Anyone want to disagree with me? Question my research? Please, do. Really. This may sound confrontational at first, but I truly appreciate and welcome those wiser than me helping me understand the science of nutrition and sharing other sources that I may not have discovered on my own. I’m not a researcher. I love reading books, but that and an elementary teaching degree are about the only qualifications I bring to the table as far as science goes.
If you read my posts when they first come out or via email only, you may have missed some fascinating discussion on grassfed beef and dairy, saturated fats (and fats in general), and oxidized cholesterol and homogenized milk. I’m counting on some of those commenters to help me fill in the gaps that I’m sure are evident in my research today. I’m tackling a big subject, and one rich with controversy. (Catch up on the Fat Full Fall series starting here.)
What Kind of Fats?
Let’s start with basic, elementary science (here’s where I excel!):
There are four major classifications of fat, determined by how their molecules are arranged:
- saturated fats
- polyunsaturated fats (both omega-3s and omega 6s)
- monounsaturated fats
- trans fats
The label readers among you probably already knew that from your time scanning the Nutrition Facts on various food packages. To learn more about monounsaturated fats, which I tackled first because EVERYONE agrees that they are good for you, click here. For the scoop on trans fats, including how to find them on super sneaky food packaging labels, read this. Everyone (mostly) agrees that trans fats are terrible for you. Nobody can agree about butter, so for some controversy and to learn more about saturated fats, read this.
Important note: All foods with fats have some of each of the natural fats (saturated, polyunsaturated, and monounsaturated). They’re usually classified by that which they have the most of, like avocados in the mono category and butter in the saturated fats. In reality, butter also has mono- and poly-unsaturated fats (in an ideal ratio of omega-6s to omega 3s).
Check out The Slow Cook for a very cool explanation of fats for kids (but easy to read for adults, too).
Polyunsaturated Fats: Good Fat, Bad Fat?
Today we’re moving on to the second group of unsaturated fats, the polyunsaturated ones. I’ve saved them for last because they’re more complicated and (of course) under discussion for the “good fat, bad fat?” award.
I say polyunsaturates are more complicated because we know them under so many titles. While I feel confident in saying, “Eat more monounsaturated fats,” I can’t make a blanket statement about the polyunsaturated fats because the category includes both omega-3 and omega-6 fatty acids. One is in, one is on the outs.
Americans Need More Omega-3s
We expect to find our omega-3s in fish because of the recent fish oil supplement push, but omega-3s are found in plants (leaves, to be precise) at their origin. (Fish get them from algae.) Unfortunately, scientists and farmers have been selecting for plants with less omega-3 for the past few decades because omega-3s spoil more quickly. (Enter processed foods.)
The net result of the fear of fats in our country and the increased demand for foods that will last a long time sitting on a shelf is that Americans are quite deficient in their omega-3 fats, called essential because our bodies absolutely cannot manufacture them; they must be consumed from other sources. You can read more about the health benefits of omega-3s, particularly salmon and flax, and get some ideas for increasing omega-3s in your diet as a result of KS’s Super Foods series.
Finding the Balance
Want to get more omega-3s in your diet? Eat less omega-6. It turns out that the function of the omegas in our bodies is totally dependent upon the ratio of the two. Kind of like Kitchen Stewardship: it’s all about the balance.
Both are essential fats: we need ‘em, and we can’t make ‘em. They have kind of opposing roles in the body. Check out this comparison of the functions of the omegas and you’ll start to see why you don’t want too much of one or not enough of the other:
|Brain development and processing||Fat storage|
|Thins blood (prevent stroke, heart attack)||Clotting (helps heal from skin injuries)|
|Permeability (porous-ness, spongy, in-and-out-ability) of cell membranes||Rigidity of cell walls|
|Metabolism of glucose|
|Calms inflammation||Initiates inflammation (as an appropriate response to attack)|
|Promotes ovulation||Suppresses ovulation|
|Prevents premature birth||Prompts labor to begin|
There are various numbers given for the proper ratio of 6s to 3s:
- Smart Balance claims it has “the ideal blend of 4 to 1 omega 6 to omega 3”
- Nina Planck in Real Food says it should be 1:1
- Pollan’s numbers are 3 to 1 (more omega 6s than 3s)
- Nourishing Traditions, p. 10: “The best evidence indicates that our intake of polyunsaturates should not be much greater than 4% of the caloric total, in approximate proportions of 1 1/2 % omega-3 … and 2 1/2 % omega-6.” (See the context at the WAPF website.)
Regardless, you should consume more omega-6s than 3s, but they should be fairly close in amount and kept in balance.
As Michael Pollan says in In Defense of Food, “Too much omega-6 may be just as much a problem as too little omega-3.” He calls the 3s “fleet and flexible” and the 6s “sturdy and slow.” Some of the health risks of too much “sturdy and slow” and not enough “fleet and flexible” include “blood clots, inflammation, high blood pressure, irritation of the digestive tract, depressed immune function, sterility, cancer and weight gain (NT p. 11)” and “obesity, insulin resistance, premature labor, depression [and increased risk of heart disease] (Real Food p. 205, 267).”
