Question

Are vitamins needed in large amounts during rapid cell proliferation

Answer 1

The purpose of this investigation was to examine the effects of the addition of five cytokines such as vitamin C, vitamin D, bone morphogenetic protein (BMP), transforming growth factor-beta (TGF-beta) and dexamethasone (Dex) to Dulbecco's modified Eagle (DME) medium on the proliferation of Sprague-Dawley (SD) rats' bone marrow stromal cells and osteoblastic MC3T3-E1 cells by conducting 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. For bone marrow stromal cells, vitamin C was needed for doubling the cell viability. 

Answer 2

1. Introduction to the topic2. Water-soluble vitamins3. Fat-soluble vitamins4. Nutrition5. Trace elements

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IntroductionDefinition and classification of vitamins

Vitamins represent a heterogeneous group of organic substances that the body, with a few exceptions, is unable to synthesize and thus must be obtained through diet. Different organisms differ in their capacity to synthesize various vitamins. That is why, what counts as a vitamin for humans must not be essential for other animal species. Apart from diet, other important source of some types of vitamins (e.g. K or biotin) are bacteria colonizing our largeintestine.

Identical vitamins often occur in the form of multiple compounds known as vitamers, which differ from each other in structure (for example in having different substituents or functional groups) or function (e.g. vitamers of vitamin A – retinol, retinal and retinoic acid).

In general, vitamins can be divided according to the polarity of their molecule (affecting the solubility in water) into two groups:

1) Water soluble vitamins

These vitamins have hydrophilic character, but apart from it, from the chemical point of view, they do resemble each other only very slightly. Their absorption is easier compared to the fat-soluble vitamins and the do not require any special blood transport molecule. When taken in excess, they can easily be excreted through urine without any risk of overdose. This group includes B group vitamins and vitamin C.

2) Fat-soluble vitamins

Altogether, fat-soluble vitamins are derivatives of isoprene and have a lipophilic character. Their absorption requires intact absorption of lipids and their transfer in blood takes place via lipoproteins (like other lipids) or via specific transport proteins, e.g. vitamin D binding protein or retinol binding protein. Lipophilic character enables their storage in adipose tissue (or more generally in all tissues rich in fat), where they may accumulate. On one hand it may lead to their toxicity when taken in large quantities, but on the other, the adipose tissue may act as their storage, and release them when necessary. This group involves vitamins A, E, D and K.