Vitamin B complex: Benefits, function, risks and sources

The essential role of vitamins in maintaining good health is well-established, but their complex nature and varied sources can sometimes be overwhelming. Among these crucial nutrients, the Vitamin B complex is prominent due to its extensive benefits for our bodies.

Whether boosting our energy levels, supporting brain function, or maintaining skin and hair health, the importance of Vitamin B complex cannot be understated.

This blog post aims to provide a comprehensive understanding of vitamin B complex, from its benefits and functions to potential risks and dietary sources.

As we delve into this topic, you will find helpful insights into each component of the Vitamin B complex, the symptoms of deficiency, the risks of excessive intake, and how to ensure a balanced intake.

What is vitamin B complex?

The term “Vitamin B Complex” refers to a group of eight water-soluble vitamins that play crucial roles in cell metabolism and various physiological functions in the body: 

  • B1 (Thiamine)
  • B2 (Riboflavin)
  • B3 (Niacin)
  • B5 (Pantothenic acid)
  • B6 (Pyridoxine)
  • B7 (Biotin)
  • B9 (Folate or folic acid)
  • B12 (Cobalamin)

While they are grouped and often found in similar food sources, each vitamin has unique roles and functions. 

What does vitamin B complex do?

The vitamin B complex is involved in various aspects of our physiology, from the cellular level to the functioning of our most important organ systems [1]. 

It plays a critical role in energy production, ensuring our bodies efficiently convert food into usable energy. The B vitamins also help maintain the health of our nervous system, and some, such as B9 and B12, are crucial for healthy brain function and mental health. 

Moreover, certain B vitamins are integral to the production and repair of our cells, including red blood cells, and contribute to skin, hair, nails, heart and eye health.

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Components of vitamin B complex

The Vitamin B complex comprises eight vitamins essential to various bodily functions, from energy production to brain performance [2]. While part of the complex, each B vitamin possesses unique properties and serves individual roles in keeping us healthy.

Vitamin B1 or thiamine

Thiamine is critical in the conversion of nutrients into energy. It plays a key role in metabolism and helps nerve, muscle, and heart function. Thiamine is also involved in the flow of electrolytes in and out of muscle and nerve cells.

Vitamin B2 or riboflavin

Riboflavin is crucial for breaking down proteins, fats, and carbohydrates. It supports body growth and red blood cell production. Besides, riboflavin helps in maintaining good eyesight and skin health.

Vitamin B3 or niacin

Niacin aids digestion as part of the body’s composition of two main enzymes. It helps the body use sugars and fatty acids and is also significant for skin and nerve health.

Vitamin B5 or pantothenic acid

Pantothenic acid assists in the metabolism of carbohydrates, proteins, and fats. It’s also involved in the production of red blood cells and steroid hormones.

Vitamin B6 or pyridoxine

Pyridoxine is involved in protein and glucose metabolism. It also aids in producing neurotransmitters and hemoglobin, a protein in red blood cells.

Vitamin B7 or biotin

Biotin is essential for carbohydrate and fat metabolism. It’s often associated with improved hair health and maintaining the proper function of the nervous system.

Vitamin B9 or folate or folic acid

Folate plays a vital role in cell growth, amino acid metabolism, formation of white and red blood cells, and proper cell division. It’s particularly important during pregnancy for the development of the baby’s neural tube.

Vitamin B12 or cobalamin

Cobalamin is necessary for creating DNA, the genetic material in all cells. It’s also involved in nerve function and the production of red blood cells.

What are the health benefits of vitamin B complex?

1. Enhances brain function and mental health

Certain B vitamins, including B1, B3, B6, and B12, are key players in brain health and cognitive function [3]. They aid in producing neurotransmitters, which carry signals between brain cells.

Vitamin B6, B9 (folate), and B12 are known to help reduce symptoms of depression and anxiety by playing a role in the creation of brain chemicals like serotonin that regulates mood and stress levels.

Supports energy production

2. Supports energy production

The B vitamins, particularly B1, B2, B3, and B5, are directly involved in turning the food you eat into energy by breaking down proteins, carbohydrates, and fats.

3. Aids in healthy digestion 

B vitamins, such as B1, B3, B5, and B7, assist in the absorption and metabolism of nutrients, thus promoting a healthy digestive system.

4. Boosts heart health

Vitamins B6, B9, and B12 can reduce levels of homocysteine, a type of amino acid found in your blood that, when present at high levels, can lead to heart disease.

