Thursday, May 14, 2009

Factoid: Tomato pomace

The leftovers from production of tomato juice, sauce and paste include seeds, skin and pulp – about 750,000 metric tons yearly. Since humans don’t eat tomato pomace, where does it go? That’s right – the pet food market, like beet pulp, grape pomace and other by-products of processing for human food.

Dried tomato pomace has a nutritional profile of about 20% protein, 13-15% fat, 3-5% fat, and 25-57% crude fiber. The fiber includes 4% soluble fibers- the stuff that primarily supports probiotic populations in the gut. The other fiber can also be fermented by bacteria as well, and as with many foods, there is a concern that a high fiber content can lead to flatulence. As it turns out, testing shows that tomato pomace produces less gas on fermentation than most other fiber sources.

Tomato pomace contains approximately 50% linoleic acid, followed by oleic (20%) and palmitic (15%) acids. Other FAs present in lower concentrations are myristic, stearic, arachidic, linolenic, behenic, erucic, and lignoceric acids. Because of this high fat content, tomato pomace usually has a preservative added by the manufacturer (which, you will recall, means that this preservative is not listed in the final ingredient list on a pet food bag). The pomace is included in pet foods at about 3-7% of the total mix.

Other nutrients contained in tomato pomace include lycopene, Vitamin E and other tocopherols and phytosterols, giving it antioxidant potential. The nutrient composition might be expected to differ between lots of this product however, depending on the types of tomatoes used and how they are raised. One study found differences in the contents of minerals like cesium, iron, potassion, molybdenum, and sodium between tomato seeds from conventional or organic systems.

Some people have voiced concern about the connection of nightshade products to arthritis and other problems. Vegetables in the nightshade family – potato, tomato, eggplants and peppers – contain much lower levels of the offending alkaloids than do the poisonous plants in this family. They do contain traces of alkaloids such as solanine, chaconine, nicotine, and tomatine, but the connection with arthritis remains unclear if it exists. On the other hand, some of these alkaloids seem to prevent cancer, at least in test tubes.

My conclusion remains the same – feed your pets a variety of different brands and flavors, and if some of them contain tomato pomace, that’s ok.

Aldrich G. Functional Fiber with Color. Pet Food Industry, April 2009, p. 42-43
Cámara, M., Del Valle, M., Torija, M.E. and Castilho, C. 2001. Fatty acid composition of tomato pomace. Acta Hort. (ISHS) 542:175-180
A. A. Ferrari, E. A. De Nadai Fernandes, F. S. Tagliaferro, M. A. Bacchi and T. C. G. Martins. Chemical composition of tomato seeds affected by conventional and organic production systems. Journal of Radioanalytical and Nuclear Chemistry. Volume 278, Number 2 / November, 2008.

Wednesday, May 13, 2009

Critical care nutrition - what to expect if your pet is hospitalized?

None of us want to consider the eventuality that our pets may develop some sort of critical illness requiring hospitalization. If it does happen, we want to be sure that the critical care being provided is the best it can be. One sign that this is the case is when the attending clinician demonstrates an eye to nutrition from the first days of hospitalization.

Active nutrition therapy is known to preserve normal immune function, attenuate the metabolic response to stress, prevent oxidative damage and may involve feeding enterally (through a tube that supplies food via the GI tract, known as enteral nutrition (EN)) or parenterally (intravenous nutrient infusion, known as parenteral nutrition or PN).

The American Society for Parenteral and Enteral Nutrition (ASPEN) has published guidelines for nutrition support for hospitalized people in critical condition. While guidelines for people cannot be applied to dogs and cats without question, the sad fact is that there is a lack of evidence to support most of their recommendations, and there is even less to support any recommendations at all for dogs and cats.

It’s the best we have, and veterinary internists, criticalists, and nutritionists will use evidence from human clinical trials in light of their knowledge about metabolic differences between the species to find the best plan for each individual patient. The recommendations are made, but provided with qualifiers so we can see the level of evidence supporting them. Those levels are A (supported by more than one controlled clinical trial) through E (uncontrolled studies or expert opinion).

So without further delay, here are relevant recommendations for nutrition support of critical patients – they are abridged, paraphrased and modified for animals here, and the grade is supplied in parentheses at the end. I present them here so that pet owners can have a conversation with their veterinarians about providing nutrition actively, and for veterinarians to have a sense of the place of nutrition in the human ICU. These recommendations should not be viewed as a standard of care, but rather as a point of discussion.

A. Regarding the Initiation of Enteral Feeding

Nutritional assessment should include a history that documents changes in weight and food intake and the functional status of the GI tract as well as the severity of the disease and other medical conditions (E). For pet owners, this means you need to be very aware of weight changes in your pet – get a diary and document this on your own at every hospital visit.

