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There are 8 different B vitamins - B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folate) and B12 (cobalamin) - each with individual important functions within the body, as well synergistically supporting vital processes such as cell energy (ATP) production. This means B vitamins are required for just about every major function in the body directly impacting function of your cardiovascular system including red blood cell formation, your weight from impacting metabolism, your mood and brain health through impact on neurotransmitter synthesis and nerve health, and even your digestion.

The B vitamins are all water-soluble so we require a daily intake through dietary sources, including seeds, grains, beans, pulses, green leafy vegetables and broccoli (rich in biotin and folate) and fish, meats and eggs (particularly rich in Vitamin B12). However, adequate dietary intake and/or poor digestion will quickly lead to B vitamin deficiency leading to many health issues including anemia; fatigue; constipation and poor digestion; heart problems including irregular heart beat; confusion and poor memory; poor skin, hair and nail quality. B vitamin deficiency is also linked as part of the pathological progression in some cases of chronic conditions such as cardiovascular disease and Alzheimer’s disease.

Improving Cognitive Function

One study has shown that moderate doses of supplementary B vitamins – namely folate (0.8mg/day), Vitamin B12 (0.5mg/day) and Vitamin B6 (20mg/day) over 2 years could halve the rate of brain shrinkage – a physical symptom associated with memory loss and dementia in the elderly.[1] At the end of the trial the effects of the vitamin treatment were found to be dramatic, and most pronounced in participants who started out with the highest rates of brain shrinkage.

On average, taking B vitamins slowed the rate of brain atrophy by 30%, and in many cases reductions as high as 53% were seen.

Brain atrophy involves the loss of neurons and their connections and can be caused by a number of diseases. Some degree of atrophy and subsequent brain shrinkage is common with old age, even in people who are cognitively healthy. However, brain shrinkage is accelerated in people with mild cognitive impairment and even faster in those who ultimately progress from mild cognitive impairment to Alzheimer’s disease. A range of factors has been implicated in affecting the rate of brain atrophy, one of which is high levels of an amino acid in the blood called homocysteine. Studies have shown that raised levels of homocysteine increase the risk of Alzheimer’s disease[2],[3] and that B vitamins helps reduce homocysteine contributing to brain atrophy.[4],[5],[6]

Managing Mood

Homocysteine levels may also affect mood. One study of 3503 adults (average age 65 years) from the Chicago Health and Ageing project showed that Vitamins B6 and B12 can help alleviate depression.[7] Higher total intakes of both Vitamins B6 and B12 in the study were associated with a decreased likelihood of the development of depressive symptoms over an average of 7.2 years. For example, each additional 10mg of Vitamin B6 and 10µg of Vitamin B12 via total intake from food and supplements were associated with 2% lower odds of development of depressive symptoms per year. [8]

B Vitamin

B Vitamins and the Methylation Cycle

So what’s the link between B vitamins, homocysteine, brain atrophy and mood?

Biochemically, Vitamin B6, folate, and Vitamin B12 are involved in the metabolism of several important amino acids involved in the methylation cycle, namely homocysteine, S-adenosyl methionine (SAMe), and methionine. The methylation cycle is a biochemical pathway that manages or contributes to a wide range of crucial cell functions including detoxification, immune function, protecting cells from oxidative stress and DNA repair.[9]

SAMe and methionine produced by methylation cycles are critical to the production of neurotransmitters in the brain, including monoamines, involved in mood and maintaining healthy brain tissue.[10]

Although the exact mechanism is unknown, the prevailing homocysteine hypothesis of depression suggests that deficiencies in Vitamin B6, folate, and Vitamin B12 can lead to elevated homocysteine concentrations through reduced methylation enzyme function and, in turn, decreased levels of SAMe and methionine, which have been associated with depression.[11] Vitamin B6 supplementation has also been demonstrated to reduce depression in premenopausal women.[12]

The resulting high levels of homocysteine resulting from the methylation cycle B vitamin deficiencies are a known risk factor for blood vessel damage reducing supply of oxygenated blood to the brain, as well as affecting the entire cardiovascular system contributing to stroke and cardiovascular disease. Reduced oxygenated blood in the brain may contribute to cell death and brain atrophy, as well as increased oxidative stress, and raised levels of amyloid and tau proteins, which are central to the formation of neuritic plaques and neurofibrillary tangles found in the Alzheimer’s brain.[13],[14]

Sleeping Soundly?

But it’s not just mood and the health of brain tissue that is affected by B vitamin levels. A new study of 100 participants has found that taking Vitamin B6 could help people recall their dreams without impacting on dream content including vividness, colour or bizarreness.[15]

So why may this be useful? According to research author Denholm Aspy: “The average person spends around six years of their lives dreaming. If we are able to become lucid and control our dreams, we can then use our dreaming time more productively.”

"Lucid dreaming, where you know that you are dreaming while the dream is still happening, has many potential benefits. For example, it may be possible to use lucid dreaming for overcoming nightmares, treating phobias, creative problem solving, refining motor skills, and even helping with rehabilitation from physical trauma,” Aspy explains.

