What’s the deal with seed oils?

In this blog post I will be examining the polyunsaturated fatty acids or PUFA’s found in seed oils. What are they, where are they found in our diets and are they a healthy alternative to saturated fat?

Types of unsaturated fats

There are two types of unsaturated fats; monounsaturated and polyunsaturated. These fats are less ‘saturated’ with hydrogen and are liquid at room temperature. Many seed and vegetable oils contain a mix of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA). As PUFA’s are consumed in high quantities in our diets and have been linked to chronic health conditions we will be focusing on them in this post.

Types of PUFA

There are two types of fatty acids contained in PUFA; omega 3 and omega 6 fatty acids. They are both considered essential fatty acids (EFA), meaning the body cannot make them and we need to obtain them from our diet. Both fatty acids are important structural components of cell membranes. They are also important for vision and central nervous system functioning. Omega 3 and Omega 6 have a different chemical structure with the first double bond being three bonds and six bonds from the omega end of the fatty acid for Omega 3’s and Omega 6’s respectively.

Omega 3 naturally occurs in wild caught fatty fish, pasture raised eggs, flax seeds, walnuts and soybeans They have anti-inflammatory effects and help to reduce the creation of new fat cells. Omega 6 is also found naturally in foods such as grass-fed meat and dairy products, soybeans, nuts, seeds, cereals and eggs. However, industrially processed seed oils are extremely high in omega 6 and as these oils are used in the production of a large number of processed foods and used to cook with in restaurants, take away foods and as cooking oils in homes we are exposed to them in huge quantities. Overexposure to omega 6 leads to an increase in pro-inflammatory signaling molecules (eicosanoids) and promotes fat tissue deposition (1).

Prior to industrialisation the ratio of omega 6 to omega 3 in the diet was approximately 1:1. This ratio is important as the pathways in the body used to metabolise both compete with one another for enzyme activity. An overabundance of omega 6 limits the metabolic production of omega 3 from plant sources. Western diets now have a ratio of omega 6 to omega 3 as high as 16:1 and herein lies the problem (2).

The seed and vegetable oils high in PUFA include:

• soybean oil (50% PUFA)

• corn oil (53%) - Omega 6:3 = 60:1 :(

• cottonseed oil

• sunflower oil (65%)

• safflower

• peanut oil

• sesame oil

• rice bran oil

• safflower

• canola oil (also known as rapeseed) (25%)

Restaurants and takeaway businesses use mainly seed oils for all their cooking

These oils should be avoided but they are hard to avoid because they are in TONNES of processed foods. Go to your cupboard/fridge and have a look at the ingredient labels on biscuits, bakery goods, salad dressing, margarines, spreads, curry pastes, mayonnaise and you will start to see how heavily exposed we are to these oils. PUFA’s are also found in conventionally grown chicken and pork due to their feed being made up of PUFA containing seed and corn and is the oil of choice for almost every café and restaurant due to the low cost and high availability.

What’s bad about them?

PUFA’s oxidise when exposed to light and air

This occurs during manufacture, when sitting on shelves in stores (in clear plastic bottles) and then inside our bodies. Oxygen is present inside our bodies and when we ingest these oils they react with the oxygen and form oxidation products = inflammation. Some oils such as walnut oil when tested were found to have oxidised at room temperature!!

Give off toxic chemicals when heated

Oils with a high PUFA content when heated can give off chemicals such as acrolein (3) that have been found to damage the mitochondria in our cells which can lead to metabolic syndrome, insulin resistance and diabetes. PUFA are also found in the liquid used in vapes.

Linoleic acid – a driver of obesity and inflammatory disorders

Linoleic acid is the primary omega 6 in most seed oils. Research has shown that over the past 50 years the fat in our bodies has become increasingly made up of linoleic acid (4). The saying you are what you eat is true in that the fat in our body has changed from more saturated fat to PUFA. Interesting how the rise in diabetes and obesity coincided with the dietary guidelines to lower saturated fat intake. This resulted in the replacement of saturated fats (tallow, butter, ghee, coconut oil) with seed oils. The saturated fat content of our bodies was lowered, replacing a stable anti-inflammatory fat with an unstable, inflammatory and easily oxidised fat. These fats are so toxic our amazing body tries to reduce the risk to us by storing them in our fat. However whenever the body is forced to break down fat to use as fuel such as when fasting or when exercising first thing in the morning (fasted state) this fat is drawn out of storage and the metabolised fat being drawn out is more toxic than the oil we first consumed.

In The U.S. the consumption of soybean oil alone has increased more than 1000% between 1909 and 1999. This oil has been shown to be more obesogenic, diabetogenic and more detrimental to metabolic health than coconut oil which consists primarily of saturated fat (5). In one study four groups of rats were fed a high fat diet with an equal number of calories. The groups were beef fat (tallow), beef fat + linseed oil, olive oil + linseed oil and safflower oil + linseed oil. The outcomes of the beef fat only group were not reported for some reason however the three groups with added linseed oil gained 27.6%, 37.2% and 43.2% more weight respectively (6). This research demonstrated that the group consuming the highest amount of omega 6 (safflower + linseed) gained the most weight and the group consuming the saturated fat (beef fat) and the least omega 6 gained the least weight. Not all fats are created equal even if the calories from those fats are.

PUFA in skin care

Yep, not only is PUFA a problem in food but applying PUFA containing oils/creams to your skin is also a problem. Skin care manufacturers may claim that certain oils are high in vitamin E or other antioxidants yet the PUFA in the oils readily oxidise in the presence of light and oxygen. Therefore, when you apply these creams and go outside, they will oxidise at the point of contact – your skin - potentially leading to skin damage. PUFA is being consumed in our diets, these fats are incorporated into the cells of our body – including skin cells and applied to skin in both skin creams and sunscreens. Could this be contributing to the increase in skin cancer rates we are seeing?

Reducing exposure to PUFA

Reducing the number of foods containing omega 6 is needed to bring the ratio of omega 6 to omega 3 down. This is an issue all of us need to be aware of due to the sheer number of products that contain these oils. To reduce exposure, it is important to examine the ways in which you might be regularly exposed to PUFA. Do you use seed oils for cooking at home? Do you eat out a lot? Is it in your skin care? Reading food labels and finding alternative products is also needed to avoid these oils. Always look closely at the ingredients, cook more at home with butter, ghee, tallow, macadamia nut oil (3% PUFA) and small amounts of olive oil (10% PUFA) and adding in seafood twice a week to increase the amount of anti-inflammatory Omega 3.

While everyone is being screamed at to stop eating sugar and reduce saturated fat the wolf in sheep’s clothing that has gone unnoticed by many are seed oils. The essential fatty acids found in PUFA’s are needed for good health but in the right ratio. The lack of omega 3 and the extremely high intake of omega 6 means the balance of these fatty acids is silently eroding our metabolic health, leaving us fatter and sicker. Bringing back balance to our diet by reducing exposure to omega 6 containing foods and increasing omega 3 rich foods may help to reduce inflammation and improve health long term.

The information provided on this website is for information purposes only and is not meant to be nor should be considered medical advice.