Deconstructing vitamin B12

What are the functions of vitamin B12?

Vitamin B12 serves a number of vital functions in human health.

• It produces the red blood cells, which are required for the synthesis of hemoglobin.
• It is responsible for keeping our nerve cells healthy.
• It is relevant for the production of deoxyribonucleic acid (DNA, the genetic material).
• It is required for several enzyme reactions.

How much vitamin B12 do I need on a daily basis?

Our requirements vary based on our age and gender. The recommendation values presented here are only applicable to fellow Indians.

• Adult men and women need 2.2 micrograms of vitamin B12 per day
• Pregnant women need an additional 0.25 micrograms per day while lactating women need an additional 1 micro gram per day of vitamin B12
• Infants up to six months of age are totally dependent on breast milk for all their nutritional requirements (exclusive breast feeding to six months is a recommended practice) which is why lactating women have to ensure their vitamin B12 adequacy.
• Infants from 6 months onwards up to 5 years of age (preschool children) need 1.2 micrograms of vitamin B12 per day
• School children and adolescents (5-17 years), just like adults, need 2.2 micrograms per day.

What are the causes of vitamin B12 deficiency?

1. If you are consuming a diet that is deficient in vitamin B12.
2. If there is poor to no absorption of vitamin B12 in the digestive tract {due to destruction of stomach cells that produce intrinsic factor which is required for active absorption of vitamin B12}.
3. Some prescription drugs may interact and interfere with the absorption of vitamin B12, such as gastric acid or proton pump inhibitors (which are prescribed for the treatment of acidity, peptic ulcers, gastroesophageal reflux disease), H2 blockers (reduce the amount of acid produced in the stomach), and metformin (reduce the amount of sugar in the blood, often prescribed to pre-diabetics, type 2 diabetics and women suffering from polycystic ovary syndrome). That said, please stick to your prescription drugs, but make sure to talk with your physician about maintaining a normal vitamin B12 status.

Who is vulnerable to vitamin B12 deficiency?

• Those who shun all animal and animal-related food products in their diet (known as vegans)
• Those who are gluten sensitive, suffer from celiac disease and Crohn’s disease
• Those who have pernicious anemia or suffer from atrophic gastritis.
• Those who have undergone surgery of the gastrointestinal tract (for weight loss or have had a part or whole of their stomach removed).
• Older people who are unable to produce stomach acid (known as age-related hypochlorhydria).

What symptoms should I watch out for in case of vitamin B12 deficiency?

Because our body can store substantial vitamin B12 (ranging between 1 to 5 mg) in the liver, the symptoms of deficiency take time to manifest. A B12 deficiency will first lead to inadequate production of red blood cells. Then, over a period of time, when the symptoms begin to appear, you will start feeling tired and lethargic, a condition called megaloblastic anemia. Since nerve cells are affected by vitamin B12 deficiency, your hands and feet may become numb or you may get a tingling sensation.  Some may experience loss of appetite and eventual weight loss while others may develop pale skin and experience palpitations of the heart. Some people may develop gait problems and may also suffer from poor memory and episodic confusion.

How do I check my vitamin B12 status?

A blood test to check your serum or plasma vitamin B12 will be recommended. However, the estimation of methylmalnoic acid and homocysteine will better reflect your vitamin B12 status. 

What are the normal values in blood work?

The values of an indicator (biomarker) vary based on the method used for estimation and also differ from laboratory to laboratory. However, below are the cut-offs that are agreed upon to diagnose vitamin B12 deficiency;

• Serum or plasma vitamin B12 <150 pmol/litre
• Plasma homocysteine >13 micro moles/litre
• Serum methylmalnoic acid >260 micro moles/litre

How do I correct my vitamin B12 deficiency?

The deficiency is only to be corrected under medical guidance to determine the appropriate dose and duration of treatment. Severe vitamin B12 deficiency is usually treated with prescribed intramuscular vitamin B12 injections or with oral vitamin B12 mega dose. Oral exclusive vitamin B12 supplements are prescribed for those who may not have a severe deficiency.

