Exploring Fats. Part 2: Omega-6 Fatty Acids and Seed Oils

A couple of posts ago, I started off this series of three posts on Exploring Fats, in response to several requests from different readers. My first post in this series was on the different types of fat: Saturated, Unsaturated and Trans. If you missed that post, I would strongly encourage you to revisit it before reading ahead, as this is one aspect of nutrition science that can get tricky quickly!

Last time, after much explanation of the specifics of the different types of fats, I boiled down the post to the very simple: less animal fats, more plant oils.

This time, I’ll attempt to boil down a slightly more tricky topic, Omega-6 fatty acids, and whether it’s true to say that seed oils (that are high in Omega-6 fatty acids) are ‘toxic’ for you.




As we established last time, animal fats are usually high in saturated fatty acids; plant oils are usually high in unsaturated fatty acids. Unsaturated fatty acids can either be monounsaturated or polyunsaturated.

Polyunsaturated fatty acids can be further broken down into either Omega-3 or Omega-6 fatty acids. So Omega-6, which we’re talking about today, is one of the two types of polyunsaturated fatty acids.

See below for a diagram of how all of this is related:

Fats diagram

Omega-6 is found in seeds, oils, nuts, and in general is something we easily get plenty of in the average Western diet.

The other type of polyunsaturated fatty acid, Omega-3, is found in oily fish (herring/kippers, mackerel, salmon, sardines, tuna etc), fortified eggs, walnuts, canola oil/margarine and linseeds/flaxseeds (and flaxseed oil). Omega-3 is much harder to get enough of, and generally in a modern Western context, we have to go out of our way to get enough. I’ll go into Omega-3 fatty acids in more detail in my next post.

Omega-6 and Omega-3 fatty acids are also called essential fatty acids. They are called essential because, unlike other types of fatty acids, humans cannot synthesise them from other fatty acids inside our bodies. So we need to get them in our diet.


Canned fish is a convenient way to get your omega-3 fatty acids. Tuna and mackerel (pictured above) are two good sources of omega-3.

Canned fish is a convenient way to get your omega-3 fatty acids.
Tuna and mackerel (pictured above) are two good sources of omega-3.


What’s the big deal with Omega-6?

There’s been a lot of talk over the years that we have too much Omega-6 in our diet. Supporters argue that eating too many foods high in Omega-6 fatty acids increases the risk of disease, because it is broken down in our bodies to a number of compounds that promote inflammation. A growing body of research indicates that chronic (long-term) inflammation increases the risk of a number of diseases.


Interesting theory, but does it play out?

Actually, no, at least as far as the latest evidence is concerned. A Science Advisory from the American Heart Association, published in the prestigious journal Circulation in 2009, gives an excellent review of the evidence. They note that while Omega-6 acts as a precursor to compounds that promote inflammation in the body, it actually also acts as a precursor to compounds that are either anti-inflammatory, or help our arteries in other ways. They note that, while the theory of Omega-6 being pro-inflammatory has been around for a while, there is no solid evidence to support it.

They also state that:

“On the basis of the intakes of omega-6 [polyunsaturated fatty acids] used in the randomized trials, metabolic studies, and nonhuman primate studies discussed below, reductions in [coronary heart disease] risk might be expected with omega-6 [polyunsaturated fatty acid] intakes of 10% to 21% of energy compared with lower intakes, with no clinical evidence for adverse events.”

* Brackets inserted where the original source gave an acronym.


There is strong evidence to support replacing saturated fats with polyunsaturated fats, including omega-6, for heart health. This is from a meta-analysis, (a review of data from several research trials combined) as well as a number of observational studies. In this meta-analysis, the risk of a heart attack was reduced by 19% for subjects who replaced saturated fat with polyunsaturated fat, compared to their controls who made no changes. That’s a huge amount.

In terms of the role of Omega-6 in other health conditions, Bill Shrapnel from Sceptical Nutritionist does an excellent summing up the evidence here. He found that Omega-6 has no effect on the risk of cancer or macular degeneration, and it appears that polyunsaturated fat (including Omega-6) may in fact reduce the risk of Parkinson’s Disease. Check out his post for more details.


Pumpkin seeds (a.k.a. pepitas), a good source of omega-6 fatty acids. Source: Ponsulak. 10079040. FreeDigitalPhotos.net

Pumpkin seeds (a.k.a. pepitas), a good source of omega-6 fatty acids. Source: Ponsulak. 10079040. FreeDigitalPhotos.net


Confounders: The red herrings of science

It’s also important to be mindful of what we call ‘confounders’ when reviewing a lot of this evidence. A confounder is a red herring in health studies, that puts you off the scent of what is actually responsible for a health benefit/harm.

