What is the difference between all the B vitamins?

January 11, 2026 •

3 min read

An estimated 20% of older adults in the US and UK have a vitamin B12 deficiency, but often don't understand the nuance of this complex family of nutrients. Each of the eight B vitamins has a unique structure and critical function within the body.

Quick Summary

The B-complex consists of eight distinct, water-soluble vitamins, each with a unique biochemical function in the body. While all are crucial for cellular metabolism and energy production, their individual roles vary widely, from nerve function and DNA synthesis to red blood cell formation and hormone production.

Key Points

Distinct Functions: Each of the eight B vitamins has a unique biochemical role, despite their collective association with energy metabolism.
Water-Soluble: B vitamins are water-soluble, meaning the body doesn't store them efficiently and a consistent dietary intake is needed, except for B12 and B9.
Specialized Roles: B1 aids nerve function, B6 helps in protein metabolism, and B12 is crucial for nerve health and red blood cell formation.
Deficiency Effects: Specific deficiency symptoms are linked to individual B vitamins, ranging from anemia (B9, B12) to nerve damage (B1, B12).
Food Sources Vary: The richest sources for each B vitamin differ; for example, B12 is primarily found in animal products, while B9 is abundant in leafy greens.

The B-Complex: A Family of Essential Co-enzymes

B vitamins are not a single compound but a group of eight chemically distinct, water-soluble vitamins that frequently coexist in the same foods and work synergistically. Since they are not stored in the body in significant amounts (with the notable exception of B12 and B9), a consistent dietary intake is crucial. Each B vitamin acts as a co-enzyme, assisting enzymes that drive vital metabolic processes across nearly every system of the body. Though their roles overlap in some areas, their specific functions are highly specialized.

A Closer Look at the Individual B Vitamins

Vitamin B1 (Thiamine)

Thiamine is vital for energy metabolism, converting carbohydrates into energy, and is essential for nerve function. Severe deficiency can cause beriberi and Wernicke-Korsakoff syndrome.

Vitamin B2 (Riboflavin)

Riboflavin supports cellular growth and function, metabolizes fats and drugs, aids energy production, and has antioxidant properties. Deficiency is uncommon but can cause skin and vision issues.

Vitamin B3 (Niacin)

Niacin is crucial for energy conversion and supports the nervous and digestive systems. It is converted to NAD, involved in many enzyme reactions. Deficiency leads to pellagra.

Vitamin B5 (Pantothenic Acid)

Essential for synthesizing fatty acids, cholesterol, and hormones, B5 also helps metabolize macronutrients. Deficiency is very rare.

Vitamin B6 (Pyridoxine)

B6 is involved in amino acid metabolism, neurotransmitter synthesis, brain development, immune function, and hemoglobin production. Deficiency is uncommon but can cause anemia and neurological symptoms.

Vitamin B7 (Biotin)

Biotin is important for metabolizing fats, carbs, and proteins and is linked to hair and skin health. Deficiency is rare.

Vitamin B9 (Folate/Folic Acid)

Folate is essential for cell division, DNA synthesis, and red blood cell formation. It is critical during pregnancy to prevent neural tube defects. Deficiency causes megaloblastic anemia.

Vitamin B12 (Cobalamin)

B12 is vital for nerve function, DNA synthesis, and red blood cell formation, working closely with folate. Found mainly in animal products, deficiency is more common in certain groups and causes anemia and neurological issues.

