Vitamin B12

What it is

Vitamin B12, also known as cobalamin, is a vital nutrient that our bodies need to function properly. It's a water-soluble vitamin, meaning that any excess is generally flushed out of the body through urine. Unlike some other vitamins, B12 is not naturally found in many plant-based foods. It's primarily present in animal products like meat, fish, eggs, and dairy.

Our bodies can't make vitamin B12 on their own, so we need to get it from our diet or through supplements. Once consumed, it's absorbed in the small intestine with the help of a substance called intrinsic factor, which is produced in the stomach.

Why it matters

Vitamin B12 plays a crucial role in several essential bodily processes.

One of its main functions is in the production of red blood cells. These cells are responsible for carrying oxygen from your lungs to all parts of your body. Without enough B12, your body may struggle to produce enough healthy red blood cells, which can lead to a type of anaemia called megaloblastic anaemia.

B12 is also fundamental for the healthy functioning of your nervous system. It helps in the formation of myelin, a protective sheath that covers nerve fibres, allowing for efficient transmission of nerve signals. This is why maintaining adequate B12 levels is important for nerve health and function.

Furthermore, vitamin B12 is involved in DNA synthesis, the process by which our cells create copies of their genetic material. This is essential for cell growth and repair throughout the body.

What can cause it to be high or low

The reference range for Vitamin B12 in the UK is typically between 197–771 ng/l.

Low Vitamin B12 levels can be associated with several factors:

• Dietary intake: People who follow strict vegan or vegetarian diets may have a lower intake of B12, as it's mainly found in animal products.
• Absorption issues: Conditions affecting the stomach or small intestine can impair B12 absorption. This includes conditions like pernicious anaemia (an autoimmune condition affecting intrinsic factor production), atrophic gastritis (thinning of the stomach lining), Crohn's disease, coeliac disease, or following certain types of stomach surgery.
• Age: As we get older, our ability to absorb B12 from food can sometimes decrease.
• Certain medications: Some medications, such as metformin (often used for diabetes) or proton pump inhibitors (used to reduce stomach acid), can interfere with B12 absorption.

High Vitamin B12 levels are less common and are often not associated with any specific health problems. In some cases, very high levels might be seen in individuals with certain liver conditions or blood disorders, but this is usually identified in conjunction with other abnormal blood results.

Lifestyle factors that may help

For individuals concerned about their vitamin B12 levels, certain lifestyle adjustments might be considered, and these can be a good topic to discuss with your GP.

• Dietary choices: If you consume animal products, including a variety of meat, fish, eggs, and dairy in your diet can help ensure adequate B12 intake. For those following plant-based diets, incorporating fortified foods (such as some breakfast cereals, plant-based milks, and nutritional yeast) or considering a B12 supplement is often recommended.
• Regular health check-ups: Attending regular health check-ups can help monitor your overall health, including nutritional status.

Questions to discuss with your GP

If you have concerns about your vitamin B12 levels or are experiencing symptoms that might be related, it's always best to have a conversation with your GP. Here are some questions you might consider discussing:

• What does my vitamin B12 level mean in the context of my overall health?
• Are there any specific dietary changes you would recommend for me to consider?
• Could any of the medications I'm taking be affecting my vitamin B12 levels?
• Are there any other tests that might be helpful to understand my B12 status or absorption?
• What are the signs and symptoms I should be aware of that might indicate a B12 deficiency?
• If supplementation is recommended, what form and dosage would be most appropriate for me?