What is nutrigenetics

Nutrigenetics is an emerging field of study that investigates the relationship between the genes of an individual, diet, and health outcomes.

Now more commonly referred to as "personalized nutrition" or "precision nutrition", it's the science of characterizing a genetic variation and its corresponding impact on a nutrient requirement. Simply put, it examines how your body responds to nutrients based on your genetics.

Things like nutrient absorption and utilization, food intolerances/allergies, and nutrient deficiencies are determined by both diet and genes. Studying the relationship between genes and nutrition allows a more personalized approach.

Since 1941, the Food and Nutrition Board has been setting "Recommended Dietary Allowances" (RDAs) of nutrients. These guidelines are "the average daily level of intake sufficient to meet the requirements of 97%-98% of healthy people" [1].

While this is helpful, exact nutrient requirements will vary from person to person and those who have genetic variations in certain genes may need more or less of a nutrient.

Nutrigenetics versus nutrigenomics

Nutrigenetics is not to be confused with nutrigenomics, which is the reverse of nutrigenetics. Nutrigenomics studies how nutrients affect your body's gene expression.

It frequently puzzled researchers how two people could have similar diet and lifestyles yet one develops a chronic disease while the other remains healthy. It was hypothesized that genetics played a role in this phenomenon, but there was little proof until recent years with the study of nutrigenetics and nutrigenomics illuminating it.

The human genome project

The start of nutrigenetics and nutrigenomics began with the completion of the Human Genome Project in 2003. This project identified all the genes in humans and determined the sequence of the 3 billion chemical base pairs that make up our DNA.

Once researchers had all genetic sequencing mapped out, it allowed examination of the relationship between genetic makeup, diet, and health outcomes [2].

This project showed us that genetic variation among humans is minimal. Most people are approximately 99% genetically identical. But this 1% genetic variation results in a wide variability of health outcomes (depending on diet, lifestyle, and other environmental factors). Some of this genetic variation is from single nucleotide polymorphisms, or SNPs [2].

SNPs

SNPs, pronounced "snips", are common genetic variations among people. DNA is made up of four nucleotides: adenine (A), thymine (T), guanine (G), and cytosine (C). These nucleotides attach to each other (A with T and G with C) to form chemical bonds that connect two DNA strands.

SNPs are locations in the human genome where the type of nucleotide present differs between individuals. It's a variant in a single base pair in a gene, located mostly within a gene or in a regulatory region near a gene.

SNP function

A SNP can affect health by affecting a gene's function (but they can also have no effect).

Whether it does depends on the gene its associated with, the genotype of the SNP, or whether the person has one or two copies of a genotype of a SNP [2].

They can act as biological markers as they're associated with genes regulating diseases like cardiovascular disease, diabetes, cancer, schizophrenia, blood pressure, migraine, and Alzheimer [3]. In most cases, it either increases or decreases chronic disease risk. In rare cases, it can cause disease.

SNPs and nutrition research

In relation to nutrigenetics, some SNPs cause changes in the quantity of protein produced or the structure of the protein molecule. This alters protein expression and can lead to alterations in absorption and metabolism of dietary components [4].

This is why the future of nutrition involves genetic tests for SNPs that affect nutrition status. It will allow medical professionals to formulate accurate nutrition recommendations for each person.

With millions of SNPs in our genome (and likely thousands of them affecting nutrition status), there is a ways to go in mapping out all SNPs and their health effects.

Discoveries in nutrigenetics

MTHFR gene

The methylenetetrahydrofolate reductase gene (MTHFR) is one of the most well defined examples of a gene-nutrient interaction.

MTHFR is involved in the metabolism of folic acid which influences blood levels of homocysteine. A particular MTHFR gene SNP is associated with elevated blood homocysteine levels, especially if there is a folate deficiency [6].

Elevated homocysteine is associated with increased risk of many diseases, like cardiovascular disease and colon cancers. This risk is exacerbated if there is also a deficiency of folic acid.

About 85% of the population has this SNP: it's important people they're aware so they can adjust their intake of folic acid and keep homocysteine levels regulated. For some people, folic acid supplementation can provide better health outcomes.

