Vitamin A is important for the overall development and maintenance of the body. Our body does not produce vitamin A on its own. It needs to be supplemented through diet; that's why it's called an essential vitamin.
The retina is the film screen, located at the very back of the eye. It contains two important cells that process the light entering our eyes.
The rod cells help us see in low light, while the cone cells help our color vision. The rod cells contain an important protein called rhodopsin, which moderates low light vision. A form of vitamin A called the retinal helps activate rhodopsin.
This is why a severe deficiency of vitamin A can cause night blindness.
Vitamin A is also crucial for maintaining skin integrity and forming new skin cells. Since vitamin A is an excellent antioxidant, including it in your diet every day can lower your risk for heart attack.
We all know that carrots are a good source of vitamin A. They are a rich source of a molecule called beta-carotene. Beta-carotene is a provitamin A. Provitamins are substances that are converted into active vitamins in the body.
Beta-carotene is what is responsible for the bright orange color of the carrot. All plants provide vitamin A in the form of beta-carotene, among other forms.
Vitamin A is present as retinol, a form of active vitamin A, in animal food sources. Now, the beta-carotene from plant sources must be converted to active vitamin A for it to be useful to the body.
Let’s see how that happens.
The structure of beta carotene resembles that of a dumbbell - two ring-like structures joined by a chain. This chain is cut in a particular way to give rise to two molecules of retinol, or active vitamin A. This cleavage happens in the liver.
Image: Cleavage of beta-carotene to retinol
Vitamin A in the body can be converted or interconverted into different formats. The retinol and retinal forms are interchangeable, while there’s only a one-way conversion from retinal to retinoic acid.
Image: Different forms of active vitamin A
The retinal form of vitamin A is absorbed by the intestinal villi along with fats. From there, it is transported to and stored in the liver. Whenever there's a requirement for vitamin A, retinal is released by the liver. It then binds to the specific retinol-binding protein, which serves as a carrier to transport it to various locations of the body.
The cleavage or the cutting of beta-carotene to form retinol is carried out by an enzyme called Beta Carotene Oxygenase or Monooxygenase. This enzyme is produced by the gene called BCMO1 or BCO1.
Every person has two copies of the BCMO1 gene. But, about 45 percent of the population carries at least one change or variation in the gene that reduces the enzyme activity. This results in a significantly impaired ability to convert beta-carotene into retinal.
Depending on which combination of variants someone has, beta-carotene conversion can be nearly 70 percent lower than its normal efficiency.
Vitamin A deficiency has serious health implications.
Knowing your BCMO1 gene status can help you gauge your genetic risk for vitamin A deficiency. This can be done through a genetic test.
Most genetic tests provide your DNA information in the form of a text file called the raw DNA data. This data may seem like Greek and Latin to you.
At Xcode Life, can help you interpret this data. All you have to do is upload your raw data and order a nutrition report. Xcode Life then analyzes your raw data in detail to provide you with comprehensive nutrition analysis, including information on your vitamin A requirements.
Vitamin A plays a very important role in the overall development and maintenance of the body. This fat-soluble vitamin is stored in the liver and is available externally in two forms
Vitamin A is known to support a variety of metabolic functions. It helps with better vision and improves your immunity. Getting the right dose of vitamin A also plays a role in keeping the skin and teeth healthy. The right amounts of vitamin A protect the skeletal system and the soft tissues in the body.
In pregnant women, right vitamin A levels help with tissue repair after delivery and also keeps the risks of infections low.
It took almost 130 years for researchers to identify the existence of vitamin A and understand its effects on the human body.
Early accounts of Vitamin A Deficiency (VAD) have only been recorded in terms of night blindness amongst children, soldiers, and sailors. Back then, the only solution offered was to consume cod liver oil or eat an excess of cooked liver. Doctors knew this worked, but didn’t understand why it worked.
There were innumerable studies that tried to understand the effects of nutritional deprivation on animals and human beings between the mid-1800s and 1900s.
In 1912, Sir Frederick Gowland Hopkins concluded in his clinical trial that an additional factor in milk apart from carbohydrates, fats, and proteins helped rats survive on only a dairy-based food plan. He won the Nobel Prize for this study later.
This additional factor was narrowed-down to be a fat-soluble nutrient in 1918 and was finally identified as vitamin A in 1920.
In 1931, the International Conference on Vitamin Standards was first held in London and the league set to make standards and recommended values for all identified vitamins, including vitamin A.
