Dietary Hazards - Processed Fats

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Dietary Hazards - Processed Fats

Oct 16, 2005 19:09 PDT

 

www.amazingdiet.org

 

In today's world the appearance, texture and colour of food is often

considered of greater importance than the nutrient value of such

food.

In an instant world we need instant food, and to avoid spoilage and

financial loss, such food is often chemically manipulated to obtain

all

these desired effects.

 

When the chemical nature of our food is changed so that it meets the

requirements of the marketplace, then the risk is great that it no

longer meets the requirements of the body.

 

Our bodies are designed to interact with the environment in a highly

specialized way, and any interference with this delicate balance may

impact negatively on the system.

 

Modern Oil Refining Techniques

 

Extracted oil undergoes a series of steps which adversely affects

its

nutritional value. Free fatty acids are removed by vacuum extraction

and

precipitation. Furthermore, the oil is filtered and heated to 220 °C

to

obtain a clear liquid.

In order to obtain a less fluid oil, suitable for the production of

margarine, the oil is further subjected to the process of

hydrogenation,

to which liquid oils nowadays are also partially subjected.

 

This process was developed by W. Norman in the year 1900 and

involves a

catalytic reaction which changes cis fatty acids to trans fatty

acids,

thus rendering them less fluid by changing the shape of the

molecules.

 

Polyunsaturated fats contain double bonds, and this gives rise to

the

possibility of cis-trans conversions. In nature, fatty acids occur

mainly in the cis configuration, which means that the carbon chains

on

either side of the double bond are spatially arranged on the same

side

of the double bond. (See table)

 

Trans fats do not form part of the normal diet and should not be

introduced into the system as they can result in a number of

biochemical

changes, and together with saturated fats and cholesterol, can lead

to

altered membrane structure and concomitant hardening of the

arteries.

The essential fatty acids (linoleic and linolenic acids) also

naturally

have the cis configuration but the free use of extracted, partially

hydrogenated oil, rich in linoleic acid (found in corn, safflower

and

sunflower oils), has been associated with cancer promotion.

Linoleic acid is the substrate from which prostaglandins are

manufactured, and trans-linoleic acid can result in altered

prostaglandins, thus modifying the effect of these hormones or even

producing opposite effects.

Because leucotrienes play an essential role in regulating the immune

system in that they are involved in the production of antibodies and

the

destruction of viruses and cancer cells, it is essential that these

molecules be produced from essential fatty acids that have the

correct

configuration so that the delicate balance and the function may not

be

jeopardized.

 

The molecular changes found in even partially hydrogenated oils can

adversely affect the relationship between the various prostaglandins

as

well as changing them structurally.

 

Trans fatty acids depress serum levels of prostaglandins. Moreover,

hydrogenated oils do not share the properties of normal unsaturated

fats

and will also not lower cholesterol levels as do the natural oils in

whole foods.,[ii]

The consumption of trans fatty acids in the Western world is quite

high,

and it has been estimated that in the US and in Canada, men of 20-39

years of age consume 11-12 g per person per day of these fats.2 The

British Medical Committee on Cardiovascular Diseases proposed new

guidelines in 1994 on recommended consumption of fatty acids.

Recognizing that trans fatty acids have an undesirable effect on HDL

and

LDL cholesterol and coronary disease mortality, they suggested that

no

more than 2% of caloric intake come from this source, and that the

amount should even be reduced.[iii]

Margarine

Margarine is typically manufactured from the oil of soya beans,

maize,

sunflower seeds, olives, coconut and palm, with the addition of

substances which enhance the flavour and act as preservatives and

texturisers.

The typical ingredients of margarine include a combination of oils,

water, sodium chloride, vitamins A, D and E, lecithin or other

emulsifier, preservatives such as sodium benzoate and/or potassium

sorbate, milk solids including casein, colorants such as beta-

carotene

and retinyl esters, flavourants such as butter distillate or

simulated

butter taste chemicals.

The manufacturing process of margarine involves a combination of a

number of steps. The fat-insoluble gums and other substances from

the

crude oil are first removed and then the oil is neutralized with

alkali.

Subsequently it is bleached, filtered, deodorized and in most cases

hydrogenated. After this the product is again subjected to further

filtration, neutralixation, bleaching, deodorization and blending.

Finally, colorants, flavourants, vitamins, emulsifiers and

preservatives

are added, and proportioning (creating the desired balance between

water

and fat), emulsification, chilling and packaging round off the final

product.

In most cases, margarines exceed the recommended maximum levels for

saturated and trans-unsaturated fatty acids, but some countries

(Germany) have taken cognizance of the detrimental effects of trans

fatty acids and many of the margarines, shortenings and cooking fats

in

Germany are being produced essentially free from trans fatty acids.

Nevertheless, a concentrated, chemically manipulated, unnatural food

such as margarine must place excessive demands on the system, and

viable

alternatives should be sought.

Artificial foods are however the vogue, and large quantities of

spreads

and non-dairy creamers are consumed annually.

Non-dairy creamers also contain extracted saturated and hydrogenated

plant oils of coconut and palm origin, and therefore contain no less

fat

than dairy cream.

There are many ways to prepare palatable meals without the use of

extracted oils, and their use can thus be limited. The best way of

obtaining chemically sound fats, suitable for maintaining the fine

chemical balances of the body, is to eat whole food that has not

been

changed by modern refining techniques.

Whole grains, seeds, nuts as well as oil-rich fruits such as avocado

pears and olives, together with other plant sources will supply an

abundance of fats of the variety required by the body.

The Use of Oil in the Frying of Food

The frying of food in oil or lard also has detrimental effects.