We Need FEWER Omega-6s
As omega-3s are found in plant leaves, the omega-6 fatty acids are from the seeds of the plant. As we have industrialized our food supply, we’ve eaten far fewer leaves (and leaf products) and a great deal more seeds. NT says that Americans often get 30% of their total calories from polyunsaturated fats; Pollan quotes our American ratio of omega 6:3 as 10:1; Planck says we eat 20 times more omega-6s than 3s. All are a far cry from any of the possible recommended ratios listed above.
You think you don’t eat very many seeds? If you’ve paid attention to the places you find “soybean oil” or “corn (vegetable) oil” as I challenged you to do last week, then you know that corn and soy (both seeds!) are prolific in anything boxed, bottled or sold with a label.
Corn and soybeans are both inexpensive, U.S.-grown sources of oils, liquid at room temperature (convenient) and with a decent shelf life once in a processed food. However, Dr. Weston A. Price, a dentist who studied the diets of isolated traditional peoples around the world, found zero cultures who consumed polyunsaturated fat in the form of oils. This is an invention of the last century. That always makes me nervous! Strike two? Corn oil has an omega-6:3 ratio of 60:1. Yowza – that’s going to throw off your ratio no matter whose numbers you use if you eat a lot of corn oil!
By the way, guess who’s eating a lot of corn these days? Cows. Chickens. Pigs. Fish. (Conventionally farmed, that is.) Ahem. If you eat any of these delectable items at dinner, you’re consuming more omega-6s and fewer omega-3s than your grandparents did when they ate the exact same meal.
The Real Dangers of Omega-6 Oils
As convenient as the liquid oils are, the method of extraction to get that soybean or corn oil from the seed into your bottle of Italian dressing is troublesome and a downright health hazard. The food processing industry uses high heat, intense pressure (more heat), and doesn’t protect the oils from light and oxygen. The resulting oils are:
- full of free radicals (damaged molecules that attack the body, causing skin wrinkles, sets the stage for tumors, and causes plaque buildup. The majority of fat in artery clogs is polyunsaturated. Free radicals have also been linked to autoimmune diseases, Parkinson’s, Lou Gehrig’s, and Alzheimer’s. NT, p. 10-11)
- oxidized (any time damaged cells come in contact with air, they become oxidized. The recent buzz about anti-oxidants is how we can combat this problem. Another lovely word for this would be rancid oil. Sound appetizing?)
- lacking in natural antioxidants (many fats come with their own antioxidants, fat-soluble Vitamin E for example. Many of these are heat-sensitive, and thus are lost in the processed oils.)
If you need a liquid oil, you’ll want to look for terms like “expeller-expressed” and “unrefined” on the bottle. Extra Virgin Olive Oil is always processed under low heat and pressure, so you’re safe there, too. (For more on good olive oil choices and safe handling, see this post.)
There’s a bit of a myth out there that heating liquid oils too high can form trans fats. Not true, says Mary Enig. Heating liquid oils, especially polyunsaturated oils, is damaging to the oil and damaging to your body, but it’s because of the free radicals caused by oxidation, NOT trans fats.
The Other Balance: Sources on Both Sides
As always, I’m going to tell you that I don’t know much. What I do know is that I can find sources to contradict what I’ve just told you, and I’m a big believer in balance – I’ll let you pray on it and sort it out for yourself.
- For example, The American Heart Association and Cooking Light both point to polyunsaturates as heart healthy choices, but neither discusses omega-6s in particular.
- The Help Guide is a rather balanced source. The chart showing the percentages of types of fat in butter, safflower oil, margarine and olive oil is fascinating (about 4 pages down).
- About.com is another source that is influenced by the mainstream but acknowledges that there are some health risks to the polyunsaturated fats.
Final Word on Omega-6 Oils
- Omega-6s include all the “yellow oils”: corn, soybean, sunflower, safflower
- They often go rancid and/or are oxidized in processing
- They are modern oils
- They’re never to be used for cooking
- Best practice would be to cut them out entirely
- Would you still get enough omega-6 if you had no “yellow oils”? Yes – from olive oil, nuts and whole seeds, plus that from the other fats you eat – your beef, butter, eggs, etc.
- Balance omega-6s with omega-3s: eat your fish, walnuts, pastured eggs (yolks too!), flax
- You don’t need a lot of polyunsaturated fat – about 4% of your total calories will do you just fine.
A Quick Note on GMOs
GMO means Genetically Modified Organism. Scientists are quickly changing our food supply by creating tomatoes that look redder, soybeans that are resistant to certain pests and corn that won’t fall over when it’s crowded into close-knit rows. These are genetically-modified plants. It’s hard to talk about corn and soy without touching on this subject, because it’s hard (impossible?) to find corn or soy that isn’t GMO in a store unless you see a USDA Organic label on the package (the organic label prohibits GM crops).
I don’t know much about GMOs other than that plenty of people are saying they’re bad. (No source! Just me!) I don’t avoid them entirely – yet? – baby steps happening here! But at first glance, without doing my research, I have an uncomfortable distrust of GMOs, first because they’re relatively new and unproven, and second because it seems a bit like playing God, and I’m always wary about humanity’s pride in that sense.
For a practical step you can take to deal with this onslaught of possibly new information, move on to the Monday Mission for the week.
And if you eat to deal with stress, find a recipe with Super Foods in it here.
Images used with permission from GraphicStock.com.