Though people all over the world have become conscious about their nutritional intake, WHO states that about 250 million preschool children are still diagnosed with VAD. Making the right change in food habits, identifying the effects of one’s genes in his/her vitamin A requirements and taking vitamin A supplements, if needed, will all help bring down the risk of VAD.
We humans cannot produce vitamin A in our body, hence it is called an essential vitamin. We need to obtain it through diet or supplements. Vitamin A can be derived from both plant and animal sources.
Animal sources provide vitamin A in its active form, retinol, while plant sources provide vitamin A as carotene, an inactive form, which in-turn needs to be converted into the active form, retinol.
The genetics of some individuals predispose them to less efficient conversion of biologically inactive carotene to active retinol. They are usually advised to consume animal sources of vitamin A or take vitamin A supplements or consume higher amounts of plant sources to compensate for lowered conversion efficiency.
We will look into more details of specific genes that influence this predisposition in the following sections.
Everyone knows carrots are a good source of vitamin A and that they can improve general eyesight.
Did you know where this idea stemmed from?
During World War II, the British government ordered citywide blackouts to prevent German bomber flights from identifying their targets. On the other side, the British defenses were safeguarding a secret Intercept Radar System that helped their British flyers see better despite blackouts. To keep this information a secret, the British Ministry let out official information stating their flyers were able to see better in the dark because of excess consumption of carrots!
This detail has taken deep roots and is believed to date.
According to the U.S Department of Health & Human Services, here are the recommended values of vitamin A at every stage in life.
When you consume more vitamin A than recommended every day, here are some of the possible side effects recorded.
When your Daily Value Intake of vitamin A is consistently lesser than the suggested levels, you could be at a higher risk of developing the below conditions.
Insufficient dietary intake
A key source of vitamin A to the body is the food we consume. Naturally, not including enough of vitamin A rich foods is a top non-genetic reason for Vitamin A Deficiency (VAD). Not taking enough vitamin A can be a result of an unhealthy lifestyle, lack of awareness on the importance of nutrients, or poverty/unavailability of food.
People who suffer from chronic diarrhea and respiratory infections are also prone to having lower levels of vitamin A in the body.
Avoiding animal sources of vitamin A
Though vitamin A is available in both plant and animal sources, vegans have to depend exclusively on fruits and vegetables for their vit A needs. When vegans don’t plan their diet well and don’t consciously include enough carotenoid-rich foods, they can be prone to VAD.Veganism is hence a growing cause of concern as a non-genetic influence for VAD. If you follow a vegan lifestyle, you should be working on carefully choosing your food sources to prevent nutritional deficiencies.
Infants whose mothers show signs of VAD end up not getting enough Vitamin A in breast milk and hence are at a higher risk of developing VAD related health complications.
Mutations in both the TTR gene and the RBP4 gene can cause low levels of retinol in the body. The TTR gene produces a protein called transthyretin that transports vitamin A internally. The RBP4 gene (Retinol Binding Protein 4) produces the RBP4 transporting protein that delivers vitamin A from the liver to the tissues around.
RBP works with transthyretin in the plasma and prevents the kidneys from filtering out excess vitamin A.
Two gene variations can cause VAD.
BCMO1 gene – The BCMO1 gene helps encode enzymes that convert the carotenes from plant-based food sources into forms that can be used by the human body.
CYP26B1 gene – This gene is responsible for bringing down the active form of vitamin A called retinoic acid. The SNP rs2241057 with G variant in this gene can cause an increased breakdown of retinoic acid and hence can result in lowered vitamin A levels in the body.
Here is what you should do to maintain the right levels of vitamin A in the body.
Well, you’ve heard it umpteen times that you are what you eat. You are probably gearing up already to redesign your food chart to throw in a few healthy choices based on nutritionists' recommendations.
In that case, you must be familiar with the term “antioxidants” – the magical word in the lexicon of health and nutrition that has become a synonym of power-houses of nutrients.
After all, who wouldn’t want to look perennially young, be energetic, and free of ailments! Though such a proposition may sound a fantastic probability, you can turn it into a possibility by opting for a sensible diet plan that includes foods rich in antioxidants.
Antioxidants are naturally occurring chemicals in foods that help to counter the detrimental effects of oxygen free radicals, which form during normal metabolism.
External factors like pollution, ultra-violet radiation, and X-rays also produce free radicals that affect our system. Free radicals are deprived of oxygen and are responsible for the development of serious ailments, including cancer and heart disease.
