Vitamin B12 is possibly one of the most important vitamins, period. You may only be modestly familiar with it, but certainly your cells are not – since B12 is involved in the metabolism of every cell in the human body. Deficiency of B12 is akin to going crazy – quite literally, since it is linked to psychosis. It is found in a variety of foods though, so rest assured that it is fairly easy to get enough.

However, deficiency rates are much higher than they should be, and they are especially common among vegans and vegetarians. This is also true of pregnant women. So, read on about how, and why, getting enough vitamin B12 is vital to good health.

Why It’s Important

A better title for this section may be ‘why ISN’T it important?’ Vitamin B12 is vital to every cell, and nearly every chemical reaction in the body. Plants and animals are not capable of constructing vitamin B12. This is intriguing, since humans can construct a variety of things endogenously. Bacteria and archaea can biosynthesize vitamin B12 because they have the required enzymes.

DNA production requires B12, as it is a necessary co-factor. Since DNA is an important structural element to nearly all life, you can begin to understand the vital importance of B12. Cells will swell in size (they normally divide quite quickly) if B12 is low. This is known as macrocytosis. Besides DNA production, B12 is used in production of neurotransmitters. Neurotransmitters are brain chemicals which help to communicate information throughout our brain – and body.

If extremely low in vitamin B12, nerve damage can result. Does this sound like something you’d like? I didn’t think so. Symptoms usually first appear in the hands and feet, and then may move to the brain.

Another potential mechanism by which B12 – or lack thereof, can be problematic, is depression, or more accurately, in the treatment of depression. Researchers have found that low B12 levels in the body can stop serotonin production, especially important when being treated with anti-depressant medications.

Some researchers have even pinpointed obsessive-compulsive disorder as an early manifestation of B12 deficiency. This is interesting for a variety of reasons. As noted in the paper, patients with OCD have dysregulation in the serotoninergic system and in the efficacy of serotonin reuptake inhibitors (SRIs). This lends credence to the earlier point that adequate B12 levels are vital to normal physiologic function and mood, as well as sleeping patterns.

Also, the majority (a whopping 62%) of pregnant women have been found to be deficient in vitamin B12. This is a population who should be awash in vital nutrients, vitamins and minerals, and a deficiency is unfair to both you, and your unborn child. If pregnant, please be sure to get enough B12. It can, and will, make a huge difference, in a variety of ways.

Food Sources

Of the many paleo-friendly foods which contain vitamin B12, the best is by far sardines. With a whopping 337% of the daily value of B12, all for less than 200 calories, sardines are your go-to food, if you feel you may be low. Sardines are also important for a variety of other reasons, but for right now just think of them as the best option for B12.

Unsurprisingly, tuna is another great source of vitamin B12. With over 100% of the daily value for less than 200 calories, tuna contains plenty of this special vitamin. As is starting to become apparent, vegans may have a hard time getting enough B12. With B12 being found almost exclusively in animal foods, this is an important distinction to make.

It seems that fish were created almost solely as vehicles for B12! With salmon being next on our list, this domination of seafood may make you hungry to move closer to the ocean. Salmon contains over 200% of your daily value of vitamin B12, and it is also quite possibly the most perfect food you can eat, nutrient-wise.

Cod is next on our list, with just over 100% of your daily value of B12. Though not quite as nutrient-packed as our first three foods listed, cod is excellent by any other standard form of measure. With a full daily serving of selenium, cod is a great seafood choice to make, as often as possible.

The first non-seafood item on our list, lamb contains much more than your daily recommended amount of vitamin B12. Since B12 is extremely low in toxicity, this is not a concern. It is also packed with other nutrients and minerals, such as: vitamin A, copper, selenium, iron and riboflavin. There is also plenty of zinc and enough protein to make lamb an obvious choice for your next nutrient-packed meal.

Grass-fed beef is next on our list of foods which are rich in B12. Grass-fed beef is (rightfully) a huge part of the paleo movement, and I doubt I need to do much to extrapolate the importance (and delicious-ness) of a grass-fed, lettuce-wrapped burger. Vitamin E, iron, conjugated linoleic acid, and omega-3 fatty acids are just some of the benefits of eating grass-fed beef.

Scallops, though often forgotten, are an excellent source of vitamin B12, as well as many other nutrients. They are high in choline, selenium, protein, phosphorous and iodine. Easily making the cut for so-called “superfoods”, scallops should be added to any healthy “paleo” diet. Though not yet discussed, the importance of eating wild-caught seafood is palpable. Higher in omega-3 fatty acids, the most important of which is docosahexaenoic acid (DHA), wild-caught seafood is a vital part of any nutrient-dense diet.

Shrimp is next on our list, and besides being high in B12, it is also delicious! A great source of astaxanthin, which is being studied for its antioxidant properties, shrimp is also high in selenium, phosphorous, choline, protein, copper and iodine. Low in calories, but high in nutrients, shrimp is definitely a food where ‘a little bit, goes a long way’.

What should be ostensibly obvious from this list of food sources of vitamin B12, is that no plant foods made the list. This puts vegans at risk for deficiency, and as researchers have astutely noted “the vegan diet…contains no vitamin B-12 except trace amounts in some rhibozium-bacteria-containing root nodules.” This leads us to our next section – what happens when you are deficient in vitamin B12?


As noted above, deficiency in vitamin B12 is highly problematic, and should be avoided at all costs. As written by researchers “the usual dietary sources of vitamin B(12) are animal foods, meat, milk, egg, fish, and shellfish.” This should be a special alert to vegetarians that deficiency is something they may be extremely likely to encounter. This goes double for vegans, as noted by Dr. Cordain in a recent article.

For the sake of brevity, I won’t reiterate my earlier scientific warnings of what exactly can go wrong when individuals are deficient in vitamin B12. For ease of use, below is a chart listing some, but not all, of the common problems related to B12 deficiency.


Though it should be very feasible to get enough vitamin B12 when following a paleo diet, there are some reasons and situations which may require certain individuals to follow a supplementation plan. This can include, but is not limited to: improper absorption, complications due to other medications or conditions, and/or a vegan or vegetarian diet.

In fact, I recommend to all my vegan and vegetarian clients that they supplement with vitamin B12, to make sure they do not become deficient. In this case, many have debated whether it is preferable to take a certain form of B12 over another. The three kinds commonly batted about in the supplement world are: hydroxocobalamin, cyanocobalamin and methylcobalamin.

Of these, I always have my clients supplement with methylcobalamin. There are many, many studies which show the superiority of this form, and yet it is not the form widely used by most. As stated by researchers “recent biochemical evidence suggests that an ultra-high dose of methylcobalamin (methyl-B12) may up-regulate gene transcription and thereby protein synthesis”. This was known in 1994. Why the world clings to other forms, is largely due to politics, outdated viewpoints, and sheer ignorance, in this writer’s humble opinion.


Does it seem that you may be deficient in vitamin B12? It is more common than people seem to think. Hopefully I’ve outlined both the dangers of deficiency in this vitamin, and the right way to include great amounts of it in your diet. Nerve damage (sometimes irreversible) and anemia are not things that you want to experience, and eating some tuna or sardines is a small (and easy!) remedy to this potential problem.

Do you have questions or comments, or perhaps personal insights into B12 deficiency? Let us know in the comments!

This article originally appeared on PaleoHacks.

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