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July 29, 2019
New in Science
How much does your DNA influence your Vitamin A levels?
Vitamin A plays an important role in maintaining the proper functioning of organs like the heart, lungs and skeletal system.
By
Tomohiro Takano

Are multivitamin supplements a hype or do they actually have any health benefits? As long as we eat a balanced diet composed of healthy foods, fruits, and vegetables, we may not need any supplements.  

Vitamin A, also known as retinol, is a fat-soluble vitamin required for proper vision, healthy skin, and immune function. Additionally, vitamin A plays an important role in maintaining the proper functioning of organs like the heart, lungs and skeletal system. As per a recent study by the United States National Health and Nutrition Examination Survey (NHANES), <1% American population is at risk of vitamin A deficiency (2).

Why should I care about vitamin A?

According to WHO estimates, around 250 million preschool children worldwide are deficient in vitamin A, of which somewhere around 250,000 - 500,000 turn blind. Additionally, vitamin A deficiency affects immune function and increases the risk of infections, apart from causing a variety of issues such as dryness in the eye, night blindness, and delayed child growth.

On the other side of the coin is hypervitaminosis or too much of vitamin A, which is toxic and can lead to disastrous consequences such as liver damage, double vision and increased skin sensitivity to ultraviolet light. Vitamin A at high levels has also been shown to cause oxidative damage to DNA.

This does not happen through the creation of free radicals, but rather through the effect the vitamin in creating oxidative stress. In simple terms, Vitamin A at high levels can increase levels of other molecules which cause a significant increase in the amount of DNA damage.

Recommended dietary allowance of vitamin A is somewhere between 700-1300 micrograms (mcg) based on age, sex and pregnancy status of the individual. However, considering all humans are not the same, do we precisely know how much of vitamin A we actually need, based on our metabolism? With a DNA nutrition test, every individual can obtain insights into their own nutrition profile based on their genetic predisposition.


How does DNA influence the effects of vitamin A?

In our bodies, vitamin A is created through the breakdown of beta carotene, a chemical present in many fruits and vegetables such as carrots, sweet potatoes, and cantaloupe.

Doctors do prescribe supplements such as folic acid, vitamin A, vitamin C, vitamin D, and vitamin B12 as a precaution to some people who are at risk of vitamin deficiency like pregnant mothers, infants, and young children. So, our advice is to immediately consult your physician regarding vitamin A levels if you are a part of those high-risk groups, and see if vitamin supplementation is necessary.


But, do we know how much of vitamin our body actually needs for optimal function?


With the advancements in DNA sequencing technology, it is now possible to obtain raw DNA data at your doorstep and get it analyzed from companies like 23andMe. This information is decoded to evaluate the impact of genes on an individual’s nutritional profile. Over the last decade, a number of variants (also known as single nucleotide polymorphisms or SNPs) have been identified in several genes that are strongly associated with the metabolism of vitamins and minerals.


In one such large scale genome-wide association study (GWAS) from the National Cancer Institute, Bethesda, in the United States, scientists identified gene variants on chromosomes 10 and 18 associated with retinol metabolism (1). The study was performed in approximately 5000 male participants with European ancestry and active smoking history, while the study findings were validated in 2 independent cohorts. In fact, 2 of those top-associated SNPs were located in the neighborhood of two important retinol carrier proteins called TTR (transthyretin) and RBP4 (retinol binding protein 4) suggesting their importance in retinol transport inside the body.


Looking Ahead

While findings from this study are interesting, they only suggest the important role of DNA in determining retinol concentrations in the serum. It is interesting to note that the retinol concentrations among the study participants showed a moderate difference (1.5%), even though the dietary vitamin A intake was high and hugely variable. Does this mean our retinoic acid consumption is higher than what we need?

Diversity in data was also observed based on the sex, suggesting males and females process vitamin A differently and is primarily influenced by DNA. It is also interesting to note that the study participants were primarily of European ancestry, which indicates the variance might also be observed based on the ethnicity of an individual.


Find out what your DNA says?

Nutrigenomics is a field of study that examines the relationship between genes, nutrients and their metabolism, both in health and disease. To maximize the effectiveness of either your nutritional intake, physical exercise, dietary supplements or drugs, it is important that you understand the body inside out.

Nutrigenomics empowers you with knowledge on your genetic predisposition for nutrition and vice versa, thus allowing you to make an informed and optimized decision about the changing one needs to make in their diet, and lifestyle habits to maintain a healthy life and manage chronic conditions better.  


References

  1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3209826/
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5537775/

Did you get 23andMe, AncestryDNA, or MyHeritage results back?
Upload your raw DNA data to access 25+ traits for FREE at Genomelink!
Tomohiro Takano
Tomohiro Takano
Co-Founder and CEO
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