Antioxidants convert the free radicals into harmless waste products that are eliminated from the body before any damage is done to the body. Thus, antioxidants act as scavengers that rid our body of free radicals that cause serious metabolic disorders by damaging the tissues and cells.
Plants are one of the primary sources of antioxidants.
Fruits, vegetables, nuts, legumes, cereals, and seeds are foods that are naturally rich in antioxidants.
The best way to ensure adequate intake of the antioxidants is to consume a variety of fruits and vegetables through a diet consisting of 5 to 8 servings of fruits and vegetables per day.
Fruits and vegetables can help guard against heart disease, cancers, and the effects of radiation, pollution, and aging.
Pomegranate, grape, orange, pineapple, plum, apple, and guava are some of the fruits that have the highest concentration of antioxidants.
In addition to being deliciously sweet, berries such as raspberries, blueberries, and strawberries are rich in antioxidants.
These berries are rich in proanthocyanidins - the antioxidants that can help prevent cancer and heart disease as well.
Broccoli, cabbage, carrots, spinach, lemon, ginger, peppers, parsley, kale, red beets, and tomato are vegetables rich in antioxidants.
Broccoli, a cruciferous vegetable, is one of the best antioxidants. It contains more vitamin C than an orange and has more calcium than a glass of milk.
In addition to minerals and vitamins, broccoli is filled with disease-fighting chemicals called phytonutrients.
Sulforaphane, a phytonutrient found in broccoli, has been shown to lower the risk of many types of cancers.
Tomato is the richest source of a powerful anticancer agent called lycopene.
Broad beans, pinto beans, soybeans are some of the best antioxidant foods.
Barley, millet, oats, corn are cereals rich in antioxidants.
Pecans, walnuts, hazelnuts, groundnut or peanut and, sunflower seeds contain a good amount of antioxidants.
Garlic, ginger, cloves, cinnamon, and oregano are antioxidant spices.
It also has been used as a natural antibiotic to kill off some strains of harmful bacteria.
Garlic is also useful for decreasing blood pressure and cholesterol, removing heavy metals from the body, preventing cancer, and acting as an antifungal and antiviral agent.
One clove of garlic contains vitamins A, B, and C, selenium, iodine, potassium, iron, calcium, zinc, and magnesium.
Green tea contains high concentrations of catechin polyphenols. It is also a powerful antioxidant and is very effective against cancer, heart disease, and high cholesterol.
Vitamin A includes carotenoids and retinol.
They are essential for healthy eyes and prevent macular degeneration or age-related blindness.
The antioxidant in vitamin A neutralizes free radicals and boosts your immunity.
Beta-carotene, which is sometimes called provitamin A, can be found in fruits and vegetables such as tomatoes, broccoli, guavas, carrots, pumpkins, apricots, and all green leafy vegetables.
All B vitamins are essential to a woman’s health.
They are essential for brain functioning, red blood cell formation, and DNA building. The important B vitamins are:
Vitamin C, also called ascorbic acid, serves as an antioxidant that facilitates wound healing.
It helps in the formation of collagen, which is essential for the wounds to heal.
It also helps in the production of new red blood cells, which deliver oxygen to your brain and to the other cells of your body.
Vitamin C is present in citrus fruits, grapefruits, strawberries, tomatoes, kiwi, oranges, and broccoli.
Also called cholecalciferol, this vitamin functions as a hormone and regulates bone homeostasis, together with calcium.
It is an important vitamin for women as it maintains strong and healthy bones.
A deficiency of this vitamin can cause you to have osteoporosis.
Exposure to sunlight helps your body produce vitamin D.
The dietary sources of vitamin D are eggs, fish, and vitamin-fortified products like milk.
Vitamin E or tocopherol acts as an antioxidant that aids in the production of red blood cells and the maintenance of the integrity of cellular membranes.
It also helps to slow age-related changes in the body.
Sources of this vitamin include nuts and nut products, wheat germ, cod liver oil, corn oil, and safflower oil.
In reality, eating healthy is never a cumbersome task. It all starts with a simple step of ringing in variety to your table.
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PON1 gene in humans is located on the long arm of chromosome 7.
This gene was the first discovered gene of the paraoxonase multigene family along with the PON2 and PON3 genes.
The PON1 gene codes for the enzyme serum paraoxonase/arylesterase 1 or PON1 that has esterase and paraoxonase activity.