Enteral nutrition therapy should be provided in critically ill patients who cannot eat on their own (C). This means that if your pet is not eating in the hospital within a day or two, your doctor should be having a discussion with you about placing a feeding tube or starting parenteral nutrition as appropriate for the medical condition. Enteral nutrition is always the preferred route of feeding over parenteral nutrition (B)

In patients suffering from severe hemodynamic aberrations (for example, shock or blood loss), enteral nutrition should be initiated only after the patient is stable (E).

B. When to Use Parenteral Nutrition

If early enteral nutrition is not feasible for the first 7 days following admission of a patient with no evidence of malnutrition, it is not necessary to provide alternative nutrition support except to encourage voluntary food intake (C). If there is evidence of malnutrition, and enteral nutrition is not feasible, parenteral nutrition should be initiated as soon as possible (C)

C: Dosing of Enteral Feeding

If energy requirements cannot be met after 7-10 days of enteral feeding, supplemental parenteral nutrition should be provided (E). Earlier supplementation does not improve clinical outcomes. This means that your pet could be receiving nutrition from both a feeding tube and intravenously depending on their progress in the ICU.

D: Monitoring Tolerance and Adequacy of Enteral Nutrition

Ileus (lack of gut motility) is propagated by lack of food intake, so npo orders should be minimized (C). This means that if a patient is undergoing multiple anesthetic episodes for procedures, they are spending a lot of time with orders not to be fed. Doctor and pet owner should be aware of this and watch for weight loss in the hospital.

E. Selection of Appropriate Enteral Formulation

Immune modulating enteral formulas should be used for patients undergoing elective surgery, trauma, burns, head/neck cancer and patients on mechanical ventilation, but with caution in patients with sepsis. These formulas contain such supplements as arginine, glutamine, nucleic acids, omega-3 fatty acids and antioxidants. In particular, there is good evidence for these supplements in surgical ICU patients (A) and medical ICU patients (B). Other patients should receive standard enteral formulations (B).
Soluble fiber and small peptide formulas should be used if the patient develops diarrhea (E)

F: Adjunctive Therapy

Probiotic administration has shown definite benefit in post-op transplant and major surgery patients and those with severe trauma (C). Studies have shown both benefit and potential harm in conditions such as pancreatitis, so the benefit of probiotic use in other conditions is unknown (C). Combinations of antioxidants, including selenium, should be administed to all ICU patients. Enteral nutrition for burn,trauma and some other ICU patients should incorporate glutamine.

If a patient on enteral nutrition develops diarrhea, soluble fiber may be beneficial. Insoluble fiber should be avoided in critical patients. Hemodynamically unstable patients are at risk for bowel ischemia, and fiber supplementation of any sort may harm these patients (C).

G: When Indicated, Maximize Efficacy of Parenteral Nutrition

Serum glucose should be closely monitored and strictly controlled during parenteral or other nutrition therapy (E).

Periodic attempts to introduce enteral nutrition should be made while on parenteral nutrition. Parenteral nutrition should be terminated when enteral nutrition is providing ≥ 60% of target calories.

K: Acute Pancreatitis

People with acute pancreatitis should have a nasoesophageal tube placed and enteral nutrition therapy initiated as soon as hypovolemia (dehydration, low blood pressure) is corrected (C). This is currently being debated by veterinarians and veterinary nutritionists.

Patients with mild/moderate pancreatitis should not be fed unless they fail to eat on their own within 7 days or develop an unexpected complication (C).

Use of parenteral nutrition should be considered only where enteral nutrition is not feasible (C) and only after the first 5 days of hospitalization (E).

L. Nutrition Therapy in End-of-Life Situations

Nutrition therapy is not obligatory in futile care or end-of-life situations. Decision to provide nutrition care should be based on family desires and communication and realistic goals.

Tuesday, May 12, 2009

are grains all bad?

There is no nutritional requirement for carbohydrates for dogs. There is also none for fiber, though we well recognize the benefits, and the same could be said for other nutrients like glutamine, Vitamin C and even probiotics. Carbohydrates (in the form of starches) contain calories. Grains contain carbohydrates, vitamins, minerals, fatty acids, fiber, and a little protein.

