This post has been a long time coming, but it’s also been one of the topics I’ve been most looking forward to exploring on this blog. I try to put a reasonable amount of effort into researching each post that’s … Continue reading
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:
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.
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.
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.
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!
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.
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.
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!
This is the first in a series of three posts that looks at the role of fats and oils in our diet. This first post breaks down the different types of fat that you see on food labels: saturated, unsaturated and trans. The second and third posts will look into the highly topical omega-3 (found especially in oily fish) and omega-6 fats (found especially in seeds and their oils).
I’m writing this series in response to requests from several different readers, on similar themes. If you’ve made a request for a different post subject that I haven’t addressed yet, I thank you for your input and I will get to your topic soon!
What are fats?
Let’s start at the very basic. Fats and oils are essentially two words that refer to the same thing. We call them ‘fats’ when they’re solid at room temperature (think the fat on meat, or lard), and ‘oils’ when they’re liquid at room temperature. Fats are a essential component of our diet.
The following are all 80-100% fat:
- Vegetable oil, olive oil, sunflower oil, coconut oil etc
- Fish oil
- Cod liver oil
- Ghee (‘clarified butter’)
- Fat on meat
Fats and energy
Like carbohydrates and protein, fats give us energy. You may have heard the terms ‘calories’ or ‘kilojoules’. We measure the energy in food in calories or kilojoules, depending on whether you use an imperial or metric system. Energy in food goes towards maintaining our body weight, and gives us the energy to do all the things we do each day. If we don’t get enough energy from food, we lose weight. If we eat too much, we gain weight.
Different types of fat
On a sub-microscopic level, fats are made up of millions of smaller components, called molecules. The molecules in fat are called ‘fatty acids’.
There are several different types of fatty acid. You may have come across these on the Nutrition Information Panels of food products when you’re at the supermarket. The main types of fatty acid are: saturated, monounsaturated, polyunsaturated and trans. Or, more simply, saturated and unsaturated.
All fats/oils contain a mixture of these types of fatty acid. For example, if we look at the Nutrition Information Panel of one brand of butter (see image below), we see that although butter contains 80.5 grams of fat per 100g of butter (80.5% fat), “only” 53.1 grams of this is saturated fatty acids. So although the majority of fat in butter is saturated, some of it is unsaturated.
Saturated fatty acids
Solid fats are high in saturated fatty acids. These are usually animal fats, although coconut and palm oil, and cocoa butter, are also high in saturated fatty acids. (Coconut and palm oil are only called ‘oils’ because they are liquid at room temperature in their native tropical climate; they are solid at room temperature in temperate climates)
A diet high in saturated fats increases “bad” LDL-cholesterol, and increases your risk of having a heart attack. Public health bodies around the world recommend minimising the amount of saturated fats in our diet. I mentioned in the last post that current average intakes of saturated fat in the West are almost double the Heart Foundation’s recommendations (12% versus 7%).
Major sources of saturated fat in the average Westerner’s diet include:
- Meat, including bacon and processed meats
- Cream and sour cream
- Full-cream milk and yoghurt
- Regular fat cheese
- Coconut milk and coconut cream
- Pies and pastries
Choosing reduced fat milk, yoghurt and cheese is a great way to reduce the amount of saturated fat you eat, and still get enough calcium.
Unsaturated fatty acids
Liquid oils are high in unsaturated fatty acids. Foods high in unsaturated fatty acids include oils, nuts and seeds (i.e. they’re from plants). They’re also found in their derivatives, such as margarine and similar spreads, peanut butter and tahini. Eating a handful of nuts and/or seeds every day is good for our health.
There are two main types of unsaturated fatty acids: monounsaturated and polyunsaturated.
Monounsaturated fatty acids
Good sources include:
- Plant oils, including canola, olive & soybean
- Nuts and seeds
- Peanut butter
Polyunsaturated fatty acids
Consist of omega-3 and omega-6 fatty acids. Good sources include:
- Seed oils (such as canola, sunflower or flaxseed)
- Oily fish (such as mackerel, herring/kippers, sardines, salmon, trout, tuna)
- Walnuts and Brazil nuts
- Wheat germ
As a simple summary, trans fats are produced when plant oils are chemically altered to become solid. In the process, the unsaturated fats turn into trans fats. Trans fats are even worse for your heart than saturated fats. They are found in old-style margarines and any food where you see the words “partially hydrogenated” in the ingredients list. For more information, see my summary about trans fats in my last post.
Importantly, low-fat diets are no longer recommended. Instead, there is strong evidence to support replacing saturated fats with unsaturated fats, but still eating a moderate amount of fat. In general, this means eating fewer foods high in animal fats, and more nuts, seeds and plant oils. Aim for a handful of nuts on most days. In the case of milk, cheese and yoghurt, this means choosing reduced fat options.
- Try to minimise the amount of saturated fats in your diet.
- Try to have more unsaturated fats in your diet.
- (In general: less animal fat; more plant oils, nuts and seeds)
- Low-fat diets are no longer recommended. Instead, a way of eating that is high in unsaturated fats (plant oils, nuts and seeds) and low in saturated fats (animal fats) is recommended.
If you have any questions, or want clarification, please comment below.
Next post, I’ll explore Omega-6 fatty acids and seed oils, which have received a lot of bad press lately. Stay tuned!
Disclaimer: The summary provided above is for the general public, and should not replace advice given by a dietitian or doctor. If you need dietary advice tailored to your individual circumstances, consult your GP or Accredited Practising Dietitian (APD).