Essential B Vitamins – What You Need to Know

It is well known that vitamins are critical components of healthy nutrition, many of which are essential nutrients that the body cannot produce on its own. This is one of the reasons maintaining a healthy diet is so important, as many cellular functions, including replicating DNA, synthesizing red blood cells and effectively absorbing calcium, depend heavily on receiving an adequate intake of vitamins that act as cofactors during these essential processes. During medical school, I became fascinated with what occurs in the event of certain vitamin deficiencies. In North America, we are fortunate that our milk, cereals and breads are fortified, which reduces the incidence of vitamin deficiencies in those eating balanced diets and ingesting enough food.


While some vitamin deficiencies are well known, such as rickets in vitamin D deficiency, scurvy in vitamin C deficiency, and night blindness in vitamin A deficiency, I felt as though less is known about the deficiencies and importance of the B vitamins.  The B vitamins are actually a complex of 8 different vitamins, most of which play a role in breaking down carbohydrates into usable energy sources, producing red blood cells that carry oxygen to tissues, and maintaining the outer insulation (‘myelin’) of neurons that transmit signals throughout the nervous system. As water soluble vitamins, the B vitamins are absorbed in the first part of the small bowel, the duodenum. Adequate intake may be impacted by poor nutrition or diseases of the bowel, including celiac disease and inflammatory bowel disease (Crohn’s).


The following is a run-down of each B vitamin, how much is required per day, and diseases associated with their deficiency:

B1 (Thiamine)

Function: metabolism of carbohydrates and maintenance of nerve function.

Deficiency: results in Beri-Beri or Wernicke-Korsakoff syndrome.

Beri-Beri: results in sensory loss, motor issues and abnormal reflexes of the extremities (‘Dry Beri-Beri’) or fluid retention and swelling of the extremities due to cardiac overload and failure (‘Wet Beri-Beri’) in extreme cases.

Wernicke-Korsakoff syndrome: often associated with chronic alcoholism or poor nutritional intake or starvation, results in neurological deficits that include confusion, issues with coordination (‘ataxia’) and abnormal eye movements (‘nystagmus’).

Sources: cereal grains, legumes, leafy greens, nuts, yeast, meat and eggs.

RDA: 1.1 mg/day and 1.2 mg/day for women and men over the age of 14 yrs, respectively, and 1.4 mg/day during pregnancy.


B2 (Riboflavin)

Function: coenzyme in cellular respiration (creating energy on a cellular level from the breakdown of carbohydrates).

Deficiency: development of a painful red tongue with chapped lips and inflammation of the corners of the mouth (stomatits and angular stomatitis, respectively), anemia, headaches, congenital heart defects and limb deformities in pregnancy.

Sources: legumes, almonds, milk, eggs, liver, kidney, cheese and mushrooms.

RDA: 1.1 mg/day and 1.3 mg/day for women and men over the age of 14 yrs, respectively, and 1.4 mg/day during pregnancy.


B3 (Niacin)

Function: aids the body in metabolizing proteins and fats, and maintaining the health of the nervous system, skin and hair.

Deficiency: pellagra, headaches, anemia.

Pellagra: characterized by diarrhea, dermatitis (peeling, scaling, and thickening of sun-exposed areas of the skin) and dementia.

Sources: meats (highest in tuna, turkey and pork), fortified whole grain foods (breakfast cereals, flours, rice, pasta), certain spices (ground ginger, tarragon, dried green sweet peppers, and more).

RDA: 14 mg/day and 16 mg/day for women and men over the age of 14 yrs, respectively, and 18 mg/day during pregnancy.


B5 (Pantothenic Acid)

Function: used in the metabolism of proteins, carbohydrates and fats, and is essential in the synthesis of co-enzyme A.  

Deficiency: extremely rare, but reported to include fatigue, headache, low blood sugar, and neurological symptoms (numbness, tingling and muscle cramps).  

Sources: fortified cereals, whole grains, dried egg yolks, liver, and sunflower seeds.

RDA: there currently is no recommended daily allowance; however adequate intake is recommended to be 5 mg/day for individuals over 14 years of age.  


B6 (Pyridoxine)

Function: aids in metabolism of carbohydrates, fats and protein, production of red blood cells, maintenance of nervous system function, and the control of homocysteine levels in the blood. High levels of homocysteine have been associated with cardiovascular events, although no causal link has been made.

Deficiency: extremely rare, but reported to include irritability, muscle weakness, short-term memory loss and difficulties concentrating.    

Sources: fortified cereals, meats, legumes, sunflower seeds, bananas, carrots, spinach, and cheese.  

RDA: 1.3 mg/day for men and women over the age of 19, and 1.9 mg/day during pregnancy.   


B7 (Biotin)

Function: involved in the metabolism of fatty acids, the generation of carbohydrates in the liver from fatty acids and amino acids (‘gluconeogenesis’), and maintenance of healthy hair and nails.

Deficiency: extremely rare, but may result in hair loss, sore tongue and cracks in the corner of the mouth (‘stomatitis and angular stomatitis’), dry eyes, lethargy, as well as numbness and tingling in the hands and feet.     

Sources: meats (liver, salmon, sardines), nuts, whole wheat bread, yeast, cheese, avocado, bananas, mushrooms, and cauliflower.   

RDA: 30 micrograms/day for adults 19 years and older.  


B9 (Folate)

Function: works with B6 and B12 to control blood levels of homocysteine, as well as aids in DNA and RNA synthesis and in the production of red blood cells.

Deficiency: often associated with chronic alcoholism, celiac disease, or inflammatory bowel disease, resulting in poor growth, irritability, diarrhea, a sensation of mental slowness, short-term memory issues, loss of appetite, inflammation of the tongue and gums (‘gingivitis’), and most importantly, birth defects (‘spina bifida’) in early pregnancy.

Sources: vegetables (dark, leafy greens), legumes, milk, salmon, orange juice.    

RDA: 400 micrograms/day for adults 19 years and older, and 600 micrograms/day during pregnancy.


B12 (Cobalamin)

Function: aids in the synthesis of myelin (essential for proper nervous system function) and red blood cells.  

Deficiency: in extreme cases causes potentially irreversible damage to the nervous system and brain, while in less extreme cases it can cause lethargy, depression, delirium and anemia.

Sources: animal products (shellfish and meats) and fortified cereals.    

RDA: 2.4 micrograms/day for individuals 14 years and older. 



While the B vitamins have many critical roles within the body, the good news is a healthy diet rich in vegetables, fruits and unsaturated fats, while staying low in saturated fats and processed sugars, will often provide many of the essential nutrients that you need to stay healthy!







March 12, 2018 by Candice Griffin

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