Presentation

A vitamin B complex contains 8 water-soluble vitamins (B1, B2, B3, B5, B6, B8, B9, B12) involved in important physiological processes, including energy production.

Each of them has a specific function, which you can read about in the articles dedicated to each nutrient.

They all need to be consumed regularly in the diet. They are mainly found in the same plant food groups (wholemeal cereals, green vegetables, nuts, etc.).

However, these plants are often lacking in modern diets. This can lead to deficiencies. Excessive alcohol consumption can exacerbate deficiencies.

Some of them have common and complementary functions and can be consumed in particular by people under particular stress.

The activity of the B9-B12-B6 group has been the most studied. They are particularly involved in homocysteine metabolism. The activity of the other forms has been studied very little. However, the functions of the eight B vitamins are closely interrelated.

A significant proportion of the population in developed countries suffer from deficiencies or insufficiencies of these nutrients. In the absence of an ideal diet, supplementation may be considered to maintain brain health.

In fact, a complex of B vitamins and minerals taken in high doses has been shown to improve physical and mental well-being in healthy and diseased populations.

Men and women have different plasma levels. The levels of vitamins B1, B3, B5 and B6 are higher in men.

Properties and virtues

Gut microbiota

A complex of B vitamins is essential for the balance of the microbiota because of their close relationship with the bacteria in the gut.

They are mainly absorbed in the small intestine, where they perform many functions:

• Regulate the activity of immune cells
• Enable certain bacteria to survive
• Help eliminate pathogenic bacteria
• Modulate the body's response to certain types of bowel inflammation (colitis)

Depression, anxiety and stress

A vitamin B complex also has many mental health benefits. It can help with depression, stress and anxiety. It may also be beneficial for other psychiatric conditions.

The balance of the gut microbiota strongly influences mental health. Its role in balancing the microbiota may be partly responsible for its beneficial effects on mental disorders. B1, B3, B6, B9 and B12 are essential for neuronal function. Deficiencies have been linked to depression.

A moderate intake of thiamine (B1), niacin (B3) and pantothenic acid (B5) can reduce anxiety.

Pyroxy acid (B6) helps reduce stress.

Biotin (B8) is associated with a lower risk of depression, especially in women.

Moderate intake of folic acid (B9) is associated with a lower risk of depression.

A deficiency of these nutrients may be involved in the aetiology of mental disorders. Adequate intake may have a protective effect against these disorders, and in some cases supplementation is effective.

Cognition and neurodegenerative diseases

A vitamin B complex supplement can have many benefits for cognitive function in people without dementia.

Deficiencies are found in neurodegenerative diseases and cognitive decline; vitamins B1, B6, B9 and B12 are involved. However, their effects on cognition and degenerative diseases are still poorly understood.

According to a meta-analysis conducted in 2020, supplementation for more than 12 months would reduce cognitive decline, but a meta-analysis from the same year showed no positive results.

The nervous system

Thiamine (B1), pyridoxine (B6) and cobalamin (B12) contribute in different ways to proper neuronal function in the peripheral nervous system:

• B1 acts as an antioxidant
• B6 balances nerve metabolism
• B12 maintains the myelin sheath

Their deficiency promotes permanent nerve degeneration, which can eventually lead to the development of peripheral neuropathy.

Cardiovascular area

Taking a B vitamin complex can have other benefits.

It has a significant protective effect against the risk of stroke.

Supplementation may be of interest in the prevention of venous thrombosis.

Alcoholism

Alcoholism, combined with a diet low in vitamin B, is a source of serious deficiencies that can lead to neuropathy.

Wernicke-Korsakoff syndrome, which is associated with high morbidity and mortality, is a common neuropsychiatric sequela of alcohol abuse.

This syndrome can be easily treated by taking a vitamin B complex.

In the case of excessive alcohol consumption, supplementation with B1, B2, B5 and B6 is recommended.

Active ingredients

A vitamin B complex is involved in many functions in the body.

They are co-factors in the production of other molecules, such as hormones.

The molecules can have different names depending on their structure.

Abbreviations - Different names

• B1 Thiamine, aneurine
• B2 Riboflavin, lactoflavin
• B3 Nicotinic acid, niacin, nicotinamide
• B5 Pantetin, panthenol (pantothenol), dexpanthenol or D-panthenol, phosphopantothenate, sodium calcium pantothenate
• B6 Pyroxidine pyridoxal phosphate, PLP, pyridoxal 5'-phosphate or P5P
• B8 Biotin, Carbohydrate, lipid, and protein metabolism, cell division
• B9 Folate, folacin, pteroyl-L-glutamic acid, pteroyl-L-glutamate, pteroylmonoglutamic acid, 5-MTHF
• B12 Methylcobalamin, cobalamin, hydroxycobalamin

Precautionary measures

There are certain precautions to take when taking a vitamin B complex:

• Vitamin B3, in the form of niacin, causes vasodilation, which is responsible for temporary redness, itching and flushing in some people. High doses may increase insulin resistance.
• B5, at doses greater than 10 mg/day, may cause mild diarrhoea or intestinal discomfort.
• B6, at doses greater than 200 mg/day, may cause peripheral neuropathy, which is usually reversible.
• B9, at doses greater than or equal to 5 mg per day, may cause indigestion.
• B12 at high doses may aggravate acne.

Contraindications

Some of them can have adverse effects, sometimes serious, if taken in large quantities. It is important to respect the prescribed doses.

Vitamin B6 is contraindicated during breastfeeding and in people suffering from dysorgasmia and anorgasmia.

In male smokers, long-term supplementation with B6 and B12 increases the risk of lung cancer by 30 to 40%. This is particularly true of high-dose supplementation.

B9 is contraindicated in cases of B12 deficiency.

Interactions with other medicines

• B6: Anti-inflammatory cyclooxygenase inhibitors, including aspirin and ibuprofen.
• B9 and B12: Medications that reduce stomach acid, anti-inflammatory drugs, oral contraceptives, oral hypoglycaemic agents and certain antibiotics reduce their absorption.
• B9: Decreases the effectiveness of phenytoin and reduces some side effects of methotrexate, an immunosuppressant.
• B12: Colchicine and cholestyramine may reduce absorption.

With plants or supplements

Green tea and black tea reduce the absorption of folate (B9).

B vitamins: in which foods?

The main food sources are brewer's yeast or seeds, whole grains, nuts, organ meats, dried or green vegetables, fruit and dairy products.

• B1: Yeast, pulses, nuts, seeds, whole grains.
• B2: Offal, nuts, green vegetables, yeast, wheat germ, brown rice, mushrooms.
• B3: Yeast, whole grains, peanuts, almonds, legumes.
• B5: In most food groups, animal products, root vegetables, whole grains, mushrooms.
• B6: Yeast, meat, fish, nuts, legumes, whole grains, fruits and vegetables.
• B8: Yeast, innards, egg yolk, whole grains, nuts, legumes.
• B9: Innards, green vegetables, fruit, whole grains, yeast, pulses.
• B12: Found only in animal products, meat, innards, eggs, cheese, fish and seafood. Vegans must compensate for their dietary deficiency with supplements.

Food supplement

Natural forms would be more interesting than synthetic forms.