NQO1 gene

NAD(P)H Quinone Dehydrogenase 1 (NQO1) is an enzyme with antioxidant properties and is encoded for by the NQO1 gene.

There is one SNP in the NQO1 gene associated with poor health outcomes. It makes your body less efficient at activating coenzyme Q10 [11]. Coenzyme Q10 improves heart health and blood sugar regulation and is important in generating ATP by helping convert food into energy.

VDR

The vitamin D receptor, or VDR, is an intracellular hormone receptor that influences vitamin D status. More than 470 SNPs have been discovered on the human VDR gene [7].

Researchers have found a relationship between vitamin D status, cancer, and genetic polymorphisms.

FokI

The polymorphism FokI's f allele produces a VDR protein that is three amino acids longer and functionally less effective.

The shorter VDR protein displays higher biological activity than the longer one; "the wild-type protein FF interacts more efficiently with the transcription factor TFIIB increasing transactivation by the VDR compared to the ff protein..." [7].

Genetic variation risk factors

Simply put, the cellular consequences of the ff genotype mimic low vitamin D status.

Examining the relationship between FokI polymorphisms and cancer found a 30% increase in skin cancer risk and 14% increase in breast cancer risk with FokI ff compared with FF [7].

Another study found BMI, energy intake, and energy expenditure may influence the relationship between VDR FokI genotype and colorectal cancer risk [8]. This proves some may have a genetic susceptibility to certain chronic conditions like cancer.

BsmI

Another polymorphism on the VDR gene is BsmI. It doesn't affect the structure or function of the VDR protein but it is in "linkage disequilibrium".

Researchers examining the relationship between the BsmI polymorphism and prostate cancer risk found a 17% reduction in prostate cancer risk for carriers of the BsmI Bb compared with bb genotype [7].

Genetic variants

The genes listed above are just two examples of polymorphisms found on a singular gene that has proven to affect health outcomes.

Since the VDR gene has 470 identified SNPs, variations on this one gene alone may explain why some people develop certain chronic diseases and not others, even with similar lifestyles and dietary factors.

Taste receptors

A study examining genetics, taste function, and physiological health found 94 SNPs from 11 taste receptor genes.

Twenty tSNPs were genotyped from fat taste receptor genes (CD36, GPR120, and GPR40), 11 from sweet taste receptor genes (TAS1R2 and TAS1R3), 1 from a bitter taste receptor gene (TAS2R38), 19 from salt taste receptor genes (ENaC and TRPV1), 32 from umami taste receptor genes (TAS1R1, TAS1R3, and mGluR4), and 11 from a sour taste receptor genes (KCNJ2) [10].

Researchers found variations in the genes related to taste perception can impact the person's health via their food preferences.

For example, the sweet taste receptor TAS1R2 was associated with dyslipidemia in Mexican subjects that consumed high amounts of carbohydrates and fats [9].

SNPs for umami taste receptors were linked with an increased consumption of dietary protein. And SNPs variations that caused decreased sensitivity of fat taste receptors led to an increased consumption of fatty foods, which another study later linked to increased body mass index [10].

Nutrigenetics

There are thousands of examples of how gene variants influence our genes and thus our body's functioning and behavior.

Nutrigenetics drives better health outcomes by providing data on our genetic information, inherent strengths and weaknesses, and how certain nutritional factors can support our biology and help prevent nutrient deficiencies and associated health conditions.

Precision nutrition is the future of dietary guidelines and it probably won't be long until human DNA testing and analyzation is implemented in routine doctor's visits and health examinations. Our genetic differences create varying nutritional needs and genetic testing can unlock the knowledge everyone needs to optimize their health.

What genetic tests can tell you:

• Genetic composition
• Genetic predisposition to certain conditions like heart disease, obesity, cancers, and nutrient deficiencies.
• Genetic polymorphisms that affect lipid metabolism, amino acid metabolism, and physiological processes.

