B vitamin complex – why do we need so many?

As you will already be aware, the majority of the important vitamins are referred to by a letter, vitamin-B-Complexrather than their full chemical name.  This makes them easier to remember, but in cases such as vitamin B, it can also lead to considerable confusion.  Unlike others, it is actually a complex of several different chemicals, rather than being an individual compound.  This was only discovered several years after it was named, when chemical techniques made it possible to distinguish between closely related chemicals.  Vitamin B is now usually referred to as the B vitamin complex, and the different substances are often found together in foods.  However, despite being very similar, they have a range of different functions within the body.

  • Vitamin B1 is often called thiamin.  Men need 1mg each day, while women need slightly less at 0.8mg each day.  It is important that this requirement is met on a regular basis, because thiamine is one of the water-soluble vitamins, which means that it cannot be stored within the body, unlike those that can dissolve in fat.

Thiamin plays a role in digestion and respiration, working in conjunction with other members of the B vitamin complex to break down food and release the energy it contains.  However, it also has a secondary role in ensuring the health and continued function of both muscles and nervous tissue.  Thiamin deficiency is extremely rare, because this substance is found in such a wide variety of foods.  These include many different vegetables and fruit, eggs, liver and some fortified products such as breakfast cereal.  However, if a deficiency does develop, the nervous system is most strongly affected.  It will usually lead to the onset of a coma, followed by death.

In some research studies on Alzheimer’s disease, patients were found to have low levels of thiamin in the body.  The use of thiamin supplements had some beneficial effects on the trial patients, although the extent of this effectiveness, and whether it would be useful as a preventative measure, is not yet known.

  • Vitamin B2 is better known as riboflavin, and the amounts of this required on a daily basis are slightly higher than for thiamin; 1.3mg and 1.1mg a day for men and women respectively.  Again, it is water-soluble so will pass out of the body in urine if it is not being used, which means that this level of intake must be maintained.  Riboflavin is a chemical that will degrade in direct sunlight, so foods that provide a high level of this substance should ideally be kept in a shaded or dark place.  Riboflavin is necessary for energy to be released efficiently from foods.

Foods that are rich in riboflavin include dairy products, eggs, rice and some fortified breakfast cereals (although you should check the labels carefully to see exactly what has been added before you make your purchases).  The most noticeable symptoms of riboflavin deficiency are cracked lips, mouth ulcers, cracks at the corners of the mouth, and a sore throat.  It is relatively common for a riboflavin deficiency to occur because the substance is continually being excreted.  However, there will normally be additional vitamin deficiencies that have occurred simultaneously.

  • Vitamin B3 is niacin, which is involved in the health of both the nervous system and the digestive system.  It also helps to generate energy from food.  Unlike the other members of the B vitamin complex, niacin can be sub-divided into two further types, known as nicotinamide and nicotinic acid.  Both of these are found in a variety of foods, so it should be relatively easy to meet your daily requirements.  Meat, fish, dairy products, eggs, and anything made from flour are all rich in niacin.  Men need an average of 17mg each day, while women require 13mg.

A niacin deficiency leads to the disease known as pellagra, which leads to a variety of symptoms that can be summarised as “diarrhoea, dermatitis, dementia and death”, or “the four D’s”.  Diarrhoea will usually be the first symptom to develop, along with changes to the skin that can be extremely painful.  Over time, a prolonged lack of niacin will cause the nervous system to degrade and stop working effectively, which leads to the symptoms of dementia.  However, niacin deficiency is now relatively rare thanks to the easy availability of a greater range of foods.  Nicotinamide supplements are the preferred treatment for cases of pellagra, because it has a lower toxicity at high doses than nicotinic acid.  Once pellagra has developed, the patient has an estimated lifespan of five years if it remains untreated.

There are many other chemicals in the B vitamin complex, and it is very important that you maintain your intake of each one at the recommended level.  They can perform similar functions, which means that one deficiency can be masked by an increased intake of one of the others.  If you are unsure about whether you are getting the right balance, then you should ask your doctor to perform a blood test, which is a quick and easy way to check.  You will then be able to make adjustments to your diet if necessary, to prevent any deficiency disorders from developing.

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