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.
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).
Butter or margarine? One of the many choices when it comes to food that seems to offer no easy answer.
If you’re from the butter camp, chances are you’re aware that margarine “is naturally grey” and is only yellow because of the “artificial colours” that are added. You might see margarine as a concoction of chemicals, full of trans fats (even worse than saturated ‘animal’ fats), and not “real food” that we are made to eat.
If you’re in the margarine camp, chances are that you know most of the fat in butter is saturated ‘animal’ fat, which is the type that raises cholesterol in your body. When visiting a friend who uses butter, you might be wracked with pangs of guilt, with images of clogged arteries speeding through your mind.
Or you might be sitting on the fence, waiting for a post like this to come along!
When it comes to heart health, there’s no two ways about it: margarine is a better choice than butter. Butter is roughly 80% fat, 20% water. Saturated ‘animal’ fat makes up more than half (55%) the weight of butter, which, as we mentioned in the last post, is the major dietary factor in increasing cholesterol levels. On the other hand, being made from plant oils, margarine contains mostly unsaturated ‘healthier’ fats.
The National Heart Foundation of Australia and American Heart Association each recommend reducing saturated fat to 7%, or less, of the energy we eat, to maintain healthy arteries. To put this into perspective, saturated fat made up 12% of the energy Australians ate in 2011-12, and 11% of the energy Americans ate in 2009-10. So it is very important that we do all we can to eat far less animal fats, and replace them with plant oils.
In short: Switching from butter to margarine is a simple strategy to significantly reduce the amount of saturated fat in your diet.
What is margarine? What about trans fats?
In simple terms, margarine is solidified plant oils, with flavour and colour added. Originally, this process involved a process called partial hydrogenation. One of the issues of partial hydrogenation is that it produces trans fats. Trans fats have received a lot of media coverage for being even worse for you than saturated fats, and this is one reason that some people believe that butter is a better choice.
In Australia, a different process is now used to produce margarine, called interesterification. This process produces negligible trans fats. If you’re unsure, check the Nutrition Information Panel of a margarine product next time you’re in a supermarket. Chances are it will have an (optional) section for trans fats in the Nutrition Information Panel, showing that the levels are nil or next to nil. Labelling of trans fats content is mandatory in the United States, but not in Australia or the EU.
Thankfully for those of us in Australia and New Zealand, Britain and the United States, the amount of trans fats we eat is under the safe limit of 1% of dietary energy set by the World Health Organisation. In all of these countries, our intake of saturated fats is of far greater concern (is much too high). Interestingly, the World Health Organisation note that, due to cheap hydrogenated oils, it is people living in developing countries who are more likely to have an intake of trans fats that exceeds the 1% limit.
Alternatives to both
If you can’t quite come at the idea of margarine being ‘unnatural’, but are keen to maintain healthy arteries, there is a third option. Use butter, but use it sparingly and occasionally. If you enjoy having a sandwich with butter on it everyday and can’t come at any of the tips below, I would seriously consider switching to margarine.
Ideas for a butter and margarine-free sandwich:
- Have a salad sandwich with avocado or a drizzle of olive oil instead of butter. Add reduced fat cheese for extra flavour, protein & calcium
- Avocado. Full of healthy ‘unsaturated’ plant oils and vitamins.
- Peanut butter. It’s a great source of healthy plant oils and protein
- Tahini (sesame seed spread), available in health food shops, Middle Eastern grocers, and supermarkets. It has a nutty flavour and is high in plant oils. Goes well with tomato for some sweetness.
- A small drizzle of olive oil on bread makes the perfect accompaniment to a bowl of homemade soup
- Try going butter/margarine free. It’s amazing how many people try sandwiches without a butter-like spread, and find they can’t taste the difference. You might be one of them!
Or try branching out and have left-overs, tuna and crackers or pasta salads for lunch instead. Chances are you’ll naturally end up enjoying better nutrition and more varied, tastier food at the same time!
Margarine is a much better choice for your arteries than butter, although there’s nothing wrong with having butter occasionally. If you can’t come at switching over to margarine entirely, branch out and try other lunch options. Chances are you’ll have a tastier range of choices for lunch too!
Further reading: The National Heart Foundation of Australia has some FAQ’s on this topic.
Nutrition is certainly an evolving science. As more and more research is done into the health effect of different foods, nutrition scientists, health bodies and dietitians are constantly reviewing the evidence to ensure that the advice they give people is up-to-date. Occasionally, new evidence emerges to show that this advice is not accurate. and needs to change.
In my view, there’s no better symbol of this than the humble egg. Until relatively recently, people were advised to limit the number of eggs they ate. This was because, being high in cholesterol, eggs were thought to increase one’s risk of heart disease. (To put this into context, this was before we tested for “good” (HDL) and “bad” (LDL) cholesterol separately, and instead lumped it all into a single category. If your total cholesterol was high, that was bad. If it was low, that was good. Simple. Of course, we now know that it is the levels of good and bad cholesterol that matter, rather than total cholesterol)
The facts on cholesterol
We now know that dietary cholesterol has only a small impact on the amount of cholesterol in your body. Instead, other lifestyle factors have a much larger impact on raising your cholesterol levels. These include being overweight, smoking, being inactive, eating lots of animal (saturated) fats compared to plant oils, and drinking lots of alcohol often.
What does the Heart Foundation say about eggs?
So we’ve established that dietary cholesterol only has a relatively small impact on the amount of cholesterol in your body. Now let’s get back to eggs. According to the National Heart Foundation of Australia:
All Australians, including people with diabetes or metabolic syndrome, who follow a healthy balanced diet low in saturated fat can eat up to six eggs each week without increasing their risk of cardiovascular disease.
Similarly, the British Heart Foundation says:
Unless you have been advised otherwise by your doctor or dietician, if you like eggs, they can be included as part of a balanced and varied diet.
Eggs: A Nutrition Powerhouse
Eggs are, in fact, a nutrition powerhouse. They contain a huge range of vitamins and minerals. They are particularly high in protein, folate, iodine, vitamin A, selenium, vitamin B12, and some eggs can be good sources of omega-3 (check the label).
They are an especially good source of nutrition for people who have a poor appetite, or who live alone and don’t feel like cooking. Boiling two eggs, and serving with a source of whole grains and vegetables, can give you a nutritious meal in only a few minutes. Hard boiling them makes a quick and easy snack that you can take out with you. Of course, the best way to enjoy eggs is as part of an overall way of eating that includes plenty of fruits, vegetables, legumes and whole grains.
The healthiest way of cooking eggs? Try boiling, poaching or scrambling your eggs. Frying eggs, or making an omelette is alright too, but use a small amount of oil, rather than butter. Quiche, while delicious, is full of butter and cream, and is best saved for the occasional treat.
The Egg Farmers of Canada have a great site of egg recipes, ranging from the basic omelette to more advanced recipes for the adventurous.
Disclaimer: This is advice is only for the general population. Some people can be more sensitive to dietary cholesterol than others. If you have high cholesterol, talk to your GP or Accredited Practising Dietitian for tailored dietary advice.