5. Promotes skin, hair, and eye health

B vitamins, particularly B3, B5, and B7, are crucial in maintaining skin health. They help to improve the skin’s moisture retention, elasticity and can help reduce the appearance of skin aging.

While vitamin B7 (biotin) is often associated with hair health. A deficiency can lead to hair loss, showing biotin’s importance in maintaining a healthy scalp and hair.

Accordingly, vitamin B2 (riboflavin) is essential for eye health. It helps protect the eyes from developing cataracts and could play a role in preventing eye fatigue.

How much vitamin B complex should I take daily?

When it comes to vitamins, more doesn’t necessarily mean better. Each vitamin in the B complex has a specific recommended daily amount (RDA), which can vary based on age, gender, pregnancy, and breastfeeding. Here are the recommended dosages for adults [4]:

VitaminMenWomenAdults (general)
B1 (thiamine)1.2 mg/day1.1 mg/day
B2 (riboflavin)1.3 mg/day1.1 mg/day
B3 (niacian)16 mg/day14 mg/day
B5 (panthotenic acid)5 mg/day
B6 (pyridoxine)• 1.3 mg/day (age 19-50)
• 1.7 mg/day (above 50)
• 1.3 mg/day (age 19-50) 
• 1.5 mg/day (above 50)
B7 (biotin)30 mcg/day
B9 (folate)400 mcg/day
B12 (cobalamin)2.4 mcg/day
Please note that these RDAs can vary based on age, gender, and certain physiological conditions like pregnancy or breastfeeding. Always consult a healthcare provider or a dietitian to understand your specific needs.

Also, remember that a balanced diet should provide sufficient B vitamins for most people. Supplements should only be used under medical guidance, especially since some B vitamins can cause adverse effects when taken excessively.

What happens if you’re vitamin B complex deficient? 

Vitamin B complex deficiency is not uncommon, and it can lead to various health problems, depending on which B vitamins are deficient. Here are some conditions caused by a deficiency:

1. Beriberi

Deficiency in thiamine can cause beriberi, a condition marked by weight loss, emotional disturbances, impaired sensory perception, weakness and pain in the limbs, and irregular heartbeat. In severe cases, it can lead to heart failure.

2. Ariboflavinosis

Riboflavin deficiency can lead to ariboflavinosis, a condition characterized by cracked and red lips, inflammation of the mouth and tongue, mouth ulcers, and iron-deficiency anemia.

3. Pellagra

Severe deficiency of niacin can cause pellagra. Symptoms include diarrhea, skin changes, dementia, and if left untreated, death.

4. Acne and paresthesia

Deficiency in pantothenic acid is very rare but can lead to acne and paresthesia, or a “pins and needles” feeling [5].

5. Anemia, depression and dermatitis

Pyridoxine deficiency may lead to microcytic anemia, depression, dermatitis, high blood pressure, water retention, and elevated homocysteine levels.

6. Hair thinning and rashes

Biotin deficiency can lead to hair thinning, rashes around the eyes, nose, and mouth, and neurological issues like depression, exhaustion, hallucinations, and tingling of the arms and legs.

7. Megaloblastic anemia

Deficiency in folate can cause megaloblastic anemia, characterized by the production of unusually large, abnormal, and immature red blood cells. It can also lead to neural tube defects in developing embryos.

8. Fatigue, weakness and constipation

Cobalamin deficiency may cause megaloblastic anemia, fatigue, weakness, constipation, loss of appetite, weight loss, and neurological changes such as numbness and tingling in the hands and feet.

What are the symptoms of a vitamin B complex deficiency?

Deficiency in the B vitamins can lead to many subtle symptoms, which may be overlooked. If you notice any of the following symptoms, it might indicate a deficiency:

General symptoms

Common general symptoms that could indicate a deficiency in one or more B vitamins include fatigue, irritability, nervousness, depression, insomnia, loss of appetite, and abdominal pain.

Skin disorders

Certain skin disorders like rashes, dry and cracked skin, and acne can also be a sign of a B vitamin deficiency, particularly B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), or B7 (biotin).

Mouth and lip symptoms

Cracked or sore lips, inflammation of the mouth or tongue, and mouth ulcers may indicate a deficiency in B2 (riboflavin), B3 (niacin), or B9 (folate).

Neurological symptoms

Neurological symptoms like numbness, tingling in the hands and feet, balance issues, and cognitive difficulties may indicate a deficiency in B1 (thiamine), B6 (pyridoxine), or B12 (cobalamin).

Mood changes

Changes in mood, including depression, anxiety, and increased irritability, can be a sign of deficiency in B1 (thiamine), B6 (pyridoxine), B9 (folate), or B12 (cobalamin).

