Complex B Vitamins: Characteristics, Benefits, and Functions

In the past, specialists thought that it was only one vitamin, but today we know that vitamin B is formed of 8 different substances. These work together to help the body to develop multiple functions.
Complex B Vitamins: Characteristics, Benefits, and Functions
Anna Vilarrasa

Written and verified by the nutritionist Anna Vilarrasa.

Last update: 27 May, 2022

Complex B vitamins are a wide group of substances, not just one. That’s to say, there are actually 8 different micronutrients that play a very important role in absorbing energy from food.

The majority of healthy people meet their daily needs through food. However, in some situations, taking supplements that contain everything may be necessary and beneficial. In this article, we discuss the key uses, recommendations, and dosages of the B group vitamins.

What are complex B vitamins?

Vitamins are substances that the body needs to grow and develop in a normal way. In contrast to macronutrients, they don’t provide energy and we only need them in small quantities, but a deficit can lead to disorders and even some illnesses.

Specialists have identified a total of 8 components within this group of B vitamins. However, there are a great number of substances that we used to give the same name to, but, today, we don’t consider them to be vitamins. Examples of this would be inositol, carnitine, or amygdalin.

This group of B vitamins develops important bodily functions on a cellular metabolic level. They’re hydrosoluble, as the body eliminates the excess through urine and there’s no possibility to store them. Therefore, as a result, it’s necessary to replenish the amount daily.

Some sources of vitamin B.
Complex vitamin B has varied bodily functions. It helps every part of the body, from the blood to the nervous system.

Complex B vitamins and their functions

Today, we believe there to be a total of 8 vitamins within this group. The food supplements that contain these vitamins provide specific quantities of each. Here’s a quick list of their key functions:

  • B1 or thiamine: vital for the growth and correct functioning of organs like the brain or heart.
  • B2 or riboflavin: highlighted for its antioxidant capacity and the role it plays in removing drugs and toxins.
  • B3 or niacin: works collaboratively in the correct function of the enzymes. It helps the body to prepare DNA and has important functions in the digestive, nervous, and dermic systems.
  • B5 or pantothenic acid: highlighted for its role in hormone and cholesterol synthesis. It’s essential for the health of the brain and the nervous system.
  • B6 or pyridoxine: helps the body to create new red blood cells and to maintain the immune system.
  • B7 or biotin: promotes the growth of some tissue like the bones, hair, and nails.
  • B9 or folic acid: the body uses it to create genetic material like DNA. In pregnancy, it reduces the risk of congenital defects in the brain and spinal column.
  • B12 or cobalamin: works collaboratively to maintain the nervous system and it’s necessary for the creation of red blood cells.

Dosage and commercial presentation

In complex B vitamin supplements, all 8 substances are usually present. However, it’s also possible to find each substance on its own in a supplement. The most common way to take them is in tablet form.

The daily requirements for minerals and vitamins are established by specialist bodies. Although, on some occasions, they can differ a little depending on the region or country consulted. The recommended daily intake (RDI) ensures that we receive the necessary amount and avoid deficiency-related illnesses. The Office of Dietary Supplements establishes the following for B vitamins:

B1  1.2 mg  1.1 mg  1.4 mg  1.4 mg
B2  1.3 mg  1.1 mg  1.4 mg  1.6 mg
B3  16 mg  14 mg  18 mg  17 mg
B5  5 mg  5 mg   6 mg  7 mg
B6  1.3 mg  1.5 mg  1.9 mg  2 mg
B7  30 mcg030 mcg  30 mcg  35 mcg
B9  400 mcg  400 mcg  600 mcg  500 mcg
B12  2.4 mcg  2.4mcg  2.6 mcg  2.8 mcg

Some supplements help us obtain our daily needs. However, others provide much higher dosages. Although they can be useful in some cases, it’s always best to consult a medical professional before you take them.

Uses and benefits of complex B vitamins

This group of micronutrients develops a great number of essential functions within the body. But taking supplements of complex B vitamins can also provide benefits for our health. Let’s take a look at these scientifically-backed specific uses.