For example, the following would not be an accurate conclusion from the research: “Omega-6 levels have increased in recent years. At the same time, rates of Alzheimer’s disease, cancer, obesity, autoimmune conditions and diabetes have also increased. This indicates that Omega-6 causes these conditions.”

There are many confounders in all of this, including that people are eating more food and exercising less than decades ago, which of course would lead to obesity. And we know that obesity is a risk factor for some of these conditions, like several types of cancer and type 2 diabetes. So you certainly couldn’t say that eating foods high in Omega-6 causes these conditions!!!


Omega 6 : Omega-3 ratio

The importance of having a balance of Omega-6 and Omega-3 fatty acids in our diet has also been discussed both in the popular media and in the scientific literature. Briefly, there is evidence to indicate that the ratio of Omega-6 to Omega-3 in traditional hunter-gatherer diets was fairly even, estimated to be 0.79. So they had a similar intake of Omega-6 and Omega-3 fatty acids. Nowadays, estimates place the average ratio at around 16:1, or in other words, we have far more Omega-6 in our diet than Omega-3.

This is a growing area of research, and it’s too early to draw any firm conclusions from what’s currently available. But keep in mind with all of this that Omega-6 is only half the picture. A growing body of research supports the health benefits of Omega-3, and many of the trials that have looked at polyunsaturated fat don’t separate out the two forms. See my next post for more on this.

A traditional Mediterranean style of eating is rich in plant foods and fish. The ratio of Omega-6:Omega-3 is fairly even in a traditional Mediterranean (Cretan) way of eating

A traditional Mediterranean style of eating is rich in plant foods and fish, including a fairly large amount of olive oil. The ratio of Omega-6:Omega-3 is fairly even in a traditional Mediterranean (Cretan) way of eating. Source: KEKO64, FreeDigitalPhotos.net



In short, there isn’t enough evidence to date to support changing our stance from the last post:

Eat less animal fats, more plant oils (and fatty fish!)

(Remember that ‘plant oils’ includes whole food sources: seeds, nuts, avocado, peanut butter, tahini, and also includes margarine)

One way of eating that reflects the evidence supporting plant oils is a traditional Mediterranean one. A traditional Mediterranean way of eating has plenty of plant oils, and level 1 (highest possible) scientific evidence supporting its health benefits. It also has an even balance of Omega-6 and Omega-3 fatty acids. See a Dietitian for practical guidance and recipes if you want to make a major change to your way of eating.


In my last post in this series, I’ll be looking at Omega-3 fatty acids in more detail. Which conditions does Omega-3 help with, and for which is there no point? Is fish oil supplementation a good idea, or is it overhyped? Stay tuned!


– Sonia



For a more detailed examination of this issue, go to Part 1 and Part 2 of a series on Bill Shrapnel’s (APD) blog, Skeptical Nutrition. Or check out this ABC interview of the author of a highly publicised book on this topic, as well as a range of medical and nutrition professionals. Both the article and the interview address a couple of fundamental flaws in the argument that Omega-6 is bad for you in more detail, including inaccurate conclusions drawn from scientific studies that are often cited in this argument.

Disclaimer: This post is designed for the general population. If you suffer from a specific medical condition, consult your GP or Dietitian (AU/UK/US) for advice.


Fat vs Sugar. Who can you trust?

I feel like I’ve had a big week this week. The weather here in Melbourne has also been a bit lousy, which is never good for one’s mood. Although, given that it’s currently winter here, it’s hardly surprising! Tuesday, with its gale-force winds and rain, was particularly unpleasant. I was grateful not to be in Canberra (Australia’s capital), though, where locals had similar winds, but a maximum of just 6 degrees Celsius.

I’m not usually one for watching long TV programs or movies. But on days like Tuesday, there’s nothing like cosying up to a hot drink and hot water bottle, and sitting down for some good TV.


Some of you may have heard of popular personalities promoting diets high in butter and other animal fats, and saying that sugar is ‘toxic’. Many of you have probably heard of the old ‘low-fat’ eating advice, which was recommended by health professionals a decade or more ago. This perspective saw fat as the enemy.

“Fat vs. Sugar” (links to full documentary) aired a few days ago here in Australia, and aims to answer this question once and for all. Is fat or sugar the enemy?

The BBC documentary follows two British medical doctors who are identical twins, as they set out to explore whether fat or sugar is worse for you.  One of the twins follows a high-fat diet for one month, while the other twin follows a low-fat, high ‘sugar’ (carbohydrate) diet for the same period. The show spends most of the time investigating the effects of the diets on the twins.

