
                            VegSocUK Information Sheet
                             THE VEGETARIAN SOCIETY


   ___________________________________

                               FATS & CHOLESTEROL

   Fats provide a concentrated source of energy in the diet. The building
   blocks of fats are called fatty acids. These can be either saturated,
   monounsaturated or poly-unsaturated. Foods rich in saturated fats are
   usually of animal origin. Vegetable fats are generally unsaturated.

   Saturated fat raises the level of cholesterol in the blood.  Cholesterol is
   present in animal foods but not plant foods. It is essential for metabolism
   but is not needed in the diet as our bodies can  produce all that is needed.
   Raised  blood cholesterol is associated with an increased risk of heart
   disease.

   Fats and oils are essentially the same. Fats tend to be solid at room
   temperature whilst oils are liquid. The term lipids include both fats and
   oils.
   ___________________________________

  STRUCTURE & FUNCTIONS

   Fats consist of fatty acids and glycerol. Nearly all the fats in our  bodies
   and in foods are triglycerides, being made up of three fatty acid molecules
   to one glycerol molecule. There are about 16 di fferent fatty acids commonly
   present in foods. The nature of fat  depends on its constituent fatty acids.

   Fats can be classed as either saturated, monounsaturated or  polyunsaturated.
   This depends on the type of chemical bonds present in the fatty acid. If a
   fatty acid has all the hydrogen atoms it can ho ld it is termed saturated.
   However, if some of the hydrogen atoms are absent and the usual  single bond
   between carbon atoms has been replaced by a double bond, then it is
   unsaturated. If there is just one double bond then it is monounsaturated. If
   there is more than one then it is  polyunsaturated. Most fats contain a
   proportion of each of these three basic types of fatty acid but are
   generally described according to which type predominates.

   Saturated fats tend to be animal fats and are solid at room  temperature.
   Butter, lard, suet and meat fat are saturated fats. Unsaturated fats are
   liquid at room temperature. They are usually of plant  origin, though fish
   oils may also be high in polyunsaturated fatty acids. Plant oils may be
   hardened by the addition of hydrogen atoms, converting double bonds to single
   bonds. This process is known as hydrogenation. Hydrogenated vegetable oils
   are often present in margarine and other processed foods.

   Fats have a number of important functions in the body. As well as being a
   concentrated source of energy, fats act as carriers for fat-soluble vitamins
   A, D, E and K. Fats are also essential for the structure of cell membranes
   and are precursors of many hormones.
   ___________________________________

  ESSENTIAL FATTY ACIDS

   Two fatty acids are termed essential fatty acids. These are linoleic
   acid and a-linolenic acid. These must be present in the diet as the body
   is unable to make them itself. They are widely present in  plant oils
   such as sunflower, rapeseed and soyabean oils.

   Linoleic acid is converted into the body to arachidonic acid from  which
   prostoglandins and other vital compounds are made. Because of this
   conversion, arachidonic acid is not an essential fatty acid  as was once
   believed.  a-Linolenic acid is converted to eicosapentanoic acid (EPA) which
   is  important in proper nerve function. EPA is present in fish oils and is
   claimed to be beneficial in reducing the symptoms of arthri tis and the risk
   of heart disease. For this reason, fish oils are sometimes used
   therapeutically. Plant  oils containing large amounts of a-linolenic acid
   can be used as an alternative by vegetarians. Linseeds and linseed oil
   are particularly rich sources of a-linolenic acid.

   ___________________________________

  CHOLESTEROL

   Cholesterol belongs to the sterol group of fats. It is present in all animal
   tissues but is absent from plants. Cholesterol is essential as a component of
   cell membranes and a precursor of bile acids and certain hormones. The body
   can make its own cholesterol and so a dietary source is not required.

   Cholesterol is transported in to various proteins. These complex  molecules
   are called lipoproteins. There are four main types of lipoprotein involved in
   cholesterol transport. The most commonly refer red to are low density
   lipoprotein (LDL) and high density lipoprotein  (HDL).

   Cholesterol may form plaques on artery walls if levels in the blood are too
   high. This can lead to atherosclerosis. Because of this high blood
   cholesterol is linked with heart disease. It is the LDL cholesterol which
   has been linked to heart disease. HDL cholesterol may help protect against
   the risk of heart disease.

   The amount of dietary cholesterol is not clearly linked to levels of
   cholesterol in the blood. Blood cholesterol is more closely related to the
   amount of saturated fat in the diet, saturated fat raising blood
   cholesterol.  Unsaturated fats are not thought to raise blood
   cholesterol and may  indeed lower levels.
   ___________________________________

   TRANS FATTY ACIDS

   Unsaturated fatty acids can exist in two different geometric forms.
   These are called the cis and trans forms. Unsaturated fatty acids exist
   naturally in the cis form. During food manufacturing processes these
   cis fatty acids may be changed to trans fatty acids. Hydrogenation of
   margarine causes this  to occur. It has been suggested that trans fatty
   acids can increase the risk of heart disease.

___________________________________

  FREE RADICALS

   Free radicals are highly reactive molecules which have been linked to both
   heart disease and cancer. A number of factors, including alcohol, stress and
   environmental pollutants can increase the generation of free radicals in the
   body. Polyunsaturated fats can also generate free radicals, especially when
   exposed to heat or sunlight. Because of this it is suggested that vegetable
   oils should be stored out of direct sunlight. Mono-unsaturated olive oil is
   less vulnerable to free radical generation and so is a better choice for
   frying.

   Anti-oxidants such as vitamins A, C and E offer protection against  free
   radicals. Fresh fruit and vegetables are rich in these anti-oxidants.
   ___________________________________

  DIETARY SOURCES

   Saturated fats are nearly always from animal foods. Meat, eggs and  dairy
   products all contain saturated fats. Lard and suet are saturated fats.
   Coconut oil and palm oil are vegetable sources of saturated fats. Olive oil
   is a monounsaturated fat. Polyunsaturated fats are usually from plant
   sources.

   The ratio of polyunsaturated to saturated fats in the diet is often called
   the P:S ratio.

   Cholesterol is present in all animal foods but not plant foods. Egg yolks
   and high-fat dairy products are high in cholesterol.
   ___________________________________

  REQUIRED INTAKES

   Currently it is believed that around 42% of energy in the typical British
   diet is from fat. Dietary advice is to reduce this. The COMA (Committee on
   Medical Aspects of Food Policy) report advocated t hat no more than 35% of
   daily energy  requirement should come from fat whilst the NACNE (National
   Advisory  Committee on Nutritional Education) paper recommends a reduction to
   no more than 30%. Special emphasis is placed on reducing the a mount of
   saturated fat in the diet.

   Vegetarian diets tend to be lower in fat than omnivore diets.  However,
   vegetarians consuming dairy products and processed foods high in fat may
   still be consuming too much. Advice to vegetarians is t o keep fat intake
   to a minimum, avoid high fat dairy products and processed foods containing
   dairy fats and hydrogenated vegetable fats, and to use olive oil for
   cooking purposes.

   ___________________________________


//
This article is copyright to the Vegetarian Society (UK), but may be freely
copied for non-commercial use provided it is kept intact, not altered
and these lines are included.

For futher information contact: The Vegetarian Society, Parkdale, Dunham Road,
Altrincham, Cheshire WA14 4QG, England. Tel: (England) 061 928 0793
email: vegsoc@vegsoc.demon.co.uk
//



[The text of this file was obtained from the Vegetarian Society (UK) in
March 1995.]

