamarind (Dalium guineense) pulp were: 4.63%, 8.22%,
5.80%, 7.15%, 24.3% and 49.9% respectively. The water and oil
absorption capacities were: 238% and 162% which makes the pulp
exhibit a high water retention capacity. The least gelation
concentration was 17.0% while the foaming capacity and stability
were: 43.5% and 62.2% respectively. The in-vitro protein
digestibility was 66%. Glutamic acid was the most concentrated
amino acid with the value of 14.8 mg/g crude protein while
histidine (2.12 mg/g crude protein) was the least concentrated
amino acid. The % total essential amino acid with histidine was
34.2% while the % total essential amino acid with histidine was
60.8%. The calculated isoelectric point was 0.54 while the
predicted protein efficiency ratio (P-PER*) was 2.62."

In this study, we tested for the presence of sexual dimorphism in the hepatic transcriptome of the adult zebrafish and examined the effect of long term manipulation of dietary carbohydrate on gene expression in both sexes. Zebrafish were fed diets comprised of 0%, 15%, 25%, or 35% carbohydrate from the larval stage through sexual maturity, then sampled for hepatic tissue, growth, proximate body composition, and retention efficiencies. Using Affymetrix microarrays and qRT-PCR, we observed substantial sexual dimorphism in the hepatic transcriptome. Males upregulated genes associated with oxidative metabolism, carbohydrate metabolism, energy production, and amelioration of oxidative stress, while females had higher expression levels of genes associated with translation. Restriction of dietary carbohydrate (0% diet) significantly affected hepatic gene expression, growth performance, retention efficiencies of protein and energy, and percentages of moisture, lipid, and ash. The response of some genes to dietary manipulation varied by sex; with increased dietary carbohydrate, males up-regulated genes associated with oxidative metabolism (e.g. hadhβ) while females up-regulated genes associated with glucose phosphorylation (e.g. glucokinase). Our data support the use of the zebrafish model for the study of fish nutritional genomics, but highlight the importance of accounting for sexual dimorphism in these studies.

To be able to perform a comprehensive and rigorous benefit-risk analysis of individual food components, and of foods, a number of fundamental questions need to be addressed first. These include whether it is feasible to detect all relevant biological effects of foods and individual food components, how such effects can confidently be categorised into benefits and risks in relation to health and, for that matter, how health can be quantified. This article examines the last of these issues, focusing upon concepts for the development of new biomarkers of health. Clearly, there is scope for refinement of classical biomarkers so that they may be used to detect even earlier signs of disease, but this approach defines health solely as the absence of detectable disease or disease risk. We suggest that the health of a biological system may better be reflected by its ability to withstand and manage relevant physiological challenges so that homeostasis is maintained. We discuss the potential f...