Part I: the basics, plus oils for cooking
When you hear about fats and oils in the news, it always seems like the focus is on avoiding them. Advertising trumpets “low fat” this and “fat free” that. Now, many of us are beginning to understand that not all fats are bad for us. (Our store has always understood this!) Some of us may have even heard that certain fats are good – even essential! – for us. But more than any other health-related topic, it seems, fats and oils are still a source of confusion and misinformation.
There’s a lot of complicated chemistry behind fats and oils. If you want to get into more detail with the chemistry, ask me or Carolyn, or check out Fats and Oils, by Mary Enig; Fats that Heal, Fats that Kill, by Udo Erasmus; or a biochemistry text. We have a number of these resources in our reference library.
Starting from the beginning:
What’s a “fatty acid”? “Fatty acid” is a chemistry term, referring to a single, isolated kind of fat molecule. Natural fats and oils are combinations of various fatty acids.
What’s the difference between a saturated fatty acid and an unsaturated one? Which kind is better? Most people will tell you that the unsaturated fats are better, but it’s not as simple as that. What it boils down to is this: unsaturated fats, much more so than their saturated cousins, are able to interact with other chemicals. This is what makes them so valuable in the body, because the body can use them in all sorts of creative and important ways.
But the chemical reactivity of unsaturated fats comes with a price. Unsaturated fats are more chemically reactive than saturated fats in general, not just in the ways we want them to be. Given the chance, delicate unsaturated fats will react with all sorts of stuff you don’t want them to. Oxygen, heat, and light, will all accelerate this process, called “oxidation.” And once fats become oxidized, they are unhealthy for you. Oxidized oils interfere with normal functioning of cell membranes, contribute to hardening of the arteries, deplete our antioxidants, and may even cause cancer.
This oxidation doesn’t occur just in the bottle or the frying pan; it may even occur in the body itself. One study compared rats on an unsaturated-rich diet to those getting their fat from pure, saturated butter. Then all the rats were exposed to intense UV light for a number of weeks. The rats on the unsaturated-rich diet had much higher cancer rates than the rats on the butter.
But remember, unsaturated oils aren’t all bad. Some of them are powerful medicines. Some of them are necessary for life itself (the topic for next month). You just have to treat them with care. Don’t expose them to high heat. Buy oils that were cold-pressed or expeller-pressed, meaning they were squeezed out of the seed without added heat; and unrefined, meaning the good stuff hasn’t been filtered out. Unrefined oils do tend to have stronger flavors, but flavor is a good thing! And besides, that flavors come from stuff like antioxidants, which protect the oil from damage. Why do you think extra virgin olive oil is so good for you? It’s the only oil on the market which is commonly sold cold-pressed and unrefined!
Finally, if your diet includes a lot of unsaturated fats, especially refined vegetable oils or fatty acid supplements, you should protect them by upping your antioxidant intake. Look especially to the fat-soluble antioxidants like vitamin E, carotenoids, turmeric, and fresh rosemary.
Saturated fats, on the other hand, have gotten a bad rap, but I don’t think they deserve it. Yes, short-term studies show that saturated fat intake is tied to higher cholesterol levels, and this started the whole unsaturated fat craze. But long-term studies, where people replaced saturated fats with unsaturated ones have not shown a decreased risk of actually dying. (Incidentally, heart disease was practically unheard of 100 years ago, before people began using the new, stylish, polyunsaturated vegetable oils!) I really see no problem with saturated fats. I do understand that this goes against a great deal of conventional “wisdom.” What I’ll say is this: if anybody can bring in a scientific study showing that natural saturated fats, as part of a balanced diet, are unhealthy, I will print an apology and retraction next month. Until then, I’m buttering my toast and stir-frying in coconut oil!
What are hydrogenated fats? Are they the same as trans-fats? They are the same. Basically, hydrogenation is a process whereby unsaturated fats are saturated artificially. People do this because naturally saturated fats are expensive: it’s cheaper to send some soybean oil to a factory than to buy butter in the first place. And food processors like saturated fats because of their longer shelf life (less chemical reactivity), and because saturated fats tend to remain solid at room temperature. In case you haven’t noticed, however, even the medical establishment has come around recently in terms of condemning these artificial fats for promoting heart disease and everything else. They should not be consumed. Our store policy is not to carry these products. I am aware of only two exceptions to that policy.
What does it mean when an oil is “fractionated?” Every natural oil contains a different combination of saturated, and unsaturated, fatty acids. Fractionated oils are when certain fatty acid fractions of the oil have been removed, concentrating others. This is not an inherently unhealthy process.
Are polyunsaturated fatty acids immunosuppressive, like a bunch of people have been saying recently? No. I wasted three hours hunting down their source data, only to find out they misinterpreted it beyond belief. I don’t have the space to go into it here, but trust me, they’re wrong.
What are essential fatty acids? The topic of next month’s newsletter!
A quick run-down of some special, and not-so-special cooking oils:
Olive oil: Ahhh… the flavor! This is one of the best all-purpose oils for cooking with, dipping, salad dressings, etc. Buy extra-virgin, so none of the good stuff has been filtered out.
Coconut Oil: (a.k.a. “coconut butter.”) I absolutely love this oil for delicate-crisp veggie stir-fries. Its 91% saturated fat content means it can stand up to the harshest cooking conditions. Plus, it has a high level of medium chain triglycerides, special fats which actually increase the rate at which a person burns calories, and which are absorbed very easily, even in people with gallbladder or liver problems.
Cottonseed oil: cottonseed contains small levels of naturally-occurring toxins. Avoid!
Sesame seed oil: Sesame seed oil is somewhat special in that it has antioxidants that aren’t destroyed by heat, so even though it’s mostly polyunsaturated, you can still stir-fry with it. Plus it has a lots of gamma-tocopherol vitamin E! (Did you see that article in the Wall Street Journal about gamma-tocopherol and heart disease? Well, we wrote about it more than six months ago in the newsletter!) Tastes good, too!
Macadamia Nut oil: There’s something special about this polyunsaturated oil which helps it stand up to heat. It’s got the highest smoking point of any oil, at 410 degrees! Debra calls it “fragrant and delicious.”
Margarine: Bad, bad, bad. Trans-fats galore. A 1938 study looked at boys in a British boarding school. Half of them got margarine, and half got butter; otherwise, their diets were identical. The ones on the margarine grew 0.38 inches less in a year. I don’t know what that means…
Pumpkinseed oil: mineral-rich and deeply-flavored, this dark green oil should not be cooked with. It makes an extraordinary dipping oil. Try tossing it with some salad greens and smoked salmon.
Canola, Safflower, and Soybean oil: when people were getting so scared about saturated fats, these polyunsaturated vegetable oils were touted as the saviors. If you can get them relatively fresh, and keep them refrigerated, they’re okay. But I see no reason why these oils should be emphasized.
Butter and Clarified Butter (ghee): Ideal for high-heat cooking. Plus the major fatty acid in butter, butyric acid, is especially useful for feeding and repairing the cells of the gut wall.