Issue 82
Why do we need minerals?
Mineral absorption
Calcium
Iron
Zinc
Selenium
Magnesium
Why do we need minerals?
Minerals are essential constituents of all body cells, forming the greater proportion
of bones, teeth and nails. Minerals are also essential components of soft tissues,
muscles, nerve cells (certain minerals are involved in the excitation of muscle
and nerve tissue), enzymes and blood. Some minerals are also necessary for maintaining
pH (acid-base levels) and in fluid/water balance both in and between the cells.
Although minerals comprise only 4-5% of total body weight, life would be impossible
without them.
Modern man has become increasingly reliant on convenience or processed foods
of little nutritive value. Together with intensive farming methods, monocropping,
transportation and prolonged storage of fresh produce, it is now practically
impossible to achieve optimal nutrient intakes from the food we eat.
Taking these factors into account, it is sensible advice to supplement a "balanced
diet" with additional vitamins and minerals to help maintain good health.
It is not surprising therefore, that minerals are part of many supplements sold
in health food shops- including of course multivitamin and minerals. Also, they
account for a considerable volume of sales in their own right. The most popular
mineral supplements are calcium, iron, zinc, selenium and magnesium.
Mineral absorption
The prime function of digestion is to break down the foods consumed into smaller
units that can be utilised by the body. The process begins in the mouth where
food is chewed (mechanical digestion) and amylase (secreted in the saliva) starts
to digest dietary starches. Digestion continues in the harsh environment of
the stomach where hydrochloric acid and gastric enzymes begin the breakdown
of proteins, this is where minerals are released from food. After several hours,
peristaltic movements force the partially digested food "chyme" out
of the stomach into the small intestine. Bile and a number of pancreatic enzymes
complete the digestive process in the small intestine. The upper portion of
the small intestine is the principle site for mineral absorption.
When choosing a dietary supplement, the form of nutrient is of paramount importance
in order to achieve a high rate of absorption and utilisation in the body (i.e.
maximum bioavailablility).
During digestion in the stomach inorganic minerals (for example: sulphates,
oxides, chlorides and carbonates) dissociate from their carrier resulting
in the formation of a positive mineral ion. Absorption of these inorganic minerals
is very variable because after the positive mineral ion has been formed it may
be passively absorbed into the bloodstream, or it may become chelated and be
absorbed into the bloodstream by active transport mechanisms. But equally the
positive ion may stick to the gut lining causing irritation or it may become
bound to phytates or oxalates (from the diet) and render the mineral unavailable
for absorption.
Organic forms of minerals frequently ionise (dissociate) in the digestive tract
but irritation of the gut wall is rare. The minerals are absorbed moderately
well, however, the positive ions are in danger of coming face to face with inhibitory
dietary factors (as with the organic forms).
Some minerals are available in a pre-formed, stable chelate with an amino acid.
During digestion, amino acid chelates do not dissociate (i.e. the carrier
and mineral remain intact). Due to the neutral state of these complexes, they
are readily absorbed in the small intestine. Amino acid chelates do not cause
irritation and are unaffected by inhibitory factors in the diet. Many minerals
carry two positive charges and are therefore best absorbed as an amino acid
chelate (the form in which most minerals are transported around the body).
It is not only the chelating agent that dictates the absorption of minerals.
Other nutrients and minerals are often required for efficient absorption (and
utilisation) to take place.
Next we will take a look at some of the most important minerals, their role
in the body and factors that may affect the bodys requirements and the rate
of absorption.
Calcium
Calcium is the most abundant mineral in the human body, comprising over 1.5%
of the total body weight. About 99% of the bodys calcium is found in the bones.
Calcium is involved in the structural formation of the bones and the teeth as
well as being needed for muscle and nerve function.
Supplemental uses of calcium are varied. It can be taken by anyone who is worried
that they may have a deficiency. This could include vegetarians, vegans, women
at risk of osteoporosis and pregnant and lactating women. The best dietary sources
are dairy products and green leafy vegetables.
Iron
The body contains only 4-5g of iron. However it is a very important mineral
in human physiology. The main function of iron in the diet is as an important
constituent of the blood pigment haemoglobin. Haemoglobin is contained within
red blood cells and is the carrier of vital oxygen around the body. The classic
iron deficiency disease is anaemia. The symptoms of this condition are fatigue,
light headedness and weakness accompanied by correspondingly low blood haemoglobin
levels.
Women of child bearing age are at the most risk of iron deficiency because
of their monthly menstrual blood losses. Other people who may need an iron supplement
include vegetarians, pregnant women, adolescents, athletes and the elderly.
Children may also be deficient in iron. Studies in Bradford and Birmingham
have been very revealing. In Bradford, 12% of white and 28% of Asian children
were anaemic. In Birmingham 26% of a group studied between the ages of 6 months
and 6 years were anaemic.
A multivitamin and mineral supplement containing iron is recommended for children,
but iron at higher levels should not be taken by children except under medical
advice.
Zinc
Zinc is a component of over 80 enzymes and is involved in a multitude of reactions
within the human body. Its functions include a very important role in cell division,
and the immune system. It is also necessary for growth and can be useful in
detoxification. The most common reasons for taking a zinc supplement include
skin conditions (it has been shown to be effective in acne and eczema), wound
healing and for fertility and prostate health (zinc is a vital component of
the male reproductive system).
Selenium
Selenium carries out its main functions as part of the antioxidant enzyme glutathione
peroxidase. Selenium is known to play a part in the preservation of normal liver
function, protection of cells, the maintenance of a healthy heart as well as
the production of anti-inflammatory substances. Groups who may wish to take
selenium include vegetarians, the elderly and smokers. Vitamin E is a very important
synergistic factor which enhances the benefits of selenium and vice versa. Good
food sources include meat and whole grains.
Magnesium
Magnesium is found alongside calcium and provides structure and support in the
bone. It is also a key factor in energy release and cell production. Symptoms
of magnesium deficiency are likely to be cramps and twitches, low blood sugar,
anxiety and insomnia.
Magnesium is commonly taken by women who wish to ease the symptoms of PMS such
as cramps and sugar cravings. People sometimes find magnesium helps with involuntary
muscle twitches and it can be taken in combination with calcium for muscle cramps.
Take a Multi mineral
Many of the minerals work in conjunction with each other and therefore it can
be beneficial to take minerals as a group in a good quality multi mineral product.
If you want further information about the role of minerals and the way in which
minerals can be of benefit to health you can contact the Quest nutritionists
on 0121 3590056 or email them at nutrition@questvitamins.co.uk .
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