Rootine

Rootine considers your unique DNA, blood, and lifestyle data when formulating your micronutrient formula. Our DNA Test analyzes 50+ SNPs that are proven to impact nutrient needs due to the influence on nutrient absorption, distribution, metabolism, excretion, and receptor function.

By researching, analyzing, and understanding how your genetics impact how well your body ingests and absorbs nutrients, Rootine creates a multivitamin formula to help your body achieve optimal health starting at the cellular level.

Sources

1. https://ods.od.nih.gov/HealthInformation/Dietary_Reference_Intakes.aspx
2. Baumler, M. (2012, September). Nutrigenetics - building a platform for Dietitians to offer personalized nutrition. Today's Dietitian. Retrieved June 22, 2022, from https://www.todaysdietitian.com/newarchives/090112p48.shtml
3. Kaur, S., Ali, A., Ahmad, U., Siahbalaei, Y., Pandey, A. K., & Singh, B. (2019, July 8). Role of single nucleotide polymorphisms (snps) in common migraine - the Egyptian Journal of Neurology, Psychiatry and neurosurgery. SpringerOpen. Retrieved June 22, 2022, from https://ejnpn.springeropen.com/articles/10.1186/s41983-019-0093-8
4. Gaboon, N. E. A. (2011, May 12). Nutritional genomics and personalized diet. Egyptian Journal of Medical Human Genetics. Retrieved June 22, 2022, from https://www.sciencedirect.com/science/article/pii/S1110863011000024
5. Bhattacharya, T., Dutta, S., Akter, R., Rahman, M. H., Karthika, C., Nagaswarupa, H. P., Murthy, H. C. A., Fratila, O., Brata, R., & Bungau, S. (2021, August 9). Role of phytonutrients in nutrigenetics and nutrigenomics perspective in curing breast cancer. MDPI. Retrieved June 22, 2022, from https://www.mdpi.com/2218-273X/11/8/1176/htm
6. Elsamanoudy, A. Z., Neamat-Allah, M. A. M., Mohammad Fatma Azzahra̕ Hisham, Hassanien, M., & Nada, H. A. (2016, March 8). The role of nutrition related genes and nutrigenetics in understanding the pathogenesis of cancer. Journal of Microscopy and Ultrastructure. Retrieved June 22, 2022, from https://www.sciencedirect.com/science/article/pii/S2213879X16000183
7. Davis, C. D., & Milner, J. A. (2011). Nutrigenomics, Vitamin D and Cancer Prevention. Journal of nutrigenetics and nutrigenomics. Retrieved June 23, 2022, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3219444/#B37
8. Slattery ML, Murtaugh M, Caan B, Ma KN, Wolff R, Samowitz W. Associations between BMI, energy intake, energy expenditures, VDR genotype and colon and rectal cancers (United States) Cancer Causes Control. 2004;9:863–872.
9. Ramos-Lopez, O., Milagro, F. I., Allayee, H., Chmurzynska, A., Choi, M. S., Curi, R., Caterina, R. D., Ferguson, L. R., Goni, L., Kang, J. X., Kohlmeier, M., Marti, A., Moreno, L. A., Pérusse, L., Prasad, C., Qi, L., Reifen, R., Riezu-Boj, J. I., San-Cristobal, R., … Martínez, J. A. (2017, July 8). Guide for current Nutrigenetic, nutrigenomic, and nutriepigenetic approaches for precision nutrition involving the Prevention and management of chronic diseases associated with obesity. Lifestyle Genomics. Retrieved June 23, 2022, from https://www.karger.com/Article/Fulltext/477729
10. Chamoun, E., Liu, A. S., Duizer, L. M., Feng, Z., Darlington, G., Duncan, A. M., Haines, J., & Ma, D. W. L. (2020, December 5). Single nucleotide polymorphisms in sweet, fat, umami, salt, bitter and sour taste receptor genes are associated with gustatory function and taste preferences in young adults. Nutrition Research. Retrieved June 23, 2022, from https://www.sciencedirect.com/science/article/pii/S0271531720305893
11. https://www.mygenefood.com/genes/longevity-genes/nqo1/