Omega 3 fatty acids and AMD

[21/06/2012]

Omega 3 fatty acids and AMD

 

In my previous post I had talked about nutritional supplements for AMD and further research is now ongoing to look at the benefits of omega 3 fatty acids as well as lutein and zeaxanthin in a large clinical trial known as AREDS 2 (Age Related Eye Diseases Study).


What are Omega 3 fatty acids?

The chart above shows where omega 3 fatty acids come from and which sorts of foods are rich in them. These polyunsaturated fats are essential nutrients as they cannot be synthesized in our body. The omega 3 fatty acids are made up of short chain alpha-linolenic acid and the long chain docosahexanoic acid (DHA) and eicosapentanoic acid (EPA).

Importance to the retina?

The brain and eye are highly enriched with omega 3 fatty acids which accumulate in these tissues during early neonatal life. DHA is a major structural lipid in the retina particularly the disc membranes of the photoreceptor outer segments. The photoreceptors are very metabolically active as they are responsible for converting light energy into electrical impulses to be transmitted to the brain for interpretation of images. Consequently, a steady supply of DHA is required for normal retinal function. The complete function of omega 3 fatty acids in the retina is still not fully understood but it is postulated that they have other neuroprotective and anti-angiogenic effects.

 

Omega 3 and Omega 6 fatty acids imbalance

Humans evolved on a diet with a 1:1 ratio of omega 6:omega 3 but in the industrialized countries nowadays, our diets are more like 12:1 or even 18:1! This hugely disproportionate intake of omega 6 fatty acids has been contributory in the observed increased incidence of heart disease, cancer and other inflammatory disorders. Basically, omega 6 fatty acids exert pro-inflammatory effects whereas omega 3 fatty acids exert anti-inflammatory effects but both are required by our body (in proportionate amounts) for normal functioning.

 

Omega 3 and AMD

Age Related Macular Degeneration is the leading cause of blindness in developed nations and intense research into the treatment and prevention of this disease has led to observational studies showing evidence supporting the association between omega 3 fatty acids and AMD. A high intake of individual fatty acids such as linoleic acid and a high cholesterol intake could lead to an increased risk of AMD. In contrast, epidemiological studies have shown that an increased intake of omega 3 fatty acids could have a protective role especially in wet AMD.

Historically, low incidences of AMD have been reported in Japan and Iceland where fish consumption is high but in recent times, more and more of this disease have been seen in these countries which could reflect a change in the dietary behavior towards a more "western diet".

 

Striking a Balance - Making a Difference


It is therefore, very important to have the correct balance of omega 6 and omega 3 fatty acids in our diet. In our current food environment, it is very difficult to get away from the omega 6 overload as almost all our food is cooked with sunflower oil or corn oil or other vegetable oils and all these are laden with omega 6. A lot of food manufacturers of health foods in specialty stores will also coat their products with vegetable oil to improve the texture and taste and unwitting consumers who believe they are taking the healthy option, are in fact tipping the scales towards the omega 6 imbalance.

The tables below provide a guide to our approximate daily requirements of omega 6 and omega 3 fatty acids.

 



How to tip the balance in your favour?

Cut your omega 6:-

1) Change your cooking oil - stop using corn oil, sunflower oil, grape seed oil, cottonseed oil. Use instead olive oil, macadamia oil or coconut oil. (For a cooking oil guide, click here)

2) Limit processed foods - choosing whole foods over processed ones could cut one third of omega 6 fats from your diet

3) Check the food labels carefully

4) Beware salad dressings, margarine, mayonnaise where omega 6 fats could be hiding

5) Choose low fat or fat free foods

6) Avoid deep fried foods

 

Up your omega 3:-

1) Eating fish - not necessary to eat fish everyday. 2 portions of fish per week should suffice and can be topped up with other seafood as well.

2) Dark leafy vegetables - these are good source of alpha-linolenic acid as well as other vitamins, minerals and antioxidants.

3) Take free range or pasture fed meats as they will have more DHA and EPA.

4) EPA & DHA supplements - for vegetarians or people who cannot take seafood, these are an option. However, before taking any supplements, be aware of any interactions these may have with other drugs (blood thinners or diabetic medications)