What are the signs and symptoms of a B complex vitamin deficiency?

From the Guidelines

B complex vitamin deficiency presents with various symptoms depending on which specific B vitamin is lacking, including fatigue, weakness, anemia, skin rashes, and neurological issues, and can be prevented through a balanced diet or supplementation, especially in high-risk groups such as older adults and strict vegetarians or vegans. The symptoms of B complex vitamin deficiency can vary widely depending on the specific vitamin that is lacking. Common signs include fatigue, weakness, anemia, skin rashes, cracks around the mouth, swollen tongue, numbness or tingling in extremities, confusion, irritability, depression, and poor concentration 1. Deficiencies in specific B vitamins cause distinctive symptoms:

• B1 (thiamine) deficiency leads to beriberi with nerve damage and heart problems
• B3 (niacin) deficiency causes pellagra with dermatitis, diarrhea, and dementia
• B6 deficiency results in skin inflammation and neurological issues, as it plays a crucial role in amino acid metabolism and is associated with a wide range of physiological processes, including the synthesis of haeme, neurotransmitters, and hormones 1
• B12 deficiency causes pernicious anemia with fatigue and neurological damage
• Folate deficiency leads to megaloblastic anemia and neural tube defects in developing fetuses. Treatment involves supplementation with B complex vitamins, typically 100mg daily of a B complex supplement, though individual deficiencies may require specific dosing, such as hydroxocobalamin 1 mg intramuscularly for vitamin B12 deficiency 1. Most people can prevent deficiency through a balanced diet including whole grains, meat, eggs, dairy, leafy greens, and legumes, with fortified breakfast cereals providing a practical means of improving B vitamin status, especially for older adults 1. Those at higher risk include alcoholics, older adults, pregnant women, those with malabsorption conditions, and strict vegetarians or vegans who should consider regular supplementation to prevent deficiency and related diseases, such as cardiovascular disease, cognitive dysfunction, and osteoporosis 1.

From the FDA Drug Label

Clinical Pharmacology ... Increased levels of pyruvic acid in the blood indicate vitamin B1 deficiency. Body depletion of vitamin B1 can occur after approximately three weeks of total absence of thiamine in the diet.

The signs and symptoms of a B complex vitamin deficiency are not fully described in the label, but it is mentioned that increased levels of pyruvic acid in the blood indicate a vitamin B1 deficiency.

• Vitamin B1 deficiency can occur after approximately three weeks of total absence of thiamine in the diet 2.

From the Research

Signs and Symptoms of B Complex Vitamin Deficiency

The signs and symptoms of a B complex vitamin deficiency can vary depending on the specific vitamin that is lacking. Some common symptoms include:

• Cognitive impairment and dementia, which have been linked to deficiencies in vitamins B1, B3, B6, B9, and B12 3
• Depression, which has been linked to deficiencies in vitamins B1, B3, B6, B9, and B12 3
• Nervousness, irritability, insomnia, delusional ideas, and hallucinations, which can occur in cases of pellagra caused by niacin deficiency 4
• Cutaneous pigmentation, pigmentation on mucous membranes, palmoplantar keratoderma, palmar streaking, yellow streaking on the nails, nail layering, and intranail hemorrhage, which can occur in cases of vitamin deficiencies, including B complex vitamins 5
• Megaloblastic anemia, cognitive impairment, and psychosis, which can occur in cases of vitamin B12 deficiency 6

Specific Vitamin Deficiencies

Some specific vitamin deficiencies and their symptoms include:

• Vitamin B12 deficiency, which can cause megaloblastic anemia, cognitive impairment, and psychosis 6
• Niacin deficiency, which can cause pellagra, characterized by symptoms such as nervousness, irritability, insomnia, delusional ideas, and hallucinations 4
• Deficiencies in vitamins B1, B3, B6, B9, and B12, which have been linked to depression and cognitive impairment 3

Diagnosis and Treatment

Diagnosis of B complex vitamin deficiencies typically involves clinical suspicion followed by laboratory testing. Treatment usually involves supplementation with the deficient vitamin or vitamins. In some cases, treatment with multiple vitamin therapy, including nicotinic acid, may be necessary to resolve symptoms 4, 6