B Vitamins Explained: B1, B2, B6, B12 — What Each One Does (and Who Needs What)

Fatigue. Brain fog. Tingling in your hands and feet. Dry, cracked lips. Mood changes and irritability. Low energy despite adequate sleep.

These symptoms are vague enough that they could point to a dozen different causes. But one class of nutrients — the B vitamins — underlies all of them, and deficiency in any individual B vitamin produces a surprisingly distinct and recognisable pattern of symptoms.

The problem is that B vitamins are often treated as a group ("take a B complex"), with little understanding of what each individual vitamin does and whether you might be specifically low in one over others.

This guide breaks down the eight B vitamins — their unique roles, deficiency signs, food sources, and who is most at risk — so you can identify which ones matter most for your health.

The B Vitamin Family: A Quick Overview

The eight B vitamins are all water-soluble, which means the body does not store them in significant amounts (with some exceptions, particularly B12 which is stored in the liver). They need to be replenished regularly through diet or supplementation.

They are numbered — but not consecutively — because what was originally called B4, B8, B10, and B11 were later found not to be essential vitamins and were removed from the official B-vitamin list.

Vitamin B1 (Thiamine) — The Energy Ignition Vitamin

What it does: Thiamine is a coenzyme required for converting carbohydrates into ATP (cellular energy). It is particularly critical for nerve and brain function, as the nervous system is almost entirely dependent on glucose for energy — and glucose metabolism requires thiamine.

Signs of deficiency:

• Fatigue and weakness
• Irritability and poor concentration
• Tingling or numbness in hands and feet (peripheral neuropathy)
• Loss of appetite
• Severe deficiency causes Beriberi and Wernicke's encephalopathy (a neurological emergency)

Who is most at risk:

• People with high alcohol intake (alcohol blocks thiamine absorption and increases excretion)
• Those eating a diet very high in refined carbohydrates (white rice, white bread) which provide carbohydrates without thiamine to metabolise them
• People with malabsorption conditions
• Dialysis patients

Best food sources: Whole grains, legumes, sunflower seeds, pork, liver

LOVITA product: Vitamin B1

Vitamin B2 (Riboflavin) — The Metabolism and Energy Vitamin

What it does: Riboflavin is a core component of two coenzymes (FAD and FMN) that participate in the mitochondrial electron transport chain — the process that generates the majority of your cellular ATP. It is also required for the metabolism of B6, B9, and B12, making adequate B2 a prerequisite for other B vitamins to function.

Additionally, riboflavin is involved in recycling glutathione (the master antioxidant) and is required for normal red blood cell production.

Signs of deficiency:

• Fatigue and weakness
• Sore, cracked, or inflamed lips (angular cheilitis)
• Sore throat
• Swollen, cracked tongue (glossitis)
• Bloodshot, sensitive eyes
• Skin rash, particularly around the nose and mouth
• Anaemia

Who is most at risk:

• People following vegan or dairy-free diets (dairy is a primary B2 source)
• Pregnant and breastfeeding women (B2 requirements increase significantly)
• Endurance athletes (who have higher riboflavin turnover)
• People over 50 (absorption efficiency declines with age)

Best food sources: Dairy products, eggs, organ meats, almonds, mushrooms, dark leafy greens

LOVITA product: Vitamin B2

Vitamin B3 (Niacin) — The Cholesterol and Skin Vitamin

What it does: Niacin participates in over 400 enzymatic reactions as a component of NAD+ and NADP+ — the same coenzymes central to energy production and DNA repair discussed in our NAD+ articles. Niacin is essentially one of the building blocks for your body's NAD+ supply.

Niacin also has well-documented effects on cholesterol: high-dose niacin (prescription-level) significantly raises HDL and lowers triglycerides, though it is used less commonly now due to side effects at high doses.

Signs of deficiency:

• Pellagra (in severe cases): dermatitis, diarrhoea, dementia — the "3 Ds"
• More commonly: fatigue, depression, headaches, and skin changes
• Niacin deficiency is uncommon in developed countries but occurs in people with corn-based diets lacking tryptophan (which the body can convert to niacin) and in people with Hartnup disease or carcinoid syndrome.

Vitamin B5 (Pantothenic Acid) — The Stress and Hormone Vitamin

What it does: Pantothenic acid is a component of Coenzyme A (CoA), which is essential for fatty acid metabolism and the citric acid cycle. It also supports the synthesis of cortisol and sex hormones in the adrenal glands — earning it the informal title of "anti-stress vitamin."

Deficiency is very rare because pantothenic acid is found in virtually all foods ("pantothenic" comes from the Greek word for "from everywhere"). However, marginal insufficiency has been proposed as a contributing factor in fatigue, mood disruption, and impaired stress resilience.

