Fit Fare

Editor’s note - This piece is the second in a series by Jade Ledger on Fats. The first article in the series can be found here.

I almost hesitate to broach this topic. I’d hate to spawn a collective of spidery souls who shudder at the sight of a plastic bottle of nondescript vegetable oil. But then misery does love company. So I’ll let you in on a great catch 22.

By now I think its fair to assume that we all know that highly saturated fats are unhealthy for us. You know, those fats where every carbon molecule hangs out with two hydrogen buddies. Currently, we are reaching a consensus that trans fats are even more harmful. That means the days when food producers could rely on taking unsaturated fats, partially hydrogenating them, and calling it good are over. The very reason the food industry has adored these trans fats for so long is that they are a very stable form of fat, they are fairly cheap to make, and while they are still unsaturated, they have the same physical properties as saturated fats. So a large number of us are cooking with polyunsaturated vegetable oils because we’ve been told they are our healthiest choice. The problem with all this is that unsaturated fats are not as stable as saturated fats, because double bonds offer sites for free radicals* to attack and form oxidation products in the presence of oxygen.

When fats oxidize they form products that are carcinogenic and toxic. Linoleic acid, one of the fatty acids making up common polyunsaturated vegetable oils, has its double bonds arranged in such a manner, with relation to each other, that it is highly susceptible to oxidation. Not only that, but oxidation sets off a chain reaction, where each oxidized linoleic fatty acid initiates the oxidation of another molecule of linoleic fatty acid. Heat just speeds the process up.

Similarly, cholesterol, found in animal fats, also contains a double bond that is vulnerable to attack. The main oxidation product of cholesterol is oxysterol, which is also believed to be carcinogenic. Small quantities of oxysterols are found in pasteurized milk products, more are found in dehydrated milk products (0.01-15 μg/g), in cooked meat products (.18-1.9 μg/g), and even more in foods fried in the presence of animal fats (1.4-16.7 mg/g).

There is some evidence that polyunsaturated vegetable oils containing high proportions of linoleic acid — corn oil, safflower oil, sunflower oil, and soy oil — are more likely to encourage the development of cancer than saturated fats or monounsaturated fats. If you are more concerned about your heart health, you might be interested in reading a study which links the increased use of polyunsaturated vegetable oils in India with an increase in cases of heart disease and diabetes.

Olive oil has several merits when it comes to cooking. It is mostly composed of monounsaturated fatty acids, which have been shown to be more stable against oxidation than polyunsaturated fatty acids. Yet it still provides a small percentage of omega 6 (8-10%) and omega 3 (less than 1%), the essential fatty acids. Although not in an ideal ratio, olive oil has a relatively high percent of omega 3 fatty acids in relation to omega 6 fatty acids. Furthermore, extra virgin olive oil naturally contains antioxidants which both delay and slow oxidation during cooking and within the body. Although some people object to its taste, the alcohol and ester molecules, which are responsible for the strong olive flavor, evaporate quickly upon heating.

When oils are refined, they are subjected to very extreme conditions, such as strongly reactive chemicals, heat and pressure. The refining process typically removes antioxidants, so synthetic antioxidants are commonly added. Synthetic antioxidants such as butylated hydroxytoluene (BHT), hyroxyanisol (BHA) and tertiary butylhydroquinone (TBHQ) can cause health problems in high doses, so their use has been restricted in several countries. In any case, minimally processed or cold processed oils offer the best health advantages.

For cooking purposes, it would be ideal to use a fairly stable oil for high temperature or long duration operations. I would recommend coconut oil, because it is saturated yet lacks the cholesterol content and bioaccumulated persistent organic pollutants of butter or lard. For most sautéing and stove-top applications, extra virgin olive oil works well. For cold temperature applications, such as salad dressings or pasta salads it might be advantageous to use polyunsaturated oils, especially ones with high omega 3, such as flax or walnut oils. Avoid heating oils high in omega 3s as they have particularly high oxidation potential.

Whichever oils you choose, always keep them as safe from heat, light, and oxygen as is practical. If you don’t have a cool dark storage space, store your oil in the refrigerator. At cold temperatures oil may begin to solidify, but it will become fluid again once warmed. Also avoid plastic bottles, as phthalates could leach into the oil. While the U.S. Center for Disease Control admits that a major exposure risk is presented by “food that is in contact with packaging that contains phthatlates,” the research on how phthalates effect our bodies is far from crystal clear. Our bodies are capable of breaking phthalates down and excreting them, however some research indicates that phthalates are endocrine distrupters which may stimulate the growth of breast cancer cells and also lead to thyroid problems. If your oil comes in a plastic bottle, especially plastic #3, it may be wise to transfer it as soon as you open it into an appropriate sized glass bottle to limit your exposure to phthalates. Use an opaque bottle to limit exposure to light as well.

Before you make significant changes in the fats you consume, I recommend you review some of the literature for yourself and come to your own conclusions regarding what fats you choose to consume regularly.

* free radicals are atoms or molecules with an unpaired electron