Complex B: Components, Side Effects, Administration, Interactions, Recommendations and Natural Sources

Refers to all known essential water-soluble vitamins except vitamin C.

These vitamin complexes include thiamine, riboflavin, niacin, pantothenic acid, pyridoxine, biotin, folic acid and cobalamins.

“Vitamin B” was once thought to be a unique nutrient.

The researchers later discovered that these extracts contained several vitamins, which were given distinctive numbers, leading many people to the erroneous conclusion that these vitamins have a special relationship between them.

In addition to the confusion has been the “unofficial” designation of other non-essential vitamins, such as members of the B complex, such as choline, inositol and para-aminobenzoic acid.

Each member of the B complex has a unique structure and performs unique functions in the human body.

Vitamins B1, B2, B3 and biotin are involved in different aspects of energy production, vitamin B6 is essential for the metabolism of amino acids and vitamin B12 and folic acid facilitate the steps necessary for cell division.

Each of these vitamins has many additional functions, although none require all of the B vitamins simultaneously.

The human requirements for each vitamin B vary considerably, from 3 mcg per day of vitamin B12 to 18 mg per day of vitamin B3 in adult men.

Therefore, taking equal amounts of each, as provided in many B-complex supplements, makes little sense.

Megadoses of B vitamins, sometimes taken to combat daily stress, increase energy or control food cravings, do not seem to offer benefits unless a person is deficient in one or more of them.

Most multivitamin products contain the B complex along with the rest of the essential vitamins and minerals.

Because they are more complete than B-complex vitamins alone, multiple vitamin and mineral supplements are recommended to improve total micronutrient intake and prevent deficiencies.

Some brands of B vitamins also contain ingredients such as vitamin C, vitamin E, biotin or zinc.


B vitamins are a class of water-soluble vitamins that play an important role in cellular metabolism.

Although these vitamins share similar names, research shows that they are chemically distinct vitamins that often coexist in the same foods.

In general, dietary supplements that contain the eight vitamins are known as a vitamin B complex.

Individual vitamin B supplements are known by the specific number or name of each vitamin: B1 = thiamine, B2 = riboflavin, B3 = niacin, etc.

Some are better known by their name than the number: niacin, pantothenic acid, biotin and folic acid, etc.

Vitamin B1

Vitamin B1 or thiamine is a coenzyme that acts in the catabolism of sugars and amino acids.

Thiamine plays a central role in the release of energy from carbohydrates. This enzyme is involved in the production of DNA and RNA, as well as in nerve function.

Its active form is a coenzyme called thiamine pyrophosphate (TPP), which participates in the conversion of pyruvate to acetyl coenzyme A (CoA) in the metabolism.

Vitamin B2

Vitamin B2 or rivoflavin is involved in the release of energy in the electron transport chain, the citric acid cycle and the catabolism of fatty acids (beta oxidation).

Vitamin B3

Vitamin B3 or niacin is a precursor of coenzymes called NAD and NADP, which are needed in many metabolic processes.

Niacin is composed of two structures: nicotinic acid and nicotinamide.

There are two coenzyme forms of niacin: nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP).

Both play an important role in the reactions of energy transfer in the metabolism of glucose, fat and alcohol.

It transports hydrogens and their electrons during metabolic reactions, including the citric acid cycle path to the electron transport chain.

Nicotinamide adenine dinucleotide phosphate is a coenzyme that contributes to the synthesis of lipids and nucleic acids.

Vitamin B5

This vitamin also known as pantothenic acid is involved in the oxidation of fatty acids and carbohydrates.

Coenzyme A, which can be synthesized from pantothenic acid, participates in the synthesis of amino acids, fatty acids, ketone bodies, cholesterol, phospholipids, steroid hormones, neurotransmitters (such as acetylcholine ) and antibodies.

Vitamin B6

Pyridoxine, pyridoxal, pyridoxamine are names given to this vitamin that serves as a cofactor in many enzymatic reactions mainly in the metabolism of amino acids, including the biosynthesis of neurotransmitters.