Vitamin B6 (Pyridoxine) — The Mood and Hormone Vitamin

What it does: B6 is one of the most versatile B vitamins, acting as a coenzyme in over 100 enzymatic reactions. Its most clinically significant roles include:

Neurotransmitter synthesis — B6 is required for producing serotonin, dopamine, GABA, and norepinephrine

Hormone metabolism — B6 influences oestrogen and progesterone processing, making it particularly relevant for women throughout the menstrual cycle and during perimenopause

Homocysteine regulation — High homocysteine (a cardiovascular risk marker) is partly regulated by B6

Haemoglobin production — B6 is required for haem synthesis

Signs of deficiency:

• Depression, anxiety, and irritability (neurotransmitter disruption)
• Premenstrual syndrome (PMS) — multiple trials support B6 for PMS
• Anaemia
• Peripheral neuropathy
• Weakened immune function
• Skin inflammation

Who is most at risk:

• Women taking oral contraceptives (the pill increases B6 metabolism and excretion)
• Pregnant women (B6 requirement increases; also used for morning sickness at 10–25mg/day)
• People with inflammatory bowel disease
• Those on isoniazid (tuberculosis medication)

Best food sources: Poultry, fish, potatoes, bananas, chickpeas, fortified cereals

LOVITA product: Vitamin B6

Vitamin B7 (Biotin) — The Hair, Skin, and Nail Vitamin

What it does: Biotin (also called Vitamin H) is a coenzyme for five carboxylase enzymes involved in fatty acid synthesis, amino acid metabolism, and gluconeogenesis. It is best known for its role in keratin production — the structural protein of hair, skin, and nails.

For a full discussion of biotin and hair growth research, see our dedicated article on Does Biotin Really Grow Hair?

Vitamin B9 (Folate/Folic Acid) — The DNA and Pregnancy Vitamin

What it does: Folate is essential for DNA synthesis and cell division — which is why it is most critical during periods of rapid cellular growth: pregnancy, infancy, and adolescence. Folate also regulates homocysteine levels (alongside B6 and B12) and supports the methylation cycle, a fundamental biochemical pathway affecting hundreds of cellular processes.

Signs of deficiency:

• Megaloblastic anaemia (large, immature red blood cells)
• Fatigue, weakness, shortness of breath
• Mouth sores
• Neural tube defects in pregnancy (spina bifida, anencephaly)
• Elevated homocysteine

Who is most at risk:

• Pregnant women and those trying to conceive
• People with MTHFR gene variants (reduced ability to activate folic acid — methylfolate is preferable)
• Heavy alcohol users
• People on methotrexate or certain anticonvulsants

Best food sources: Dark leafy greens (spinach, kale), legumes, liver, fortified grains, avocado

Vitamin B12 (Cobalamin) — The Energy and Nerve Vitamin

What it does: B12 is unique among B vitamins in that it is stored in the liver and can take years to become depleted after dietary intake stops. It is required for:

Red blood cell formation — B12 deficiency causes megaloblastic anaemia, resulting in severe fatigue

Neurological function — B12 maintains the myelin sheath (the protective coating around nerve fibres). Deficiency causes progressive and potentially irreversible nerve damage

DNA synthesis and cellular repair

Homocysteine conversion (with folate and B6)

Signs of deficiency:

• Fatigue and weakness (often severe)
• Numbness and tingling in hands and feet
• Difficulty walking (balance problems)
• Memory problems and cognitive decline
• Depression
• Pale or yellowish skin
• Sore, inflamed tongue

Who is most at risk:

• Vegans and vegetarians (B12 is found almost exclusively in animal foods)
• Adults over 50 (stomach acid required for B12 absorption declines with age)
• People taking metformin (reduces B12 absorption)
• People taking long-term proton pump inhibitors (PPIs)
• Those with pernicious anaemia (lack of intrinsic factor needed for B12 absorption)

Best food sources: Meat, fish, shellfish, eggs, dairy, nutritional yeast (fortified)

The most important form: Methylcobalamin — the active, bioavailable form that does not require conversion. Cyanocobalamin (the most common form in cheap supplements) must be converted and is less effective for those with metabolic inefficiencies.

LOVITA product: Vitamin B12

Should I Take Individual B Vitamins or a B Complex?

Individual B vitamins make sense when:

• You have a confirmed deficiency in a specific B vitamin (via blood test)
• You have specific symptoms that point to a particular B vitamin (e.g., morning sickness pointing to B6; vegan diet pointing to B12)
• You are taking therapeutic doses for a specific purpose (e.g., B6 for PMS; B12 injection for confirmed deficiency)

B complex makes sense for:

• General energy, mood, and cognitive support
• Daily nutritional foundation for busy adults
• Preventing subclinical deficiencies across the B vitamin family
• Post-antibiotic gut recovery (when B vitamin production from gut bacteria is disrupted)
• Look for a B complex using active, methylated forms — methylcobalamin (B12) and methylfolate (B9) — for maximum efficacy, particularly if you have any MTHFR gene variant.