Genes and microbes

The body’s assortment of microorganisms depends on what we eat, drugs we take, the stress we are subjected to and the environment we interact with (eg, the infamous SARS-CoV-2 virus). Yet genes also have their say.

In a study of 977 twins in UK, the most heritable taxonomic group of bacteria was found to be Christensenellaceae (Goodrich et al, 2014). These bacteria is present in higher amounts in genetically-lean individuals. It encourages growth of other microbes connected to body weight and energy conservation such as methanogenic Archaea.

A study of over 1500 healthy individuals in Canada (Turpin et al, 2016), associated another abundant bacteria Faecalibacterium with immune system gene CNTN6 (rs1394174), and linked several other genes and bacteria of minor clinical importance (rs59846192 of DMRTB1 - Lachnospira, rs28473221 of SALL3 - Eubacterium, ), rs62171178 nearest UBR3 - Rikenellaceae).

A new paper posted this month on BioRxiv, reports results of a larger genome-wide association study performed for 7,738 individuals from the northern Netherlands.

The authors investigated 5.5 million common genetic variants using linear mixed models on hundreds of bacterial groups and pathways. Potential confounders such as medication usage, anthropometric data and stool characteristics were carefully considered along with dietary information. 

The strongest associations were identified in intronic regions of genes. In particular, between rs182549 in intronic region of the MCM6 gene and Bifidobacteria. This SNP was found to be responsible for lactose intolerance in European population. And so was Bifidobacteria - the most researched and most effective probiotic against lactose intolerance.

Another interesting microbe Collinsella and its family Coriobacteriaceae, associated with rheumatoid arthritis, cholesterol metabolism and leaky gut, was linked to several SNPs regulating genes responsible for the blood group antigens. Blood types does matter. 

Genetic factors might influence our preferences of vegetables, fruit, starchy foods, meat, fish, dairy and snacks. The Dutch study confirmed an earlier finding that rs642387, a genetic variation near genes influencing brain function, is linked to microbial family Rikenellaceae. The paper found that these bacteria, when present in large numbers in the gut, led to decreased consumption of salt. They also showed that an increase in the bacterial pathway of histidine degradation led to increased intake of processed meat.

The paper provides a wealth of information and comes with a lot of supplementary material.

REEFERENES

Goodrich JK, Waters JL, Poole AC, Sutter JL, Koren O, Blekhman R, Beaumont M, Van Treuren W, Knight R, Bell JT, Spector TD. Human genetics shape the gut microbiome. Cell. 2014 Nov 6;159(4):789-99. 

Turpin W, Espin-Garcia O, Xu W, Silverberg MS, Kevans D, Smith MI, Guttman DS, Griffiths A, Panaccione R, Otley A, Xu L. Association of host genome with intestinal microbial composition in a large healthy cohort. Nature genetics. 2016 Nov;48(11):1413.

Lopera-Maya EA, Kurilshikov A, van der Graaf A, Hu S, Andreu-Sánchez S, Chen L, Vila AV, Gacesa R, Sinha T, Collij V, Klaassen MA. Effect of host genetics on the gut microbiome in 7,738 participants of the Dutch Microbiome Project. bioRxiv. 2020 Jan 1.

Molecular Nutrition and Dietetics

Image by Marco Veringa via Flickr

Diet and food components are prime factors that affect our genes, proteins and metabolism, defining our health or disease. We are starting to understand the molecular basis of the interaction of foods with our molecules and cells. Nutrition and dietetic science are going genomic, protein and metabolic connections are getting better understood, preparing the basis for next generation dietitians and nutrition practitioners.

How to become one?

E-How lists a few steps starting from takingbiology, chemistry, mathematics, home economics and health courses in high school.

American Dietetic Association, visually explains the pathways from High School to Registered Dietitian (RD) or Dietetic Technician Registered (DTR)

To become a registered dietitian you would need to:

* Enroll in a Coordinated Program. This may be a bachelor or master's degree program that combines classroom and supervised practical experience and is accredited by the Commission on Accreditation for Dietetics Education. Graduates are then eligible to take the Registration Examination for Dietitians to become credentialed as RDs, registered dietitians.
Or:
* Enroll in a Didactic Program in Dietetics academic program. This is a program, granting at
least a bachelor's degree, that is accredited or approved by CADE. After you receive your degree, you will then need to apply for and complete supervised practical experience in a CADE-accredited Dietetic Internship Program. You will then be eligible to take the Registration Examination for Dietitians to become credentialed as a RD, registered dietitian.

There are three steps to becoming a professionally qualified dietitian in Canada - education, supervised practical experience and registration with the dietetic regulatory body (College or Association) in the province where you intend to practice

The first step is a Bachelor's degree with major credits in Foods and Nutrition from a university offering a Dietitians of Canada accredited dietetic education program or an academically equivalent program. Step 2 is successful completion of a program of supervised practical experience and step 3 is registration with the regulatory body.

Knowledge, Skills and Competencies for entry level education programs in dietetics
and entry-level dietitians:
1. COMMUNICATIONS
2. PHYSICAL AND BIOLOGICAL SCIENCES
3. SOCIAL SCIENCES
4. RESEARCH
5. FOOD (food tech, biotech, ...)
6. NUTRITION
7. MANAGEMENT
8. HEALTH CARE SYSTEMS

Nutrigenomics, Nutriproteomics and Nutrimetabolomics links

• Novel omics technologies in nutrition research.
• Nutritional Genomics in Practice — Where Do We Begin? (PDF)
• Metabolomics in Practice — Emerging Knowledge to Guide Future Dietetic Advice toward Individualized Health (PDF)
• Nutrigenomics, Proteomics, Metabolomics and the Practice of Dietetics (PDF)
• Nutrigenomics — From Molecular Nutrition to Prevention of Disease (PDF)
• Nutrigenetics, Plasma Lipids and Cardiovascular Risk (PDF)
• Single-Gene Autosomal Recessive Disorders and Prader-Willi Syndrome — An Update for Food and Nutrition Professionals (PDF)
• Ethical and Legal Issues in Nutritional Genomics (PDF)
• Epigenetics — What It Is and How It Can Affect Dietetics Practice (PDF)
• Genetic and Epigenetic Contributions to Human Nutrition and Health — Managing Genome-Diet Interactions (PDF)
• Nutritional Genomics, Polyphenols, Diets and Their Impact on Dietetics (PDF)
• Nutriproteomics: Identifying the Molecular Targets of Nutritive and
  Non-nutritive Components of the Diet (PDF)
• Nutrimetabolomics from the points of systemic estimation of function of metabolic complexes
• Nutrimetabonomics: an approach to assess individuals health trajectory (PDF)