While I will be the first to admit that their experiment is far from being strong evidence, it does provide some good entertainment. I also find that sometimes, seeing something in real-life puts a more personal spin on the nutritional advice you read about (especially if you’re not a ‘numbers person’).



The short answer is:

Neither fats nor carbohydrates (carbs; what the documentary calls ‘sugars’) are ‘toxic’, they’re essential nutrients. We need to eat sources of both. The best way to do this is to follow a simple way of eating, rich in plant foods (see my post on what food to eat). 

Dietitians don’t recommend low-fat diets, they recommend minimising animal fats. Replacing animal fats with plant oils, such as in nuts and avocado, is recommended (see related post).

‘Extras’ foods, like ice-cream, cakes, chocolate, lollies, pastry, soft drink… have no part in our everyday diet. Save them for an occasional (read: not everyday) treat.


My first tip would be to get your nutrition (and health) information from reputable sources. Advocating a balanced view of healthy eating isn’t exactly the way to become a millionaire overnight. So often you find people with questionable qualifications out to make a quick buck proclaiming a certain part of food as ‘toxic’, or a ‘saviour’, and a secret conspiracy by nutrition professionals to hide this saviour from you ([dramatic music] ‘The Holy Grail that nutrition experts don’t want you to know about…’).

If you’re reading mainstream magazines, watching commercial TV, or reading the websites of certain cashed-up nutrition ‘gurus’, you’re probably not doing yourself a huge favour. I also would have a headache and feel very confused if I listened to these gurus’ latest wild theories, and there seems to be a new wild theory every few months! Advertisements and health claims of packaged, processed foods also often just worsen the confusion.


From Whitney E and Rolfes SR. Understanding Nutrition. 11th ed. Belmont: Thomson Higher Education; 2008.


Tips to find reputable health information:

  • Websites ending in .gov, .gov.au, .gov.uk are Government-published websites, which have no commercial agenda. These are highly trustworthy, and give a balanced view of the facts.
  • For readers wanting it simple, simple, simple!: Go to the Mayo Clinic, or Better Health Channel websites.
  • For readers wanting more detail, but still in simple language: Go to Patient.co.uk.


Tips to find reputable nutrition information:

  • Consult an Accredited Practising Dietitian or a Registered Dietitian (US/UK) for personalised nutritional advice. This is often rebatable from your health fund or insurance plan, but check with your provider for details.
  • The British Dietetic Association has some great fact sheets on a range of nutrition-related subjects.
  • Scoop Nutrition and the Nutrition Blog Network both have comprehensive directories of the blogs of Registered Dietitians.
  • If you’ve got a particular question about a diet, or a nutrition topic that’s been in the media, eDietitians has a range of articles written by qualified dietitians, written in a magazine style.
  • For a particular medical condition, often the association for that condition will also have some great information. For example, the Heart Foundation (Au/UK/US), Coeliac Foundation (Au/UK/US), and Diabetes Associations (Au/UK/US) are great resources. With smaller associations, it’s often a good idea to ensure that the person writing the article is a Dietitian, Medical Doctor, or Medical Researcher in that field, to ensure you can trust the information.


Got another website or other source of nutrition information that you can recommend? What do you think of the Fat vs. Sugar documentary?

I look forward to coming back next week and setting the facts straight about Omega-6 and seed oils, in Part 2 of my post series on Fats and Oils.

Hope everyone has a great weekend!


– Sonia.

Paleo Diets




Source: tiverylucky. 100211927. http://www.freedigitalphotos.net/images/grilled-salmon-steak-photo-p211927


Paleo Diets have received quite a bit of attention in recent times. Aimed at mimicking a traditional hunter gatherer way of eating, Paleo Diets encourage eating plenty of vegetables, fruit, meat, poultry and fish, while cutting out all grains, legumes, dairy and processed foods.

Interested in whether their touted benefits play out?

Check out my recent article over at eDietitians.com. Comments and questions are welcome!


Image courtesy of tiverylucky at Free Digital Photos.net.

7 Facts Behind Vitamin and Mineral Supplements

Vitamin and mineral supplementation is big money in the Western world. There is very limited data regarding the size of the industry, but the National Institute of Complementary Medicine says that as of 2001, the worldwide value of vitamin sales was estimated to be $AUD49 billion. It’s big business here in Australia. The National Health Survey showed that as of 2011-12, almost 1 in 3 (29%) Australians used a dietary supplement. More than half (16%) of this was multi-vitamin or multi-mineral supplements, with the remainder being fish oil. Working in community pharmacy during my high school and university years, I saw first-hand how commonplace supplements have become.