Cardiovascular symptoms

Symptoms like an irregular heartbeat, changes in blood pressure, and shortness of breath could signal a deficiency in B1 (thiamine) or B6 (pyridoxine).

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Which foods contain B vitamins?

Getting enough B vitamins is essential for your health, and the best way to ensure adequate intake is through a balanced and varied diet. Here are some excellent sources of each of the B vitamins:

Animal sources

1. Meat

Meat, particularly organ meats like liver and kidney, are rich in a variety of B vitamins, including B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), and B12 (cobalamin).

2. Fish

Various types of fish, especially fatty fish like salmon and tuna, are great sources of B3 (niacin) and B12 (cobalamin).

3. Poultry

Poultry, such as chicken and turkey, are rich in B3 (niacin) and B6 (pyridoxine).

4. Eggs

Eggs are a good source of B2 (riboflavin), B5 (pantothenic acid), and B7 (biotin). The yolk also contains B12 (cobalamin).

5. Dairy products

Milk, cheese, and other dairy products are excellent sources of B2 (riboflavin) and B12 (cobalamin).

Vitamin B Complex: Benefits, function, risks and sources

Plant sources

1. Whole grains

Whole grains, including whole wheat, brown rice, oatmeal, and quinoa, are a good source of several B vitamins, including B1 (thiamine), B2 (riboflavin), B3 (niacin), and B5 (pantothenic acid).

2. Green vegetables

Leafy green vegetables like spinach, broccoli, and asparagus are excellent sources of B2 (riboflavin) and B9 (folate).

3. Legumes

Beans, peas, lentils, and other legumes are rich in B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), and B9 (folate).

4. Nuts and seeds

Nuts and seeds, like sunflower seeds, pumpkin seeds, almonds, and peanuts, are rich in B1 (thiamine), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), and B6 (pyridoxine).

Fortified foods

These foods have nutrients added to them that don’t naturally occur in the food or are added in higher amounts. Fortified foods can be an excellent option for individuals struggling to meet their B vitamin needs through diet alone. Here’s a look at some of the most common fortified foods:

  • Breakfast cereals
  • Plant-based milk
  • Bread and grains
  • Nutritional yeast
  • Energy bars
  • Protein shakes

What is the bioavailability of vitamin B complex?

Bioavailability refers to the proportion of a nutrient that, once ingested, is absorbed and utilized by the body. It’s a critical concept when discussing vitamin B intake because not all sources of these vitamins have the same bioavailability.

Factors affecting bioavailability

Form of the nutrient

The chemical form of a nutrient can influence its absorption. For instance, B vitamins are often present in food as part of complex molecules, some more readily absorbed and used by the body than others.

Dietary composition

The composition of your diet can impact the absorption of B vitamins. For example, the presence of dietary fat can improve the absorption of vitamin B12. Meanwhile, certain dietary fibers can inhibit the absorption of some B vitamins by binding to them in the digestive tract.

Age and life stage

Age can impact nutrient absorption. Older adults may have decreased absorption of certain nutrients, including B12. Additionally, pregnancy and breastfeeding significantly increase the demand for B vitamins, which can affect their bioavailability.


Certain genetic factors can influence how effectively individuals absorb and metabolize B vitamins. For example, some people have genetic variations that affect their ability to metabolize folate efficiently.

Gut health

The health of your gastrointestinal tract can also impact the absorption of nutrients. Conditions like Crohn’s, celiac, or atrophic gastritis can reduce the body’s ability to absorb B12 and other B vitamins.

Alcohol consumption

Chronic heavy drinking can interfere with the absorption and utilization of several B vitamins, including thiamine (B1), pyridoxine (B6), and folate (B9).

When should you take B vitamin supplements?

While a balanced diet should provide all the B vitamins your body needs, there are circumstances when supplementation may be necessary. Here are some scenarios where supplementing with B vitamins might be recommended:

1. Vegan or vegetarian diets

Those following vegan or vegetarian diets may require B12 supplementation since this vitamin is predominantly found in animal products. Fortified foods can also be a good source of B12 for those on plant-based diets.

2. Pregnancy and breastfeeding

Pregnant or breastfeeding women have higher needs for B vitamins, particularly B9 (folate) and B12 (cobalamin). A prenatal vitamin supplement often includes increased amounts of these vitamins to support the health of the mother and baby.

3. Age-related absorption issues

As we age, our bodies become less efficient at absorbing certain nutrients, including B12. People over 50 may require B12 supplementation or should consume foods fortified with this vitamin.

