Understanding the B Vitamins

“Vitamin B” is not one vitamin but eight. Each has its own name, number and role, yet they are often found in the same foods and work together in the body’s energy-releasing reactions. That is why they are commonly sold together as a B complex.

The eight B vitamins

• Thiamin (B1): helps turn food into energy and supports nerve function. Found in whole grains, pork, beans and fortified cereals.
• Riboflavin (B2): needed for energy production and cell growth. Found in milk, eggs, lean meat and green vegetables. It can turn urine bright yellow, which is harmless.
• Niacin (B3): helps release energy from food. Found in poultry, fish, meat, nuts and fortified grains.
• Pantothenic acid (B5): needed to make and break down fats. Found in almost all foods.
• Vitamin B6: involved in more than 100 enzyme reactions, mostly in protein metabolism. Found in poultry, fish, potatoes, chickpeas and bananas.
• Biotin (B7): helps metabolize carbohydrates, fats and proteins. Found in eggs, fish, meat, seeds and nuts.
• Folate (B9): needed to make DNA and for cell division. Found in leafy greens, beans, citrus fruit and fortified grains. Folic acid is the form used in supplements and fortified foods.
• Vitamin B12: keeps nerve and blood cells healthy and helps make DNA. Found in fish, meat, poultry, eggs, dairy and fortified foods.

Do B vitamins give you energy?

B vitamins help the body release energy from the food you eat. They do not supply energy themselves, and taking extra will not make a well-nourished person more energetic. Tiredness has many causes; if it persists, see a doctor.

Vitamin B12: who needs to pay attention

Adults need 2.4 micrograms a day. Because plants do not make B12, people who eat little or no animal food must rely on fortified foods or supplements. Absorption also depends on stomach acid and a protein called intrinsic factor, so the following groups are at higher risk of deficiency:

• many older adults;
• people with pernicious anemia;
• people who have had stomach or intestinal surgery;
• people with digestive disorders such as celiac disease or Crohn’s disease;
• people taking certain medicines long term, including metformin and some acid-reducing drugs.

Deficiency can cause tiredness, weakness, a type of anemia, and numbness or tingling in the hands and feet. Nerve damage can become permanent, so symptoms should be assessed promptly.

Folate and pregnancy

Anyone who could become pregnant is advised to get 400 micrograms of folic acid daily from supplements or fortified foods, in addition to folate from a varied diet. Adequate folic acid before conception and in early pregnancy reduces the risk of neural tube defects.

Vitamin B6: more is not better

Adults aged 19 to 50 need 1.3 mg a day. The upper limit for adults is 100 mg a day. Taking high doses of B6 supplements for a year or longer can cause severe nerve damage, leading to loss of control of body movements.

Should you take a B complex?

Most people who eat a varied diet get enough B vitamins. A B complex, such as our Vitamin B Complex, provides all eight together and may suit people with restricted diets. Check with a doctor or pharmacist first if you are pregnant, take regular medicines or have a medical condition.

The bottom line

The B vitamins are a team of eight with related jobs in energy metabolism, blood and nerves. Food supplies them for most people, with B12 and folic acid the main exceptions. Explore them in our vitamins and nutrition department.

Sources

1. NIH Office of Dietary Supplements. Vitamin B12.
2. NIH Office of Dietary Supplements. Vitamin B6.
3. NIH Office of Dietary Supplements. Folate.
4. MedlinePlus. Vitamins.