Vitamin B-Complex : Components, Uses and Benefits

Parul Dube

February 7, 2022

B complex vitamins are water-soluble vitamins that our bodies can absorb easily and excreted via urine. They are essential for several metabolic processes. For example, they help regulate red blood cell formation, nervous system functions, the brain, and many other vital functions in our body. You may be familiar with vitamin B. However, there are a total of eight B complex vitamins.

Nutritional supplements containing all eight B vitamins are known as B-complex vitamins. B-complex vitamins consist of all eight B vitamins, and vitamin B represents each of the B-complex vitamins individually. Therefore, each B complex vitamin has a distinct name. For example, folate and biotin are commonly known as B complex vitamins. 

While a balanced diet can meet the daily requirements of the majority of B complex vitamins, some of these vitamins are present in very minimal amounts in food. Vitamin B12 is one such vitamin. 

Deficiency of B complex vitamins can result in symptoms such as numbness and tingling sensation in hands and feet, muscle weakness. However, factors like age, pregnancy, dietary choices, medical conditions, genetics, medication and alcohol use also determine the body’s demand for B vitamins. 

Detecting Vitamin B Deficiency

If you experience any of the following symptoms, you may have a vitamin B deficiency.

  • Anaemia
  • Brittle hair and nails
  • Cardiovascular symptoms
  • Depression
  • Difficulty concentrating
  • Fatigue
  • Hair loss
  • Irritability
  • Nervousness
  • Short-term memory loss
  • Skin disorders
  • Upset stomach
  • Weakness
  • Weight loss

Regular occurrence of these symptoms may be an indicator of vitamin B deficiency. To overcome the same, you need to consume B complex vitamin supplements or foods that may help you fulfil your requirements. However, before we move to the foods, let us understand the components of B complex vitamins.

Components of B-Complex Vitamins

A batch of eight water-soluble vitamins forms B-complex vitamins. They are:

1. Vitamin B1/Thiamine

It helps in converting glucose into energy. It is also responsible for keeping the nervous system healthy. The body eliminates any excess vitamin B1 content through urine. 

2. Vitamin B2/Riboflavin

It helps convert carbohydrates, protein, and fats we get from our food to energy. 

3. Vitamin B3/Niacin

The body synthesise niacin from an amino acid called tryptophan. It is crucial for the digestion of protein, fats, carbohydrates, and alcohol to produce energy. Niacin is the only heat-stable vitamin from the B complex vitamins.

4. Vitamin B5/Pantothenic Acid

It helps break down carbohydrates, fats and proteins. It also helps form haemoglobin and steroid hormones in the body. An average adult should get 5 milligrams of vitamin B5 daily. Vitamin B5 supplements also help treat celiac disease, asthma, depression, insomnia, yeast infections, and leg cramps. 

5. Vitamin B6/pyridoxine

It helps boost immunity and the formation of blood cells. The gut bacteria of the large intestine synthesise B6 vitamins. However, the quantity is not sufficient enough to meet our daily requirements. So it is vital to obtain vitamin B6 through diet.

6. Vitamin B7/Biotin

It supports nails, skin, and hair. It also reduces blood sugar levels in people with diabetes. Dietary biotin is absorbed in the small intestine. During early pregnancy, mothers may experience mild vitamin B7 deficiency. So it is recommended to eat 30 micrograms of vitamin B7 per day. 

7. Vitamin B9/Folate

It stimulates the growth of red blood cells that carry oxygen throughout the body. The American FDA recommends pregnant women to consume Vitamin B9. Adequate intake of the B9 vitamin lowers the chances of giving birth to infants with disabilities. Folate is also essential for DNA replication and metabolism.

8. Vitamin B12/Cobalamin

As the name suggests, vitamin B12 contains cobalt. It plays a vital role in proper growth by creating new red blood cells. Cobalamin also enhances metabolic efficiency. Despite having a rich bioavailability, B12 insufficiency is relatively persistent. 

Vitamin B12 has an interdependent relationship with vitamin B9.

Benefits and Uses of Vitamin B Complex

All B vitamins help the body convert food into energy. All the components have their own unique set of health benefits. However, some of the typical functions and uses of B-complex vitamins are increasing energy, enhancing mood, improving memory, boosting skin and hair health, stimulating the immune system, and forming red blood cells.

1. Regulates Digestion

Your digestive system requires the essential vitamin B complex to function smoothly. It regulates multiple digestive tract mechanisms, including the breakdown of alcohols, fats, and carbs. In addition, thiamine, riboflavin, niacin, pantothenic acid and pyridoxine help digest carbohydrate, fat and protein.