Comparison of B Vitamins: Key Differences


Vitamin	Chemical Name	Primary Function	Found in	Deficiency Symptoms
B1	Thiamine	Converts carbs to energy, nerve function	Whole grains, beans, pork	Beriberi, nerve damage, fatigue
B2	Riboflavin	Energy production, cell growth, antioxidant	Dairy, eggs, green vegetables	Skin disorders, mouth sores
B3	Niacin	Energy metabolism, nervous system, skin health	Meat, fish, nuts, grains	Pellagra (dermatitis, dementia)
B5	Pantothenic Acid	Synthesizes fats, proteins, hormones	Chicken, beef, mushrooms	Rare, but includes fatigue, headache
B6	Pyridoxine	Amino acid metabolism, neurotransmitter synthesis	Beef liver, fish, chickpeas	Anemia, depression, confusion
B7	Biotin	Metabolizes fats, carbs, proteins	Egg yolks, nuts, sweet potatoes	Hair loss, skin issues
B9	Folate/Folic Acid	DNA synthesis, cell growth, red blood cells	Leafy greens, beans, peas	Megaloblastic anemia, fatigue
B12	Cobalamin	Nerve function, DNA synthesis, red blood cells	Meat, dairy, eggs, fish	Anemia, nerve damage, memory problems

Choosing the Right B-Complex for Your Needs

A balanced diet provides B vitamins, but supplements may be needed for some, such as vegans needing B12 or pregnant women needing folate. A B-complex is often suitable, but targeted supplements address specific deficiencies. Always consult a healthcare provider before starting supplements.

Conclusion

Understanding the differences between B vitamins is key to good health. While all contribute to energy and cellular function, each has a specialized role, from B1 for nerves to B12 for DNA and nervous system health. This knowledge helps in choosing appropriate dietary sources or supplements. The National Institutes of Health offers more information on specific uses and protocols.

A List of Key Roles

Thiamine (B1): Converts carbs to energy, supports nerve function.
Riboflavin (B2): Energy production, cell growth, antioxidant.
Niacin (B3): Energy metabolism, nervous system, skin health.
Pantothenic Acid (B5): Synthesizes hormones, breaks down macronutrients.
Pyridoxine (B6): Protein metabolism, brain development, neurotransmitter formation.
Biotin (B7): Metabolizes fats, carbs, proteins, supports hair/skin.
Folate (B9): DNA synthesis, cell division, prevents birth defects.
Cobalamin (B12): Nerve function, red blood cell production, DNA synthesis.

A List of Deficiency Symptoms

B1 Deficiency: Fatigue, disorientation, nerve damage, beriberi.
B2 Deficiency: Skin/mouth sores, swollen tongue.
B3 Deficiency: Pellagra (dermatitis, dementia).
B5 Deficiency: Headache, fatigue, nerve symptoms.
B6 Deficiency: Anemia, depression, confusion, weak immunity.
B7 Deficiency: Hair loss, skin rashes, nerve symptoms.
B9 Deficiency: Megaloblastic anemia, fatigue, weakness.
B12 Deficiency: Anemia, nerve damage, memory loss, tingling.

Frequently Asked Questions

Vitamin B is a collective term for the eight B vitamins (known as B-complex), while vitamin B12 is just one of those eight. Each B vitamin has a different role, and B12 is specifically crucial for nerve health and red blood cell production.

Some numbers were assigned to substances that were later discovered not to be true vitamins because they can be synthesized by the body or are not essential nutrients. This is why numbers like B4, B8, and B10 are not part of the standard B-complex.

Folate (B9) is one of the most critical B vitamins during pregnancy as it significantly reduces the risk of neural tube defects in the baby. Adequate vitamin B12 is also very important for fetal development.

Most people can get sufficient B vitamins from a balanced diet, as they are found in a wide variety of foods. However, individuals with restrictive diets (like vegans) or certain health conditions may need to supplement, particularly for B12.

Since B vitamins are water-soluble, excess amounts are typically excreted in the urine. However, high doses of certain B vitamins, like B6 and niacin, can cause side effects or even toxicity, so it's important to follow dosage instructions and consult a doctor.

Many B vitamins work together, so a B-complex supplement is often recommended for general health. Individual B vitamins are more appropriate for treating a specific, diagnosed deficiency.

All eight B vitamins play a role in converting food into energy, acting as co-enzymes in various metabolic processes. This is why a deficiency in any B vitamin can lead to feelings of fatigue.