Low B12? Why it matters and what to do about it

I have seen so many vitamin B 12 levels from clients lately that are just so low that is mind boggling. Vitamin B12 (cobalamin) is essential for several key functions in the human body, including:

  • Brain function: essential for the production of neurotransmitters and helps to maintain healthy nerve cells and red blood cells.
  • DNA synthesis: plays a role in the synthesis of DNA, the genetic material that controls the growth and division of cells.
  • Energy metabolism: helps the body convert food into energy and is necessary for the production of red blood cells.
  • Mental health: B12 deficiency can cause mood changes, memory loss, and depression.
  • Pregnancy and fetal development: B12 is important for the healthy development of the nervous system and brain in fetuses and infants.

Normal reference range for B12 is 110-600pmol/l here in New Zealand (and similar in other Western countries). Interestingly, and for reference, in Japan it is considered low if it is below 500pg/dl (and this equates to 369pmol/l). The prevalence of Vitamin B12 deficiency in the Western world is estimated to range from 1-15%. Factors such as age, dietary habits, and gut health can increase the risk of deficiency.

Older adults are particularly susceptible to B12 deficiency as the ability to absorb the vitamin from food decreases with age. Vegetarians and vegans, who don’t consume meat and animal-derived products, are also at increased risk for B12 deficiency as the only bioavailable sources of B12 are animal-based foods. Additionally, people with gut conditions such as Crohn’s disease, celiac disease, and certain other autoimmune disorders can have difficulty absorbing B12 from food, leading to deficiency.

Subclinical Vitamin B12 deficiency may be a much broader problem, and missed by health professionals as blood levels can fall within normal range. This refers to a state where the levels of B12 in the body are low, but not low enough to cause obvious symptoms. This can be a problem for women in particular for several reasons:

  • Pregnancy: can lead to negative effects on fetal brain development and increase the risk of preterm birth and low birth weight.
  • Cognitive function: Low B12 levels have been linked to cognitive decline and memory loss, particularly in older women, but in men also.
  • Cardiovascular health: B12 plays a role in maintaining healthy homocysteine levels, an amino acid that has been linked to increased risk of heart disease. Subclinical B12 deficiency can therefore increase the risk of cardiovascular disease in women and men, and this is often a marker used to determine if B12 is too low.
  • Mood and mental health: B12 is important for the production of neurotransmitters and low levels can contribute to mood changes and depression.

Therefore, it is important for women to be aware of the potential consequences of subclinical B12 deficiency and to have their B12 levels monitored regularly, especially during pregnancy or as they age. Actually though, many women that I speak to are in their perimenopausal years (thus, not defined by these age brackets) and are struggling with some of these sub clinical problems but aren’t registering as low according to their blood test results.

One of the main symptoms that people, especially women, can experience is brain fog. Brain fog is a term used to describe a feeling of confusion, forgetfulness, and mental fatigue. Low levels of Vitamin B12 can contribute to brain fog by affecting several key functions in the body:

  • Nerve function: B12 is necessary for the maintenance of healthy nerve cells and helps to prevent neurodegeneration. Low levels of B12 can cause numbness, tingling, and cognitive problems.
  • Energy metabolism: B12 helps the body convert food into energy and low levels can lead to feelings of fatigue and mental exhaustion.
  • Neurotransmitter production: B12 is involved in the production of neurotransmitters, which are chemicals that help regulate mood and cognitive function. Low levels of B12 can contribute to depression, anxiety, and mood changes.
  • Blood cell production: B12 is necessary for the production of red blood cells, which carry oxygen to the brain. Low levels of B12 can cause anemia, which can lead to brain fog and cognitive problems.

It is not immediately obvious, though, that your B12 level is insufficient. Yes, the number (as stated above) is a clear indication. However, having B12 in your blood doesn’t always indicate that you can use it. This is due to the way that Vitamin B12 is stored and regulated in the body. Vitamin B12 is stored in the liver and that can take years to deplete, meaning that a person can have normal Vitamin B12 levels in the blood despite not having enough Vitamin B12 for their body’s needs. Additionally, certain factors, such as age and certain medical conditions, can affect the body’s ability to absorb Vitamin B12, leading to a deficiency despite normal Vitamin B12 levels in the blood.

Therefore, it is important to consider other symptoms and factors in addition to Vitamin B12 levels in the blood to determine if a person is deficient in Vitamin B12. Clinical tests, such as measuring methylmalonic acid (MMA) or homocysteine levels, can also help to provide a more complete picture of a person’s Vitamin B12 status.

The Methylmalonic Acid (MMA) test measures the levels of MMA in the blood, which is a byproduct of protein metabolism. In individuals with adequate Vitamin B12 levels, MMA is converted to succinyl-CoA, which is then used in the citric acid cycle to produce energy. However, in individuals with Vitamin B12 deficiency, the conversion of MMA to succinyl-CoA is hindered, leading to elevated levels of MMA in the blood. Hence, a high level of MMA in the blood indicates a Vitamin B12 deficiency. The MMA test is considered to be a more accurate indicator of Vitamin B12 deficiency compared to traditional Vitamin B12 tests, as Vitamin B12 levels can sometimes be normal even in the presence of a deficiency.

Similar to MMA, homocysteine levels in the blood can be used as an indicator of Vitamin B12 deficiency because Vitamin B12 is involved in the conversion of homocysteine to methionine. In cases of Vitamin B12 deficiency, homocysteine levels can build up because the conversion is hindered, leading to elevated homocysteine levels in the blood. Therefore, a high homocysteine level in the blood can suggest Vitamin B12 deficiency, although it is not a definitive diagnosis and other tests and factors should also be taken into consideration.

There are many supplemental forms of B12 that someone can take, the most common one is in the form of cyanacobalamin. Cyanocobalamin is a commonly used form of Vitamin B12 in dietary supplements, but it is not considered the best form for supplementation by some health professionals. The reason for this is that cyanocobalamin must be converted by the body into active forms of Vitamin B12, such as methylcobalamin and adenosylcobalamin, in order to be used effectively. The conversion process may not occur efficiently in some individuals, particularly older adults and those with certain health conditions, leading to ineffective use of the Vitamin B12 from cyanocobalamin supplements. Therefore, methylcobalamin, transcobalamin and adenosylcobalamin are often considered to be a better form of Vitamin B12 supplementation as they are already in their active form and do not require conversion by the body. As the B vitamins work synergistically, it is often recommended to take alongside other B vitamins, such as folate, or in a complex.

Brands of b vitamins that are worth considering include ThorneJarrowBiobalance and Life Extension. There are many others but these are widely available without the need for a practitioner script. Taking these in the morning is recommended (as they can keep you alert and awake), and it is very difficult to take too much of any of these.

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