Mood, anxiety, and stress

Generally, we’re becoming more aware of the fact that a person’s nutritional status has an important impact on neurological and psychiatric disorders. Some nutrients provide a positive effect on this, as proved in a systematic review of the effect of B vitamin supplements on the mood.

Moreover, studies show that B vitamins can benefit the mood of healthy individuals just as much as those at risk. The effects are clearest in cases of stress and depression. However, these positive effects haven’t yet been found in trials with anxiety.

Topical application for wounds and injuries

Specialists have investigated the effects of applying complex vitamin B on wounds and injuries due to the role it plays in developing epithelial cells. Certain combinations of B vitamins demonstrate a positive influence, and applying it locally can aid the physiological process of curing wounds.

Contraindications and side effects

Given that group B vitamins don’t accumulate in the body, it’s difficult to take amounts that can be toxic through food. It’s also safe to take supplements providing you follow the instructions and respect the recommended dosage. With that said, before adding any food supplement to your diet, it’s best to speak to a specialist.

In some cases, you may experience side effects. According to data from the European Food Safety Authority, the following are the possible harmful effects of taking B vitamins:

  • Taking very high doses of B6 over a prolonged period of time can lead to neuron damage.
  • Bear in mind that folate supplements can mask symptoms of a B12 deficit. As a result, it can be more difficult to get a good diagnosis.
  • Pantothenic acid in high doses can produce diarrhea.
  • Some forms of B3 (nicotinamide and nicotinic acid) increase the blood sugar level, causing hypotension, fatigue, or hepatic problems.
Vitamin b1 in food.
Complex B vitamins are hydrosoluble because they’re expelled daily from the body through the urine.

The B vitamin group is sometimes useful in supplements

To maintain a good state of health, you can include complex B vitamins in your diet by consuming leafy greens, nuts, pulses, lean meats, eggs, and mushrooms. If you suffer from some illness or absorption problem, as is common in pregnancy, latency, or old age, it may be necessary to include supplements in your diet.

Furthermore, you can begin to take B vitamin supplements to combat certain health problems. However, it’s important to consult a specialist before you start doing so, as they can advise you which is the best one for you. Another important point to remember is you should never exceed the specific dose as recommended by the manufacturer.

All cited sources were thoroughly reviewed by our team to ensure their quality, reliability, currency, and validity. The bibliography of this article was considered reliable and of academic or scientific accuracy.

    • Rembe J.D. Effects of Vitamin B Complex and Vitamin C on Human Skin Cells: Is the Perceived Effect Measurable? Advances in Skin and Wound care. Mayo 2018. 31(5):225-233.
    • Scientific Committee on Food. Scientific Panel on Dietetic Products, Nutrition and Allergies. Tolerable upper intake levels for vitamins and minerals.
    • Mayola, Rogelio Sánchez, Fernando A. Díaz Mizos, and Venerando Sevilla Pérez. “Anemia sideroblastica. Presentacion de tres casos.” MediCiego 3.2 (2002).
    • Young LM, et al.  A Systematic Review and Meta-Analysis of B Vitamin Supplementation on Depressive Symptoms, Anxiety, and Stress: Effects on Healthy and ‘At-Risk’ Individuals. Nutrients. Septiembre 2019.11(9):2232.
    • Ortigoza Escobar, Juan Darío. “Estudio de defectos en el transporte y el metabolismo de tiamina asociados a encefalopatías recurrentes en la infancia.” (2017).
    • Ríos-Flórez, Jorge Alexander, and Claudia Rocío López-Gutiérrez. “Secuelas Neurofuncionales por déficit de Cobalamina (vitamina B12) en un adulto joven: Estudio de caso.” Revista Chilena de Neuropsicología 12.1 (2017): 40-47.
    • Maria, Carlos Alberto Bastos de, and Ricardo Felipe Alves Moreira. “A intrigante bioquímica da niacina: uma revisão crítica.” Química Nova 34.10 (2011): 1739-1752.

This text is provided for informational purposes only and does not replace consultation with a professional. If in doubt, consult your specialist.