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Genes And Vitamin B12 Requirements

Tags: vitamin


Vitamin B12 is one among the B vitamins and is also known as Cobalamin, since it contains the mineral called cobalt. This water-soluble Vitamin cannot be made in the body and needs to be obtained from the food we eat. 

Vitamin B12 helps with the below functions in the body:

  • Vitamin B12 keeps the blood cells in the body healthy
  • Protects your nervous system
  • Makes DNA
  • Processes fatty acids in the body
  • Reduces the risk of developing megaloblastic anemia (the presence of large and abnormally structured Red Blood Cells)

Vitamin B12 deficiency can cause irreversible damage to the body and is, unfortunately, an increasing problem in the countries around the world. There are several reasons why your body might be receiving less vitamin B12 than the recommended daily intake. We will talk about that in the coming sections.

Evolutionary Aspects: The Story Behind Vitamin B12

The story behind vitamin B12 goes as far back as the 1850s and includes the efforts of many renowned pathologists, physicists, and scientists.

Thomas Addison was an English physicist working in the famous Guy’s Hospital in London. Addison was working on the different causes and effects of diseases and identified a condition called Pernicious anemia.

Pernicious anemia is characterized by abnormal and insufficient Red Blood Cells. This disease was considered fatal between the 1800s and early 1900s. 

It took almost 40 years to find a cure for pernicious anemia. George Hoyt Whipple, an American pathologist, had intensely analyzed the effects of food on the disease and concluded that a liver-based diet in dogs helped increase RBC count in the blood. This led to the identification of liver as a food-based treatment option for treating Pernicious anemia. 

While doctors knew this diet helped reverse the condition, they didn’t fully understand why.

It took another 30 years for scientists to successfully identify and remove a water-soluble compound from liver samples and confirm that this was what actually treated the anemia. This compound’s structure was defined in 1956 and was named ‘vitamin B12’. 

There were a total of five Nobel Prizes awarded to scientists around the world for the studies related to vitamin B12. We have these great minds to thank for bringing to the world’s notice one of the most important B vitamins.

Molecular Aspects- Getting Technical

Once you consume foods rich in Vitamin B12, gastric juices in the intestine help release the vitamin from the food. Once the vitamin is free, a particular protein called R-binder attaches itself to B12 and prevents the acids in the stomach from destroying the vitamin B12 molecule. 

Now, the R-binder protein takes B12 to its next destination, the intrinsic factor (IF). This is also a kind of protein produced in the stomach. 

From here, the B12 reaches an important carrier protein called Transcobalamin II. This helps circulate B12 to different parts of the body.

For the proper absorption and circulation of vitamin B12, the gastrointestinal tract and its help are vital. This is why people with gastric issues may have problems absorbing B12. 

Did You Know?

Did you know that your body stores enough quantities of vitamin B12 for future use? If you have been getting enough or more than the daily recommended values of vitamin B12, a certain amount keeps getting stored in the liver. This reserve can last for anywhere between 3 and 5 years! 

The body knows the importance of vitamin B12 and hence keeps a stock of it for your benefit.

If you have been consistently getting lesser vitamin B12 than what’s needed, your excess reserve is continuously used and you start getting signs of vitamin B12 deficiency only after a couple of years.

The rate at which the stored levels are depleted (turnover rate) depends on your body’s ability to get and absorb vitamin B12. Healthy individuals with normal absorption rates may have a lesser turnover rate than those with gastrointestinal issues or pernicious anemia.

Recommended values

The Dietary Reference Intake (DRI) is a reference for assessing the general needs of vitamin B12 levels in children and adults on an everyday basis.

What Does Excess Of Vitamin B12 Lead To?

 Excess of vitamin B12 does not cause toxicity in the body as fat-soluble vitamins do. 

Vitamin B12 that is ingested is used for everyday functioning and a part of it keeps getting stored in the liver as a reserve. The remaining doses are easily excreted out through urine. Hence it is not very easy to get an overdose when it comes to B12.

However, if you are on vitamin B12 shots, supplements, and a diet rich in red meat, poultry, and dairy products simultaneously, excess quantities of the vitamin may cause dizziness, nausea, and headaches in some individuals. 

What Are The Symptoms Of Vitamin B12 Deficiency?

When you are consuming lesser vitamin B12 than the DRI values, you are at risk of developing the below conditions.