2. Aids Weight Loss

Vitamin B12 deficiency can be one of the reasons for obesity in overweight individuals. However, a study shows that consuming adequate vitamin B12 lowers the chances of weight gain and obesity. Also, administering B12 vitamins helps the body to speed up the metabolism. As a result, it helps prevent excess fat accumulation. Moreover, vitamin B12 increases the release of metabolic enzymes, making it easier to reduce the body fat percentage.

3. Cell Repair and Regeneration

Different combinations of B complex vitamins improve wound healing. Research studies have found B complex vitamins’ role in repairing damaged cells. They help the body form new cells, replace dead or damaged cells, and maintain healthy skin cells. A diet rich in B vitamins may promote collagen synthesis and cell turnover. As a result, it may help in restoring skin texture.

4. Beneficial During Pregnancy

Vitamin B complex aids in foetal development during pregnancy. These B nutrients, especially Vitamin B9, play a critical role in developing a baby’s nervous system, spinal cord, and brain. Therefore, women expecting twins require extra doses of B complex vitamins. The intake of B12 and B9 supplements during pregnancy ensures the maintenance of the central nervous system.

A study ascertained that folate or vitamin B9 reduces the risk of neural tube congenital disabilities. Furthermore, regular consumption of 18 milligrams of vitamin B3 eases nausea and alleviates painful migraines for moms to be. Other benefits of vitamin B complex during pregnancy are:

  • Reduces the risk of preeclampsia
  • Prevents anaemia
  • Enhances placental growth
  • May help with morning sickness
  • Prevents low birth weight
  • Reduces pregnancy-related muscle cramps

5. Helps Relieve Premenstrual Syndrome

Some studies suggest that vitamin B6 may reduce premenstrual syndrome. Moreover, taking calcium and vitamin B6 together may reduce symptoms associated with PMS. These symptoms include bloating, fatigue, abdominal cramps, backache etc. It may also aid in lowering mood disorders such as anxiety and depression.

6. Regulates Sleep Cycle

Vitamin B6 acts as a stress buster. Studies show that it improves sleep by helping the body produce norepinephrine, melatonin, and serotonin. Melatonin is the sleep hormone and helps to regulate sleep. On the other hand, serotonin is considered the happy hormone. Therefore, the combined effects of serotonin and melatonin will reduce stress and help a person get sound sleep.

7. Improves Nerve and Brain Function

Studies prove that B complex vitamins play a significant role in the healthy functioning of the brain. These eight B complex vitamins help form and regulate compounds involved in maintaining brain function. Therefore, consuming adequate amounts can prevent symptoms such as depression, memory loss, dementia, etc.

8. Lowers Cholesterol Levels

Research studies show that folic acid may be beneficial in heart health. For example, it may help reduce bad cholesterol levels in the body. As a result, it aids in lowering the risk of heart diseases such as blockage of arteries and stroke.

9. Enhances Immune Functions

Multiple studies demonstrate the role of B complex vitamins in improving immune response in the body. For example, vitamin B6, B12 and folate help enhance antibodies’ production, prevent inflammation and strengthen immunity.

10. Helps Treat Mouth Ulcers

Studies prove that vitamin B12 may help manage canker sores or mouth ulcers. It also acts as an analgesic and aids in reducing the pain due to mouth ulcers.

While most people who eat a varied diet get enough B vitamins from food, some people are at an increased risk of deficiency, particularly:

  • People over 50 years of age
  • Pregnant or breastfeeding women
  • Following a vegan diet
  • Drink alcohol regularly

The National Institutes of Health (NIH) provides the following recommended daily intakes (RDI) for each of the eight B vitamins. Maintaining your RDI for B vitamins can help prevent deficiencies.

Recommended Daily Intakes (RDIs) for B Vitamins
MalesFemalesDuring pregnancyDuring breastfeeding
B1 (Thiamin)1.2 mg1.1 mg1.4 mg1.4 mg
B2 (Riboflavin)1.3 mg1.1 mg1.4 mg1.6 mg
B3 (Niacin)16 mg14 mg18 mg17 mg
B5 (Pantothenic acid)5 mg5 mg6 mg7 mg
B6 (Pyridoxine)1.3 mg1.5 mg1.9 mg2.0 mg
B7 (Biotin)30 mcg30 mcg30 mcg35 mcg
B9 (Folate)400 mcg400 mcg600 mcg500 mcg
B12 (Cobalamin)2.4 mcg2.4 mcg2.6 mcg2.8 mcg

Dietary Sources of B Vitamins

Vitamin B1 Sources ( Thiamine)

The best sources of vitamin B1 are whole grains such as brown rice, whole-wheat pasta, wholemeal bread, and oats. You can also get vitamin B1 through yeast extract, nuts, and pulses. 

