Vitamin B12 Guide: How to Treat Vitamin B12 Deficiency


Most people have heard that B12 is only found in animal products, which is true. That's why B12 is an essential supplement if you are on a vegan diet.

What a lot of people do not know is that B12 deficiency is common, even on a diet rich in animal protein. In this article, we will talk about why that can happen and how to treat B12 deficiency.

There are also four main types of B12, and they are all not created equal. We will discuss the different types of vitamin B12 and the best ones to supplement with to support optimal health levels.

Also, how do you know if you are low in Vitamin B12? Blood tests can be inaccurate, especially if you are supplementing with B12. It may look like you have lots of Vitamin B12 in the blood, but maybe you are still low at a cellular level.

Read on to find out why you need Vitamin B12, learn how to treat vitamin B12 deficiency, accurate ways to test your B12 levels, and which type of B12 you need to take if you're deficient.

12 Top Benefits of Vitamin B12


Vitamin B12 has many benefits and it goes way beyond energy production and a healthy nervous system, and like all vitamins, B12 is essential for optimal health.

Boosts Mood and Improves Depression 

The exact mechanism is not known but studies show that people with low Vitamin B12 are at twice the risk of severe depression. This could be due to its effect on serotonin or even the increased energy levels. Vitamin B12 is also linked to better treatment outcomes when used in patients with major depression.

Supports Healthy Red Blood Cell Formation 

Vitamin B12 is essential for red blood cell production and a lack of B12 will affect large red blood cells (check RDW on your blood test) leading to megaloblastic anemia. This means you will not be able to transport oxygen around the body causing fatigue.

Benefits Mother and Baby During Pregnancy

Vitamin B12 is essential for preventing birth defects and miscarriage. A lot of people focus on folate which is also important but B12 is just as important and is involved in the development of the nervous system.

Prevents Osteoporosis 

A lot of people focus on calcium and vitamin D for bone health but Vitamin B12 is also essential for healthy bones, through its role of regulating homocysteine levels.

Supports Optimal Vision

We are used to our vision deteriorating as we get older and Vitamin B12 deficiency is associated with macular degeneration and glaucoma, this is because of its effect on the nervous system and also homocysteine levels (have you had your homocysteine checked?)

Enhances Cardiovascular Health 

High homocysteine is linked to an increased risk of cardiovascular disease, and B12 along with folate are important nutrients to maintain healthy homocysteine levels.

Healthy Skin, Hair, and Nails

You don’t often think of Vitamin B12 being important for skin health but low B12 levels are one of a number of factors that can cause vitiligo, acne, rosacea, and dermatitis. If you are deficient in Vitamin B12 supplementation can help improve your skin, hair, and nail quality.

Improves Brain Health 

Vitamin B12 has been associated with dementia, Alzheimer’s, and memory loss in older adults. These changes don’t just happen suddenly when you are older and it is important to maintain optimal B12 levels when you are younger.

Boosts Your Energy Levels 

All B vitamins are important for energy production. Low levels of vitamin B12 can cause both mental and physical fatigue if you have less than optimal levels. 

Reduces Pain Levels 

Studies have shown that Vitamin B12 can help with neuralgia, reduce pain and help with the regeneration of nerves.

Helps People with Obesity and Insulin Resistance 

Low vitamin B12 levels are associated with increased insulin resistance and obesity, the mechanism is not clear but it could also be associated with high homocysteine levels. Metformin, a common diabetic drug is also a cause of B12 deficiency.

Improves Singing! 

This is an unusual one but a survey of singers and singing teachers found that B12 supplementation is beneficial for them. I think I must need more B12!

How To Test For A Vitamin B12 Deficiency

Testing recommendations for vitamin B12 deficiency

The simplest way to assess your vitamin B12 levels is to ask your doctor for a complete blood count, also known as a CBC, and get your vitamin B12 levels tested (read on to find out why this may not be the most accurate way).

B12 is an added extra to the CBC and is not measured as part of a standard physical checkup.

While B12 is important for so many different areas of health and a low-level deficiency can go undetected for years, it is not tested as part of a standard pathology test. So you will need to ask your doctor specifically to test for B12.

The reference range for B12 can vary from lab to lab but it is usually between 200 - 700 pmol/l or pg/ml if you are in the U.S.A. 

You don’t want to just be in the reference range, the optimal range for B12 is much higher and ideally, you want to be above 400, and there does not seem to be an upper limit or toxicity from high Vitamin B12 levels.

It is possible to be in the reference range and be still low in Vitamin B12 at a cellular level, especially if you are supplementing with B12.

The Best Way to Test Vitamin B12 Levels

While the standard CBC and B12 test may be the simplest way to measure your B12 levels it may not be the best.