4. Certain medical conditions

Individuals with certain medical conditions like Crohn’s disease, celiac disease, or pernicious anemia may have impaired absorption of B vitamins and require supplementation.

5. Certain genetic variations

Some individuals have genetic variations that affect the metabolism of certain B vitamins, particularly B9 (folate) and B12 (cobalamin). They may require higher doses of these vitamins in supplement form.

6. Chronic alcoholism

Chronic alcohol consumption can lead to deficiencies in several B vitamins, which may necessitate supplementation.

Chronic alcoholism

How to choose the right vitamin B complex supplement?

Here are some key considerations when choosing a B complex supplement:

1. Check the ingredient list

The supplement should contain all eight B vitamins. However, pay special attention to B12 and folate, as these are the two B vitamins most commonly needed in supplement form.

2. Consider the dosage

The dosage should be appropriate for your needs. While B vitamins are generally safe, consuming too much of certain types (like B6 and niacin) can lead to adverse effects. Check with a healthcare provider to determine the right dosage for you.

3. Look for third party testing

A supplement that has been third-party tested offers greater assurance of quality and accuracy in labeling. Look for certification from NSF International, U.S. Pharmacopeia (USP), or ConsumerLab.

4. Choose a reputable brand

Go for brands with a good reputation in the industry. Check customer reviews and consider recommendations from healthcare providers.

5. Consider your dietary preferences and restrictions

If you follow a special diet (like vegan or gluten-free), ensure the supplement fits your dietary needs. Many supplements may contain animal-derived ingredients or allergens.

6. Form of supplement

B vitamins are available in various forms including tablets, capsules, liquids, and sprays or patches. Choose a form that suits your preference and lifestyle.

What are the risks of over-supplementation? 

Here are some key concerns related to the over-supplementation of B vitamins:

Overdoing water-soluble vitamins

B vitamins are water-soluble, which means any excess is usually excreted through urine. However, consistently consuming high doses can lead to health problems over time. For instance, excess B6 can cause nerve toxicity, while high doses of niacin can cause skin flushing and, in rare cases, liver damage.

Masking deficiencies

High doses of certain B vitamins can mask deficiencies in other vitamins. For instance, excess folic acid (B9) can mask a vitamin B12 deficiency, potentially delaying diagnosis and treatment.

Potential interactions with medications

High doses of B vitamins can interact with certain medications, altering their effectiveness. For instance, B6 can interfere with certain medications for seizures and Parkinson’s disease, while B9 can affect anticonvulsant drugs.

Increased risk of certain health conditions

Some research suggests that high doses of certain B vitamins (particularly B6, B9, and B12) might increase the risk of certain health conditions in some people, including lung cancer in men and cardiovascular disease in people with high blood homocysteine levels.

Closing thoughts

Vitamin B complex plays a crucial role in maintaining good health and well-being. The benefits of B vitamins are far-reaching from supporting the body’s energy production to maintaining healthy brain function.

However, the intake of these vitamins should be personalized, considering individual dietary habits, lifestyle, and specific health conditions. While a balanced and varied diet is the ideal source of these vitamins, certain groups of people may need to supplement to meet their needs.

Supplementation should be approached thoughtfully, considering factors like the quality of the supplement, the appropriate dosage, and the potential for over-supplementation. It’s always recommended to consult with a healthcare provider before taking a new supplement regimen.

Understanding the vitamin B complex’s role, sources, and intricacies helps you make informed choices about your diet and supplements, ultimately supporting your journey toward optimal health.


What are B-complex vitamins good for?

B-complex vitamins are essential for various bodily functions, including supporting energy production, maintaining healthy brain function, aiding red blood cell formation, and supporting cell growth and division. They also contribute to the proper functioning of the immune system and maintain skin, hair, and eye health.

Is it safe to take B complex every day?

Yes, taking B complex vitamins daily is generally safe, as they are water-soluble and any excess is typically excreted in the urine. However, excessive intake over the recommended daily allowance can lead to certain side effects, so it’s advisable to consult a healthcare provider for personalized advice.

Should I take B complex day or night?

B-complex vitamins can be taken at any time of the day, as they are not known to affect sleep or wakefulness. However, some people may prefer to take them in the morning with a meal to aid absorption and minimize any potential digestive discomfort.

Can I take vitamin C and vitamin B complex together?

Yes, you can take vitamin C and vitamin B complex together. Both are water-soluble vitamins and can be taken simultaneously without causing any harm, provided you adhere to the recommended dosages.

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