There is a place for vitamin and mineral supplements. The question is whether that place is a niche market for the few who really need them, or a booming industry for the worried well. With such a large percentage of us taking vitamin pills, I thought I’d give a run-down of what the science says.


Fact: In wealthy countries, multivitamins are only needed in rare instances.

If you’re eating an average Western diet and don’t have a serious medical disease, chances are you’re wasting your money on that multivitamin. Multivitamins are usually only recommended in isolated cases, for example people suffering from malnutrition (including anorexia nervosa) and diseases of malabsorption, such as cystic fibrosis. In Australia, studies of the population’s nutritional intake that have been conducted by public health bodies have regularly shown that, with the exception of some isolated nutrients such as calcium, we are doing very well. In fact, with current obesity levels in Australia being unprecedented, overnutrition (eating too much) and overall diet quality are now considered to be larger issues here than undernutrition.


Fact: Individual vitamin and mineral supplementation can occasionally be necessary.

If you are deficient in a vitamin or mineral, you’ll usually only need that specific nutrient- not a multivitamin.

For example, if you avoid eating dairy products, you may need a calcium supplement (although trying to include more sources of calcium in your diet, such as canned fish with bones or lactose-free products, is recommended). If you have been diagnosed with iron deficiency anaemia, you may need iron tablets. Likewise for Vitamin D. For women planning on becoming pregnant in the next 3 months, and in the first 3 months of pregnancy, public health bodies recommend a folic acid and iodine supplement to support the healthy development of the baby. Vegans will need foods fortified with Vitamin B12 and calcium or a supplement, and should also consider an algal omega-3 supplement. People who drink a large quantity of alcohol on an ongoing basis should consider a thiamin supplement (as well as seeking professional support).

What you probably don’t need is a multivitamin containing everything else.


Fact: More of a good thing is not better.

A lot of us who take vitamin pills take them as a safety net. The idea that taking a pill to make up for those days where our diet isn’t so great, on the surface, seems to make sense. However there’s no evidence that getting more than the Recommended Dietary Intake (RDI)- the amount that meets the nutrient requirements of 99% of the healthy population- has any health benefits. While any excess of water-soluble vitamins will just go down the toilet (see below), fat-soluble vitamins (Vitamins A, D, E, K) are stored in your body. Excesses of these can do damage.

Here in Australia, vitamin supplements containing Vitamin A must show a disclaimer that states ‘WARNING – When taken in excess of 3000 micrograms retinol equivalents, vitamin A can cause birth defects’.  2 studies with very large sample sizes conducted in the 1990’s discovered that, rather than reducing the risk of lung cancer as had been expected, Vitamin A supplementation increased the risk, as well as increasing overall mortality. There is also some evidence that Vitamin E  may increase the risk of heart failure and overall mortality. Being acidic, chewable Vitamin C may increase the risk of dental caries.

One thing to keep in mind, too, is that science is constantly learning more about the effects of many of these supplements. For now, it’s probably best to keep to your fruit and vegetables to be safe.


Fact: Water-soluble vitamins get flushed down the toilet.

‘Water-soluble’ literally means ‘dissolves in water’. Water-soluble vitamins are Vitamin C and the B-group vitamins (Thiamin, riboflavin, niacin (B6), folate/folic acid, Vitamin B12, biotin and pantothenic acid). Your body takes what it needs from food, and excretes the rest out in your urine.


Fact: Supplements are not all clinically tested.

In Australia, the Therapeutic Goods Administration (TGA) divides therapeutic goods (including medicines and vitamins) into 2 classes: listed and registered. Vitamin supplements are usually classed as ‘listed’, although a select few are ‘registered’. Listed medicines (contain ‘Aust L’ on the label) are assessed as having a lower level of risk than those that need to be registered. Crucially, ‘listed’ medicines do not need to be tested to show that they actually work, and many may be no better than a placebo.


The Nutrition Information Panel of a packaged breakfast cereal sold in Australia. Note the number of vitamins and minerals that have been added (see bottom half of the table)


Fact: A lot of packaged foods are already fortified with vitamins.

Next time you eat breakfast cereal (if you eat it), look at the Nutrition Information Panel on the box. Chances are there’ll be a whole bucketload of vitamins and minerals added to the product. Also, in Australia as of 2009, all bread-making flour (except organic) must be fortified with iodine and folic acid. Iodine because Australian soil is very low in iodine, and Australia has high rates of iodine deficiency. Folic acid fortification was introduced as a means of reducing the rate of neural tube defects, like spina bifida.


So there you have it: 7 facts behind vitamin pills. Hopefully that’s helped clear some confusion! Of course, this is general advice for the average healthy population. If you want advice about your own situation, consult your GP or Accredited Practising Dietitian (APD).