B vitamins are essential for energy, brain function, nerve health, and overall wellbeing. Each type of B vitamin serves a different purpose.
What Are B Vitamins and What Do They Do?
B vitamins are a group of water-soluble nutrients that include:
- B1 (Thiamine) supports energy and nerve function
- B2 (Riboflavin) helps with energy and antioxidant protection
- B3 (Niacin) needed for metabolism and skin health
- B5 (Pantothenic Acid) helps your body use fats, carbs and proteins
- B6 (Pyridoxine / P-5-P) supports brain, mood and red blood cells
- B7 (Biotin) supports hair, skin, nails and metabolism
- B9 (Folate) important for DNA, red blood cells and brain function
- B12 (Cobalamin) needed for nerves, brain and red blood cells
They help turn food into energy, keep your nerves and brain healthy, make red blood cells, and even regulate mood and hormone balance. They also help keep a substance called homocysteine under control, which is important for heart health.
Why Some B Vitamins Need to Be Active
Some B vitamins need to be “activated” before your body can use them. For example:
- Folate → 5-MTHF (methyl folate)
- B12 → methylcobalamin or adenosylcobalamin
- B6 → P-5-P
If your body has certain gene changes, like MTHFR variants, it may struggle to convert standard vitamins into active forms. In these cases, taking methylated or active forms is important because your body can use them straight away. Such patients will always benefit from methylated versions. You may be one of them!
Active B vitamins support energy, mood, nerve function and key processes like DNA and neurotransmitter production.
Pernicious Anaemia and B12 Absorption
Even if you take high-quality B12, it might not work for everyone. Pernicious anaemia is an autoimmune condition where your stomach stops producing intrinsic factor, a protein needed to absorb B12.
Without intrinsic factor, oral B12 (even methyl cobalamin) cannot be absorbed properly, meaning you can still become deficient.
People with this condition may need:
- Sublingual B12 – absorbed under the tongue
- High-dose oral B12 – very large doses can sometimes be absorbed passively
- B12 injections – bypass the gut entirely
Other conditions that can affect absorption include gut surgery, gastritis, Crohn’s disease, and long-term use of acid-blocking medication.
| B Vitamin | Why Levels May Be Low | Common Effects of Deficiency |
| B1 Thiamine | Heavy alcohol use, poor diet, malnutrition | Fatigue, weakness, nerve problems |
| B2 Riboflavin | Poor intake, absorption issues | Low energy, mouth sores, reduced support for MTHFR function |
| B3 Niacin | Poor diet, absorption problems | Pellagra, skin changes, diarrhoea, cognitive decline |
| B6 | Poor intake, certain medications, conversion issues | Low mood, irritability, nerve symptoms, anaemia |
| B7 Biotin | Rare, genetic factors, long term gut issues | Hair loss, skin rashes, brittle nails |
| B9 Folate | Poor diet, pregnancy, malabsorption, MTHFR variants | Fatigue, anaemia, poor DNA production |
| B12 Cobalamin | Pernicious anaemia, gut disorders, vegan diet | Fatigue, neuropathy, memory issues, anaemia |
How to choose supplements!
When choosing B vitamin supplements in the UK, consider your individual needs and lifestyle. For general daily support, a balanced B complex with methylated forms of folate and B12 is usually sufficient. If you have methylation challenges or genetic variants, active forms such as 5-MTHF, methylcobalamin and P-5-P are recommended. For absorption issues, including pernicious anaemia, sublingual, injectable or liposomal B12 can improve uptake. People experiencing fatigue, brain fog, mood changes or high homocysteine may require higher doses of active B vitamins, but it is important to consult a healthcare professional before starting high-dose supplementation. Simple rules include confirming deficiencies with a lab test where possible, using active forms for genetic or absorption concerns, and selecting a balanced B complex for general wellbeing. The key is to match the vitamin form and dose to your own needs rather than assuming one size fits all.
Choosing the right form, dose and delivery method can make a real difference, especially if you have genetic or absorption issues. You can always contact us for advice on which form would be most suitable!
References
Lyon P, Strippoli V, Fang B, Cimmino L. B Vitamins and One-Carbon Metabolism: Implications in Human Health and Disease. Nutrients. 2020 Sep 19;12(9):2867. doi: 10.3390/nu12092867. PMID: 32961717; PMCID: PMC7551072.
Giammarco S, Chiusolo P, Maggi R, Rossi M, Minnella G, Metafuni E, D’Alò F, Sica S. MTHFR polymorphisms and vitamin B12 deficiency: correlation between mthfr polymorphisms and clinical and laboratory findings. Ann Hematol. 2024 Oct;103(10):3973-3977. doi:
Caffrey A, Lamers Y, Murphy MM, Letourneau N, Irwin RE, Pentieva K, Ward M, Tan A, Rojas-Gómez A, Santos-Calderón LA, Canals-Sans J, Leung BMY, Bell R, Giesbrecht GF, Dewey D, Field CJ, Kobor M, Walsh CP, McNulty H. Epigenetic effects of folate and related B vitamins on brain health throughout life: Scientific substantiation and translation of the evidence for health improvement strategies. Nutr Bull. 2023 Jun;48(2):267-277. doi: 10.1111/nbu.12611. Epub 2023 Feb 21. PMID: 36807740; PMCID: PMC10946506.
