Nutrition - resources and article
Nutrition is interpreted as the study of the
organic process by which an organism assimilates and uses food
and liquids for normal functioning, growth and maintenance and
to maintain the balance between health and disease. Also included
is the idea of an optimal balance of nutrients and whole foods,
to enable the optimal performance of the body.
As recently as the 1960s doctors told their patients that nutrition
had little to do with their health. Now we know otherwise: "you
are what you eat!" More specifically, in humans, the matter
which comprises the cells of the body (except those cells produced
before birth) is acquired from food in the digestive system. Not
all the food matter in the stomach can be used for the body; the
matter that is left over as waste is removed.
Study in this field must take into account the state of the animal
before ingestion and after digestion as well as the chemical content
of the food and the waste. The specific types of matter (chemicals)
that are absorbed by the body can be determined by comparing the
waste to the food. The effect that the absorbed matter has on
the body can be determined by finding the difference between the
pre ingestion state and the post digestion state.
The effect may only be discernible after an extended period of
time in which all food and ingestion must be exactly regulated
and all waste must be analyzed. The number of active variables
involved in this type of experimentation is very high. This makes
scientifically valid nutritional study very time consuming which
accounts for why a proper science of human nutrition is rather
new.
History and recent developments
This new science has rapidly expanded. Vitamins were first written
about in 1912, by Sir Frederick Gowland Hopkins, who was knighted
and received the Nobel Prize in 1929 for his achievements.
In the 20th century, after clarification of the nature and role
of proteins, carbohydrates, vitamins and minerals, it was thought
that we had adequate knowledge about the elements of food. Food
was seen as the fuel, and we simply had to have enough of its
ingredients in order to go on living. However, there followed
an accelerating series of discoveries starting with fibre, which
has revealed increasingly large gaps in our knowledge about the
role of food in our health and proper functioning.
We now know that there are many thousands of phytochemicals in
our food, each of them performing an essential role in the proper
functioning of our bodies. Furthermore, it is thought that there
are many more phytochemicals and other components of food to be
discovered. There are also enzymes which play an important part
in nutrition: these are chemical catalysts in our food and also
produced in our digestive system. They are vitally important in
all the metabolic activity in our bodies.
Antioxidants are another recent discovery. Using energy in our
bodies often has damaging side effects on cells, and certain food
elements such as vitamin C have been seen to be vital in protecting
against the aging effect of this oxidizing damage. Recently the
health benefits of vitamin E have been called into question.
The balance of essential fatty acids (linoleic and linolenic
oil) has been discovered to be crucial in maintaining good health.
This involves omega 3 and omega 6 oils, as well as the need to
minimise hydrogenated fats which contain heavy metals.
Results
are emerging to indicate that phytoestrogens in our food are
related to the avoidance of metabolic syndrome, the regulation
of cholestorol, and maintenance of bone density.
It is now also known that the human digestion system contains
a population of a range of bacteria which are essential to digestion,
and which are also affected by the food we eat.
The previous mechanistic view of food as fuel, and the simplistic
notion that protein, carbohydrate etc. were each obtained from
one type of food (the meat and two veg model) has all but been
replaced. Increasing complexity means that nutrition researchers
today advocate a holistic approach. They readily admit that there
are many nutrients and other factors we don't know enough about,
and that most foods contain most types of nutrients in various
proportion. Provided excess is avoided, particularly of carbohydrates
and hydrogenated fats, then it has been shown that our needs are
best met through eating a wide variety of fresh, unprocessed and
unmanufactured food.
The Institute for Food Additives and Ingredients gives the following
information:
"Far more is now known about the science of nutrition than
ever before and the overriding message is that a very broad diet,
taking in vital categories of essential nutrients, is better than
a narrowly focussed diet, even if that diet sets out to avoid
dangerous foodstuffs such as saturated fats.
"A survey has shown that the Japanese tend to eat a greater
variety of different foods every day than Westerners (27 different
foods a day whereas the recommended minimum in the West is 30
different foods per week); they are less prone to the 'diseases
of civilization' - diabetes, heart disease and cancer - than Europeans,
and their varied diet is thought to contribute to this."
