Sunday, May 17, 2009

For serious students - the details of the 'anti-cancer' diet

Special diets for canine cancer patients have been in use since the 90's, based on research that spans from the 1940's to present. Proof that they really make a difference is lacking, but I do tend to use them because many dogs show general improvements in health and over attitude - at least when homemade versions are used.

Tumors take up large amounts of glucose, and they can metabolize it only via anaerobic glycolysis. The end result of tumor glycolysis is release of lactate into circulation. The patient converts lactate back to glucose via the Cori cycle. Increased lactate negatively effects Cori cycle functioning, resulting in a net loss in energy. Tumors also preferentially metabolize certain amino acids at the expense of the host.

Ultimately the metabolic state of cancer patients resembles that of a Type II diabetic – these patients exhibit glucose intolerance, glucose recycling, increased hepatic glucose production, and insulin resistance. A recent study showed that administration of insulin to human patients with a variety of cancers significantly improved food intake and survival (Lundholm, 2007).

Lactate, resting insulin and glucose levels are elevated in dogs with cancer (Ogilvie, 1994a), and they do not improve after treatment (Ogilvie, 1992). Studies in dogs have shown that those with cancer have different lipid profiles than normal dogs. Dogs with cancer had higher levels of cholesterol, total triglyceride and very low density triglycerides, and treatment normalized only cholesterol levels (Ogilvie, 1994b).

In theory, a diet in low in carbohydrates would help to minimize lactate production and prevent complications of glucose intolerance. Special diets targeted towards ameliorating these metabolic changes have been tested in dogs, though apparently not in humans. A high carbohydrate, low fat diet resulted in elevated lactate and insulin levels in dogs with cancer. A high fat, low carbohydrate diet increases the probability that dogs with lymphoma would go into remission and have longer survival times (Ogilvie 2003), (Tisdale, 1987), although these limited data remain unconvincing to many veterinary nutritionists.

A commercial diet formulated to be low in digestible carbohydrates, high in fat (particularly n-3 PUFA) and moderate in protein is Hill’s N/D for dogs. This was the diet tested to improve outcomes in canine lymphoma. However, that study (Ogilvie 2000) did not test a high carb diet vs a low carb diet - both diets tested were low in digestible carbohydrates.Dietary management using these principles is still controversial, as oncologists note that the majority of dogs and cats die or are euthanized because of their tumors but are not cachectic, suggesting that this state of insulin resistance and hyperlactatemia has little clinical significance. I do recommend low carbohydrate diets, however, based on the fact that dogs and cats have no dietary requirement for carbohydrates and on my positive observations of cancer patients on these diets over the years.

Pet owners often find “grainless” commercial “holistic” diets, but should be made aware that if the food in question is a dry food, it must be processed using some kind of starch, and most of these foods contain potato or tapioca. These are starch sources and should perhaps be avoided if possible. The other difference between the commercial low carbohydrate diets and N/D is that the omega-3 levels are not nearly as high nor the proportion of n-3:n-6 fatty acids controlled.

I really prefer homemade food if we are going to change a cancer patient's diet. One of the problems with any of the commercial diets is their very high fat contents. Meat comes with fat, ya know. Homemade diets can be formulated for an individual's specific tastes, medical history and body condition score. Take a fat dog with a history of pancreatitis, for instance - the commercial diets are simply not an option. Not only can we manipulate the fat content, we can change the ingredients to address patient preferences, especially as they may change due to chemo-induced nausea.

My recipes always include veggies and some fruits as well. Plant-derived flavonoids have been studied in the prevention of cancer. These include resveratrol from red grapes (and wine), green tea polyphenols, and phytoestrogens from soy and other plants. Other less well known flavonoids commonly found in medicinal herbs include curcumin (from turmeric), apigenin, anthocyanidins (from berries), quercetin, and many others (approximately 4000 flavonoids have been described). In addition to well-recognized antioxidant effects that may help in prevention of cancer, certain flavonoids have been found to have activity in inducing differentiation and apoptosis, inhibiting protein kinases, facilitating cell-cell communication, inhibiting angiogenesis, cancer cell invasion mechanisms and metastasis mechanisms, as well as enhancing immune function (Boik 2002), (Lopez-Lazaro 2002).

I know, that was a lot of details.

9 comments:

  1. Hi Dr. Wynn,

    Thank you for the very informative post about the dietary management of cancer patients. I was particularly interested in the fact that dogs with cancer have higher levels of cholesterol, total triglyceride and low density triglycerides. As you know, triglycerides and cholesterol can also be elevated in a number of endocrine disorders as well, including hyperadrenocorticism. In dogs with pituitary-dependent HAC or adrenal tumor, cholesterol and triglycerides are often increased due to altered lipid metabolism and fat mobilization. Are the mechanisms for the altered lipid metabolism seen in cancer patients similar to those with Cushing's syndrome?