Vitamin B7

Vitamin B7 also called biotin plays a key role in the metabolism of lipids, proteins and carbohydrates.

It is a coenzyme criticism of four carboxylases: acetyl CoA carboxylase, which participates in the synthesis of fatty acids from acetate.

CoA carboxylase pyruvate, involved in gluconeogenesis; β-methylcrotonyl CoA carboxylase, involved in the metabolism of leucine; and propionyl CoA carboxylase, which participates in the metabolism of energy, amino acids and cholesterol.

Vitamin B9

Vitamin B9, folate or folic acid acts as a coenzyme in the form of tetrahydrofolate (THF), which participates in the transfer of single carbon units in the metabolism of nucleic acids and amino acids.

THF is involved in the synthesis of pyrimidine nucleotides, so it is necessary for normal cell division, especially during pregnancy and childhood, which are times of rapid growth.

Folate also helps in the production of red blood cells and erythropoiesis .

Vitamin B12

Vitamin B12 or cobalamin is involved in the cellular metabolism of lipids, proteins and carbohydrates. It is essential in the production of blood cells in the bone marrow.

Vitamin B12 functions as a coenzyme in the intermediary metabolism for the reaction of methionine synthase with methylcobalamin and the reaction of methylmalonyl CoA mutase with adenosylcobalamin.

How to take the B complex?

Take it as prescribed by your doctor. Do not take it in quantities or doses out of the prescribed or for more than the recommended time.

Avoid taking more than one multivitamin at the same time unless your doctor tells you to.

Taking similar multivitamins simultaneously can cause serious side effects and even an overdose.

Many multivitamin products also contain minerals such as calcium, iron, magnesium, potassium and zinc.

It is important to always read the label of any medication that is prescribed to make sure of what it contains.

Take your pill or syrup with a full glass of water.

Place the sublingual tablet under your tongue and allow it to dissolve completely. Do not chew a sublingual tablet or swallow it whole.

The liquid medication should always be measured with a dispenser. If you do not have any element to measure the dose you should ask your pharmacist for one.

Store at room temperature away from moisture and heat. Avoid if the medication is liquid, it freezes.

Store multivitamins in their original container. Storing multivitamins in a glass container can damage the medication.

Do not use a spoon for domestic use. Some liquid products should be shaken before each dose.

Take this medication regularly to get the most benefit from it. Take it every day at the same time to make it easier to remember.

In case of overdose seek emergency medical attention. An overdose of any type of vitamins can put life at risk.

Side effects

It may cause stomach upset or mild redness.

The side effects caused by the intake of the multivitamin are generally temporary and may dissipate as your body adjusts to the medication.

If any of the side effects continue or get worse, you should contact your doctor or pharmacist immediately.

Remember that if your doctor has indicated you take this medication it is because he or she established that the benefit to you is greater.

Most people who take this medication do not have any symptoms or side effects.

A very severe adverse reaction is rare.

However, seek immediate urgent medical attention if you notice any symptoms of an allergic reaction, including: severe dizziness, itching or swelling (especially of the face, tongue or throat), difficulty breathing or a rash.

Common side effects

  • Black spots.
  • Constipation.
  • Diarrhea.
  • Severe abdominal pain.

RARE side effects

  • Broncoespasmo.
  • Confusion
  • Gases.
  • Itch.
  • Loss of appetite
  • Discomfort.
  • Overexcitement
  • Acne.
  • Redness of the skin.
  • Sleep disorder
  • Swelling of the abdomen
  • Problems to perceive flavors.
  • Depression .
  • Ease to get angry.


Before taking this product, you should tell your doctor if you are allergic to any of its components or to any other medication.

This product may contain inactive ingredients that can cause allergic reactions or other problems.

If you have any type of health problem such as hypertension , diabetes, anemia, liver problems, etc. inform your doctor.

Chewable tablets or liquid products may contain aspartame.

If you suffer from phenylketonuria (PKU) or any other medical condition that restricts the use of phenylalanine or aspartame, consult your pharmacist for more details at the time of taking it.

Liquid forms of this product may contain alcohol or sugar, which is why caution is recommended if you are diabetic or suffer from liver disease.