The PON1 enzyme is composed of 354 amino acids and is synthesized by the liver.
PON1 associates itself with High-Density Lipoprotein (HDL) in the circulation.
The PON1 gene shows many polymorphisms in the coding and promoting regions.
Polymorphisms in the PON1 gene have an association with coronary artery disease and diabetic retinopathy.
PON1 plays a major role in oxidative stress and inflammatory response by virtue of its association with HDL cholesterol in the body.
HDL facilitates the secretion of the PON1 enzyme, which in turn prevents the oxidation of HDL and stimulates cholesterol efflux from the cells.
These together offer an atheroprotective function to HDL.
As the name goes, these substances and compounds inhibit oxidation in the body.
Antioxidants are natural compounds that help neutralize free radicals in our bodies.
Free radicals are substances whose elevated levels can be harmful to the body.
The elevated levels have an association with diseases like cancer, heart disease, diabetes, and aging.
Our body cells constantly produce free radicals as a reaction to internal body and environmental pressures and stresses.
The cells in our body are responsible for the production of these free radicals.
These are unstable molecules, and thus can cause slow cell damage.
Since these free radicals are reactive oxygen species, the antioxidants naturally counter them.
Antioxidants are neutralizers of these free radicals and can be obtained by consuming foods that are rich in them.
In individuals who are healthy and disease-free, there is a balance of antioxidants that counter the effects of the reactive free radicals.
[table id=129 /]
SNP rs854560 is a polymorphism that is present on the PON1 gene associated with antioxidant needs.
The variants of this SNP affect levels of the PON1 enzyme and have an association with coronary diseases and diabetes. The T allele is the more favorable form of the SNP and codes for methionine, which leads too elevated levels of paraoxonase.
This is beneficial to the body.
However, the A allele codes for leucine; this leads to reduced paraoxonase activity, which is harmful to the body.
[table id=130 /]
SNP rs662, also called as Q192R is a polymorphism of the PON1 gene.
The C allele codes for arginine, whereas the less common T allele codes for glutamine.
The presence of the TT allele can imply lower or decreased levels of PON1 enzyme activity. Higher the PON1 enzyme activity, the lower is the risk for heart disease.
The TT allele also increases the risk of coronary heart disease by 2.3x and also increased the risk of vascular dementia, kidney disease, ischaemic heart disease, and male infertility.
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Vitamin A is important for good vision, healthy eyes, healthy skin, and to fight infections.
Yet, it cannot be synthesized by the body.
Therefore, it becomes an essential nutrient that needs to be included in the diet.
Conversion of beta carotene to vitamin A is an important metabolic pathway which is genetically influenced.
Vitamin A refers to the interconvertible compounds retinal and retinol.
Both these can be converted into various other metabolites that are functionally important.
The transformation into these metabolites is irreversible.
Retinoic acid is one such metabolite.
Foods like milk, liver, fish oil, and eggs contain preformed vitamin A.
Beta carotene found in carrots and green leafy vegetables can be converted in the body into vitamin A, an important source for vegetarians.
Beta carotene is an ideal provitamin A carotenoid, and it needs to be converted into active vitamin A in the body.
Carotenoids are found in plants, and they are responsible for the distinct colors that some fruits and vegetables boast of.
Carrots get their orange color because of beta carotene.
According to the National Institute of Health, the following are the recommended units for the daily intake of beta carotene:
Once it is consumed, beta carotene is converted into vitamin A, which is then utilized by the body for various functions.
It is estimated that nearly 50% of vitamin A in a diet is due to beta carotene and other such carotenoids.
The major organs that are associated with beta carotene conversion are the liver and the intestines.
The liver is associated with storing significant proportion of retinoid.
There are two enzymes associated with beta carotene conversion to vitamin A, including:
Converting beta carotene to vitamin A is extremely variable with the estimated number of low responders to dietary beta carotene as high as 45%.
Genetic variants in the BCMO1 gene are associated with the conversion of beta carotene into retinol.
Check your Ancestry DNA or 23andMe raw data results for SNP rs7501331 that you carry
[table id=64 /]
Check your Ancestry DNA or 23andMe raw data results for SNP rs12934922 that you variants
[table id=65 /]
Enzyme activity based on genetic variant carried
A study by researchers from Newcastle University showed that individuals who carry the T allele of rs7501331 have a 32% reduction in enzyme activity while individuals who carried T allele for both rs7501331 and rs12934922 had a 69% reduction in enzyme activity.