Methylmalonic Acid 

Methylmalonic Acid (MMA) is recognized as the best way to test Vitamin B12 levels as it measures B12 at a cellular level, it is possible to have normal or even high levels of B12 in the blood but be low at a cellular level.

A high level of MMA is associated with a B12 deficiency, this is important because many people see this B12 marker as high on their test results and think that their B12 levels are fine.

I prefer to test Methylmalonic Acid with the Organic Acids Test (OAT) as it also tests for other B vitamins (and much more), especially Vitamin B2 which is an essential cofactor for B12.

MMA can also be tested with a blood test, so this can be a good option if you don’t want to do the full OAT test, or you have previously done the OAT test and you just want to retest your B12 levels.

If the MMA levels are elevated that means you are deficient in Vitamin B12, but more specifically you are deficient in adenosylcobalamin which is a specific form of B12 for energy and mitochondria function - so supplementation with methylcobalamin may not be the best way to improve this.


Homocysteine is another way to assess Vitamin B12 levels, it is not as specific as MMA because high homocysteine levels can also indicate a deficiency in B2, B6, folate, and B12.

This is why doing the Organic Acids Test is beneficial as you can assess all of these nutrients.

The optimal range for homocysteine is between 5-8 but the reference range on your lab test will be between 0-15, so it is important to not just be in the range but be in the optimal range.

Homocysteine is important to test in conjunction with MMA as a high level indicates a possible methylcobalamin deficiency, this is the second form of B12 that is important for methylation in the body, along with DNA/ RNA repair.

High homocysteine is associated with cardiovascular disease, Alzheimer’s, vascular diseases, and cancer so it is an important marker to assess, yet is rarely done as part of a standard pathology test.

Complete Blood Count

Complete Blood Count, also known as CBC is usually done as part of every blood test and I think it is important to do this test in conjunction with the MMA and homocysteine as it can also give important clues to B12 and other B vitamin deficiencies. It is important to note that the CBC can be normal but you can still have a B12 deficiency.

The CBC includes MCV, Hemoglobin, RDW, and Hematocrit.

MCV is a marker of the size of the red blood cells. The deficiency in B12 (or folate) will lead to larger red blood cells and increased MCV above 98. This is known as macrocytic anemia. 

Hemoglobin allows red blood cells to transport oxygen around the body. Low levels are known as anemia, low B12 levels can lead to low Hemoglobin but not in all people. Low hemoglobin can also be caused by low iron and low folate levels which is why it is important to do comprehensive testing.

Hematocrit is a measure of how much space red blood cells take up in your blood. A low level is associated with anemia and this is another reason to identify the cause of anemia, which could be iron deficiency, B12, or folate deficiency.

Why Are My Vitamin B12 Levels Low?

If you are a vegan or vegetarian then your Vitamin B12 levels will be low because you are not eating animal products and it is essential to supplement with B12. Ideally, it should be a combination of adenosylcobalamin and methylcobalamin, or hydroxocobalamin as this can be converted into the other two active forms of B12.

9 Causes of Low Vitamin B12

how to treat vitamin B12 deficiency


Older adults are at a greater risk of a B12 deficiency due to poor absorption. The symptoms like fatigue and cognitive decline can often be missed as they simply put down to “getting older”.


A vegan or vegetarian diet increases the risk of B12 deficiency as the absorbable form of B12 is only found in animal products. Also non-vegetarians who are eating a highly processed poor quality diet are at risk of B12 deficiency.

Celiac Disease

The damage to the small intestine in celiac disease affects the absorption of Vitamin B12, this can be reversed over time once gluten has been eliminated 100% and the intestines have had time to heal.

Pernicious Anemia

This is an autoimmune condition that affects the production of Intrinsic factor which is a protein made in the stomach and is essential for B12 absorption. Pernicious anemia can have a genetic link and is more common in people who have other autoimmune conditions like thyroid, type 1 diabetes, Addison’s and Grave’s disease.


Small Intestinal Bacterial Overgrowth, commonly known as SIBO can affect the absorption of B12 as the bacteria use up your Vitamin B12 and affect absorption.


Inflammatory Bowel Disease affects the absorption of Vitamin B12 and a number of other nutrients, anyone with IBD should keep a check on their B12 levels with methylmalonic acid and homocysteine testing.


Many common and regularly used medications will affect the absorption of Vitamin B12, this includes the following drugs:

  • Acid lowering drugs known as PPI used to treat reflux
  • Antibiotics
  • Metformin, which is a common drug used to treat diabetes
  • Anti-seizure medications
  • Antidepressants affect folate levels and this can have an influence on B12 levels

Note: If you are taking these medications and have low B12 do not stop your medication without consulting your doctor. Many of these medications are treating symptoms that can be addressed with diet and lifestyle changes rather than medications but first, you need to make these changes.