  • Half a cup of boiled beans can supply nearly 27% daily required value of vitamin B1. 
  • More than 50% of vitamin B1 comes from fortified breakfast cereals. 
  • Meat, beef liver and steak have the highest B1 content. 

Vitamin B2 Sources ( Riboflavin)

Vitamin B2 sources are mostly organ meat and fortified foods. Foods high in vitamin B2 include eggs, avocados, almonds, pork, mushrooms, and beef. 

  • One hundred grams of fortified tofu contains 0.4 mg of vitamin B2. 
  • A six-ounce salmon fillet can fulfil nearly 64% of the vitamin B2 requirement. 
  • Additional sources are wild rice, low-fat milk, fortified soya milk, and breakfast cereals.

Vitamin B3 Sources ( Niacin)

Liver, tuna, and turkey are the best natural sources of vitamin B3. You can also get it from plant-based sections, brown rice, wild rice, muesli, quinoa, and peanuts. 

  • Nutritional data shows that two tablespoons of peanut butter provide more than 4 mg of B3. 
  • In addition to nuts, mushrooms and green peas are also rich in niacin.

Vitamin B5 Sources ( Pantothenic acid) 

Pantothenic acid or vitamin B5 is readily available in oranges, oatmeal, chestnuts, pork, beef, and eggs. 

  • One hundred grams of shiitake mushrooms supply almost 4 milligrams of vitamin B5. 
  • Sunflower seeds, especially the dry roasted variety, contain 7 milligrams of pantothenic acid per 100 grams. 
  • One hundred grams of salmon has 1.9 milligrams of vitamin B5. 

Vitamin B6 Sources ( Pyridoxine)

The healthiest vitamin B6 sources are pistachios, avocados, bananas, sunflower seeds, and milk. Dairy options include goat’s milk, ricotta cheese, and eggs. 

  • A single egg supplies 5% of the recommended values for vitamin B-6. 

Vitamin B7 Sources

You can get vitamin B7 from peanuts, oatmeal, sunflower seeds, pecans, and pistachios. However, you can get the recommended vitamin B7 by eating a varied diet. Nuts and seeds are popular vitamin B7 sources. Certain organ meats are also good dietary choices. 

  • Thirty grams of roasted almonds supplies 1.5 micrograms of folate. 
  • Around 75-80 grams of cooked beef provides more than 30 micrograms of vitamin B7.

Vitamin B9 Sources

Folate or vitamin B9 is abundant in legumes, asparagus, eggs, and leafy greens. Adding Brussels sprouts, broccoli, kale, lettuce, and cherry tomatoes will enhance the B9 vitamin levels in your daily diet. 

  • Thirty grams of raw spinach supplies 58 micrograms of folate. 
  • Besides green vegetables, per cup of beetroot contains 148 micrograms of vitamin B9. 

Vitamin B12 Sources ( Cobalamin)

Vitamin B12 is primarily present in dairy and meat products. Studies suggest that egg yolks possess higher vitamin B12 levels than egg whites. Plant-based foods have poor content of Vitamin B12.

As a result, people following the vegan or vegetarian diet may experience vitamin deficiency. Thus, these diets can get enriched with vitamin B12 by including fortified plant milk, yeast flakes, and dairy-free yoghurt.

Vitamin B Deficiencies: How Severe Can it Get?

Ignoring vitamin B deficiency may cause severe diseases. Here are some of the most common ones:


As the name suggests, beriberi or thiamine deficiency results from the depletion of vitamin B1. There are two variants of beriberi:

  • Wet Beriberi affects the circulatory system. In severe deficiency, it may result in heart failure.
  • Dry Beriberi targets the muscular and nervous systems. It begins by causing muscle weakness and results in muscle paralysis. If untreated, dry beriberi can become life-threatening.


Severe vitamin B3 deficiency leads to a systemic disease called pellagra. It is medically known as 4D’s- dementia, diarrhoea, dermatitis, and death. However, not all four symptoms are necessarily seen in people with pellagra. Pellagra may lead to hyperpigmented skin and diarrhoea. Today, developed countries ensure to supply niacin fortified rice and cereals to prevent pellagra.

Consuming almost 15-20 mg vitamin B3 prevents pellagra in all age groups. Niacin supplements are recommended for patients with severe disease progression. However, additional vitamin B complex supplements may be required to resolve the symptoms completely.

