Micronutrients
and
Malnutrition
HNE-28305
Start Course
Hendrikx, Merel
WUR
,Nutrition and Health: Micronutrients and Malnutrition
Basic Principles of Micronutrients
Learning outcomes:
Describe the basic features of vitamins and minerals
Understand the difference between fat-soluble and water-soluble vitamins
Understand the difference between minerals and trace elements
Describe the purpose of the Dietary Reference Intake (DRI), its components and how
the DRI is determined
To have insight into which groups or individuals may benefit from vitamin and/or
mineral supplements
Basic principles
We only need and consume micronutrients in relatively small amounts, which means less
than 1 gram per day. Micronutrients do not provide energy.
Micronutrients consist of two main groups:
- The minerals
o Major minerals
o Trace elements
- The vitamins
o Fat soluble vitamins
o Water soluble vitamins
Vitamins are organic molecules, and minerals are inorganic molecules. So, vitamins contain
carbon atoms and usually have a pretty complex structure. Minerals do not contain any
carbon.
Vitamins
Vitamins are organic molecules that are needed in small amounts for growth, metabolism
and for maintaining good health.
- Nutritional essential components
o Humans do not produce them in sufficient amounts to meet the normal needs
o Have to obtain them through food
- All animals need vitamins, but not every vitamin is needed in the diet of each animal
species
o Some animals can make specific vitamins in their body
There are thirteen groups of compounds recognized as vitamins.
A provitamin is a compound that can be converted within the body to a vitamin.
- Certain carotenoids can be converted in the active form of vitamin A called retinol.
Classification
Whether a vitamin is water- or fat-soluble depends on their chemical structure.
,Nutrition and Health: Micronutrients and Malnutrition
Fat soluble (4):
- Vitamin A
- Vitamin D
- Vitamin E
- Vitamin K
Water-soluble (9):
- Vitamin C
- 8 B-vitamins
Properties
Whether a vitamin is fat soluble or water soluble has a major influence on how the vitamin is
processed in the body, whether it can be stored, and, when you ingest a lot of it, whether it
may cause toxicity.
Fat soluble:
1. More stable to heat
o Less likely to be lost during processing and cooking
2. Absorbed from the intestine along with fats in foods
o So anything that interferes with fat absorption results in lower absorption of
this class of vitamins.
3. First absorbed into the lymph system and then to the blood
4. Not soluble in water and blood
o Require specific carrier proteins to transport them through the body
5. Not excreted in the urine
o Stored to a considerable extent in the body (liver and fatty tissues)
o Deficiency symptoms develop relatively slowly
The storage of fat-soluble vitamins is not all good because it may also lead to toxicity, for
example when using supplements. This is especially an issue for vitamin A and to a lesser
extent for vitamin D but is much less of an issue for the water-soluble vitamins, because an
overdose simply leaves the body through the urine.
To meet the requirement, fat soluble vitamins can be consumed in large quantities once in a
while.
Water-soluble:
1. Less stable to heat
2. Move directly into the blood after absorption
3. Soluble in blood
o Do not need carrier proteins and travel freely
4. Poorly retained by the body and any excess is mostly excreted via the urine
, Nutrition and Health: Micronutrients and Malnutrition
o Needs to be eaten more regularly
As an exception to this rule, vitamin B12 is a water-soluble vitamin, but it is retained in the
body quite well.
A high concentration of water-soluble vitamins in the urine is almost always the result of
excess vitamin intake, usually via supplements.
Discovery of the vitamins
The discovery that vitamins are an essential part of the diet, was a scientific breakthrough
that changed the world. It brought recognition that, given an adequate diet, it is possible to
cure diseases, such as scurvy, rickets, beriberi and pellagra.
As the chemical identity of the different vitamins was established, chemical names gradually
replaced the earlier designation for specific chemical compounds found to have vitamin
activity. However, the letter system is used in referring to groups of closely related
substances that show common vitamin activity.
Most of the individual vitamins exist in nature in several chemical forms called vitamers.
Minerals
In chemical terms, dietary minerals are inorganic molecules, and that means that they do
not contain any carbon atoms. The group of dietary minerals encompasses the chemical
elements that are essential for the human body.
Actually, a more appropriate description for dietary minerals would be dietary elements.
- There are 17 chemical elements that together comprise the dietary minerals
Classification
Depending on their abundance in our body, dietary minerals are further divided into major
minerals and trace minerals or trace elements.
The remaining nearly 100 chemical elements of the periodic table are all non-essential and
they vary from being relatively harmless (an example would be helium) to extremely toxic
(examples would be polonium, plutonium).
Of course, it should be realized that even the essential elements can be toxic when taken in
excess.
Major mineral
- When it’s present in the body in excess of 5g.
- That includes, in order of abundance: calcium, phosphorus, potassium, sulfur,
sodium, chloride and magnesium.
Trace elements
- Iron, zinc, copper, manganese, molybdenum, fluoride, cobalt, iodine, selenium and
chromium.
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