Table of Contents
Page created on February 27, 2019. Not updated since.
Introduction
The word vitamin comes from the Latin word for “life” + the word “amine”. Not all vitamins are amine, however. The definition of a vitamin is “a small organic molecule that the body cannot produce but requires for survival and health maintenance”. Another essential component is that for a molecule to be a vitamin should there be described a deficiency syndrome state for the molecule. This means that there should be some health consequences if a person doesn’t consume enough of the molecule.
This last part is important for the definition, as it excludes some molecules from the “vitamin” definition, like antioxidants. There has never been described any symptoms associated with decreased intake of antioxidants, so they aren’t vitamins. That doesn’t mean they can’t be beneficial, however.
Different vitamins serve different functions in the body, but they all fall into one or more of the following three categories:
- Enzyme cofactors
- Transcription factors
- Antioxidants
According to the department is this what we should know about the different vitamins. That is what these topics will focus on:
- Name
- The function it serves in the body
- Whether it is stored and how much
- The recommended daily allowance
- The characteristic sources
- The possible causes of its deficiency
- The deficiency syndrome (hypovitaminosis)
- The symptoms of overdose (hypervitaminosis, if any)
Contrary to the name of the topic will I use this topic to introduce some concepts about vitamins. The specific hypovitaminoses and hypervitaminoses will be described in the next two topics.
Vitamin intake
The body needs vitamins, and it needs them every day. If you don’t consume enough of a vitamin one day will the body tap into the body stores of that specific vitamin for that day, if that vitamin has stores. If there are no stores, or the stores are empty, will the function normally supported by the vitamin be impaired. Usually are no symptoms seen until deficiency has been maintained for some time.
The science of how much of each vitamin should be consumed is not a simple one. The amount of vitamin necessary varies from person to person and from population to population. To keep a long story short is the recommended daily allowance (RDA) the daily amount of vitamin that should be sufficient for 97.5% of the population to prevent symptoms.
Some subpopulations, especially pregnant women, lactating women and children have other RDA than the rest of the population. In some cases the RDA differs between genders as well.
There are many reasons for decreased vitamin intake:
- Insufficient intake
- Malabsorption
- Increased requirement
- Rapid growth
- Pregnancy
- Alcoholism
- Intake of antagonists – some drugs are vitamin antagonists
- Chronic diseases
Clinical symptoms
It’s possible to have suboptimal plasma levels and not have any specific clinical symptoms (but general symptoms like fatigue can occur) – this is a subclinical vitamin deficiency. This is mostly diagnosed from a blood test. Vitamins levels can also be detected in RBCs.
When specific clinical symptoms occur in a vitamin deficiency the condition is called hypovitaminosis or even avitaminosis if the severity is high. The latter term is rarely used though.
When specific clinical symptoms occur in a vitamin overdose is the condition called hypervitaminosis. This occurs in excessive intake, either oral or intravenous. Not all vitamins have a hypervitaminosis condition associated with them.
Micronutrients
The definition of a micronutrient is that it is an essential element required by organisms in small amounts. The border between what is classified as a micronutrient and what is classified as a macronutrient is approximately 100mg/daily. If an element is needed in more than 100mg doses per day is it considered a macronutrient – anything less is considered a micronutrient.
The micronutrients can be divided into two subparts:
- Trace minerals
- Iron
- Cobalt
- Copper
- Iodine
- Manganese
- Molybdenum
- Selenium
- Zinc
- The vitamins
Of the two sub-types of micronutrients are the vitamins of highest clinical importance, as deficiency of the trace minerals isn’t that frequent (except for iron).