Riboflavin Deficiency

Riboflavin deficiency shows symptoms such as conjunctivitis, sore throat, lesions of lips, mucosa of the mouth, dry skin, etc. There are two types of deficiencies of riboflavin:

Primary riboflavin deficiency

It occurs due to poor food intake. Therefore, adding vitamin B2 rich food to the daily diet can help in preventing primary riboflavin deficiency.

Secondary riboflavin deficiency

It occurs due to other physiological conditions such as malabsorption of nutrients in the intestine or excretion of vitamins through urine. Even long-term use of barbiturates leads to secondary riboflavin deficiency. Therefore, people with this condition should consume oral riboflavin supplements.

Megaloblastic Anaemia

Vitamin B12 deficiency can lead to megaloblastic anaemia. The bone marrow produces large, irregularly shaped red blood cells in this condition. Due to this irregular shape, there is an increase in blood pressure.

People with type 2 diabetes who use metformin to treat insulin resistance have a high risk of getting vitamin B12 deficiency. As a result, they are more prone to have megaloblastic anaemia. The general treatment approach includes oral supplements and B12 injections. However, regular consumption of vitamin B12-rich or fortified foods can help reduce the risk of megaloblastic anaemia in diabetics.

Potential Toxicities of Vitamin B Complex Supplements

Vitamin B complex toxicity occurs from the overconsumption of B vitamins for an extended period.

Vitamin B1 Toxicity

Limited reports have been presented regarding thiamine overdose as it is unlikely to reach the toxic levels from food sources. However, studies have found that toxicity from ​thiamine hydrochloride​, a synthetic B1 vitamin, causes allergic reactions. Experiencing digestive distress is common among people showing intolerance towards vitamin B1 supplements. 

Probable side effects of synthetic vitamin B1 include:

  • Diarrhoea
  • Vomiting
  • Gastrointestinal irritation
  • Skin and eye irritation
  • Spastic paralysis

Vitamin B3 Toxicity 

The tolerable upper intake level for B3 vitamins from diet and supplements combined is 35 mg. If you consume more vitamin B3 than the tolerable level, it may lead to toxicity. It influences the nervous system and induces maculopathy, a rare toxic reaction. Thus, ophthalmologists restrict B3 supplements to prevent potential eye structure damages. 

Symptoms of vitamin B3 toxicity include:

  • Flushing of the skin 
  • Signs of liver toxicity 
  • Itching 
  • Vomiting 
  • Dry skin 
  • Nausea 
  • Skin rash 
  • Headache

Vitamin B6 Toxicity

Excessive vitamin B6 intake leads to B6 or pyridoxine toxicity. Moreover, studies show that it predominantly arises from high-level vitamin B6 supplementation, not through diet. Consuming large doses of vitamin B6 for a long time affects overall vitamin B complex levels​ in the blood. Vitamin B6 toxicity causes severe nerve damage. Abnormal consumption may accumulate B6 vitamins in the red blood cells, muscles, plasma, and liver. 

Chronic administration of this B complex vitamin results in neurological symptoms, dermatological lesions, heartburn, and nausea.

Vitamin B7 Toxicity

Side effects from biotin or vitamin B7 toxicity can be hazardous. Biotin is relatively safe when consumed in an adequate amount. However, research suggests that B7 poisoning causes excessive urination. In addition, it can overburden the kidneys.

Other potential side effects from biotin toxicity or overdose include:

  • Alterations in insulin release
  • Skin rashes
  • Interference with the liver functioning 
  • Digestive distress
  • Elevates blood sugar levels that can be dangerous to diabetic people
  • Too much vitamin B7 lowers vitamin C levels and weakens the immune system.


B complex vitamins participate in multiple essential roles in the human body. Therefore, ensuring adequate intake of vitamin B while maintaining a healthy diet is vital. All the eight B-complex vitamins B1, B1, B3, B5, B6, B7, B9, and B12 may seem similar and share common functions. However, every vitamin has a significant function and different chemical compositions. Therefore, they are safe to consume as long as you follow the recommended daily intake and tolerable upper intake levels. Overdosage may lead to potential toxicity and complications. 

Frequently Asked Questions (FAQs)

Q. What is vitamin B complex used for?

A. Vitamin B complex is used for maintaining proper health and immunity. Vitamin B6 and B12 are used to promote collagen synthesis and cell turnover. Furthermore, people utilise B vitamins to reduce stress and prevent infections. 

Q. Is it good to take B complex every day?

A. Yes, daily intake of B complex vitamins promotes healthy metabolism and increases blood cells’ formation. They also aid in cell functions and enhance the immune system. However, you should only take them in recommended amounts. Overdose of B complex leads to poisoning or toxicity. 