  • Fatigue and tiredness
  • Numbness in the hands and feet
  • Memory loss and confusion
  • Megaloblastic anemia
  • Loss of appetite and weight loss
  • Soreness in mouth and tongue
  • Difficulty in maintaining balance

Non-genetic Factors Affecting Vitamin B12 Levels

  • Gastrointestinal disorders - People who have gastrointestinal disorders like Crohn’s disease or Celiac disease or those who have had surgeries in the gastrointestinal tract are not able to absorb enough vitamin B12 from food sources. 
  • Age - Age is a non-genetic factor to consider too. People above 50 years of age can develop a condition called atrophic gastritis (decreased secretion of hydrochloric acid in the stomach). This also reduces the absorption levels of vitamin B12 from the food they eat. Such individuals are advised to be on vitamin B12 supplements and choose fortified foods.
  • Vegetarian and vegan lifestyle - Except for very few plant sources (fermented plant matter, seaweed), most sources of vitamin B12 are animal-based foods. Hence, vegetarians and vegans are naturally at a higher risk of having lesser vitamin B12 levels. Choosing fortified foods and checking vitamin B12 levels regularly helps avoid the complications of being vit B12 deficient. Some of the top plant sources of vitamin B12 are tempeh, edible seaweed like nori, porphyra, and laver. 
  • Pregnancy and lactation - Vitamin B12 passes from the mother to the child both via the placenta and breastmilk. Pregnant and lactating women hence need slightly higher levels of vitamin B12. In case such women don’t eat animal products, they are definitely recommended to start on vitamin B12 supplements and fortified foods.
  • Medical history - There are certain medicines that are known to interfere with vitamin B12 absorption in the body. Few common ones are metformin for bringing down blood sugar levels, Chloramphenicol to treat gastrointestinal disorders, and histamine to treat peptic ulcers. Check with your doctor about your current medications and diversify your diet and opt for fortified foods to match your nutrient needs. 
  • H. pylori infection - H.pylori is a bacteria that lives in the digestive tract. This bacteria can affect the production of gastric acid and certain digestive enzymes, which in turn can affect absorption of vitamin B12 from food. Most people with H.pylori infection are unaware of the same. You need to get yourself tested and treated for the same to prevent this from causing B12 deficiency. 

Genetic association

The FUT2 gene encodes a protein that helps a harmful bacteria called Helicobacter pylori attach itself to the digestive tract. This bacteria can inhibit the absorption of vitamin B12 in the body. Here is a list of FUT2 gene variants that can result in increased/ decreased levels of vitamin B12 in the body.

The TCN2 gene encodes a protein that helps in the final transportation of vitamin B12 from the blood to the cells in the body. A certain variant of the TCN2 gene in the Caucasian population is known to cause increased/decreased levels of B12 in the body.

Recommendations for healthy Vitamin B12 levels

Maintaining healthy vitamin B12 levels in the body is beneficial for overall health maintenance. It keeps you energetic, strong, and healthy. Here are expert recommendations on getting your daily dose of vitamin B12 right.

  • Variety is the key when it comes to food. Consciously choose foods like liver, red meat, fish, poultry, and eggs to get your daily dose.
  • Include enough dairy products like milk, cheese, yogurt, and butter. These help match the DRI levels recommended. 
  • For vegetarians and vegans, there are a lot of vitamin B12 fortified food options to choose. You can opt for nutritional yeast, fortified breakfast cereals, fortified non-dairy milk products, and meat substitutes.
  • Get your genetic testing done to see if you are likely to require more vitamin B12 to maintain healthy levels in the  body. If so, talk to your doctor about supplements or vitamin B12 shots.
  • If you are on medications that affect vitamin B12 absorption, get your blood test done to see if these have bought down your vit B12 levels. If so, make changes to your diet to keep up with the increased demand. 


  1. Vitamin B12 is a water-soluble and essential  vitamin that cannot be made in the body. It is available from ingredients you eat, in fortified packaged foods, and in the form of oral supplements and vitamin B12 shots.
  2. Vitamin B12 deficiency can cause a variety of problems including neurological abnormalities, anemia, fatigue and tiredness, and memory issues. It is very difficult to have vitamin B12 overdose. Higher levels are removed from the body through urine.
  3. Non-genetically, factors like age, medications consumed, pregnancy and lactation, and a vegetarian/vegan lifestyle can increase your risk of being vitamin B12 deficient.
  4. Genetically, some people are not able to absorb vitamin B12 from foods and may have lesser levels than what is normal.
  5. A simple blood test will show your vitamin B12 levels. Genetic testing will let you understand if your body is likely to require more vitamin B12 than others. Getting these tests done will help you plan your diet and supplement needs. 


The post Genes And Vitamin B12 Requirements appeared first on Xcode Life.

This post first appeared on How To Cure Lactose Intolerance –, please read the originial post: here

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Genes And Vitamin B12 Requirements


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