Vitamin B₆, as well as being involved in the metabolism of carbohydrates, fats, and proteins, supports the formation of haemoglobin, a substance found in red blood cells that is responsible for transporting oxygen to all tissues. It is also essential for the normal functioning of the nervous system and plays a part in the synthesis of neurotransmitters including serotonin, which is involved in the regulation of sleep, mood, appetite, and memory. Vitamin B₆ is also important for correct immune system function.

Vitamin B₉, also known as folic acid, plays an essential role in the synthesis of DNA and proteins, and the formation of haemoglobin. Because it is involved in cell growth processes, it is particularly important at certain stages of life: childhood, adolescence and during pregnancy.

Vitamin B₁₂ is involved in the metabolism of amino acids and fatty acids and is essential for DNA and RNA synthesis, the genetic material of cells. It is also necessary for the formation and maturation of red blood cells and helps maintain normal nerve function.

There are various signs of vitamin B deficiency, depending on the type of B vitamin affected. These include tiredness and fatigue, mental confusion, irritability, depression, nausea, anaemia, and dermatitis. B group vitamin supplementation can also be helpful in cases of tiredness and fatigue, which often occur during seasonal changes or convalescence, periods when energy support is often needed.

The B vitamins belong to a group of essential micronutrients that our bodies are unable to synthesise on their own, or in sufficient quantities, and therefore need to be taken regularly in the food. Foods’s rich in vitamin B₆ are cereals, dried fruits, potatoes, peas, lentils, and leafy green vegetables.

Vitamin B₉ is found in many green leafy vegetables such as spinach, lettuce, broccoli, asparagus, and oranges, legumes, and cereals.

Vitamin B₁₂ is present in all foods of animal origin, albeit in minute quantities. It is found in meat, fish, liver, milk, and eggs. There are no naturally occurring plants or vegetables that contain vitamin B₁₂ in sufficient quantities to meet human requirements.