Dr. Fuhrman Dr. Fuhrman

Polyunsaturated oils

beautiful sunflower

Many health organizations recommend the use of oils that consist primarily of polyunsaturated fatty acids (PUFA's), like sunflower oil because they are said to be heart healthy. Let's look at the facts.

There are two separate issues that are important when assessing the healthfulness of polyunsaturated oils:

  1. Health aspects of polyunsaturated fatty acids.
  2. Health aspects of extracted oil made from those fatty acids.

Different kinds of polyunsaturated fatty acids

PUFA's can be divided into two major groups: omega-3 and omega-6. For years, experts thought the two were interchangeable in their health benefits, but lately the omega-3 fatty acids get most of the attention, and it is now known that too much omega-6 PUFA's are actually unhealthy.

Omega 3 fatty acids

The three most important omega 3 fatty acids are ALA, EPA and DHA. Your body cannot make ALA, you have to get it in your diet. Flax seeds, walnuts and greens are naturally rich in ALA.

ALA itself has health benefits, but the omega 3 fatty acids that are so good for your brain are DHA and EPA. Your body can convert ALA into EPA and EPA into DHA, if you eat a healthy diet and are very healthy. Natural sources of EPA and DHA are fish, specially bred animals and algae.

Omega 6 fatty acids

The three most important omega 6 fatty acids are LA, GLA and AA. Your body cannot make LA, but it can convert LA into the other omega 6 fatty acids. Some health experts still recommend the use of sunflower oil and other LA rich products because they are so heart healthy, but our diets are already very rich in LA, we certainly do not need extra LA. Sunflower oil may or may not be healthier than saturated fats like butter and palm oil, but that is not the issue: you should avoid both.

Health benefits of PUFA's

PUFA's lower cholesterol. High levels of cholesterol are associated with higher rates of heart disease, lower levels of cholesterol are associated with lower (or even absent) levels of heart disease. It is important to note though, that PUFA's lower both LDL (bad) and HDL (good) cholesterol and that populations that have low levels of heart disease do not consume large amounts of PUFA's.

Health dangers of PUFA's

PUFA's are prone to oxidation and rancidity. Oxidation does not just affect taste, it affects the health properties of the fats. Their original packaging (whole nuts and seeds) protects the fragile oils with many anti-oxidants. As extracted oils the fats are much more likely to go bad than as properly stored nuts and seeds. If you do not want your arteries to rust, always store PUFA rich products in a sealed container in a refrigerator or freezer and do not overheat them.

Omega 6 fatty acids, particularly AA (a fatty acid almost exclusively found in animal products), but also an overload of LA compared to ALA, lead to inflammatory diseases like asthma and arthritis.


Nuts and seeds are very high in polyunsaturated fatty acids. Polyunsaturated fats are very unstable, so it is best to eat them in their original packaging and not use extracted polyunsaturated oils. An exception could be small amounts of sesame oil, because it still contains many anti-oxidants and a large amount of (more stable) mono-unsaturated fatty acids. I recommend to add sesame oil to the meal when it is done, not to fry in it. A good quality cold pressed rapeseed oil could also be used sparingly as a salad dressing, because of its favorable omega 3/6 ratio, but many rapeseed oils sold today do not have that much omega 3 fatty acids anymore. Canola oil (which is refined rapeseed oil) does, but I do not recommend the use of refined oils.

Do use nuts and seeds in your diet -- despite my reservations about high amounts of PUFA's, nuts and seeds have been shown to be good for you in many studies. Make sure to include flax seeds and walnuts, as well as lots of greens, in order to keep a favorable omega 3/6 ratio.

Later this week, I will discuss the health properties of mono-unsaturated oils, most importantly olive oil.

September 25, 2006