People in Japan eat far more salt than people in the west.
Nutrition and health
In the 18th Century, many sailors on long journeys died from
scurvy; indeed, some naval ships lost more men through illness
than through enemy action. The cause of this was not understood,
until it was discovered that adding fresh limes to the ship’s
supply of preserved food seemed to boost the sailor’s resistance
to the illness, and fewer died. The existence of parts of food
essential for survival had been discovered. Other so-called vitamins
were discovered through the effect of their absence on people’s
health, and increasingly the role of nutrition’s contribution
to health was seen as equally important as exercise, hygiene,
environment, and psychological wellbeing.
The connection between nutrition and health has weakened however.
Good health became the norm in the developed world through increased
understanding of communicable diseases, micro-organisms and how
to fight them with antibiotics, and other health developments.
A hidden epidemic gradually emerged in the post World War II years,
where non-communicable endemic illnesses began to flourish, such
as heart disease, cancer, diabetes and obesity.
These illnesses are increasingly recognised now as being sometimes
caused by lifestyle issues, including poor nutrition and low levels
of exercise. Despite this knowledge, the peak of the epidemic
is still with us, and obesity-related diseases are prevalent in
the developed world.
Many nutritionists ascribe this to excess of refined carbohydrates,
decreasing levels of exercise, fewer vegetables and fruit and
the wrong types of fat in our diet. Others feel that governments
and the food industry have not yet recognised or acted upon this
insight. Fast food restaurants are spreading around the world,
and Westernisation has unfortunately brought the "diseases
of civilisation" with it. A reaction to this has been the
development of a slow food trend. This has now got its own University,
at the University of Pollenzo in Piedmont Italy whose goal is
to promote awareness of good food and health through nutrition.
Nutrition research has identified many components of good nutrition,
so that in general a wide variety of unprocessed food is recommended
as a natural preventive measure, to maintain good health rather
than individual foods as remedies for perceived deficiencies.
Nutrition can affect health in many ways. Ill-health can be brought
about by an imbalance of nutrients, producing either an excess
or deficiency which in turn affects body functioning in a cumulative
manner. The body can be affected at the micro or macro levels
by nutrition, for example cancer can arise through cell metabolism
malfunction, and high energy levels can promote health through
frequent activity.
Some examples are :
- Obesity results in fatty deposits in the abdomen which in
turn affect the efficiency of the liver, heart, gall bladder,
circulation etcetera.
- The wrong kinds of fats can cause the build-up of cholesterol-related
plaque on artery walls which can eventually result in a blockage
or poor blood supply to other organs, e.g. the brain or the
heart itself, indirectly therefore causing angina, heart failure,
brain disfunctioning, CVAs etc.
- An excess of carbohydrates, especially sugars, can lead to
imbalances in insulin production. This in turn can lead to fatigue,
chronic tiredness, diabetes, and obesity through overeating.
- Mineral or vitamin deficiencies are thought to be responsible
for many illnesses, including goitre, scurvy, osteoporosis,
poor immune system response (and indirectly some forms of cancers),
disorders of cell metabolism, premature aging etc., poor psychological
health, including eating disorders.
- Imbalances in omega 3 and omega 6 fatty acids is thought
to be related to autism and some attention disorders, and bipolar
disorder
- Intolerance of gluten (a protein in wheat and rye) is suspected
of being related to the development of schizophrenia in some
cases. (See British Medical Journal, February 21, 2004.)
- Alzheimer's disease may be linked to B vitamin deficiencies.
(See the Times newspaper, January 31 2004 "Could vitamins
help delay the onset of Alzheimer’s?" by Jerome Burne).
Food processing
Food can be made safer and more palatable through processing.
Food processing therefore has a valuable role in contributing
to good nutrition. However, some nutritionists advise caution.
Food processing is sometimes seen as adversely affecting people’s
health: polished rice was identified as a cause of beri-beri when
people realized that removing the skin of the rice was a process
which removed essential nutrients.
