What exactly is vitamin B?
Vitamin B1 was discovered before the B-vitamin complex. In fact, at the beginning of the 20th century, a doctor linked vitamin B1 deficiency to beriberi. In the past, beriberi was a very serious disease, widespread in Asia and diagnosed in populations whose diet consisted exclusively of polished rice, even though the rice bran was very rich in vitamin B1. The discovery of the other B vitamins continued until 1945.
This B-vitamin complex refers to the following 8 vitamins: B1 or thiamine, B2 or riboflavin, B3 or niacin, B5 or pantothenic acid, B6 or pyridoxine, B8 or biotin, B9 or folic acid, and B12 or cobalamin.
They are all water-soluble, meaning they dissolve in water. Therefore, they cannot be stored or kept in reserve by the body and are excreted in the urine. This is why it is essential to consume them every day, particularly through food. A balanced and varied diet is normally able to provide all these vitamins in sufficient quantities. Of the 8 vitamins, there are 2 exceptions: vitamin B3, which is produced in small quantities by our body, and vitamin B12, which can be stored in certain organs.
They are all necessary for the proper functioning of the body and cells, but each has its own specific role and different daily requirement. They are used independently of one another because combining all these B vitamins does not have any particular therapeutic indication. Nevertheless, they were grouped together because they are fairly similar at the molecular level.
They are found in many foods of both animal and plant origin. Animal products are often richer in them and sometimes contain a form that is more easily absorbed by the body than that found in plant products. The form of vitamin B12 that can be absorbed by the body is found only in animal sources. Vegans must therefore turn to dietary supplements to avoid deficiencies.
Organ meats, nuts, seeds, and yeasts (brewer's and nutritional yeast) are particularly rich in them. Other sources include meat and fish, eggs, dairy products, whole grains, green vegetables (spinach, leeks, zucchini, Brussels sprouts, lamb's lettuce, asparagus, …), pulses (lentils, chickpeas, …), almonds, fruit (oranges, lemons, kiwis, …), wheat germ, mushrooms, potatoes, …
What roles do these B vitamins play?
This group of vitamins plays an essential role in maintaining our health, particularly by acting at the level of the body's cells. An adequate intake of B vitamins is necessary to boost our physical and mental performance and reduce both physical and mental fatigue.
As you will have understood, B vitamins are involved in many functions, including:
- Energy metabolism: acting as coenzymes, they help release energy in the body. They play a key role in the metabolism of carbohydrates, proteins, and fats and therefore actively contribute to energy production in the body.
- Cell growth: they ensure cell reproduction and thus promote the healing process.
- Immunity: they also play a role in immunity by contributing to the normal functioning of the immune system.
- The nervous system: they participate in the transmission of nerve impulses and the transport of oxygen to cells, thereby helping maintain the balance of the nervous system and stimulate mental performance. As a result, they may help combat mood disorders and prevent the risk of severe fatigue and burnout.
- Muscles: they help us maintain healthy muscles by supporting the conversion of glucose into glycogen within our muscle mass.
- Red blood cells: they contribute to the formation of red blood cells and may help combat certain blood disorders.
- DNA: they play a role in the synthesis and formation of genetic material (DNA and RNA).
- Hormones and neurotransmitters: they contribute to the synthesis of sex hormones and neuromediators such as neurotransmitters involved in mood (serotonin, melatonin, and dopamine).
- Vision: they stimulate the vision mechanism and help maintain good visual capacity.
- Skin and hair health: they help maintain healthy skin and strengthen hair.
What are the recommended intakes?
As explained above, most B vitamins are neither stored nor synthesized by the body in sufficient quantities. This is why regular consumption is recommended, as an adequate intake of B vitamins contributes in particular to optimal energy production. Recommended nutritional intakes for B vitamins vary according to age, sex, and the type of vitamin. These amounts also depend on your physiological condition. In particular, pregnant and breastfeeding women have higher needs than the ANRs defined for adults.
Here are the ANRs 1 for adults:
- Vitamin B1 – Men: 1.2 mg/day and Women: 1.1 mg/day
- Vitamin B2 – Men: 1.3 mg/day and Women: 1.1 mg/day
- Vitamin B3 – Men: 16 NE2 and Women: 14 NE2
- Vitamin B5 – Women and Men: 5 mg/day
- Vitamin B6 – Women and Men: 1.3 mg/day, then between 1.5 and 1.7 after age 50
- Vitamin B8 – Women and Men: 30µg/day
- Vitamin B9 – Women and Men: 400 DFE3
- Vitamin B12 – Women and Men: 2.4µg/day
1 Recommended nutritional intake
2 Niacin equivalent
3 Dietary folate equivalent
Deficiency or overdose?
Nowadays, the risk of B-vitamin deficiency is low and has become rare, since a varied and balanced diet is sufficient in most cases to meet the need for each of them. However, in certain situations, such as a poor diet or certain health problems (Crohn's disease, …), it may not provide sufficient quantities. In this case, to combat a deficiency, it will be necessary to turn to dietary supplements to reach the recommended dosage. The main symptoms of B-vitamin deficiency are cardiac and neurological disorders, inflammation of the skin and mucous membranes, loss of appetite and weight loss, digestive problems, fatigue, headaches, nausea, numbness and tingling, dizziness, mood disorders, and depressive states.
In certain situations, it is possible to reach excessively high levels of B vitamins. Although this is very difficult to achieve, it can have adverse effects on health. Excessive consumption of vitamin B3 may in particular cause flushing (hot flashes), accompanied by stomach aches, itching, migraines, and hyperglycemia. Overdoses of vitamins B9 and B6 may respectively cause digestive disorders and nervous system conditions (neuropathy). This is why a maximum level has been set for 3 vitamins.
The tolerable upper intake levels for adults are:
- Vitamin B3 – 35 mg
- Vitamin B6 – 100 mg
- Vitamin B9 – 1 000 µg
