This Nutrient Cannot Be Made By Plants Or Animals

In this article about vitamin B12, we will discuss:

  1. How B12 is created
  2. How humans obtain B12
  3. B12 deficiencies
  4. How to get enough B12

You can conceivably obtain small amounts of every essential nutrient from eating plants, except for one. Yet this nutrient is incredibly important as it is necessary for functioning of the central nervous system, proper development, brain health, DNA synthesis and overall mood and energy. Every cell in the body requires it to function. This nutrient is vitamin B12, also known as Cobalamin.

“…all animals must obtain [B12] either from the bacteria itself or by consuming other animals”

Vitamin B12 is created by neither plants nor animals but by microorganisms such as bacteria, fungi and algae. Consequently, all animals must obtain it either from the bacteria itself or by consuming other animals. Ruminant animals like cows and goats have stomachs that consist of four chambers where these microorganisms can produce B12 before it is then absorbed in the intestine. In aquatic environments, most phytoplankton acquire B12 through a symbiotic relationship with marine bacteria, and they become food for larval fish and bivalves such as clams or oysters. Certain plants and mushroom species acquire small amounts of B12 through interactions with soil microbes. Animal products are a rich source of B12 because animals ingest these microorganisms when eating, and B12 becomes concentrated in the muscles, organs, milk and eggs.

“…humans obtain B12 in the form of methylcobalamin through the consumption of animal products”

Humans, however, cannot rely on the endogenous creation of B12 because the specialized bacteria that produce B12 reside in the end of the small intestine and in the colon, but humans absorb B12 in the upper digestive tract, or the small intestine. Therefore, humans obtain B12 in the form of methylcobalamin through the consumption of animal products. Modern humans can also utilize supplements, typically of the synthetic form, cyanocobalamin as it is more stable and cost effective. Supplementation with bioidentical forms is preferred, however, as they are safer and more bioavailable than cyanocobalamin form.

“…symptoms of a deficiency may not be expressed for years after diet, habit changes or genetic factors deplete stores.”

A deficiency can lead to “potentially irreversible neurological disorders, gastrointestinal problems, and megaloblastic anemia,” which can appear as low mood, weakness, fatigue, headaches and indigestion. Interestingly, the body stores a 10 year supply of vitamin B12 in the liver, so symptoms of a deficiency may not be expressed for years after diet, habit changes or genetic factors deplete stores. While a vegan diet is the most well-known cause for a B12 deficiency, medications, genetic factors and even stomach acid levels can impact blood levels. Stomach acid is needed to efficiently break down food and release B12 so that it can be digested and absorbed. When stomach acid levels are low which happens in a condition call atrophic gastritis or under pharmaceutical acid suppression, this process is hindered. Proton pump inhibitors (PPIs) prescribed for acid reflux, gastroesophageal reflux disease and ulcers may therefore restrict B12 absorption by suppressing stomach acid production. Metformin, a common diabetes medication, has also been shown to reduce B12 absorption.

“Consuming meat, fish and dairy products on a regular basis should maintain healthy B12 levels when systems are functioning properly.”

Consuming meat, fish, clams and dairy products on a regular basis should maintain healthy B12 levels when systems are functioning properly. While there are trace amounts of B12 in seaweed and some mushrooms, it is not enough to keep the body functioning optimally. Many packaged food products such as breakfast cereals, energy drinks and plant based dairy alternatives are now fortified with vitamin B12, however many of these products often contain ultra-processed ingredients which are not considered beneficial for your health when consumed regularly. If you do not consume any animal products as part of a vegan or strict plant-based diet, supplementing with B12 is advised to avoid deficiencies. As always, consult with a physician before supplementing.