Getting the good oil about preventing heart disease
We Australians have the dubious honour of making our country the second fattest nation on earth (no prizes for guessing number one!). Nevertheless, fats are an essential part of our diet. Just how good or bad they are depends very much on the type of fat we consume, and how much.
While it has been well recognised for many years now that being overweight and obese is a short cut to a life of ill health and premature death, the comparatively long living indigenous peoples of Alaska, Canada and Greenland posed a medical dilemma – both the food they ate and their general appearance was more fat than lean.
It was in the 1970s researchers discovered that the copious serves of fat mainly from the oily fish they consumed, rather than pre-disposing towards heart disease, was actually serving to prevent it. The so-called omega-3 fatty acids contained in the fish oil were providing the benefit.
Omega-3 fatty acids and omega-6 fatty acids are together known as polyunsaturated fatty acids – they are essential building blocks for a number of chemicals involved in important reactions in the body. They’re the good fats.
The bad fats are the saturated fats. Foods containing a high proportion of saturated fats include dairy products (especially cream and cheese), animal fats, fatty meat, chocolate and some processed foods.
While the National Heart Foundation recommends that our total fat intake should make up 20–35% of our energy requirements, it recommends that saturated fat should be less then 7%.
Furthermore, just when we think our brain is saturated with information about fats, we learn that trans fatty acids – a different form of unsaturated fats – seem to have an even greater adverse effect on the risk of heart and blood vessel disease than even the saturated fats. They increase the level of LDL cholesterol (the bad one) and decrease the level of the good HDL cholesterol.
We need both omega-3 and omega-6 polyunsaturated fatty acids, but over the past century or so, our diet has changed from predominantly fish, plants and wild game to a diet of farmed meats and processed foods and the ratio between the omega-3 fats and the omega-6 fats has become unbalanced (too much 6 not enough 3).
Chemicals with the abbreviated names of EPA and DHA are the two of the major forms of omega-3 fatty acids which seem to be responsible for their beneficial effects. They help protect us from heart and blood vessel disease and have an anti-inflammatory effect; and some studies have shown EPA/DHA supplementation is able to protect against the progression of macular degeneration and also to enhance concentration and learning in children.
So there is good evidence for dietary supplementation with fish oil. However, even with naturally occurring substances, if there’s a benefit, there’s also always a risk.
Fish oil capsules are generally well tolerated, but gastro-intestinal side effects are not uncommon – a ‘fishy’ aftertaste or heartburn and indigestion may be experienced. And people who are allergic to fish may also be allergic to fish oil supplements. Also, there can be interactions between fish oil and some prescription medicines, so check first with your pharmacist before starting treatment. On the plus side while mercury toxicity is a concern with some fish, in Australia the mercury content of fish oil capsules is required to be extremely low.
And remember, ‘oils ain’t oils’. There is a difference between fish oil supplements and cold liver oil capsules. Large quantities of the latter may provide toxic doses of vitamins A and D. You can get more of the good oil about fish oil from pharmacists providing the Pharmaceutical Society’s Self Care health information. Log on to the Pharmaceutical Society website at www.psa.org.au and click on Self Care pharmacy finder for the nearest location.