Vitamin B12: what it’s for, benefits, and potential side effects

Did you know that there are vitamins and substances, like amino acids, that are essential for the body’s proper functioning? The challenge is that sometimes, due to an imbalanced diet or factors like stress, we don’t get the minimum recommended amount, which can lead to health issues in the medium term. Specifically, a deficiency in vitamin B12 can become a serious problem.

Fortunately, there are dietary supplements that can help us reach adequate levels. However, before deciding whether to take them, let’s take a closer look— with the guidance of an expert—at what makes vitamin B12 so essential.

Vitamin B12: what it’s for

Vitamin B12 is “crucial” for red blood cell production and maintaining the central nervous system, explains María Aguirre, a nutritionist with BluaU by Sanitas. It also plays a “key” role in cellular metabolism and the synthesis of DNA and RNA, she adds.

Given its importance in the body, Aguirre emphasizes the need to ensure a sufficient supply through a balanced diet that includes foods like meat, fish, dairy, and eggs, or through supplements if recommended by a healthcare professional.

Foods rich in vitamin B12

As Aguirre notes, vitamin B12 is primarily produced by microorganisms found in soil and in the gastrointestinal tracts of animals like cows and sheep. These microorganisms synthesize it from compounds like cobalt and other nutrients in the environment. Animals that graze on cobalt-rich soils or consume foods containing these microorganisms absorb vitamin B12, storing it in their tissues and organs.

When humans eat animal products that contain vitamin B12, this nutrient is absorbed in the small intestine and transported to the liver, where it is stored before being distributed to other tissues. Foods rich in vitamin B12 include:

For those following vegetarian or vegan diets, however, obtaining sufficient vitamin B12 from natural sources can be “more challenging,” warns Aguirre. In these cases, it’s “important” to consider fortified foods or supplements.

Excess vitamin B12

As we’ve seen, vitamin B12 offers numerous benefits, with an essential role in maintaining the body’s health. However, an excess of vitamin B12 can lead to “mild” side effects such as headaches, nausea, vomiting, diarrhea, or stomach discomfort. That said, these symptoms are “very rare,” according to the nutritionist.

In “extremely rare” cases, individuals “with certain medical conditions,” such as kidney disease, may experience issues from excessive vitamin B12, including:

Vitamin B12 deficiency

A lack of vitamin B12 can result in “consequences like megaloblastic anemia (abnormally large red blood cells) or irreversible neurological damage.” To avoid these outcomes, it’s important to note that the recommended daily intake of vitamin B12 “varies by age, gender, and other individual factors,” says Aguirre.

For “most adults,” the recommended daily intake is at least 2.4 micrograms (mcg), although this may increase slightly during pregnancy and breastfeeding, to 2.6 and 2.8 mcg, respectively. Common symptoms of vitamin B12 deficiency include:

Can I take vitamin B12 without a prescription?

According to Aguirre, “it’s always advisable to consult a doctor or nutritionist” to determine individual needs and the best ways to ensure adequate vitamin B12 intake.

Original article by Jorge Parto, translated with the assitance of AI and edited by David Nelson.