VITAMINS – WATER AND FAT SOLUBLE VITAMINS
Look at these alphabets here: A,C,D,E,B, K. What do these randomly arranged alphabets mean? These are VITAMINS! And why are they important? Well, when you construct a sentence, just as alphabets are the building blocks to make a word, in a similar fashion these vitamins are organic compounds which on entering the body form the building blocks which help your body function normally.
How was the importance of vitamins discovered? The first person credited to formulate vitamins was credited to Casimir Funk in the year 1912 and he gave the term “vital amines” or “vitamine”, from there we have now progressed to use the term “VITAMIN” as the ‘e’ was removed when it was realized that these vitamins are not necessarily nitrogen-containing amines.
How much vitamins is required in the diet? A small quantity of vitamins is required and hence they are also known as micronutrients. Can human beings make their own vitamins? Unlike plants and microorganisms like bacteria and fungi, humans need to incorporate vitamins in their diet for the various body activities. Based on the solubility, how these vitamins are transported and the mode of excretion these vitamins are classified as either water-soluble or fat-soluble. In humans there are 13 vitamins: 4 fat-soluble (A, D, E, and K) and 9 water-soluble (8 B vitamins and vitamin C).
First let’s take a look at the water soluble vitamins, i.e, the vitamins B and C. They are mainly seen in the watery parts of fruits mainly citrus fruits and in grains. Other sources can also include poultry, green leafy vegetables, nuts etc. Water-soluble vitamins, being hydrophilic dissolve easily in water and once absorbed they directly enter the blood stream and get transported all over the body. The uptake of these vitamins is quite straight forward, as the blood plasma is mainly composed of water and this dissolves and transports the water soluble vitamins.
Then what about your fat or lipid soluble vitamins? Let’s look at that aspect now! Fat soluble vitamins are mainly derived from dairy products, oils, egg yolk and so on. These vitamins dissolve in fats and take a slightly different mode of absorption when compared to the water soluble vitamins. After passing through the stomach and then into the small intestine, the fat soluble vitamins are acted upon by the bile which is secreted by the liver. This then helps them to get absorbed into the intestinal wall through the small intestine villus. And unlike the water soluble vitamins which directly enter the blood stream, they first have to pass through a lymphatic vessel and then only are they sent into the blood stream. As they are hydrophobic they need a special carrier protein which helps them gets transported to various parts of the body, these are your chylomicrons.
What about the storage and excretion of these vitamins then?
Well the water soluble vitamins are readily excreted from the body, to the degree that urinary output is a strong predictor of vitamin consumption. Because they are not as readily stored, they should be supplemented or replenished daily. Fat soluble vitamins on the other hand are stored in the fat cells or adipose tissue and in the liver and they are more likely to accumulate in the body. A condition in which there is excess of vitamins in the body also known as “hypervitaminosis” is thus more common in fat soluble vitamins than in water-soluble vitamins.