Nutritional Sciences and Genetics Quiz

Nutritional Sciences

• Clinical nutrition is about nutrition and health, nutrition and disease, diet therapy.
• Community nutrition focuses on food choices, food and nutrition policy, nutritional epidemiology, nutritional education and intervention, and food security.
• Molecular nutrition is about nutritional biochemistry, nutritional proteomics, and nutritional genomics.
• Nutritional genomics focuses on the interactions between nutrients and the genome.

DNA & Genes

• DNA is a molecule containing genetic information.
• It consists of two strands in a double helix shape.
• Complementary base pairs in DNA include: Adenine (A) and Thymine (T), Guanine (G) and Cytosine (C).
• A gene is a piece of DNA that encodes specific proteins.
• The flow of genetic information is DNA - mRNA - Protein.
• RNA transmits genetic information from DNA to proteins.

Diet-Gene Interactions

• Nutritional genomics is divided into two terms: Nutrigenetics and Nutrigenomics.
• Nutrigenetics examines the effects of individual genetic variation on dietary response.
• Nutrigenomics studies the effects of diet and specific nutrients on genes.

Nutrigenetics

• Genetic polymorphism is the complete gene variation between individuals.
• Single Nucleotide Polymorphisms (SNPs) are differences in a single nucleotide from the generally accepted gene sequence.
• SNPs relate to a single nucleotide substitution in a DNA sequence.

Nutrigenetics & Folate

• A SNP influences dietary folate requirements.
• It affects the gene coding for the enzyme methylenetetrahydrofolate reductase (MTHFR).
• This causes the C677T polymorphism, where cytosine (C) is replaced by thymine (T).
• This results in the amino acid alanine (ala) being replaced by valine (val) at position 222 of the amino acid sequence.

Homocysteine Metabolism

• Tetrahydrofolate and Vitamin B12 are important for methionine production and homocysteine metabolism.
• High homocysteine levels are associated with cardiovascular disease (CVD), DNA methylation, and other complications.

Known SNPs & Their Implications

• Variations in MTHFR, cystathione betasynthase, and methionine synthase genes are linked to an increased risk of neural tube defects, CVD, and cancer.
• SNPs in the HFE gene and transferrin receptor gene are linked to iron overload and anemia.
• SNPs in the vitamin D receptor, estrogen receptor, and type 1 collagen genes affect bone health and metabolism.
• Variations in Apolipoprotein (AIV, B, C3, E), LDL receptor, and lipoprotein lipase genes impact blood cholesterol and CVD.
• SNPs in β2- and β3- Adrenoreceptors are linked to increased body fat and obesity.

Nutrigenomics

• Dietary effects on gene expression can occur through direct DNA structural changes or epigenetic mechanisms.
• Carcinogens and free radicals can cause DNA damage and mutations.
• Epigenetics involves modifications like methylation and histone modification, without affecting the DNA sequence.
• Folate plays a crucial role in DNA methylation.

Applications of Nutritional Genomics

• Increased understanding of the link between diet and disease could lead to new dietary guidelines.
• Personalized diets and lifestyle changes can be developed based on an individual's genetic makeup.
• Public health strategies can be developed to prevent and manage diseases more effectively.

Challenges of Nutritional Genomics

• Lack of knowledge and conflicting findings create a challenge for the field.
• The low prevalence and penetrance of some mutations make it difficult to study effectively.
• Ethical considerations regarding genetic testing need careful consideration.

Conclusion

• Humans and their diets are complex, requiring a multidisciplinary approach.
• Nutritional genomics can enhance public health nutrition, leading to more effective disease prevention and management.