B vitamins are a group of eight essential nutrients that play roles in many organs and bodily systems. They help with various functions, including creating energy from food, producing blood cells, and maintaining healthy skin.
In this article, we explore the function of B vitamins in the body and some key dietary sources of each.
We also look at the symptoms of each B vitamin deficiency.
B vitamins are important for making sure the body’s cells are functioning properly. They help the body convert food into energy (metabolism), create new blood cells, and maintain healthy skin cells, brain cells, and other body tissues.
There are eight types of B vitamin, each with their own function:
- thiamin (vitamin B1)
- riboflavin (vitamin B2)
- niacin (vitamin B3)
- pantothenic acid (vitamin B5)
- vitamin B6
- biotin (vitamin B7)
- folate (vitamin B9)
- vitamin B12
Together, they are called the vitamin B complex.
B vitamins often occur together in the same foods. Many people can get enough B vitamins by eating a variety of nutrient-dense foods.
However, those who can’t meet their daily needs through food can use supplements.
People may develop B vitamin deficiencies if they do not get enough of the vitamins from their diet or supplements. They may also have a deficiency if their body cannot absorb nutrients properly, or if their body eliminates too much of them due to certain health conditions or medications.
Healthcare professionals recommend that people get a certain amount of each vitamin per day to maintain good health.
The following table provides the daily values (DVs) of each B vitamin according to the Food and Drug Administration (FDA) in milligrams (mg) or micrograms (mcg):
|DVs for adults and children ages 4+
|DVs if pregnant or breastfeeding
|16 mg or equivalent
|18 mg or equivalent
|pantothenic acid (B5)
|400 mcg or equivalent
|600 mcg or equivalent
Below, we look at each B vitamin in more detail.
The heart, liver, kidney, and brain all contain high amounts of thiamin. The body
- breaking down sugar (carbohydrate) molecules from food
- creating certain neurotransmitters (brain chemicals)
- producing fatty acids
- synthesizing certain hormones
Foods with thiamin
Thiamin is present in:
- whole grains and fortified bread, cereal, pasta, and rice
- acorn squash
- legumes, such as black beans and soybeans
Thiamin deficiency is not common in the United States. However, certain groups of people may not get enough thiamin, including:
- those with alcohol dependence
- older adults
- those with HIV or AIDS
- those with diabetes
- those who have heart failure
- those who have had bariatric surgery
Symptoms of thiamin deficiency
A person with a thiamin deficiency may experience:
- weight loss
- little or no appetite
- memory problems or confusion
- heart problems
- tingling and numbness in the hands and feet
- loss of muscle mass
- poor reflexes
Alcohol dependence can cause a person to develop a thiamin deficiency. This can cause Wernicke-Korsakoff syndrome (WKS), which may result in tingling and numbness in the hands and feet, memory loss, and confusion.
- energy production
- helping the body break down fats, drugs, and steroid hormones
- converting tryptophan into niacin (vitamin B3)
- converting vitamin B6 into a coenzyme that the body needs
Foods with riboflavin
Foods rich in riboflavin include:
Symptoms of riboflavin deficiency
Riboflavin deficiency is rare but may occur when a person has an endocrine disorder, such as thyroid problems, or certain other conditions.
A person who is deficient in riboflavin may experience:
- skin disorders
- sores at the corners of the mouth
- swelling of the mouth and throat
- swollen, cracked lips
- hair loss
- red, itchy eyes
People at highest risk of riboflavin deficiency include:
The body converts niacin into a coenzyme called nicotinamide adenine dinucleotide (NAD). NAD is a necessary part of more than 400 different enzyme reactions in the body, the highest of all vitamin-derived coenzymes. These enzymes
- changing the energy in carbohydrates, fats, and proteins into a form the body can use
- metabolic processes in the body’s cells
- communication among cells
- expression of DNA in cells
Foods with niacin
Animal-based foods such as meat, poultry, and fish are high in NAD, which the body can easily use.
Plant-based foods including nuts, legumes, and grains contain a natural form of niacin that the body cannot use as easily. However, manufacturers add niacin to foods such as cereals, and the body can easily use this form.
Symptoms of niacin deficiency
- brown discoloration on skin exposed to sunlight
- patches of skin with a rough appearance
- a bright red tongue
- vomiting, diarrhea, or constipation
If pellagra goes untreated, it can lead to severe memory problems, behavioral changes, and suicidal behavior. It may also lead to an extreme loss of appetite or death.
People at risk of niacin deficiency include those who have:
Red blood cells carry pantothenic acid throughout the body so it can use the nutrient in a variety of processes for energy and metabolism.