There is a number of genetic SNPs that can affect your absorption and utilization of Vitamin B12, so far 59 B12 related SNPs have been identified and using the SelfDecode Genetic Reports it is possible to work out if this relates to you. It is important to note that just because you have the gene, it does not mean it will be an issue, but it will increase the likelihood of a deficiency especially as you get older.

Nutrient Deficiencies

Vitamin B2, B6, and folate work in combination with Vitamin B12, especially to keep homocysteine levels low. Deficiencies in these vitamins can lead to low B12 levels at a cellular level which is why testing B12 with the MMA test is a good idea.

How To Treat Vitamin B12 Deficiency - Best Supplements

So you have low Vitamin B12 levels and you want to know what is the best form of Vitamin B12 to boost your levels, the answer is not so simple and it will depend on your test results.

  • If you have high methylmalonic acid levels then you need adenosylcobalamin.
  • If you have high homocysteine levels you are likely low in methylcobalamin.
  • If you have low levels of Vitamin B12 on a blood test this does not tell us which form you need but ideally, you want to boost both of the active forms of B12.

Before we discuss the best form of B12 to take we need to briefly discuss the different forms that are available when you go to buy a Vitamin B12 supplement.

4 Different Types of Vitamin B12


Cyanocobalamin is the synthetic form of vitamin B12 found in many cheap vitamin supplements and foods fortified with B12, this form of vitamin B12 is not absorbed as well as the active forms that we will discuss next. Cyanocobalamin can be converted to the two active forms of B12 that the body needs and they are methylcobalamin and adenosylcobalamin but because of the small amount of cyanide present and the poor absorption, this form is not recommended.


Methylcobalamin is the most common form found in some of the better quality B12 and multivitamin supplements. This form of B12 is essential for methylation and the healthy functioning of our nervous system, it can be converted into adenosylcobalamin but due to a variety of genetic SNPs this is not always effective and you may need both forms of active B12


Adenosylcobalamin is the second active form of Vitamin B12 that the body needs and is essential for mitochondrial function, which means that it is essential for our body to produce energy. Adenosylcobalamin can be converted to methylcobalamin but this can also be influenced by genetics and the adenosylcobalamin form being the least stable as a supplement.


Hydroxocobalamin is considered an active form of B12 as it is found naturally in the body and can easily be converted to both methylcobalamin and adenosylcobalamin, plus it is often the best form of B12 for people who are sensitive to the other active forms of B12.

*This is also the form often found in Vitamin B12 injections but is also available in lozenges and capsules.

Best Vitamin B12 Supplements

There are a lot of quality Vitamin B12 supplements out there (and also a lot of bad ones) and the key is to get your supplements from a quality brand in the active form that you need.

Sublingual Vitamin B12 Lozenges

I prefer sublingual Vitamin B12 lozenges over capsules as they are better absorbed, especially for people with digestion problems or low stomach acid (which many old people have).

There are a couple of good options for sublingual Vitamin B supplements and one of my favourite brands is Seeking Health as you get to choose from a number of different B12 combinations.

Seeking Health Active B12

  • This is a blend of adenosylcobalamin and methylcobalamin.
  • For most people 1,000mcg per day will be enough.
  • Sometimes higher doses are needed for short periods if your levels are very low.

Seeking Health Hydro B12

  • This contains hydroxocobalamin which is an active form of B12 that can be easily converted to methylcobalamin and adenosylcobalamin.
  • A good option for people who don’t tolerate the methyl form of B12.

RN Labs Sublingual Hydroxocobalamin

  • This is a good option for people in Australia, 
  • Contact us for details on how to order.

Vitamin B12 Rich Foods

Vitamin B12 is an important сomponent of a balanced diet. You may get the necessary amount of vitamin B12 from supplements and organic products. 

Vitamin B12 is mainly found in animal products, different types of meat, and dairy products. If you're vegan, try to enrich your diet with fortified foods like fortified cereals and fortified tofu.

Check out below some examples of foods that are very high in vitamin B12.

  • Shellfish - clams, oysters, mussels, and scallops
  • Fish - tuna, herrings, mackerel, sardines, trout, snapper, and salmon
  • Crustaceans - crabs, crayfish, shrimp, and lobster
  • Beef, liver, and other organ meats
  • Eggs, cheese
How to treat vitamin B12 deficiency

If you still have questions on how to test vitamin B12 levels and how to treat vitamin B12 deficiency, don't hesitate to schedule a consultation.

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