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Vitamin B12 supplements may improve cognitive functions

Vitamin B12 supplements may improve cognitive functionsLack of vitamin B12 is known to cause fatigue, poor memory, cognitive impairment, and hippocampal atrophy. Supplementation with B12, on the other hand, can improve cognitive functions, according to a study that is published in Nutrients. The problem is that the signs of cognitive disturbance are insidious and therefore not automatically associated with a simple nutrient deficiency that is often a result of ageing, vegetarian diets, low stomach acid, or diabetes medication.

With the growing number of seniors, more and more people have learning difficulty, problems with their short-term memory, failing sense of direction, rapid mood changes, and other signs of cognitive disturbances. Dementia is one of the most common cognitive disturbances and can also develop as a result of Alzheimer’s disease, Parkinson’s disease, substance abuse, and other problems. Vascular dementia, which is also quite common, can occur as a result of blood clots, stroke (apoplexy), atherosclerosis, or cerebral oxygen shortage, and the symptoms can vary depending on which part of the brain is affected. Cognitive impairment is a progressive disease with steadily worsening symptoms that end up becoming a real burden to the patients, to their families, and to society in general.
Most cognitive impairments like Alzheimer’s disease and vascular dementia are difficult to treat. Still, it turns out that cognitive disturbances are often linked to lack of folic acid and vitamin B12, and it has also been seen that cognitive disturbances in some cases can be stopped with nutrient supplements. In the new study, the scientists wanted to see if vitamin B12 supplementation could improve cognitive functions.

Vitamin B12 in relation to the nervous system and cognitive functions

Vitamin B12 is primarily known for its role in our blood formation, but the vitamin is also of great importance to our nervous system, cognitive functions, and homocysteine conversion. This is important because it is vital not to have too much homocysteine in the blood.
Vitamin B12 is only found in animal food sources like meat, fish, eggs, and dairy products. The nutrient is absorbed in the small intestine with help from a glycoprotein named intrinsic factor. Vitamin B12 is stored in the liver. Therefore, months or even years can go by before there are any signs of deficiency symptoms as a result of ageing, poor nutrient uptake, plant-based diets (without B12), diabetes medication (metformin), or other causes.
A vitamin B12 deficiency can cause two types of anemia (macrocytic anemia and pernicious anemia) plus cognitive disturbances and peripheral neuropathy. Pernicious anemia is an autoimmune disease where you are unable to absorb vitamin B12 because the body lacks intrinsic factor
Lack of vitamin B12, folic acid, and vitamin B6 can cause elevated homocysteine levels in the blood because all these B vitamins are normally required to support the body’s conversion of homocysteine into other amino acids. When levels of homocysteine are too high, it may cause oxidative stress. This is a condition where uncontrolled free radicals can damage blood vessels and neurons and lead to things like Alzheimer’s disease, vascular dementia, Parkinson’s disease, cardiovascular disease, and stroke. Low levels of vitamin B12 are also associated with cognitive impairment and brain atrophy, including shrinkage of the hippocampus, a part of the brain that is responsible for our sense of direction and memory. Studies of supplementation with vitamin B12, folic acid, and vitamin B6 have showed conflicting results, nonetheless, at least in terms of cognitive functions. Some meta-analyses have found a positive effect, while others have failed to show any effect at all.
In the new study, the scientists focused on vitamin B12 to see if supplementing with this nutrient could improve cognitive functions in patients who lacked vitamin B12 – but not folic acid.
They also looked closer at the link between hippocampal atrophy, cognitive impairment, and homocysteine levels.

The study revealed vitamin B12’s potential in improving cognitive functions

Data was collected from 1,716 patients who had contacted their dementia clinic. A total of 39 vitamin B12-deficient patients were selected. They had all undergone the MMSE (Mini-Mental State Examination) test, which is used to assess cognitive disturbances and dementia. They also had their levels of folic acid and homocysteine measured. In addition, the scientists looked at the volume of the patients’ hippocampus. Afterwards, the 39 patients were given supplements of vitamin B12. After 21 days, all patients were asked to take the MMSE test again. They continued this procedure every other month for a total of 133 days.
Their MMSE score rose significantly, while there was a significant drop in their blood levels of homocysteine. However, the researchers did not observe any relation between vitamin B12 supplementation and the patients’ hippocampal volume.
Still, they conclude that vitamin B12 supplementation has the potential to improve cognitive functions in patients with a B12 deficiency. It is therefore a good idea to focus more on vitamin B12 deficiencies, as they are rather common. Furthermore, supplementation with the nutrient is inexpensive and has no side effects.
The new study is published in Nutrients.

  • The doctor normally takes a blood sample to measure levels of vitamin B12, and the test is often part of a more comprehensive blood analysis
  • Always remember to tell your doctor if you take any medicine or supplements that may influence the result

Supplement quality and treating a vitamin B12 deficiencies

In the case of a severe vitamin B12 deficiency, one can start by giving injections that often provide fast relief for various symptoms. If the vitamin B12 deficiency is related to dietary factors, it may be necessary to change the diet or use supplements
A vitamin B12 supplement should contain at least 2 micrograms of the nutrient, which is the same as the reference intake (RI) level. Some products contain more because they are targeted at people who have difficulty with absorbing the nutrient.
Vitamin B12 lozenges, where the nutrient is taken up directly by the oral mucosa, often have better absorption. Pernicious anemia is a chronic condition and has to be treated with regular B12 injections because of the lack of intrinsic factor that is needed to absorb the nutrient in the small intestine.

Don’t forget vitamin D and omega-3 fatty acids that are also important for cognitive functions

It also takes plenty of vitamin D and omega-3 fatty acids to maintain good cognitive functions. Click here and read more:

»High blood levels of certain nutrients are linked to improved cerebral function in the elderly«


Influences of Vitamin B12 Supplementation on Cognition and Homocysteine in Patients with Vitamin B12 Deficiency and Cognitive Impairment. Nutrients 2022

Shufeng Li et al. The preventive efficacy of vitamin B supplements on the cognitive decline of elderly adults: a systematic review and meta-analysis. BMC Geriatrics 16 June 2021

Trinity College Dublin. Many older adults are deficient in vitamin B12 and folate. ScienceDaily June 26, 2018

Vanita R Aroda et al. Long-Term Metformin Use and Vitamin B12 Deficiency in the Diabetes Prevention Program Outcomes Study. Endocrine Society 2016

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