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.

Sunday, August 12, 2012

Leaky Gut and Intestinal Hyperpermeability are sooooo different!

“Leaky Gut Syndrome” is a diagnosis coined by alternative medicine practitioners in the 1970s.  The syndrome was especially considered in the context of a branch of alternative medicine known as “environmental medicine”.  This field developed from the 1950s and espoused the theory that many modern chronic diseases were due to a plethora of toxins in the environment and environmental allergies1.   

Leaky Gut was and is said to be caused by damage to the gut lining which allows abnormal absorption of bacteria, toxins and gut proteins, and leads to development of a very large number of chronic medical conditions.  Diseases that are said to be initiated or worsened by a Leaky gut include environmental and food allergies, arthritis of several types, eczema, chronic fatigue syndrome, inflammatory bowel disease, pancreatic disease, migraines, autism, celiac disease and gluten intolerance, and fibromyalgia.

The gut is viewed as one important gateway for toxins and allergens from the environment, and constant exposure to these irritants were thought to cause gut pathology, leading to a vicious cycle of gut damage à absorption of toxins, bacteria and abnormally large intraluminal proteins directly into portal and systemic circulation à immune activation and immune-mediated diseases à àdeterioration of gut barrier,  and so on, over and over again.

The pathogenesis of leaky gut is said to include:

·         Altered GI microflora (due to repeated antibiotic therapy as well as many other drugs and a poor diet).  The intestinal microflora have many critical functions, including detoxifying some xenobiotics, maintaining an intraluminal environmental that discourages growth of pathogenic bacterial, maintaining the gut’s tight junctions and barrier function, and dialoguing with the immune tissues of the gut.
·         Overgrowth of the yeast, Candida albicans.
·         Food allergies (which if not a primary problem, becomes an associated illness once gut permeability is altered)
·         Damaged gut mucosal cells become unable to digest food normally, or to detoxify environmental xenobiotics
·         Drugs that cause direct damage to the gut mucosa, such as NSAIDs and steroids, hastened the development of a hyperpermeable gut.

Treatment involve any of the following:
·         Changing dietary components to reduce allergenicity
·         Supplementing enzymes to improve digestibility of the food.
·         Supplementing probiotics
·         Correcting possible nutrient deficiencies with a variety of vitamins and minerals
·         Treating yeast overgrowth
·         Addressing the quality of fat in the diet to emphasize less inflammatory fatty acids
·         Improving gut cell production and turnover with l-glutamine

Just as environmental medicine doctors had reported, many veterinarians using these methods noted dramatic results when pets were treated using the same principles. The problem is that “leaky gut” was never documented as a cause for these immune mediated diseases, and changes in the gut were not monitored as patients got better (although these tests are available). 

While the role of leaky gut in such a wide array of chronic diseases is still considered unproven and under the purview of alternative medicine, “ intestinal hyperpermeability” was becoming increasingly recognized by critical care specialists in the 1980s as a primary initiator of multiple organ dysfunction syndrome and death in critically ill humans 2.   And the final results are the same – invasion into the bloodstream by gut microbes and activation of the immune system – but in the case of critically ill patients, the course of the problem was more rapid and easier to recognize.

A 1998 review of “intestinal hyperpermeability” -  the approved name for the more acute condition recognized by conventional medicine – reviewed the mechanisms behind development of the condition.  They are:
·         Oxidative stress
·         Hypoxia
·         Tissue acidosis
·         Nitric oxide – an cell-signallying molecule that influences circulation, and has been shown to have deleterious effects if present in the gut in abnormally high OR low concentrations.’
·         Inflammatory cytokines – which are produced on exposure to luminal antigens and bacteria, which can happen any time the barrier is breached.
·         “Metabolic Inhibition”  - a laboratory condition that causes chemical changes in the tight junctions so critical for maintaining the intestinal barrier. 

When I look at this list, I see mechanisms that are active in chronic disease as well.  Let’s look at what I would consider a typical veterinary patient who is a candidate for management of a hyperpermeable gut.

This theoretical dog is an 11 year old Labrador with chronic osteoarthritis and a long history of allergic otitis and bad skin.  The dog has eaten the same diet for many years, and eats well.  A nonsteroidal anti-inflammatory drug has been administered daily for the past year or so.  And this dog is presented to me for acupuncture to aid in pain control for the arthritis. 

For the past 15 or so years, I’ve handled dogs like this one by delaying the acupuncture, and recommending the following:
1. Change the ingredients in the diet (making it essentially less allergenic), and make sure that it contains antioxidants in the form of vegetables and fruits.  If the dog won’t eat veggies and fruits, supplement a broad spectrum antioxidant containing Vitamins A, E, C, selenium, flavonoids, carotenoids, etc. 
2. Supplementing digestive enzymes (not just because of leaky gut, because there are those who believe that old dogs have decreased digestive function, especially in the stomach, just as geriatric people with atrophic gastritis do).
3. Possibly a probiotic supplement.
4. High doses of fish oil
5. Massage.

It’s amusing how many people attribute the improvement I see on a regular basis to the massage, because it’s just so hard to believe that dietary changes can be so effective in pain control!

I’m simply reporting my clinical experience, and I’m not saying this is right for every old arthritic pet.  But I see that conventional medicine and alternative medicine may be discovering a convergence in one very important anatomical area and organ function.  The gut is the largest immune organ in the body.  It contains more neurons than the spinal cord.  It maintains a very delicate balance between the outside environment and the critical homeostasis inside the body.  And both conventional and alternative medicine are postulating similar mechanisms for the role of the gut in all disease.  I hope this progress continues. 

1Rogers SA, 1997.  Environmental Medicine for Veterinary Practitioners in Complementary and Alternative Veterinary Medicine: Principles and Practice, Schoen A and Wynn S, Eds.  Mosby, St. Louis.

2Fink MP.  Effect of critical illness on microbial translocation and gastrointestinal mucosa permeability.  Semin Respir Infect. 1994 Dec;9(4):256-60.

3 Unno N, Fink M.  Intestinal Epithelial Hyperpermeability.  Gastroenterology Clinics of North America 1998; 27(2):289-307).