    Kind regards,
    Heidi Schmeck

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  2. Great blog Susan! it's good to see a holistic veterinarian getting the nutritional education.
    Way to go!
    Can't wait to see more!
    Caroline Goulard DVM CA

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  3. Hi Dr. Wynn,
    I just found out the other day my 14+ year old Basset Mix Polly (she weighs 47lbs) has Cushing Disease. I did some reading on the meds that can be given to control the Cushings but the side effects seem to be extreme. Then there is a chance she can get Addisons. My Vet is saying to wait a few months to see if she gets worse. I would like to know what I can do holistically with controling the effects of Cushings. Right now she pants alot. I do see some increase of her water consumption but not that much. I currently feed her Blue Buffalo Weight Control which contains chicken and brown rice. She still has a great appetite. What I really want to is make sure she has a good quality of life. I realize she is old and her time is limited. Do you have any suggestions? Thanks

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  4. Hi Polly's owner,

    You might be interested in joining CanineCushings-AutoimmuneCare, a discussion and support community for caregivers of animals with Cushing’s syndrome and related disorders.

    CCAC is hosted by Yahoo! Groups at this address:

    http://pets.groups.yahoo.com/group/CanineCushings-AutoimmuneCare/

    Kind regards,
    Heidi Schmeck
    CCAC Group Owner

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  5. Heidi, it appears that the mechanisms of lipid dysregulation are different in cancer. Cancer cells exhibit upregulation of lipid synthesis, and this is being studied as a unique target for new therapies. It appears that I can't paste a whole abstract into this reply box, so I'll direct you to Medline to read this abstract:

    Swinnen JV, Brusselmans K, Verhoeven G. Increased lipogenesis in cancer cells: new players, novel targets. Curr Opin Clin Nutr Metab Care. 2006 Jul;9(4):358-65.

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  6. For Polly's owner - it would be inappropriate for a veterinarian to give medical advice on the web for a patient they've never seen. I think joining Heidi's email list is an excellent suggestion - I send people there all the time. I would also recommend that if you want a second opinion, you should ask for a referral to an internist. Lastly, I do have luck treating early stages of Cushings disease with herbs - please find a veterinary herbalist for an exam/consultation. These websites have referral listings:
    Chi Institute: http://www.tcvmherbal.com/
    Veterinary Botanical Medicine Association: www.vbma.org
    American Holistic Veterinary Medical Association: www.ahvma.org

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  7. Dear Dr. Wynn,

    Thank you for your helpful blog, which I came across while researching cancer diets (your name was mentioned in one of the books I am reading, "Help Your Dog Fight Cancer"). I recently found out my German shepherd Alec has hemangiosarcoma. I was wondering if you think Hills N/D is the superior choice if a dog will tolerate it, or do you think a homemade food using whole ingredients that approximates the protein/fat/carbs ratio in N/D is better or equivalent (assuming that arginine, taurine, omega 3, etc. were added)? Please understand I am not asking for a specific recipe or medical advice. I was just wondering your general opinion (if you have one) on N/D vs. homemade diets for cancer patients undergoing chemo (Alec is also taking herbs and supplements prescribed by a holistic vet). You said in your post that you prefer homemade food when changing a cancer patient's diet, but I wasn't sure where N/D fell in that continuum.

    Alec's oncologist is against homemade diets for cancer dogs as she says they are extremely difficult to do correctly and are therefore too risky. Her recommendation is N/D or other commercial dog foods, including kibble. However, as far as I can tell, it seems to be an uncontroversial point that whole foods/homemade diets are nutritionally superior (if properly balanced) to processed kibble or canned food, no matter how high the quality of the commercial food. What I don't know is if having cancer complicates matters too much to venture into the realm of homemade food (as our oncologist suggested). By the way, our holistic vet recommended a raw diet, but the oncologist and other holistic sources I have consulted believe this is not optimal for cancer patients due to the possibility of bacteria, so I ruled out raw to be safe.

    Sorry for the lengthy question; I just want to do the best thing for Alec and I have found there are many conflicting opinions even among professionals. If it is the best option, I have no problem with feeding Alec N/D despite the first ingredient being a by-product, but if it is possible to safely approximate this diet with homemade ingredients, I will eagerly explore that. Even if Alec tolerates N/D (which he has been for the last two days) I would like to be prepared with an acceptable equivalent should he suddenly balk at eating N/D, as he can be picky.

    Thank you and best wishes,
    Nicole
    PS I understand the internet is not the place to look for recipes, but if you have suggestions for reliable resources regarding nutrition for the canine cancer patient, I would really appreciate it!

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  8. I agree with the oncologist who is cautious in recommending homemade diets. I find that most people do tend to create their own versions over time, even if the diet started out as balanced. As long as poeple understand that a balanced homemade diet is balanced only as long as they are following original instructions from the nutritionist that balanced it, I think homemade diets can be superior to commercial.

    I also agree that raw diets are not safe for pets undergoing immunesuppressive therapy.

    Have a veterinary nutritionist develop the diet for Alec.

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