Cobalamin (B12) & Health

What is B12 & What Does it Do?

B12 is the last of our water-soluble B-complex vitamins.  It plays many important roles and is closely connected to the actions of folate.  It is a large and complex molecule that requires a well-functioning digestive system for absorption and is commonly deficient in those over 60 due to a natural decline in digestive function.  Low vitamin B12 levels have been associated with several different diseases. (1)  Let’s take a closer look at this vitamin.

Homocysteine: 

Before we jump into our focus on vitamin B12, let’s take a detour to explore homocysteine.  We have encountered this molecule in our explorations of several B vitamins, and high levels are linked to several major medical conditions including heart disease, dementia, osteoporosis, liver disease, kidney disease, and many others. 

What is Homocysteine? 

Homocysteine is an amino acid that is created by the body.  It can be turned into two other amino acids that have multiple important functions in the body: cysteine and methionine. (2) 

Why is Homocysteine Important?

Homocysteine levels in the body are regularly measured as a marker of methylation and B vitamin status.  The higher the homocysteine levels, the slower methylation is running and the more we are at risk of developing several major medical conditions such as heart disease and cancer.

B12 is needed to convert homocysteine to methionine, which in turn is converted into another molecule, S-adenosylmethionine, which is one of our most important molecules involved in methylation. (1)  Other nutrients needed for this conversion include Folate and Vitamin B6.

B12 Deficiency: 

It is uncommon to find B12 deficiency in omnivorous adults.  However, in individuals over 60, those with chronic digestive issues, those who have had bariatric surgery, people on long-term acid suppression therapy, those with pancreatic insufficiency, those who consume alcohol frequently, and those who eat a strict vegetarian or vegan diet are at increased risk of developing a B12 deficiency. (1)

Clinical B12 deficiency results in megaloblastic anemia which presents with: 

• Fatigue

• Weakness

• Shortness of breath

B12 deficiency also leads to neurological issues that may be permanent including: 

• Numbness and tingling of the hands and feet

• Difficulty walking

• Memory loss

• Disorientation

• Dementia

Finally, B12 deficiency can also cause digestive complaints such as: 

• Soreness and inflammation of the tongue

• Loss of appetite

• Constipation

Prevention of Disease: 

Adequate levels of B12 have been shown to be protective against the following conditions: 

• Cardiovascular disease (1)

• Breast cancer (1)

• Neural tube defects (1)

• Cognitive decline (1, 4)

• Depression (1)

• Osteoporosis (1)

Treatment of Disease: 

When it comes to the treatment of disease, the symptoms of B12 deficiency can be treated. 

In the case of Autism, we have evidence that B12 supplementation can be helpful in managing some of the more troublesome symptoms that may arise.  These symptoms include trouble with: “sleep, gastrointestinal symptoms, hyperactivity, tantrums, nonverbal intellectual quotient, vision, eye contact, echolalia, stereotypy, anemia, and nocturnal enuresis.” (3)

At this time, when it comes to cardiovascular disease, cancer, osteoporosis, liver disease, and cognitive decline, there are mixed results in using B12 as a treatment.  Some studies show a strong effect and others show little to no effect when compared to placebo.  As we have seen with the other nutrients we have studied, prevention tends to be the best place to focus when considering nutrition and disease. 

Toxicity: 

Luckily, we do not see any issues with high-dose vitamin B12 intake through food or supplements.  After taking a B12 supplement, you may notice bright yellow urine; this is the excess B12 leaving your body. 

Where to Find B12: 

B12 is created by bacteria and is found concentrated in animal products, especially in shellfish.  Some B12 is created when beans and vegetables are fermented and some edible algae and mushrooms contain B12 as well. (1)

Fortified foods are another significant source of B12. 

Applications:

Our takeaways this week are: 

1. Vitamin B12 is another essential B vitamin.

2. There are several populations at risk of B12 deficiency.

3. B12 is important in methylation reactions.

4. B12 works better as preventative medicine, rather than treatment of disease.

Daily Intake:

The RDA for B12 is 2.4 mcg daily.  Those over 60 are encouraged to obtain this through fortified foods or supplements as this form is better absorbed when digestive function is reduced.  In people with pernicious anemia or who have had an ileum resection, injectable B12 is recommended.  Pregnant individuals have an increased RDA of 2.6 mcg and those who are nursing are recommended to increase their intake to 2.8 mcg. 

The Linus Pauling Institute recommends a varied diet that includes a multivitamin for healthy adults under age 50.  For those who are 50 years or older, they recommend a supplement including 100-400 mcg of B12 daily, and for strict vegetarians and women who are planning to become pregnant, 6-30 mcg of B12 are recommended daily. (1)

Medication Interactions:

Medications that can interfere with vitamin B12 absorption include: 

• Proton pump inhibitors

• Histamine receptor antagonists

• Cholestyramine

• Chloramphenicol

• Neomycin

• Colchicine

• Metformin

• Nitrous oxide

We have now covered each vitamin in detail!  If you missed any, I have put together a collection of all the nutrition articles from this year for your convenience.

Next week: 

Next week we will begin our exploration of the minerals essential for life.  We will begin with Calcium.

To our health!

References: 

1. Higdon, J, “Vitamin B12” Linus Pauling Institute, 2000; last update: 2015; accessed November 10, 2021; https://lpi.oregonstate.edu/mic/vitamins/vitamin-B12

2. Son P, Lewis L. Hyperhomocysteinemia. 2021 May 12. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan–. PMID: 32119295.

3. Rossignol DA, Frye RE. The Effectiveness of Cobalamin (B12) Treatment for Autism Spectrum Disorder: A Systematic Review and Meta-Analysis. J Pers Med. 2021 Aug 11;11(8):784. doi: 10.3390/jpm11080784. PMID: 34442428; PMCID: PMC8400809.

4. Wang Z, Zhu W, Xing Y, Jia J, Tang Y. B vitamins and prevention of cognitive decline and incident dementia: a systematic review and meta-analysis. Nutr Rev. 2021 Aug 25:nuab057. doi: 10.1093/nutrit/nuab057. Epub ahead of print. PMID: 34432056.