How to Supplement Vitamin B12 on a Plant-Based Diet
Vitamin B12 is the only supplement that I recommend absolutely everyone on a plant-based diet take, especially women who are pregnant, may become pregnant or who are breastfeeding.
WHAT IS B12?
Cobalamin, another name for vitamin B12, is a water soluble vitamin that is produced by anaerobic bacteria that live in the gastrointestinal tract of animals. There is a common misconception that only cows produce this vitamin which leads many to believe that it is important to eat meat and dairy products, however, this is not the case.
Animals ourselves do not have the enzymes necessary to synthesize it, nor do plants or fungi. One of the reasons that it is found in cows’ meat and dairy is because the bacteria in a cow’s gut synthesize it and in some cases it can be reabsorbed by their enterocytes (intestinal cells). Since it is produced in the intestine, it can be found in feces which then contaminate their food sources and are consequently consumed by the cows. Animals that are killed and sold for their meat also tend to get injected with vitamin B12 so that they are able to label their products as “a good source of B12”.
CAUSES OF B12 DEFICIENCY
Hypocobalaminemia (cobalamin deficiency) can be caused by either not getting enough B12, not being able to absorb enough of it or not being able to metabolize it correctly once already in the body.
Since vitamin B12 is mostly found in feces, in today’s antiseptic society with clean drinking water and washed vegetables, our food sources contain little to no B12. Although it can be found in fortified foods, getting enough B12 on a plant based diet is next to impossible without supplementation.
Vitamin B12 deficiency is not only a problem amongst vegans and vegetarians; meat easters also have high rates of B12 deficiency.
Causes of malabsorption of cobalamin include atrophic gastritis (the leading cause of B12 deficiency in adults over the age of 55), Celiac’s disease, Crohn’s disease, tapeworm infection, gastrectomy (total or partial removal of the stomach, mostly because of gastric cancer or weight loss surgery), prolonged use of proton pump inhibitors (PPIs) such as omeprazole, and H2 inhibitors such as famotidine, alcoholism.
EFFECTS OF B12 DEFICIENCY
A mild deficiency may not cause any symptoms, but if gone untreated may progress to cause:
-Megaloblastic anemia; called pernicious anemia when caused by GIF deficiency.
-Gastrointestinal symptoms such as either diarrhea or constipation
-Neurological symptoms such as paresthesias (numbness or tingling of fingers or toes).
-Depression, memory loss of behavioral changes.
-Irreversible brain damage, cognitive decline, Alzheimer’s disease.
TESTING B12 LEVELS
B12 Serum Levels
The most common test done to see if you are getting enough B12 is a simple blood test to see the serum concentration of B12.
Levels between 200 and 900 pg/mL are considered to be in the normal range, however this is not the most accurate measure for vitamin B12 function in the body.
Methylmalonic Acid Levels
A better indicator for vitamin B12 is methylmalonic acid (MMA) from a blood or a urine sample. MMA is much more reliable because despite having a “normal” B12 serum concentration you can still have functional B12 deficiency, indicated by an increased MMA.
The normal range for MMA in a blood sample is 0-0.4 umol/L or 0-4.7 ug/dL.
The normal range for a MMA-to-creatinine ratio in a urine sample is less than 3.8 ug/mg per mg of creatinine.
Mean Corpuscular Volume
Another indicator of B12 levels is an elevated mean corpuscular volume (MCV), which can be seen on a routine blood test or a complete blood count (CBC). The MCV indicates the average volume of red blood cells.
When the MCV is 90 fL/cell or greater it can be an indication of macrocytic anemia and B12 deficiency. However, this can be masked by excess levels of folate, which is why people who are at risk for clinical B12 deficiency should be tested properly with MMA levels.
Who Should Be Tested?
For patients who supplement B12 from the time they transition to a vegan or a whole-food plant based (WFPB) diet, testing for B12 levels is not really necessary. However, patients with unexplained neurological or psychological changes should be tested, as well as all vegan women who are trying to conceive, who are pregnant or nursing and infants of vegan mothers.
I recommend that everyone on a plant-based diet take vitamin B12 supplements or eat fortified foods in order to prevent deficiency. I personally prefer the former, rather than the latter because I find it easier, more reliable, and less expensive.
When being consumed in supplement form it is recommended we take 100 ug or more per day, 1000 ug 3 days a week, or one tablet of 2500 ug once a week, which is the most cost effective way. There are also sublingual tablets, sprays, and drops which seem to be effective, though I would like to see more scientific research before suggesting them as a first line of prevention or treatment.
Fortified foods such as different plant-based milk like soy milk, almond milk or cashew milk and nutritional yeast (be sure to read the nutritional information as not all nutritional yeasts are fortified with B12) can also be included in the diet. However, if these are your only sources then getting enough is more difficult as they need to be consumed 3 times a day in order to meet requirements, being much more costly than the tablet form.
In cases where there is already B12 deficiency, parenteral treatment with injections may be necessary. In many cases though, high doses of oral B12 (2000 ug daily for 14 days) can also do the trick. Although, for people who have malabsorption disorders, regular intramuscular injections will most likely be necessary.
There is no evidence, to my knowledge, that suggests that high levels of B12 improve energy levels, nor improve memory. We just need to get enough to prevent disease.
There are three forms of vitamin B12 supplements; cyanocobalamin, methylcobalamin and hydroxocobalamin.
An inactive form of B12. It is protein bound and when taken orally it is broken down to its free form and is then bound to GIF, later being absorbed in the small intestine.
It can be safely and reliably given as long as the person has sufficient GIF, though there are some situations to take into consideration such as renal failure and heavy smokers in which cyanocobalamin could theoretically cause cyanide toxicity. However, in order for this to occur in a person with properly functioning kidneys, they would need to take an extremely large dose of B12 (about 7 kilograms, or 7000 tablets of 1000 micrograms in a single day) for this to occur. Companies that sell other forms of vitamin B12 use this in their marketing to make it seem like their product is better and safer, without saying how extremely rare this is.
Oral cyanocobalamin is the cheapest version of B12 currently available. Other forms of administration include intramuscularly (IM) or subcutaneously (SQ).
This is the active form of cobalamin. It is the more expensive version of B12 that is available in the US. The daily dose would be 1000 micrograms every day without the option of taking it once a week in larger quantities.
In some people, especially children, who have methylation disorders such as autism, in some cases of ADHD and bipolar disorder, this may be the better option. It may also want to be considered in heavy smokers or patients with kidney failure.
Another inactive form of vitamin B12 that has a higher affinity for albumin (a protein in the blood) and has a longer half-life (it circulates longer in the body before being excreted by the kidneys or metabolized) than cyanocobalamin. This tends to be the form of vitamin B12 that is found in food.
This is generally sold as an ejection but is not approved by the Food and Drug Administration (FDA) so it would not be an option in the United States. However, it is recommended worldwide as the drug of choice for the treatment of B12 deficiency by the World Health Organization (WHO).
PREGNANCY AND BREASTFEEDING
It is important to remember that B12 is vital in the formation of the neural tube of the embryo. This occurs in early stages of the first trimester of pregnancy when many women do not even know that they are pregnant which is why all fertile women, especially vegans, should be taking vitamin B12 supplements.
Newborn babies have small stores in their body of only up to 25 micrograms and deficiency during development can have grave consequences. This is why it is particularly important that nursing mothers get enough B12 because they are still eating for two. When your child starts solids, I would suggest feeding them fortified foods.
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