A more recent study by researchers from the same university showed that apart from these two genetic variants in the BCM01 gene, there were other variants that had an influence on enzyme activity.
Other variants of interest are rs11645428, rs6420424, and rs6564851.
Vitamin A is important for vision and is used in the treatment of cataracts and age-related macular degeneration.
It is also important for the skin and immune system.
Vitamin A deficiency is major public health across the world. Each year, approximately 250,000–300,000 vitamin A-deficient children become, and half of them have been reported to die within a year after getting blind.
The following are some of the symptoms of vitamin A deficiency:
Hand-picked content for you: Genes can Influence your Vitamin A requirement- Here’s how
Beta carotene is considered pre-vitamin, but it also is known to have certain benefits.
Each carrot is known to contain about 10 - 50 mg of beta carotene, apart from other nutrients.
The following are some of the foods rich in beta carotene
[table id=66 /]
Excess of retinoids is known to lead to teratogenic effects.
High levels of beta carotene are known to increase the risk for certain types of cancers.
One study found that there was an increased risk of lung cancer after β-carotene supplementation among smokers and people who drank more than 11 g ethanol/d.
High levels of beta carotene can affect the skin and lead to a condition known as carotenodermia.
The soles of the feet and the palms turn yellow.
Too little beta carotene or too much both have their share of risk, which makes genetic testing for vitamin A needs important.
How well your body converts beta carotene into retinol or vitamin A will help you identify the amount of beta carotene that should be consumed, from the diet or as a supplement.
Does your 23andme, Ancestry DNA, FTDNA DNA raw data have vitamin A information?
|CHIP Version||Vitamin A SNPs|
|23andMe (Use your 23andme raw data to know your DRD2 Variant)|
|V5 23andme (current chip)||Present|
|AncestryDNA (Use your ancestry DNA raw data to know your DRD2 Variant)|
|v1 ancestry DNA||Present|
|V2 ancestry DNA (current chip)||Present|
|Family Tree DNA (Use your FTDNA raw data to know your DRD2 Variant)|
|OmniExpress microarray chip||Present|
According to American Heart Association (2015), cardiovascular disease is the leading global cause of death, accounting for 17.3 million deaths per year, a number that is expected to grow to more than 23.6 million by 2030.
Low dietary intake of beta carotene is associated with chronic disease such as cardiovascular disease and vitamin A deficiency. It is well known that a greater intake of fruit and vegetables can help prevent heart diseases and mortality. Antioxidant compounds found in fruit and vegetables, especially dietary carotenoids such as beta carotenes, lycopene, lutein may influence the risk of CVD by preventing the oxidation of cholesterol in arteries.
Vitamin A in the diet can come from animal or plant sources. Vitamin A exist in the form of retinol or retinoic acid, the active form in animal sources, and in the form of carotenes in plant sources. Retinol, an active form of vitamin A cannot be made by our bodies and should be obtained from the food we eat. Carotenes must be converted into retinol for them to function as vitamin A in the body. BCMO1 is the enzyme responsible for this conversion. Individuals, especially vegetarians, who get their vitamin A primarily from plant- based foods rely on this conversion to meet their vitamin A needs.
Liver and fish oils are one of the richest source of retinol and other good sources includes eggs, especially egg yolks. Carotenes are found in green leafy vegetables, broccoli, sweet potatoes, orange and yellow vegetables and in vegetable oils.
BCMO1 gene produces BCMO1 enzyme. Individuals with certain genotypes have reduced ability to convert carotenes to retinol, due to reduced BCMO1 activity. Individuals who carry certain versions of this gene may have up to 60% less enzyme activity than others and such individuals may be at risk for vitamin A deficiency. It is recommended that these individuals consume more animal sourced vitamin A, such as fish, eggs, meat and milk products to get their active form of vitamin A, retinol to meet their requirements.
Watch out for these symptoms like oily skin, acne, dry eyes, poor night vision, immune system impairment that indicates insufficiency of retinol in your body. You can also check your vitamin A levels via a blood test.
Type of BCMO1 gene has been shown to influence the vitamin A levels in blood. Want to know what type of BCMO1 gene you have? Try Xcode’s nutrigenetics test which can tell you what versions of the BCMO1 gene are in your DNA. You can also learn about how your genes may influence other traits, including your risk for certain diseases. Write to us at email@example.com to find out more.