After a diagnosis of cancer has been confirmed, many pet owners seek nutritional advice in an effort to address the disease from another angle. The fact is that no supplement or dietary approach is going to kill tumor cells directly; there is no secret super nutrient with cancer-killing properties. Instead, the goals of nutrition for the cancer patient focus on preserving body condition: maintaining a good appetite, maintaining a healthy body weight and maintaining muscle mass.
Photo Courtesy Dr. Teri Ann Oursler
Beyond this, people wonder if there is a nutritional strategy that might put a tumor at a disadvantage: Not a cancer-killing super-nutrient per se but more of a general program that might create an edge over a regular commercial pet food. Several theories have emerged on how this might be done but, unfortunately, a lot of scientific evidence has not followed. Here are commonly employed strategies:
- Low carbohydrate diets
- Raw food
- Home cooking
- High Levels of Omega 3 Fatty acids.
Let's look at these more closely.
Low Carb Diet
Cancers tend to use anaerobic metabolism, in part because they do not have normal structure or blood vessel support, and inadequate blood to a tissue means inadequate oxygen, and inadequate oxygen means anaerobic metabolism. Anaerobic metabolism burns carbohydrates rather than fats. There are actually more complex reasons for tumors to go anaerobic beyond not having a proper blood supply but the fact is that tumors tend to want to burn carbohydrates while healthy tissues want to burn fats. The theory of the low-carb diet is that fewer carbohydrates coming in means less food for the tumor.
This theory is of some controversy but if you wish to feed such a diet, it is important to seek a food with less than 20 percent carbohydrates. Be aware that grain-free diets are usually not low in carbohydrates. Grain-free diets cater to the idea that some animals are not tolerant of grain proteins so these foods employ potatoes, yams or similar vegetables as carbohydrate sources. Recently grain-free diets have been implicated in heart disease so it is best not to feed them unless there is a reason to do so, such as food allergy.
Raw food dinner
A raw food meal. Photo by Mary Buck.
Raw foods have some advantages over cooked foods. They are frequently more palatable than cooked foods. Because they are uncooked, their proteins are unaltered by the cooking process and may be less allergenic. There is some argument that raw foods are more digestible than cooked foods because they more closely match the diet that an animal evolved to digest.
On the flip side of this is bacterial contamination, a very real concern and a special risk for a cancer patient whose immune system is probably altered. There have been numerous studies showing pathogenic bacteria in raw foods (both home prepared and commercially obtained). The last thing a cancer patient needs is a bacterial intestinal infection, so most experts recommend against raw foods especially for patients who have cancer.
Home cooking can provide a highly palatable food for a patient with a sensitive appetite. The problem is that there is an abundance of recipes that turn out to be nutritionally incomplete when compared to the National Research Council (NRC) minimum requirements. Obviously, the cancer patient needs at least the same nutrition as a healthy patient.
Pet nutrition, especially when disease is involved, is not a do-it-yourself project where one assembles ingredients that seem whole and healthy and attempts to complete the diet with a multivitamin. If you are going to cook food for a pet, it is vital to have professional guidance beyond a web site that looks knowledgeable or a book that seems scholarly. A professional nutritionist should be consulted and this means a veterinarian who is a diplomate of the American College of Veterinary Nutrition.
Some helpful resources include ACVN.org and BalanceIt.com
It is not clear if anything more can be achieved with a home cooked diet as opposed to a commercially prepared one but many people feel more comfortable making foods free of artificial preservatives or flavor enhancers. The main goal is to provide a palatable but still nutritionally complete food for the patient.
Omega 3 Fatty Acids
What is a fatty acid? Biochemically, a fatty acid is what we colloquially call plain old fat. A fatty acid consists of a long carbon chain (say 20 or so carbons in length) with a biochemical acid group at one end. But there are different kinds of fat. Some fats are stored and burned as fuels and some fats form the structure of our cell membranes. It is these fatty acids that are recruited in the inflammatory cascade to be converted into prostaglandins and other inflammatory mediators. Omega 3 fatty acids are similarly recruited but do not convert to inflammatory mediators. Examples of omega three fatty acids, also called n-3 fatty acids, include alpha linolenic acid (ALA); Eicosopentanoic acid (EPA); and docosahexanoic acid (DHA).
