Truth about Trans Fatty Acids
When I was in graduate school completing a degree in nutritional sciences back in the early 1980’s, I learned about the dangers of trans fatty acids found in margarine and heated vegetable oils. I have been conscientiously avoiding all partially dehydrogenated vegetable oil since. It is not an easy task. But trans fatty acid have been linked to heart disease, autoimmune disorder, arthritis, insulin resistance, hormonal imbalance and other chronic health problems, the effort was well worthwhile. Fast forward 25 year, the FDA finally recognized the negative effects of trans fatty acids. It took decades for the cutback in hydrogenated oils to happen. It should be banned from all processed food since 2006. Is our processed food free of trans fatty acids these days? The answer is NO! The FDA allows junk food makers to label their product zero trans fat as long as each serving contains less than 500 mg of trans fatty acids. Therefore, zero is not really zero in the world of the FDA.
As it turns out, trans fatty acid is not a black and white issue. There are actually health-promoting trans fats and health-damaging trans fat. I can imagine your head starts to spin. No wonder we are confused! Well, it is not that difficult to avoid the bad ones. Think natural. It is practically impossible to avoid bad trans fatty acids when you consume vegetable oils and processed foods in the diet. What about fat-free food? Will they be safe? Again, NO! We need fat in our food for our bodies to be healthy. Fat carries fat soluble vitamins and essential fatty acids which we depend on to live.
Let’s look at the good trans fat first. In nature, there are two trans fatty acids that are beneficial. One of these is conjugated linoleic acid (CLA). CLA has been found to help burn body fat and build lean tissue. In a study published in 1998, mice fed CLA were able to reduce body fat by 43 to 88 percent in just six weeks. The researchers also found that abdominal fat was most sensitive to the effect of CLA. 1
CLA increases body fat loss by raising the metabolic rate, decreasing appetite and turning fat into energy regardless of a low-fat or high-fat diets. 2
CLA can only be found in whole milk, butter, cheese, beef, lamb and turkey. Cows fed exclusively on grass provide more CLA in the milk. In fact, confinement (commercial factory-farmed) cow dairy has little CLA.
Another good trans fatty acid is trans oleic acid. It has heart protective effect. Trans oleic acid is found in olive and macadamia nut oils. 3 In a study, trans oleic acid cuts the risk of heart-related death by two-thirds.
Bad trans fatty acids are formed when you heat vegetable oils which are high in polyunsaturated fatty acids (PUFA.) PUFA is unstable when subjected to heat in cooking. PUFA can also be converted into trans fatty acids by intestinal bacterial action. The higher PUFA in your diet, the more trans fatty acids you will absorbed into the body. Modern factory-farm animals are fed grains high in PUFA; these animals have more trans fatty acid in their fat tissue as well. Commercial French fries fried in vegetable oil have half of its oil content in trans fat.
Another new man-made fat called interesterified fat is being used in the processed food industry. It is found to increase insulin resistance and negatively affects blood sugar. I will tell you more about it in a future newsletter.
Healthy ways to consume fats
- Use only natural traditional fats such as butter, lard, olive oil, cold-pressed seed or nut oils and palm oil.
- Do not heat cold-pressed nut and seed oils, only use in salad dressings.
- Buy fresh organic and extra virgin olive, nut or seed oils in small quantity, store in cool dark places. Use within a month once the bottle is open.
- Discard older oil that has been opened and sat in the cupboard for a while, or oil that has an off-smell or taste.
- Avoid all vegetables, canola, soy oils, margarine, and interesterified fats. Hint: they are in most processed foods.
- Reduce deep fry foods such as French fries. If you want to deep fry, use stable oils such as lard, coconut, palm or peanut oils. Heat increases the rate of oxidation (rancidity.) Rancid vegetable oil is very toxic.
- Add garlic or rosemary in oils to give them a nice flavor and protection against rancidity. These herbs are high in antioxidants which slow down the rate of oxidation.
- Choose organic, free-ranged and grass-fed animal products instead of factory-farmed animal products. The former has much higher CLA.
References:
- American Journal of Physiology 1998;275:R667-672
- American Journal of Physiology 1999;276:R1172-1179
- Circulation 2006;114(3):209-215
