Healthy eating


Nutritional yeast with added B12

Vitamin B12 2/2


You only need to absorb a tiny amount of vitamin B12 daily, around 4 mcg a day. The receptors in the ileum that absorb B12 can only absorb about 1.5 mcg at once and cannot absorb any more for several hours. To obtain adequate levels of B12 on a plant-based diet, you should consume at least three servings of B12 fortified foods daily, plant-based milks and nutritional yeast are often available in fortified versions.

Another option is taking a supplement with B12. There are two main types of B12 on the market, cyanocobalamin and methylcobalamin. Cyanocobalamin, besides being cheaper, is also more shelf stable. Methylcobalamin is sensitive to light and has no other advantages over the regular cyanocobalamin.

The general recommendation for people on a plant-based diet is take a supplement. People over 50 are also recommended to take a supplement. As we age, the production of gastric juices tends to decrease, which decreases the ability to cleave the vitamin B12 from the animal protein. For the same reason, certain medications that interfere with the acid production in the stomach, for example prescribed for GERD, can also interfere with B12 absorption. People who have undergone bariatric surgery, are also dependent on supplements.

A daily B12 supplement that has at least 50 mcg is sufficient to maintain adequate levels for a healthy person. Most supplements contain more than 50 mcg. Another option is to take once or twice a week a high dose B12 supplement which contains 2000 mcg. Although the receptors that absorb B12 in the ileum get saturated, passive diffusion (1-3%) will provide you with enough of the vitamin.

Vitamin B12 can also be given by injection into the muscle. Often used to treat deficiencies, however, high dose oral supplements have shown to be just as effective as intramuscular injections in treating deficiencies. (1)

There are 3 primary ways that a B12 deficiency can occur. It can develop due to insufficient dietary intake, there can be malabsorption in the digestive tract, or there can be an autoimmune condition. Pernicious anaemia is an autoimmune condition that attacks the intrinsic factor produced in the stomach and in this way inhibits the absorption of B12 in the ileum.

When there is insufficient dietary intake, it can take several months or years before you develop a deficiency. B12 is stored in excess in the liver and we normally secrete around 1.4 mcg daily into the bile. A generally healthy person will reabsorb about half of the excreted B12 in the ileum. This reabsorption tends to increase when there is insufficient intake, and in this way delaying a deficiency. There is some variability between people in how well they recycle B12 in their digestive tract, explaining the differences between people in their B12 status.

When there is damage in the intestinal tract this can also lead to insufficient B12 absorption. In people who have had bariatric surgery, the new alimentary pathway bypasses the site of where intrinsic factor necessary for B12 absorption is produced. Medications prescribed for gastric reflux disease and Metformin, commonly prescribed for people with type2 diabetes, can also interfere with the absorption of vitamin B12. When the production of intrinsic factor is not impaired, damage to the ileum, due to Crohn’s disease or certain infections, can also impair B12 absorption.

Common signs of a B12 deficiency include anaemia, fatigue, weakness, digestive issues, soreness of mouth and tongue, numbness and tingling in the hands and feet, and brain fog. The signs of anaemia can in some cases be averted when a diet is high in folate, which is also a necessary nutrient for red blood cells to provide properly. However, the other symptoms of B12 deficiency can still be present and the deficiency is a serious problem that needs to be dealt with.


There are several lab tests to detect your B12 status, which all have their limitations. A measure often used to assess B12 status is a serum or plasma B12 test. These tests are best taken together with a serum folate test, as this is often confused as a B12 deficiency. Depending on the method of testing used, some methods cannot distinguish between the true vitamin and substances in the blood known as B12 analogues. These analogues resemble the structure of vitamin B12, but they are inactive and cannot perform the roles of the vitamin. These analogues can be potentially harmful, as they do bind to the B12 receptors, inhibiting the absorption of true vitamin B12.

Spirulina or seaweeds can be sources of these inactive analogues. As well as multi-vitamin tablets. The various vitamins and minerals combined into one pill can destroy the active form of B12, turning them into B12 analogues. (2)

Other tests that can indicate a B12 deficiency are assays of the R protein or intrinsic factor. B12 activity can also be measured by looking at a compound called Methylmalonic acid MMA. When there is a deficiency of B12, MMA levels in the blood and urine rise. Vitamin B12 is essential in the reduction of MMA and MMA is seen as the best marker for B12 status when stores are depleted.

Another compound that can build up in the blood due to a deficiency of vitamin B12 is homocysteine, an inflammatory compound. However, a deficiency of folate or vitamin B6 can have the same effect, which makes this test unreliable in determining B12 status.

In summary, it is important to ensure you have adequate levels of vitamin B12 to maintain a healthy brain, blood, and nervous system. Having a reliable source of vitamin B12 in your diet is necessary, either through food or a supplement. The preferred supplements are chewable, sublingual, or liquid. These supplements come into contact with your saliva and bind to the R protein present in your saliva, increasing the absorption rate 10-fold. Cyanocobalamin is the preferred form of vitamin B12, as this form is the most stable and the other forms have no benefit for the general population. (3)

1. Oral vitamin B12 versus intramuscular vitamin B12 for vitamin B12 deficiency.

2. Presence and formation of cobalamin analogues in multivitamin-mineral pills.

3. Cobalamin coenzyme forms are not likely to be superior to cyano- and hydroxyl-cobalamin in prevention or treatment of cobalamin deficiency.


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