Quite on the contrary, linoleic acid (omega-6 fatty acid) has been proven to be the most potent cholesterol-lowering nutrient in the diet with impressive cardiovascular benefits (20-35% reduction in clinical cardiovascular end-points) according to a study by Ascherio in 2002. Where can you find omega-6 fatty acids?
They are found in:
1. walnuts
2. sunflower oil
3. sunflower seeds
4. sunflower margarine spread

In the 1980s, two lines of evidence came together on the cardio-protective effect of omega-3 fatty acids. Firstly, epidemiological studies proved beyond any shadow of doubt that populations eating large quantities of fish have very low rates of heart disease. A meta-analysis by He et al found that 5 or more fish meals a week was associated with a 40% reduction in cardiovascular disease. Secondly, long chain omega-3 fatty acids were shown to significantly lower blood fats (triglycerides), reduce inflammation, blood thinning (anti-thrombotic) and relax blood vessels (vasodilatory). All factors are beneficial for lowering cardiovascular risks.

Fish that live in cold water are rich in omega-3 poly unsaturated fatty acids – particularly docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA). The NHMRC Nutrient Reference Value for EPA, DPA and DHA is 160mg/day for men and 90mg/day for women. To prevent chronic disease, the values have been set at the 90th percentile. At this level, the targets for omega-3 fatty acids have been revised higher to 610mg/day for men and 430mg/day for women respectively. Where can you find these fatty acids?

From the above table, it is obvious that fish provide the highest quantity of omega-3 fatty acids. A 610mg per day target for men translates into approximately 100g of fish most days of the week! The upper limit for children, adolescents and adults are currently set at 3000mg/day. The GISSI – Prevenzione intervention study found that intake of 850mg of EPA and DHA significantly reduced the risk of sudden cardiac death by 45%. Dietary intake of 850mg of omega-3 fatty acids could be difficult to achieve on a daily basis. One may consider a 1000mg/day fish oil supplement as a preventative measure.

In 2000, De Catherina et al found that both omega-6 fatty acids and omega-3 fatty acids have anti-inflammatory properties; the protective effect appears to increase depending on how unsaturated the molecules (i.e. the number of double bonds). With this new evidence, Nutrient Reference Values have been formally set for these nutrients. The NRV for adequate intake of omega-3 (alpa-linolenic acid) and omega-6 fatty acids (linoleic acid) are 1.3g/day and 13g/day respectively for men and 0.8g/day and 8g/day respectively for women.

Strong scientific evidence linking dietary deficiency of omega-3s with increase risk for cardiovascular events has lead to the creation of the Omega-3 Index (by Clemens von Schacky and Bill Harris). Essentially, the Omega-3 Index represents the percentage of EPA and DHA in red blood cell membranes.
This Index is a measure of the omega-3 status of an individual. As I write, this index is increasingly being used as a valid risk factor for heart disease!

References

1. He K et al. Circulation 2004; 109:2705-11.
2. Sands SA et al. Lipids 2005; 40:343-7.
3. Harris WS. Pharmacol Res 2007; 55:217-223.
4. Sacks FM, Campos H. J Clin Endocrinol Metab 2006; 91:398-400.
5. Asherio A, Am J Med 2002; 113:9S-12S.
6. De Caterina R et al. Am J Clin Nutr 2000; 71:213S-223S.
7. Ferrucci L et al. J Clin Endocrinol Metab 2006; 91:439-446.