Studies

have shown that heated oils and fats undergo autoxidation and that

the

rate of autoxidation is proportional to the degree of unsaturation

and

the presence of absence of pro- and anti-oxidants.

It has been established that animal fats undergo autoxidation more

readily than oils of plant origin,

in spite of the fact that animal fats are saturated fats, but this

has

been attributed to the virtual absence of natural antioxidants in

animal

fats.

Polyunsaturates, however, sustain the most thermo-oxidative damage

when

oil is heated.

In this regard it is enlightening that a tri-unsaturated fatty acid

will

undergo autoxidation 10 000 times more readily than a

monounsaturated

fatty acid.[iv]

The rate and degree of autoxidation of unsaturated and saturated

fats is

presented in figure 3.10.

Source: Grundy, S.M. 1989. Monounsaturated fatty acids adn

cholesterol

metabolism: Implications for dietary recommendations. J. Nutr.

119:529

Heat Damage Sustained By Oil

The products formed in fats and oils that are heated to high

temperatures are peroxides, aldehydes, ketones, hydroperoxides,

polymers

and cyclic monomers, any one of which can have toxic effects.

Subjecting saturated and polyunsaturated fats, such as butter and

sunflower oil to temperatures of 170 °C for two hours will also

alter

the composition that if fed to experimental animals they will induce

liver ailments in these animals.

If animal fat, polyunsaturated oil, and even monounsaturated oil

such as

olive oil, is however heated to 180 °C for longer periods of time,

serious liver disorders are induced in experimental animals that are

fed

these oils.

[v] The peroxidised fatty acids in heated fats also affect the

cardiovascular system, possibly even causing lesions in the cardiac

muscles and arterial lining as well as enhancing clot formation.[vi]

As most processed oils are heated to 220 °C during the manufacturing

process, and are still further heated during the frying process, the

use

of free oil should for these reasons alone, not be encouraged.

The frying of food should therefore be avoided if healthful living

practices are introduced into the household.

This does not necessarily mean that taste should be sacrificed, but

it

does mean that age-old habits will have to be revised and

substituted

with a little bit of ingenuity.

If oil is used at all, it should be used in moderation and the

cold-pressed variety should be used as this have been least

subjected to

heat during the extraction and clarifying processes.

Also oils rich in monounsaturated fats, such as olive oil, should be

the

oils of choice as monounsaturated fats undergo the least damage

during

heating.

Whilst it is true that increased dietary consumption of

polyunsaturated

fats has led to a decrease in cholesterolaemia and associated drop

in

cardiovascular disease, it has been accompanied by a rise in deaths

from

non-vascular diseases such as cancer,[vii] cholelithiasis[viii] and

a

general drop in life expectancy,[ix] probably resulting from the

peroxidation of the polyunsaturates.

Peroxidation of polyunsaturates takes place because these molecules

are

unstable, and the more double bonds there are in the molecules the

more

readily the process of peroxidation takes place.

During this process " free radicals " are formed which are extremely

reactive in view of their unpaired electron.

Free radical formation is largely prevented in whole foods, as

natural

antixodants, which are present in these foods, prevent their

formation.

A natural balance exists between antioxidants such as the fat-

soluble

vitamins A and E and the quantity of polyunsaturated fats that are

present in whole foods.

An imbalance between polyunsaturates and antioxidants will result in

a

rise in free radical formation with concomitant harmful results such

as

an increase in the rate of the aging process,[x] inflammation,[xi]

carcinogenesis,[xii] liver disorders and arteriosclerosis.[xiii]

Unfortunately modern food processing techniques often strip food of

the

essential fatty acids and vital prepacked antioxidants and in this

way

deprive the system of these essential nutrients.

During the refining process grains, for example, are stripped of the

germ, which contains the essential oils and fat-soluble antioxidant

vitamins in a perfect biorelationship, and the lack is then

substituted

for with large intakes of disproportionate combinations of processed

oils and fats.

In this regard it is enlightening to note that the daily vitamin E

requirements (which amount to about 10 mg per day) increases 20 fold

it

polyunsaturates are added to the diet.[xiv]

It is doubtful whether any diet will supply this additional

requirement

without supplementation, and it is therefore not surprising that the

degenerate diseases are so prevalent in Western societies.

The eating of whole foods that have not been stripped of their

essential

components will supply all the essential oils required in healthful

combinations and should therefore be encouraged.

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Reference:

Jonnalagagadda, S.S., Mustad, V.A., Yu, S., Etherton, T.D.,

Kris-Etherton, P.M. 1996. Effects of individual fatty acids on

chronic

diseases. Nutrition Today. 31 (3) May/June 1996.

[ii] Mensink, R.P., Katan, M.B. 1990. Effect of dietary trans fatty

acids on high-density and low-density lipoprotein cholesterol levels

in

healthy subjects. New Enlg.J.Med. 323:439.

[iii] Nutrition Today Newsbreaks. 1995. British scientists endorse

new

fatty acid guidelines. Nutrition Today. 30 (1), January/February

1995.

P.5.

[iv] Fedeli, E. 1984. La auto-ossidazione Lipidica. In: Simp. Su

Rrilettura di un problema: 1 lipidi Alimentari:, Rimini (Italia)

[v] Alexander, J.C. 1978. Biological effects due to changes in fats

during heating. (In: Symp. On frying oils, Presented at AOCS 68th

Annual

meeting, New York City, New York (USA) 11.5 1977). J.Am.oil

Chem.Soc.

55:711.

[vi] Giani, E., Masi, I., Galli, I. 1985. Heated fat, vitamin E and

vascualr eicosanoids. Lipids. 20:439.

JoAnn Guest

mrsjo-

www.geocities.com/mrsjoguest/Diets