B Vits: Biochemically Brilliant!

By: 

Esther Mills, nutritionist and health journalist

Issue: 
Summer
Year of publication: 
2010

Chickens. Mention B vitamins to any nutritional biochemist, and how the story of their science began, and they’ll mention chickens. For these ‘vital amines’, as they were originally called, were first of interest when it was noticed that chickens fed refined diets (eating polished rice instead of with the vitamin B1-rich husk) became ill with Beriberi. This was in 1892. By 1911 a scientist named Funk prepared a crystalline material from rice bran which, when fed to birds with Beriberi, cured them. He called it ‘beriberi vitamine’. Nutritional biochemistry was born.

Scientists made the most of technological developments which meant that chemical compounds could be better studied, the hunt for more of these ‘vital amines’ was on. Vitamin B1: thiamine, vitamin B2: riboflavin, vitamin B3, vitamin B4, vitamin B5, vitamin B6, vitamin B7... and so the list goes on until around 50 initial ‘vitamine’ compounds were isolated. Now for the tough stuff. What did all these have in common? How should a true ‘vitamin’ chemically react? What properties should it have? So they started to get rid of some. Vitamin B8, they decided, wasn’t a true vitamin at all, neither was B9. By 1935, the exact chemical structures for these vitamins were being established. And so we have the list nutritionists work with today – predominantly vitamins B1, B2, B3, B6, B12. Let’s take a closer look.

Vitamin B1: thiamine, and thiamine phosphate

In the body, vitamin B1, thiamine, is the precursor of thiamine pyrophosphate, which is vital for carbohydrate metabolism. More specifically, it chops off two groups of chemicals called aldehydes and ketones. Along a series of chemical reactions, energy bonds are broken, releasing energy. Without vitamin B1, this is compromised and this also translates to wider deficiency symptoms such as tiredness, irritability, poor memory, sleep disturbance and abdominal discomfort.

Vitamin B2: Riboflavin, and the flavin coenzymes

This powerfully yellow crystalline structure is easily spotted. It’s what makes B2-rich milk more yellow in the summer than the winter. It’s what gives a B complex supplement its yellowy hue. Its name even says so with ‘flavin’ from the Latin for ‘yellow’. Biochemically, riboflavin and vitamin B3 work very closely together, ensuring full energy release from pathways all along the energy production cycle. This is why the American government decided to enrich cereals with it, alongside B1 and iron in the 1940s. A lack of it in the diet can lead to cracking and peeling of the lips, sore corners of the mouth and eyes, as well as the sensation of ‘burning feet’.

Vitamin B3: Nicotinic acid and the nicotinamide coenzymes, also called ‘niacin’

 In the same way as other B vitamins, nicotinic acid, and nicotinamide coenzymes are very specific in the way that they assist energy release, in particular working on alcohol groups, lactates and biochemical reactions towards the end of energy production. You might have heard of NADH. Nicotinamide adenine dinucleotide (NADH) is important for driving energy release in cells. It all sounds quite complicated, but in reality, if enough vitamin B3 is present, energy production will work efficiently. Conversely, if there isn’t sufficient niacin present, it can have unusual knock-on effects, leading to dermatitis, diarrhoea and dementia, as was discovered in 1937.

Vitamin B6: Pyridoxine and pyridoxal phosphate I

n 1926, studies on rats showed that nutritionally-deficient diets in rats could lead to skin disorders, especially on the ears, paws and tail. The compound which cured it was named vitamin B6, pyridoxine, which was isolated in 1938. After 1945, when pyridoxal and pyridoxamine (the animal form of viamin B6) were isolated, it was shown that this vitamin is vital for correct metabolism of protein building blocks, named amino acids. Deficiency syndromes include dermatitis, depression and confusion. This B vitamin also aids female hormone balance which is why it’s often recommended for PMS.

Vitamin B12: Cynaocobalamin, cobalamin

Relatively new on the biochemical circuit is vitamin B12, whose structure was determined in 1961. This nutrient is a biochemical re-arranger, assisting many biochemical reactions, such as degradation of fatty acids. Again, this all sounds rather technical, but we can look to the deficiency syndromes to see where this plays a part - very pale skin, depression and neurological symptoms to name just a few.

Keywords: 
NUTRIENTS, thiamine, riboflavin, flavin coenzymes, nicotinic acid, pyridoxine
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