Fat-Friend or Foe
Fats (sometimes referred to as lipids) are organic substances which provide the body with an important source of energy and are stored by the body in adipose tissue. Fats provide at least twice as much energy than either proteins or carbohydrates. Animals require fat in their diets as it has many important roles other than just as an energy source. As far as pet food is concerned fat is used to increase the palatability of the diet, but it is also vital for the absorption of the fat-soluble vitamins A, D, E and K. Fat provides insulation and waterproofing for the body and protects and cushions many of the internal organs plus being integral to the synthesis of some hormones and the formation of cell walls.
An excess intake of fat leads to fat being deposited around the body, ultimately leading to obesity – a very common problem in pet dogs and cats, - however its deficiency can also have negative effects, which can lead to impaired skin and coat condition and reproduction problems.
As far as nutrition is concerned fats are referred to as fatty acids of which there are three essential fatty acids – linoleic acid, alpha linolenic acid (care with these as their spelling is very similar but they are very different from each other) and arachidonic acid. Fatty acids are chains of carbon atoms to which both hydrogen and oxygen atoms are attached and can be categorised as short, medium and long chain depending upon the number of carbon atoms.
Saturated fats (often referred to as ‘empty calories’ as they have no nutritional benefit other than to provide energy) are found chiefly in animal products e.g. dairy foods and meat. Short chain saturated fatty acids provide an excellent source of ‘quick release’ energy, which are particularly beneficial for working dogs, neonates and diabetic patients. Saturated fatty acids do not have a double bond between carbon atoms and therefore they are ‘saturated’ with hydrogen atoms.
Conversely, unsaturated fatty acids contain between one to six double bonds. Monounsaturated fatty acids having just one double bond and polyunsaturated fatty acids have two or more. Unsaturated fatty acids include the essential fatty acids linoleic acid, alpha linolenic acid and arachidonic acid as well as others which are crucial for life. Unfortunately, unsaturated fatty acids are easily degraded and become rancid, hence the need for antioxidants such as vitamin E.
Linoleic acid is an essential omega 6 fatty acid and is crucial for the synthesis of cell membranes. Omega 6 fatty acids are found in vegetable oils and some unsaturated animal fats especially those from poultry, land fowl and water fowl which contain large amounts of linoleic acid.
Other important omega 6 fatty acids, such as gamma-linolenic acid (GLA) and arachidonic acid are derived from linoleic acid. GLA has beneficial effects in animals with allergies and helps combat inflammatory conditions. Arachidonic acid is only found in animal fats and cats are unable to synthesise arachidonic acid and therefore their diet must contain this, further compounding the fact that they are obligatory carnivores.
Omega 3 fatty acids act as anti-inflammatory agents and are synthesised from the essential omega 3 fatty acid - alpha linolenic acid (ALA) which is found in some vegetable oils. The very long chain omega 3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are both derived from ALA. In particular, EPA and DHA are vital to the normal development of the brain and retina and DHA specifically is linked to the learning capacity and maturity of the nervous system in young animals and can improve brain function in older animals. Sources of EPA and DHA include fatty fish such as salmon, mackerel and herring.
In conclusion, we can see that although excess fat is one of the most common causes of obesity in our pets it forms an essential part of their diet. When assessing ingredients in pet food look for the ‘good fats’ which will have positive effects on health and wellbeing and be mindful that if those specific ingredients are not listed then the maybe the manufacturer has a reason!