In the late 1800s in the United States, babies started developing
scurvy; there was a veritable plague. It turned out that the vast
majority of sufferers were being fed milk that had been heat treated
(as suggested by Pasteur) to control bacterial disease. Pasteurization
was effective against bacteria, but it destroyed the vitamin C,
causing a nutritional disease.
Other examples of adverse effects of food processing, together
with research findings and the need to be cautious in the light
of our limited and incomplete knowledge, have called food processing
into question.
Today's leading nutritionists advise against the processing of
food where possible, since undiscovered but possibly essential
nutrients may be thereby removed, or toxins may be added or produced
through processing and high temperature cooking. Also processing
can replace some of the mechanical/biochemical body processes
which are essential for full digestion, and hence good nutrition.
Cornell nutritional biochemist T. Colin Campbell, Professor and
director of the China project stated at a symposium on epidemiology:
"Analyses of data from the China studies ... is leading to
policy recommendations."
He mentioned three:
- "The greater the variety of plant-based foods in the
diet, the greater the benefit. Variety insures broader coverage
of known and unknown nutrient needs.
- Provided there is plant food variety, quality and quantity,
a healthful and nutritionally complete diet can be attained
without animal-based food.
- The closer the food is to its native state -- with minimal
heating, salting and processing -- the
greater will be the benefit.
Nutrition and longevity
Lifespan is somehow related to the amount of food energy consumed:
this was first systematically investigated in the seminal study
by Weidruch et al (1986).
A simplistic pursuit of this principle of caloric restriction
followed, involving research into longevity of those who simply
reduced their food energy intake. Perhaps not suprisingly, people
found that cutting down on food reduced their quality of life
so considerably as to negate any possible advantages of lengthening
their lives.
Underlying this research was the hypothesis that oxidative damage
was the agent which accelerated aging, and that aging was retarded
when the amount of carbohydrates was reduced through dietary restriction.
However, recent research has produced increased longevity in
animals (and shows promise for increased human longevity) through
the use of insulin uptake retardation. This was done through altering
an animal’s metabolism to allow it to consume similar food-energy
levels to other animals, but without building up fatty tissue.
In effect, it is now thought that the agent which increases longevity
is leanness in animals, and that it is the accumulation of fatty
tissue over the years which may gradually and inevitably reduce
life expectancy.
This has set researchers off on a line of study which presumes
that it is not low food energy consumption which increases longevity.
Instead, longevity may depend on an efficient fat processing metabolism,
and the consequent long term efficient functioning of our organs
free from the encumbrance of accumulating fatty deposits. (Das
et al, 2004)
Lifestyle and nutritional needs
Adequate nutrition contributes to three outcomes which are necessary
for the organism’s normal functioning.
These are:
- Adequate energy levels
- Maintaining proper body structures and processes, e.g. muscle
function, immune protection, bone density and strength
- Repair and development of all of the organism’s systems.
In the case of humans, ‘normal functioning’ is affected
by a range of situations, which are often open to choice. A weightlifter,
labourer, Inuit fisherman, Sumo wrestler, clerical worker, infant
and bed-bound person will all have different definitions of ‘normal
functioning’, they all have different body shapes and sizes,
and their nutritional needs will vary also.
Consequently, suitable nutrition varies according to each individual’s
situation, and to some extent on the choice of lifestyle. Athletes
may need high levels of protein and energy to enable high performance
and repair for the high stresses on their body. People working
hard in a cold environment may need high fat levels in their diets,
to help maintain normal body temperature. This beneficial high
fat level may be very harmful for people in other situations,
eg a sedentary worker in an air-conditioned office.
So the aim of good nutrition in terms of body maintenance, repair
and functioning will be often relative to the choices and circumstances
of the individual.
However, the holistic model of nutrition points out that for
example high energy needs can be met in various ways, some more
healthful than others. Food energy can be obtained from most foods,
and are probably best obtained from those foods which have as
high a concentration of other nutrients as possible.
Thus although nutrition and food types vary widely according
to lifestyles and situations, nevertheless within each different
set of requirements the principles of good nutrition can still
be applied.
See Nicholas Institute for Sports Medicine and Trauma for nutrition
advice for athletes.