Q. What is the difference between vitamin B and vitamin B complex?

A. There are 8 B vitamins. While each of these vitamins is called vitamin B individually, they are known as B complex vitamins.

Q. Does B complex make you gain weight?

A. No, intake of vitamin B complex does not make you gain unwanted weight. Taking vitamin B12 supplements or injections assist in weight loss rather than weight gain. Adding B complex vitamins to a daily diet helps you regain muscle strength and muscle mass. It is not the same as weight gain. 

Q. Can I take vitamin C and B complex together?

A. There are no detrimental interactions between vitamin C and B complex. So, it is safe to take them together. Furthermore, since these two vitamins are water-soluble, they do not stay long in the body to cause any unwanted effects. Moreover, a combination of vitamin C and B complex is beneficial for treating severe deficiency caused by poor diet. 

Q. What are the signs of vitamin B complex deficiency?

A. The common signs of B complex deficiency include pale skin, fatigue, appetite loss, malabsorption, lightheadedness, diarrhoea, and hyperpigmentation. 

Q. Does the B complex give you energy?

A. No, the B complex does not act as a fuel for energy. It only supports the necessary metabolic process to prevent fatigue. However, a B complex deficiency leads to a drop in body energy levels. 

Q. When should the B complex be taken?

A. You can consume b complex supplements in the morning. It helps make you feel energised throughout the day and improves metabolism.

Q. Will vitamin B complex help me sleep?

A. Vitamin B6 has positive effects in regulating the sleep cycle by promoting melatonin production. Since melatonin is a sleep hormone, it will help you fall asleep. 

Q. Can I take the B complex at night?

A. It is recommended to take B complex early morning to maximise its absorption. However, taking them at night may alter sleeping patterns.

Q. Can I take the B complex twice a day?

A. The dosage of B complex depends on your needs and health status. Usually, you should take it once daily to prevent overdose. However, people with severe deficiencies require multiple doses of different B vitamins. Therefore, it is advisable to follow the dosage prescribed by a medical health professional.

Q. Will B-complex help me lose weight?

A. Yes, especially vitamin B12 aids with weight loss. It increases metabolism and prevents unwanted fat deposition. A healthy metabolism will eventually help to shed weight. 

Q. Can I take the B complex on an empty stomach?

A. Yes, you can take most B complex supplements on an empty stomach. You can consume it one or two hours before your meal. If stomach discomfort occurs from this method, it’s advised to take it along with food. 

Q. Does B Complex increase BP?

A. Adequate levels of B complex does not raise BP (Blood Pressure). However, thiamine or vitamin B1 overdose leads to hypertension or high blood pressure. 

Q. Is vitamin B complex good for hair?

A. B complex vitamins, especially biotin, promote hair growth. It improves blood flow towards the scalp and nourishes the hair follicle. 

Q. Is vitamin B complex good for skin?

A. Vitamin B12 and B6 help create new cells or regenerate dead or damaged skin cells. Most of the B complex vitamins help with skin cell turnover and collagen synthesis as well. 

Q. Is B12 bad for high blood pressure?

A. There is an inverse relationship between B12 and blood pressure. Higher the intake of B12, lower the blood pressure. So you must take B12 in recommended quantities to maintain blood pressure balance. 

Q. How much vitamin B should a diabetic take?

A. They should take it according to their current blood glucose levels. Normally it is advised to take no more than 2.4 micrograms per day. 

Q. Can I take the B complex with metformin?

A. There is no chemical interaction between the B complex and metformin. However, metformin tends to reduce the absorption of vitamin B12 without directly interacting with the vitamin. Therefore, you should consult a doctor before combining medications with supplements. 

Q. What vitamins should diabetics avoid?

A. Diabetics should avoid niacin or vitamin B3 because it directly affects blood sugar levels and causes fluctuations. In addition, an insulin spike is not ideal for diabetics. 

About the Author

Parul holds a Masters of Medical Science in Public Health Nutrition from the University of Glasgow, Scotland, and has worked across the globe from the U.K to New Zealand (NZ) gaining her License with the Health Professionals Council (HPC, UK) and the NZ Nutrition Council. From being a Gold medalist in Clinical Nutrition to being awarded an internship with World Health Organisation (WHO, Cairo, Egypt) and Contracts with CDC Parul has had a wide spectrum of work experiences. She is very passionate about Nutrition and Fitness and holds strong to her guiding mantras ‘ Move more’ and ‘Eat Food that your grandmother can recognize’!

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