Vitamin B Complex

What It Is

“Vitamin B complex” is a group of eight water-soluble B-vitamins taken together: B1 (thiamine), B2 (riboflavin), B3 (niacin / niacinamide), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folate), and B12 (cobalamin). Each has distinct biochemical roles, but they often co-occur in foods and are co-needed in the same metabolic pathways, which is why they are commonly supplemented as a set.

How It Works

The B-vitamins act largely as coenzymes. They do not supply energy themselves but enable enzymes to extract energy from carbohydrates, fats, and proteins. They are deeply involved in mitochondrial function, DNA synthesis and repair, neurotransmitter synthesis (serotonin, dopamine, GABA, norepinephrine), red blood cell production, and methylation reactions that influence homocysteine, gene regulation, and detoxification. Because they are water-soluble and not appreciably stored (except some B12 in the liver), they require a regular dietary supply.

Why It’s Important

Adequate B-vitamins are necessary for stable energy production, cognitive function, mood regulation, stress resilience, pregnancy and fetal development (especially folate), and cardiovascular health through homocysteine control. Deficiencies can manifest as fatigue, peripheral neuropathy, glossitis, dermatitis, impaired concentration, mood symptoms, anemia, or—when severe—irreversible neurological damage (classically with B12 deficiency).

Considerations

B-complex is generally well-tolerated, but not universally appropriate. Some people may not absorb B12 or folate well and need active forms (methylcobalamin or adenosylcobalamin; L-methylfolate instead of folic acid). High-dose niacin can cause flushing or affect liver enzymes; extended-release niacin should not be used casually. Excess B6, in megadose form and over time, can paradoxically cause neuropathy. Folate supplementation can mask hematologic signs of B12 deficiency while nerve damage progresses silently, so B12 status matters when using folate. Certain drugs deplete B-vitamins (e.g., metformin lowers B12; proton-pump inhibitors impair B12 absorption; isoniazid uses up B6). Because B-vitamins influence neurotransmitter synthesis and methylation, some people feel either better or temporarily “wired” when starting high doses. Pregnancy, alcohol use, vegan diet, malabsorption disorders, and older age materially change B-vitamin requirements and risk profiles, making context more important than taking a generic “one-size-fits-all” B-complex.