"In order to have lucid dreams it is very important to first be able to recall dreams on a regular basis. This study suggests that Vitamin B6 may be one way to help people have lucid dreams."

Nerve Function

Vitamin B12 is also critical for nerve function with clinical manifestations of its deficiency linked to neurological disorders such as multiple sclerosis.[16]

Deficiency in this B vitamin is more common than you may think, with estimates of up to 26% of the population experiencing sub-clinical deficiency. This is in part due to inadequate dietary intake, such as in vegetarian or vegan diets and also because Vitamin B12 absorption requires a special protein carrier called Intrinsic Factor which is produced and released from the parietal cells in the stomach in response to rising gastric acid levels. Without adequate IF, Vitamin B12 is not absorbed in the small intestine. The prevalence of antacid medication in the population, both from chemist and over the counter drugs such as prescribed PPIs (Proton Pump Inhibitors like omeprazole), is cause for concern for Vitamin B12 deficiency and all the associated health problems.[17]

So what can we do to ensure we have a ready supply and sufficient levels of B vitamins and optimal digestion to ensure their absorption?

B Vitamin Bioavailability

Diets rich in fruit and vegetables and containing a mix of complex carbohydrates and some animal protein sources aim to deliver adequate levels of B vitamins. However, poor dietary intake including for some vegetarian and vegan diets may fall short of some B vitamins, in particular Vitamin B12, as the main dietary sources are from animal products.

B vitamin supplements may well be the answer to dietary shortfalls.

  • Vitamin B12, in methylcobalamin form, can be supplemented to support adequate daily intake.
  • Folate is the natural form of folic acid; supplementing with the 5-methyltetrahyrfolate (5MTHF) form may be better utilised in people, especially those with specific genetic anomaly in the 5-methyltetrahydrofolate reductase enzyme meaning they cannot metabolise the folic acid form found in some supplements.
  • Specific B vitamin supplement complexes can supply levels of Vitamin B6, B12 and folate, alongside trimethylglycine (TMG), a plant-derived amino acid, to reduce homocysteine and support healthy methylation cycles.

B vitamins are also crucial for many other areas of health including the cardiovascular system, skin and nails so make sure you get your B vitamin complex today!


[1] Smith, A. et al (2010). Homocysteine-Lowering by B Vitamins Slows the Rate of Accelerated Brain Atrophy in Mild Cognitive Impairment: A Randomized Controlled Trial PLoS ONE, 5 (9)

[2] Sui R, Zhang L. Depression, Parkinson disease, Alzheimer disease. The homocysteine hypothesis. Neurosciences (Riyadh). 2010 Jul;15(3):211-3.

[3] McCaddon A, Hudson PR. L-methylfolate, methylcobalamin, and N-acetylcysteine in the treatment of Alzheimer’s disease-related cognitive decline. CNS Spectr. 2010 Jan;15(1 Suppl 1):2-5; discussion 6.

[4] Douaud G, Refsum H, de Jager CA, et al. Preventing Alzheimer's disease-related gray matter atrophy by B-vitamin treatment. Proc Natl Acad Sci USA. 2013;

[5] https://www.alzheimersresearchuk.org/b-vitamins-slow-brain-changes-in-a-subgroup-of-older-people/

[6] Smith et al (2010) Homocysteine-Lowering by B Vitamins Slows the Rate of Accelerated Brain Atrophy in Mild Cognitive Impairment: A Randomized Controlled Trial 5 | Issue 9 | e12244

[7] Kamphuis, MH, Geerlings, MI, Grobbee, DE & Kromhout, D. Dietary intake of B6-9-12 vitamins, serum homocysteine levels and their association with depressive symptoms: the Zutphen Elderly Study. Eur J Clin Nutr 2008;62:939–45

[8] Hvas, AM, Juul, S, Bech, P & Nexo, E. Vitamin B6 level is associated with symptoms of depression. Psychother Psychosom 2004;73:340–3

[9] https://www.clinicaleducation.org/resources/reviews/review-of-homocysteine/

[10] Bottiglieri T et al (1984). S-Adenosylmethionine influences monoamine metabolism. Lancet 224

[11] Bottiglieri, T. (2005) Homocysteine and folate metabolism in depression. Prog Neuropsychopharmacol Biol Psychiatry 29:1103–12

[12] Williams, A et al (2005) The role for vitamin B-6 as treatment for depression: a systematic review. Fam Pract 22:532–7

[13] Chinthapalli K. (2014) Alzheimer's disease: still a perplexing problem. BMJ 349

[14] Larson EB e al (2013) New Insights into the Dementia Epidemic. N Engl J Med 369(24):2275-7

[15] Aspy (2018) Effects of Vitamin B6 (Pyridoxine) and a B Complex Preparation on Dreaming and Sleep. Percept Motor Skills 1

[16] Stabler (2013) Vitamin B12 Deficiency N Engl J Med 2013; 368:149-160

[17] Heidelbaugh (2013) Proton pump inhibitors and risk of vitamin and mineral deficiency: evidence and clinical implications. Ther Adv Drug Saf 4(3) 125–133

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