Policy advice and guidance on nutrition
Most Governments provide guidance on good nutrition, and some
also impose mandatory labelling requirements upon processed food
manufacturers to assist consumers in complying with such guidance.
Current dietary guidelines in the United States are presented
in the concept of a food pyramid. Canadian guidelines are similar
to the US ones and are published in "Canada's Food Guide".
Both dietary guidelines are horribly outdated and are fundamentally
flawed because they allegedly serve the interests of the food
industry. (See Wall
Street Journal). Detailed information on general nutrition
is available from the Department
of Agriculture's Food and Nutrition Information Center.
Nutrition is a fast-changing science, yet agriculture, food distribution,
food manufacturing and Government policy are slow-changing things.
Because of these facts, there is a recognition that official Government
guidance may not be the best advice to follow: more fluid and
responsive channels for advice may be needed in the future. "Recommended
daily allowances" and the "five portions" policies
are increasingly looking like arbitrary figures, as our knowledge
increases.
Cornell nutritional biochemist T. Colin Campbell, Professor and
director of the China project states:
"...merely eating some low-fat foods or complying with
current U.S. dietary recommendations is unlikely to prevent much
disease... To get really significant changes in disease rates,
it will be necessary to shift the American diet from its heavy
reliance on animal-based foods to one that relies far more on
plant-based foods" (Cornell Chronicle 10/1/94)
(See also: Walter C. Willett and Meir J. Stampfer,Rebuilding
the Food Pyramid, Scientific American January 2003.)
A holistic approach
There are many more nutrients than we know about in food, and
the overall process of ingestion and utilisation of nutrients
is still poorly understood. Good nutrition is also part of, and
depends on, such matters as healthy lifestyle, food policy, and
public health. Such figures as longevity do not necessarily correlate
to the developed status of a country. (For instance, Costa Rica
and Guadaloupe have higher life expectancy than the United States,
U.N figures 2002).
Because of these limitations, nutritionists are moving towards
providing more holistic advice: they recommend increased exercise,
a wider range of foods, using less food processing and cooking,
increased vegetable and fruits, and less animal-based foods.
If these wider areas of advice are followed, then specific traditional
nutritional intervention may only be needed for individual situations
of illness or deficiency.
Examples are the comments by T. Colin Campbell on policy recommendations
(see quotes above, in 'Nutrtion and health'), and the advice of
Professor Thomas Sanders, the director of the Nutrition, Food
& Health Research Centre at King’s College London, who
says:“In trials, there is no evidence suggesting that reducing
fat intake has an effect on obesity. As long as your expenditure
equals what you eat, you won't put on weight, regardless of how
high the fat content is in your diet.” (Times newspaper,
10 March 2004 or 3 October 2004, whatever those silly all-digit
dates 10/3/04 meant)
Current issues and controversies
Controversies in modern nutrition include:
'Artificial' interventions in food production and supply:
- Should genetic engineering be used in the production of food
crops and animals?
- Are the use of pesticides, and fertilizers damaging to the
foods produced by use of these methods (see also organic farming)?
- Are the use of antibiotics and hormones in animal farming
ethical and/or safe?
Sociological issues:
- How do we minimise the current disparity in food availability
between first and third world populations ?
- How can public advice agencies, policy making and food supply
companies be coordinated to promote healthy eating ?
- How much meat and animal products are appropriate in diet?
- Do we need nutritional supplements in the form of pills,
powders, liquids, etc.?
- How can the developed world promote good worldwide nutrition
through minimising import tariffs and export subsidies on food
transfers?
Research Issues
- How large a place should dairy products take in the food
pyramid?
- Does an increase in the plant content of our diet reduce
the risk of developing some chronic illnesses? Conversely, is
it true that increases in animal products in food increases
the incidence of some diseases?
- What more can we discover through what has been called the
phytochemical revolution?
- How essential to proper digestion are the enzymes contained
in food itself, which are usually destroyed in cooking(see Living
foods diet)?
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informational article is licensed under the GNU
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article Nutrition
Additional
Nutrition listings in this site are from the O.D.P
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