Recently, carbohydrates (presumably starch, in particular) included in diets for dogs have been vilified, especially in the form of grains such as rice, wheat, corn, barley, oats, etc. The reasons are myriad:

Fallacy 1: Dogs have a shorter GI tract than people, so they cannot digest grains unless they are partially digested first.
Fact: Decades of research proves that dogs digest grains as well as starch quite well.
• The lack of salivary amylase has been stated to be one reason why dogs don’t digest carbohydrates well. Why would dogs need salivary amylase when they gulp their food? Dogs produce potent pancreatic amylase as well as ‘brush border’ enzymes to digest their carbs (like humans).
• Most digestion of carbohydrate occurs in the first part of the small intestine (like humans).
• Some have stated that dogs have more acidic stomachs and retain food in their stomachs longer than people, making a meat based diet more suitable for dogs since protein is initially digested in the stomach. The pH of the dog's stomach ranges from 1.08 to 5.5 (Ouyang et al., 2006, Smith, 1965, Buddington et al., 2003, Sagawa 2009). For people, the pH ranges from 1-4 (Krause's Food and Nutrition Therapy). This makes the acidity equivalent between the species, with the dog ranging slightly more alkaline in certain settings.
It is true that like humans, dogs cannot digest cellulose, a single structural carbohydrate used by plants to form stalks, seed coats, vegetable structure etc. Only herbivores like cows can digest cellulose, turning it into some other vital nutrient, but it doesn’t seem reasonable to compare the GI tracts of dogs and people to cows. Canine digestive physiology resembles human digestive physiology much more closely, so grains and veggies should be cooked or ground as finely as possible (either before or during the act of chewing) to derive the benefits contained in them.

Fallacy 2: Feeding carbohydrates place stress on the pancreas.
Fact: The pancreas was created to produce enzymes to digest fats, proteins and starches. That’s its job. Many people feed digestive enzymes as a daily supplement, I suppose to support what they see as this delicate flower of an organ do its job with protein and fat. There is evidence that supplementing enzymes actually downregulates the pancreas’ own production of proteases. That’s not necessarily a good thing – see my blog from 1-27-09 for more information. But during bouts of pancreatic inflammation (otherwise known as pancreatitis), where those very enzymes are released to cause inflammation and damage to the pancreas and surrounding organs and tissues, the treatment is to reduce fat in the diet in order to suppress production of those enzymes. The treatment is…….high starch diets - and they work.

Fallacy 3: Since food moves through the GI tract rapidly, there is no time to ferment carbohydrates and therefore no need for them. Because carbohydrates are not fermented, if they are included in the diet they will cause gas and voluminous stools.
Fact: Like humans, dogs harbour many lactic acid producing bacteria which ferment starch and soluble fibers contained in grains. This fermentation itself can cause gas. Odiferous gas can also be caused by clostridial organisms. Clostridia are more numerous in the GI tract when dogs are fed a high meat, high fat diet such as raw, grainless diets.

Fallacy 4: Grains cause allergies.
Fact: If dogs have the genetic predisposition to develop food allergies, they can become allergic to certain foods. A recent review of 7 studies indicates that dogs are most commonly allergic to the proteins in the following foods (in descending order): beef, dairy, wheat, egg, chicken, lamb/mutton, soy, pork, rabbit and fish. In cats, the most common allergens are beef, dairy, fish, lamb, poultry and barley/wheat (in equal numbers), egg and rabbit in equal numbers. I will admit that I’ve seen higher numbers of corn allergy than would be suggested by these numbers, as well, but please note that grains do not constitute the majority of allergy offenders.

While dogs do not require the starch found in grains or potatoes or any other food, there are some instances where you still might derive benefit from them being there. For instance, grains (and starch-containing tubers) contain certain fibers that are beneficial for the growth of probiotic bacteria in the gut. They also contain various required vitamins and minerals. And since grains, as compared to meats, contain lower fat contents, they can be used as a “place-holder” in a diet that fills a dog up while reducing the fat content. I’ve seen people feed pitifully small amounts of raw diets to dogs whose weights needed better control. Poor hungry dogs!

This is not to say I approve of diets formulated with high concentrations of starch-containing ingredients simply to limit cost. I just want to note that there is no reason to expressly avoid them unless your dog has a specific intolerance to them or some condition that requires use of a diet that is low in carbohydrates. And remember that cats are another matter entirely- they are true, pure carnivores, and as such, should probably not be fed diets that contain noticeable carbohydrate levels.

Back to carbohydrates vs grains – take this to the bank: If it’s a dry kibble, it contains carbohydrates. This is because kibble is made by the process of extrusion, which doesn’t work without a certain minimal level of starch. So those grainless diets that sound so good, and so paleolithic – yeah, those contain carbohydrates. Just in the form of potato, tapioca, or other starch containing food.

My point is that if we are going to eschew grains, let’s do it for the right reasons, and if we instead want to avoid starch, we *have* to read the labels carefully.

I'm back!

OK, I’ve spent a couple of months finishing some schooling and moving my house. One I’ve almost finished, and the next I’ll never do again. At any rate, I can get back to studying, which means my notes become your blog postings. I hope to be a more regular correspondent!

Controversial post, coming up next....