Saturated Vs. Unsaturated
There is more evidence for omega 3 fatty acid having anti-cancer properties at high doses. The best source of DHA and EPA is cold water fish oils. Flax seed oil is a good source of ALA and is preferred by many people who want the benefits of an omega 3 fatty acid without the fishy taste. ALA, unfortunately, is not a very useful omega 3 fatty acids for dogs and cats so DHA and EPA are needed. Luckily, most pets like the fishy smell and taste.
Examples of omega three fatty acids (also called n-3 fatty acids): Alpha linolenic acid, Eicosapentaenoic acid, docosahexanoic acid.
An excellent source is cold water fish oils.
Omega-3 fatty acids have been shown to inhibit the growth and spread of cancer, plus they have anti-inflammatory properties. In the study that launched Hill's n/d, a food for cancer patients, 32 dogs with lymphoma were divided randomly into two groups: one that received a diet heavy in menhaden fish oil and one that received a diet heavy in soy bean oil. Both groups also received chemotherapy with doxorubicin. The dogs that received this omega 3 fatty acid diet went into remission sooner and stayed in remission longer than dogs that received the soy bean oil diet.
Both the low carb and omega three fatty acid therapies are incorporated into some therapeutic diets available only at your clinic, which are canned food and for dogs only.
Should my Dog Use this Diet?
The Hill's n/d may be of tremendous benefit to a dog with lymphoma but there are a few caveats:
- This diet is frequently found unpalatable by dogs and the high fat levels tend to produce diarrhea. Remember that enjoyment of food is an important life quality parameter. If a dog eats n/d diet poorly and loses body condition due to poor appetite, it is probably best to use a different diet that is more palatable.
- Despite studies by Hills when the diet was first introduced, most oncologists have felt more proof of effect is needed before including it in standard therapy for lymphoma.
Hollywood Brand Safflower Oil and Mycosis Fungoides
There is a particularly difficult form of T-cell lymphoma called Mycosis fungoides. This type of lymphoma is limited to the skin and, like most T-cell forms of lymphoma, it is resistant to the usual lymphoma treatments. It seems there is some basis for using one of the omega 6 fatty acids: linoleum acid.
There are two major brands of safflower oil on the market: Hain and Hollywood. Apparently Hollywood is the brand with the most linoleic acid and is the brand of choice in this somewhat controversial treatment. In one study using eight dogs with Mycosis fungoides (the skin T-cell form of lymphoma), six dogs achieved remission with no other therapy.
Minimal adverse effects come with the use of this oil (if too much oil is used there is a possibility of pancreatitis but, in general, obesity from the fat is the only problem). Safflower oil is inexpensive and readily available.
Effect of fish oil, arginine, and doxorubicin chemotherapy on remission and survival time for dogs with lymphoma: a double-blind, randomized placebo-controlled study.
Cancer 88:1916-28 2000 Apr 15
Ogilvie GK, Fettman MJ, Mallinckrodt CH, Walton JA, Hansen RA, Davenport DJ, Gross KL, Richardson KL, Rogers Q, Hand MS
Cancer Lett 1992 May 30;64(1):17-22
Linoleate produces remission in canine mycosis fungoides.
Iwamoto KS, Bennett LR, Norman A, Villalobos AE, Hutson CA
Department of Radiological Sciences, University of California, Los Angeles 90024.
The Use of Safflower Oil for the Treatment of Mycosis Fungoides in Two Dogs.
Peterson, A., Wood, S., and Rosser, E. Dept of Small Animal Clinical Sciences, D208 Veterinary Medical Center, Michigan State University, East Lansing, MI.