- Erucic acid is the main fatty acid found in rapeseed oil, which is commonly used in cooking in Spain, North Africa, the Middle East, and India. Too much erucic acid can cause a condition known as thrombocytopenia. This blood clotting problem creates prominent blue and purple bruises even without injury. These skin markings can last not just for weeks but for years.
- Erucic acid can also be problematic for people taking chemotherapy. Anticancer drugs like Adriamycin (doxorubicin) often damage the heart. The erucic acid in rapeseed oil can make the heart damage worse.
- Mead acid is the fatty acid found in gristle and cartilage, sometimes included in less expensive brands of ground meat and also in gelatin. Mead acid is chemically very similar to arachidonic acid, which is the building block of dozens of different inflammatory hormones that increase blood pressure, increase sensitivity to pain, trigger blood clots, and activate the immune system to destroy tissues even if they have not been damaged. Mead acid specifically activates the COX system which causes inflammation in joints. Even if you cut back on eggs, fatty beef, and processed meats to reduce your consumption of arachidonic acid, mead acid can cause inflammation problems.
- Oleic acid is the monounsaturated fatty acid abundant in olive oil. Most of the effects of olive oil are beneficial-except in women who have a genetic tendency for certain kinds of breast cancer. Although the exact causal relationship has not been scientifically determined, increased oleic acid content in red blood cells is associated with increased risk of breast cancer in women.
Everything about omega-9 fatty acids isn't bad. A combination of canola and soybean oils may lower men's testosterone levels that trigger prostate cancer and increase the risk of stroke. Of course, in men who have problems such as erectile dysfunction and overweight that would benefit from additional testosterone, lowering testosterone levels is not a good thing.
Likewise, cooking oils that are high in omega-9 fatty acids, such as canola oil and sunflower oil, can be used longer without burning or changing color-but any plant oil you use for frying loses its antioxidant content nearly immediately, and any plant oil you use for frying in an open pan can form harmful free radicals that pass into your food. These free radicals concentrate in your red blood cells.
When it comes to omega-9 fatty acids, canola and sunflower are the "best of the worst." Limit your use of any kind omega-9 fat, and make sure you get enough omega-3 and omega-6.
- Okuyama H, Ohara N, Tatematsu K, Fuma S, Nonogaki T, Yamada K, Ichikawa Y, Miyazawa D, Yasui Y, Honma S. Testosterone-lowering activity of canola and hydrogenated soybean oil in the stroke-prone spontaneously hypertensive rat. J Toxicol Sci. 2010;35(5):743-7.
- Walczewska A, Dziedzic B, Stepien T, Swiatek E, Nowak D. Effect of dietary fats on oxidative-antioxidative status of blood in rats. J Clin Biochem Nutr. 2010 Jul;47(1):18-26. Epub 2010 Apr 23.