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Supplementation with B vitamins protects older people against dementia and Alzheimer’s disease

Supplementation with B vitamins protects older people against dementia and Alzheimer’s diseaseThe number of seniors worldwide is increasing and more and more are affected by Alzheimer’s disease, the leading cause of dementia. We should therefore focus much more on this health problem that comes with an enormous human and socio-economic price tag. According to a new meta-analysis, supplementation with B vitamins appears to prevent or delay mild cognitive impairment in older people, which is normally an early sign of Alzheimer’s disease. In fact, supplementation with B vitamins may even represent an inexpensive therapy form with a huge potential.

The risk of contracting Alzheimer’s disease goes up with age. It turns out that changes in the brain occur decades before the disease shows. In the early phases, there are signs of mild cognitive impairment with symptoms such as forgetfulness, loss of short-term memory, and an impaired ability to acquire new knowledge. The symptoms grow worse and eventually include aphasia (a condition that robs you of the ability to communicate), poor sense of direction, a tendency to get lost, and loss of motivation. The disease also results in personality change and it typically leads to death after 7-10 years.
Alzheimer’s disease is the leading cause of dementia. Fifty million people worldwide are believed to suffer from dementia and the number is expected to increase to 152 million by 2050. The human and socio-economic price tag, needless to say, increases as the disease progresses. Although mild cognitive impairment with poor memory and loss of cognitive skills is not necessarily a sign of Alzheimer’s disease, these symptoms may be preclinical. Enormous sums of money could be saved by preventing or delaying the mild cognitive impairment in the early stages. Therefore, the scientists behind the new study point out that we should focus more on timely intervention.

What does Alzheimer’s do to your brain?

Alzheimer’s disease causes neurons to slowly perish in several parts of the brain, and the brain shrinks (brain atrophy). Scientists have observed accumulation of plaque (β-amyloid peptides) and tau protein that is harmful for brain cells and associated with inflammation. It is also known that elevated blood levels of the amino acid homocysteine may cause accumulation of β-amyloid plaque in the brain and loss of brain tissue.
Homocysteine is a normal waste product that results from protein breakdown. Afterwards, homocysteine is converted into other amino acids with the help of vitamin B12, folic acid, and vitamin B6. If you lack these B vitamins in the blood, levels of homocysteine may go up. This can result in damaged blood vessels and damaged neurons and is linked to Alzheimer’s disease, cardiovascular disease, and stroke. On the other hand, vitamin B12, folic acid, and vitamin B6 have a homocysteine-lowering effect. Although studies have shown that supplementation with B vitamins can lower levels of homocysteine in the blood, it remains to be shown if this can prevent cognitive impairment in senior life.

The meta-analysis unveiled the B vitamins’ effect

In their new meta-analysis, the scientists looked at 21 randomized, controlled studies with a total of 7,571 patients aged 60-82 years. All patients suffered from mild cognitive impairment and had elevated blood levels of homocysteine.
They were given supplements of B vitamins or placebo. Eleven of the studies lasted less than a year, while 10 of the studies lasted longer than a year. The cognitive function of the participants was assessed with help from specific scales. It turned out that supplements of B vitamins significantly lowered blood levels of homocysteine, but they were also able to prevent loss of cognitive skills. The scientists concluded that supplementation with B vitamins can prevent or delay age-related cognitive impairment by lowering blood levels of homocysteine.
The new meta-analysis is published I BM Geriatrics. Earlier research suggests that vitamin B supplementation helps prevent inflammation and oxidative stress in the brain, which are also seen in connection with Alzheimer’s disease.

How do we get enough of the B vitamins – and why is this difficult for older people?

B vitamins are a group of vitamins that work together as a complicated biological team in the body. Because these vitamins are water-soluble and therefore not stored in the body (apart from vitamin B12) we need to get them regularly from our diet or from supplements.
The different B vitamins are typically found in foods such as whole grains, oats, legumes, vegetables, fruit, brown rice, garlic, nuts, seeds, kernels, and brewer’s yeast in particular. Moreover, you get B vitamins from liver, meat, fish, eggs, and dairy products.
It should be mentioned that vitamin B12 is only found in animal foods. B12 deficiency symptoms are insidious. Therefore, many older people, vegans and vegetarians fail to see link between their diet and their symptoms.
Ageing processes can also impair the uptake of vitamin B12 and other nutrients. In addition, seniors often don’t eat a very balanced diet and take medicine that can block the uptake and utilization of B vitamins. This is why lack of B12 vitamins in particular is often mistaken for dementia. A blood test can easily show if a person has too little vitamin B12.
There are high-dosed vitamin B supplements on the market and you can also get vitamin B12 in lozenges that enables absorption of the nutrient through the oral mucosa.

  • Alzheimer’s disease is associated with elevated homocysteine levels in the blood
  • A regular blood test can show your homocysteine levels
  • It is possible to lower elevated blood levels of homocysteine by taking supplements of vitamin B6, folic acid, and vitamin B12
  • Studies show that Alzheimer’s disease is linked to insulin resistance in the brain. This is why the disease is also called type 3 diabetes
  • It is important to look at other factors, as well, such as diet habits, blood sugar levels, and physical activity


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

Hui Chen et al. Folic Acid Supplementation Mitigates Alzheimer´s Disease by Reducing Inflammation: A Randomized Controlled Trial. Mediators of Inflammation. 2016

Sybille Hildebrandt. Insulinresistens i hjernen kan udløse Alzheimers. Dagens Medicin. 2016

Diabetes Health. Alzheimer’s new name: Type 3 Diabetes. 2014

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