Parul Kharod
By Parul Kharod
If you are eating a vegetarian or vegan diet, you may have heard that you may not get enough Vitamin B 12 and may need supplementation.
What is Vitamin B 12?
Vitamin B 12 contains the mineral cobalt and exists in several forms. Compounds with vitamin B 12 activity are called cobalamins. Methylcobalamin and adenosylcobalamin are two forms that are active in human metabolism. The other forms are hydroxocobalamin and cyanocobalamin that must be metabolized into the two active forms to be used in human cells.
Sources of Vitamin B 12
The most important thing to remember is that Vitamin B 12 is not made by plants or by animals, but by bacteria.
B 12 is made by anaerobic microorganisms (i.e., bacteria that do not require oxygen to live). Anaerobic bacteria are common in the gastrointestinal tract of animals. Many herbivorous mammals, including cattle and sheep, absorb B 12 produced by bacteria in their own digestive system. B 12 is found to some extent in soil and plants. When animals eat grass or other soil-based foods that may have bacteria, or larger animals may eat other smaller animals, certain types of bacteria enter their gut. Thus, animals make their own B 12 from these sources. When humans eat animals, they are getting the B 12 from these animals. Which is why non-vegetarians may get adequate B 12 from their diet, but vegetarians and especially vegans may not.
These are the recommendations from the Vegetarian Nutrition Dietetic Practice Group of the Academy of Nutrition & Dietetics:
• All vegetarians should periodically be screened for B 12 deficiency, using either methylmalonic acid (MMA) or TCII (transcobalamin) assessment.
• All women considering pregnancy and those already pregnant should take 250 mcg per day of a B 12 supplement. (This amount is about 100 times higher than the RDA since only about 1 percent of ingested B 12 from supplements is absorbed.)
• All vegans should take 250 mcg per day of a B 12 supplement.
• All lacto-ovo vegetarians should consider taking 250 mcg per day of a B 12 supplement a few times per week.
Why is Vitamin B 12 important?
Like all other B Vitamins, Vitamin B 12 is a water-soluble vitamin. This means it can dissolve in water and travel through the bloodstream. The body can store vitamin B 12 for up to 4 years, and it can get rid of any excess or unwanted vitamin B 12 in the urine.
Vitamin B 12 has many important functions in the body including:
• Essential for normal red blood cell production
• Normal functioning of the brain and nervous system
• Cognitive functioning (ability to think)
• Formation of red blood cells and anemia prevention
• Helping create and regulate DNA
• Possibly preventing congenital abnormalities
• Helping protect the eyes from macular degeneration
• Necessary for energy production
Vitamin B 12 plays very important roles as a cofactor in various pathways for DNA, RNA, protein, lipids and hormones.
Vitamin B 12 deficiency
Vitamin B 12 deficiency leads to megaloblastic anemia, fatigue, weakness, constipation, loss of appetite, soreness of the mouth or tongue, and weight loss; and neurological conditions, such as numbness and tingling of the hands and feet, difficulty with balance, depression, confusion, dementia, and poor memory. Some neurological symptoms are irreversible which is why it is extremely important to prevent Vitamin B 12 deficiency. Deficiency can also be cause by Pernicious anemia which is an autoimmune disease.
Large intake of folic acid can mask the damaging effects of B 12 deficiency by correcting anemia without addressing the neurological damage that occurs. High folic acid may even exacerbate anemia and cognitive symptoms. It isn’t recommended to exceed 1,000 mcg/day of folic acid in healthy adults.
Vitamin B 12 deficiency can also happen because your stomach/intestines may not be able to absorb Vitamin B 12 from your diet. This can happen with Celiac disease or Crohn’s disease. Overuse of commonly prescribed heartburn medications, known as PPIs, which reduce acid production in the stomach, can also lead to problems with B 12 absorption as hydrochloric acid in the stomach is needed to absorb vitamin B 12. The condition is also likely to occur in older adults due to reduced stomach acid production that often occurs with aging.
Another condition that can cause Vitamin B 12 deficiency is a genetic mutation with the acronym MTHFR, which stands for methylenetetrahydrofolate reductase. Approximately 30 percent of the population worldwide has it. This mutation affects the ability of the body to turn vitamin B 12 and folate into forms the body can utilize. People with this mutation cannot absorb other forms of Vitamin B 12. They may need to supplement their diet with methylcobalamin (methylated B 12).
Summary
Vitamin B 12 is a unique vitamin. Unlike other vitamins, there are no direct food sources. It is found in animal-based foods because it is made in the gut of these animals by the bacteria. No plant-based foods have this vitamin. Deficiency can be irreversible and cause serious damage, so it is important to take a supplement.
Parul Kharod is a registered dietitian and licensed nutritionist and works as a Clinical Dietitian. She can be reached at [email protected]
