Tuesday, October 23, 2012
Canola oil safety?
Recently I’ve received many questions about the safety of canola oil. The most comprehensive collection of concerns are presented on the Weston A. Price website.
I formulate a great many homemade diet recipes with organic canola oil because it has a very good balance of omega-3 and omega-6 fatty acids. I am convinced of the safety and sustainability of the oil as long as it comes from a reputable organic producer (which is admittedly harder and harder to find - see this NYT article on organic companies being controlled by Big Ag - http://www.nytimes.com/2012/07/08/business/organic-food-purists-worry-about-big-companies-influence.html?pagewanted=all&_r=0)
Below are the concerns listed on the Weston A. Price page, and the real story if you dig further. I'm open to argument and learning differently on this subject, but you had better be able to produce meaningful peer-reviewed scientific references to back up your point of view. This means large epidemiologic studies or clinical trials in people or dogs/cats. Test tube and lab animal studies don't count.
1. Canola oil is associated with fibrotic lesions in the heart
a. The studies cited are all lab animal studies conducted in rats artificially prone to cardiovascular disease. It is well established that these kinds of experimental studies have limited applicability to clinical patients, especially considering the fact that dogs and cats do not develop atherosclerosis and other types of heart disease typically seen in humans and these experimental animals.
b. In addition, the review of these studies specifically shows that the results are conflicting, and that the conclusion is that the critical factor in development of cardiovascular disease in these animals was the *balance* of fats in the diet, and not the mere presence of canola oil or omega-3 fatty acids. Almost all pet diets are balanced with saturated and polyunsaturated fats, containing a high level of animal fats (which are touted by Weston A Price as the healthiest of fats).
2. Canola oil causes vitamin E deficiency
a. All omega-3 fatty acids cause Vitamin E depletion in the body. A more powerful omega-3 fatty acid source - fish oil- depletes Vitamin E the even more rapidly. This is why all commercial omega-3 fatty acid supplements should be fortified with Vitamin E.
3. Canola oil causes platelet changes
a. Platelet changes are not unique to canola oil - fish oil and other omega-3 fatty acids also cause platelet and blood coagulation changes. This is actually utilized by cardiologists when they recommend fish oil for human cardiovascular patients to reduce the risk of stroke.
4. Canola oil causes shortened life spans in stroke prone rats when it is the only oil in the animals' diet.
a. Not only are these rats not in any way clinically relevant to people who develop strokes, much less dogs and cats, but the experimental situation was artificial - the sole fat in the diet was canola oil. This would be nearly impossible to replicate in any real-life management situation for dogs and cats, and certainly bears no relationship to the fat balance in normal pet foods or healthy human diets. In addition, no food formulator would attempt it as that would clearly lead to nutritional deficiencies in dogs and cats.
5. Canola oil causes growth retardation
a. This claim is not referenced and not explained in the report - they say only that experimental animals given soy and canola oil-based diets grew better when coconut oil was added to the diet. This is not the same as growth retardation and could be explained simply by supplying certain fatty acids in the coconut oil that are essential or conditionally essential in those animals.
6. That all of these issues are mitigated when saturated fats are added to the diet and that the problems seem to be related to high levels of omega-3 fatty acids.
a. Again, no food formulator would attempt to supply all dietary fat as canola oil or any other single source unless it was biologically appropriate. In dog and cat diets, a small amount of canola oil (in relation to the large amount of animal fat) supplies omega -3 fatty acid (ALA) that is essential in dogs and cats. This fatty acid is not available in the fat of animals raised by modern agricultural methods and so must be supplemented in the diet.
7. The paper reports increased rates of lung cancer in women who cook with canola oil.
The source is a Wall Street Journal article - this is not a scientific, critical look at actual epidemiologic associations and cannot be considered a credible claim.
8. Processing of canola oil leads to the introduction of trans-fatty acids.
It depends on the manufacturer – I would call them to get their trans-fatty acid analyzed levels.
9.The report implies that the original development of the commercial plant was via modern GMO methods, which is untrue.
"Seed splitting" is simply partitioning the harvested seeds so for analysis by gas liquid chromatography for certain genetic traits, and based on the results of that testing, the other half of seeds with the most desirable characteristics were selected for the breeding program. It is nothing but seed hybridization. The paper additionally claims that almost all canola oil is sourced from genetically modified plants. My understanding is that this is true, and I recommend ONLY organic canola oil for my patients.
All of this being said - we use canola oil for the nice balance of essential fatty acids. There are other sources of these fatty acids, depending on which ones are required to balance the diet and supply the animal's requirements. Some alternatives that may work (but you have to do the math!) are walnut oil, hemp oil, and others. On the other hand, it's problematic to use some of the more popular oils, like coconut or flax. Some don't contain any of the essential fatty acids at all, and some in such low concentrations that it's necessary to use a combination of oils. A nutritionist will try to tailor this essential part of a recipe to the animal's requirements and the owner's preferences.