Tell your doctor about your pregnancy or if you suspect you are pregnant before taking the multivitamin.

This medication can be taken safely during pregnancy if the indications are followed.

Certain congenital defects can be avoided by maintaining adequate amounts of folic acid during pregnancy.

This product is mixed with breast milk. While there have been no reports of harm to infants, check with your doctor if you are going to breastfeed or are in process.


If you are taking this product under your doctor’s direction, your doctor or pharmacist may already be aware of any possible interaction with other medications and may be monitoring you.

Do not change, start or eliminate the dosage of any medication before consulting with a health professional first.

Before you start taking this product, you should inform your doctor about all prescription and over-the-counter medications you are taking, especially: cisplatin, levodopa, altretamine, antibiotics, anticonvulsant medications, or other vitamins or nutritional supplements.

This product may hinder certain laboratory tests, possibly causing false test results.

You must record the authorized personnel who are testing you and your doctor, who is taking the multivitamin.


You should call in emergencies if a case of overdose occurs or serious symptoms appear.

Another option in these cases can be to call a poison control center immediately.

Symptoms of overdose may include stomach pain, vomiting, diarrhea, constipation, loss of appetite, hair loss, peeling, tingling in or around the mouth.

Also changes in menstrual periods, weight loss, severe headache, muscle or joint pain, severe back pain, blood in the urine, pale skin, and bruising or bleeding.


Always stay in touch with your doctor and go to all the consultations.

This product is not a substitute for a proper diet. Remember that it is best to get your vitamins from healthy foods.

B vitamins are found naturally in green leafy vegetables and other vegetables, meat, fish, poultry, bread and enriched cereals.

Missed dose

If you are taking this product on a regular schedule and skip a dose, take it as soon as you remember.

If you are near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Never take more than the prescribed dose to catch up.


  • Check the information about the storage of the product that is in the package.
  • Keep all types of medications out of the reach of children and pets.
  • Avoid taking medicines to the toilet or in the drain unless it is indicated.

Natural foods vitamin B containers

Vitamin B1

Foods fortified with vitamin B1 include cereals, rice, wheat, and flours.

In addition, you can have multigrain bread, fortified cereals, whole wheat pasta, legumes or lentils such as green soybeans, red lentils and chickpeas, since they are loaded with vitamin B1.

You can also eat red beans, dark green leafy vegetables such as spinach, asparagus, fenugreek, lettuce and cabbage.

Some other items that have vitamin B1 are soy foods, pork, fish, eggs, milk, meat, ham, nuts and whole grains such as wheat germ.

Vitamin B2

The best sources of riboflavin or vitamin B2 include eggs, chicken, fish, legumes (such as peas and lentils).

In addition, milk and dairy products such as yogurt and cheese, nuts are loaded with vitamin B2.

You can also add green leafy vegetables such as spinach, broccoli, asparagus and fortified cereals to your diet and meet the necessary requirements of riboflavin.

Vitamin B3

Vitamin B3 or niacin is found in chicken and salmon. In addition to these, tuna is an excellent source of niacin.

And for vegetarians, they can opt for legumes, whole grains and whole wheat as a source of niacin.

Vitamin B5

To meet the requirements of vitamin B5, include avocados, broccoli, kale, meat, whole grains, potatoes, eggs and legumes to your daily diet.

Vitamin B6

Foods such as potatoes, eggs, beans, red meat and fortified cereals contain a large amount of vitamin B6.

Vitamin B7

The richest dietary sources of biotin include the liver and egg yolks. Avocado, salmon and pork are other good sources of biotin.

Vitamin B9

Green leafy vegetables such as spinach, fenugreek, green turnip and asparagus are high in folate.

You can also look for fresh fruits and vegetables that are excellent sources of folic acid. For example, liver, legumes, dried beans and fresh orange juice.

In addition, fortified bread, cereals and rice are loaded with folic acid.

Vitamin B12

Natural sources of vitamin B12 are found in fish, red meat, eggs, poultry, milk, dairy products and cheese.

Soy products and cereals are also high in vitamin B12.