Foods with pantothenic acid
Many foods contain at least some pantothenic acid, but some of the highest amounts are present in:
Symptoms of pantothenic acid deficiency
Pantothenic acid deficiency is rare in the U.S. because it is plentiful in many foods. However, it may affect people with severe malnutrition. In such cases, they are usually deficient in other nutrients as well.
Symptoms of deficiency include:
- numbness and burning of the hands and feet
- restlessness and poor sleep
- a lack of appetite
People with a specific gene mutation called pantothenate kinase-associated neurodegeneration 2 mutation are at a high risk of deficiency.
Vitamin B6, or pyridoxine, plays a role in
- amino acid metabolism
- breaking down carbohydrates and fats
- brain development
- immune function
Foods with vitamin B6
The richest sources of vitamin B6 include:
Symptoms of vitamin B6 deficiency
Many deficiencies in vitamin B6 are linked to low levels of vitamin B12. Vitamin B6 deficiency may cause:
- scaling on the lips
- cracks at the corners of the mouth
- swollen tongue
- weakened immune system
People at risk of a vitamin B6 deficiency include those who have:
Manufacturers add biotin to many hair, skin, and nail supplements. However, the National Institute of Health (NIH) states that there is
The human body needs biotin for:
- breaking down fats, carbohydrates, and protein
- communication among cells in the body
- regulation of DNA
Foods with biotin
Many foods contain biotin, including:
Symptoms of biotin deficiency
Signs of a biotin deficiency include:
Deficiency is rare in the U.S., but the following groups may be more at risk:
- people with a metabolic disorder called biotinidase deficiency
- people with alcohol use disorder
- women who are pregnant or lactating
The natural form of vitamin B9 is called folate. Folic acid, which is present in fortified foods and some supplements, is a synthetic form of the vitamin.
As most people cannot take in enough leafy green vegetables for the levels needed in pregnancy, the
Folate is also
- DNA replication
- metabolism of vitamins
- metabolism of amino acids
- proper cell division
Foods with folate
Natural folate occurs in:
Symptoms of folate deficiency
- heart palpitations
- sores on the tongue or in the mouth
- skin, hair, or nail changes
- alcohol use disorder
- celiac disease
- conditions that interfere with nutrient absorption
People should not take more than
Vitamin B12 contains the mineral cobalt and is
- creating new red blood cells
- DNA synthesis
- brain and neurological function
- fat and protein metabolism
Foods with vitamin B12
Vitamin B12 occurs naturally in animal products such as:
People who do not eat animal products may need to get vitamin B12 from supplements or fortified foods such as breakfast cereals and nutritional yeast.
Symptoms of vitamin B12 deficiency
- weight loss
- loss of appetite
- numbness and tingling in the hands and feet
- memory problems
People who are at risk of a B12 deficiency include those who have:
- conditions that interfere with the absorption of nutrients
- older adults
- celiac disease
- Crohn’s disease
- had gastric bypass surgery or surgery on the stomach
Most people are able to get sufficient B vitamins from their diet.
Supplementation is generally unnecessary unless a healthcare professional confirms a deficiency in a particular B vitamin. If a person is deficient, their healthcare provider will typically advise on whether they should take a vitamin B complex or a specific B supplement.
Certain factors may increase the likelihood of needing supplementation,
- being 65 years of age or older
- presence of specific chronic health conditions
- long-term use of certain medications
- adherence to a vegan diet
It’s important to remember that dietary supplements are not regulated by the Food and Drug Administration (FDA). Therefore, a person should only purchase supplements from a reputable brand to ensure they’re taking a high quality product.
Below are some commonly asked questions about B vitamins.
What are the symptoms of vitamin B complex deficiency?
There is no such thing as a vitamin B complex deficiency. Rather, a person may have a vitamin B deficiency.
However, there are
For example, a vitamin B9 deficiency may cause headaches and heart palpitations while a vitamin B2 deficiency may cause cracked lips and hair loss. It is possible to have more than one B vitamin deficiency at one time.
Is vitamin B the same as vitamin B12?
No, vitamin B is not the same as vitamin B12.
Vitamin B12 is one of many B vitamins which, together, are
All B vitamins are essential for health.
Which food has vitamin B?
The following foods are sources of B vitamins:
- pork (B1, B7)
- nuts (B1, B3, B9)
- legumes (B1, B3)
- yogurt (B2, B12)
- avocado (B5, B9)
- chickpeas (B6)
- beef (B7, B12)
B vitamins each have their own unique functions, but they depend upon one another for proper absorption and the best health benefits. Eating a healthy, varied diet will generally provide all the B vitamins a person needs.
People can treat and prevent B vitamin deficiencies by increasing their dietary intake of high-vitamin foods or taking vitamin supplements.
Ask a doctor before taking any supplements to be sure they will not interact with medications.