What is the right time to take a vitamin B12 supplement?

Since B vitamins are linked to energy metabolism, it is best to take your prescribed vitamin B12 supplement in the morning. In case you miss it, take it two hours before or after a meal. Make sure to read the instructions written on the packaged supplements for any further information. If you completely miss on taking your supplement for a particular day or days together, only take the prescribed dosage and do not overdo it.

Which foods naturally contain vitamin B12?

It is only foods of animal origin that naturally contain vitamin B12. This is so because the vitamin is produced by the micro-organisms (bacteria) in the digestive tract of the animals, which is then subsequently absorbed into the animal tissues. So, eggs, fish, meat, poultry, milk and its products are the natural food sources of vitamin B12. 

Don’t plant foods contain vitamin B12?

Plant foods often touted as natural food sources of vitamin B12 actually contain analogues of vitamin B12. To simplify, they are pseudo vitamin B12 (they are chemically similar in structure to vitamin B12, but they are in their inactive form). They end up interfering with the metabolism of actual vitamin B12 by inhibiting its absorption. So, plant foods do not meet our vitamin B12 requirement at all, until and unless they have been fortified with vitamin B12. Examples of foods fortified with vitamin B12 include; fortified breakfast cereals, fortified plant milks and their products and fortified nutritional yeast. Dried purple lavers (Nori), the edible seaweed used in sushi rolls, contains small amounts of active vitamin B12, however, the amount may vary based on the type of seaweed and also where it was harvested, which is why it cannot be considered as a credible source of vitamin B12. That said, it does not mean that vegetarians or vegans change their eating patterns because they can easily meet their daily vitamin B12 requirements, which will be explored in the next section of the blog post.

How do I ensure normal B12 status if I am a vegetarian or a vegan?

• While vegetarians may still get some vitamin B12 from milk and milk products, the amount is negligible and much of it is destroyed the moment you boil the milk (for pasteurization). However, vegetarians can consume foods fortified with vitamin B12. Some examples include fortified breakfast cereals, fortified spreads and fortified nutritional yeast. Please make it a habit to read the nutrition facts panel carefully to check whether the product you are buying contains vitamin B12 or not. If yes, you have to check the amount per serving. The vitamin B12 we get from supplements and fortified foods is readily absorbed by the body. That said, it is always advisable that vegetarians keep a tab on their B12, and consult a nutritionist to check whether they would need a supplement or not.   
• If you are vegan, you have no other option but to take a vitamin B12 supplement (also known as cyanocobalamin), ofcourse under the guidance of your physician or your nutritionist for the appropriate dosage. In addition to that, make sure to consume foods fortified with vitamin B12 such as fortified breakfast cereals, fortified plant milks and their products, fortified spreads and fortified nutritional yeast.

Is there any association between vitamin B12 and non-alcoholic fatty liver disease (NAFLD)/metabolic dysfunction associated steatotic liver disease (MASLD)?

The liver is the storehouse of vitamin B12. Any damage to the liver, as in the case of MASLD or what was previously known as NAFLD, where unnatural fat deposition occurs in the liver, may lead to the release of this stored B12 into circulation, which may not necessarily imply increased B12 intake in the diet. Low as well as high vitamin B12 may be associated with a risk of developing MASLD. This calls for paying utmost attention to maintaining a close watch on vitamin B12 in those afflicted with MASLD/NAFLD.  The answer, therefore, lies in taking only recommended amounts of B12 in the diet or as supplements and ensuring to estimate B12 during the routine blood work.

To consult Dr. Roy for a personalized nutrition plan, register here or write to her at info@nafldnutrition.in

Disclaimer: The information shared in the blog is aimed at increasing your awareness and is not a substitute for medical advice pertaining to your case.   

References

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