Vegetables for dogs – to feed, or not to feed?
January 10, 2015 at 1:09 am
This is a topic that I am pretty sure I’ve written about before, but every time someone asks me – which is frequently – I can’t seem to find where. So today, I thought I might revisit the whole topic with a new post. Vegetables in the canine diet seem to carry a little controversy, largely due to the recent trend of prey model diet, wherein raw foods are used in amounts that attempt to mimic what a wolf or other wild canid would consume (I won’t say wild dogs, because dogs are domestic, and if we are talking about ferals, I highly doubt anyone would be trying to mimic what those dogs eat). Recent awareness about overconsumption of carbohydrate foods has led many to feel that all carbs are undesirable and that, sadly, includes fruit and more importantly, vegetables.
There seem to be 5 main areas we need to evaluate here, that cover the pros and cons of feeding veggies to dogs. First – as always – I am not going to come out on any kind of a side – not the side of “dogs don’t need them” as that is kind of an absurd remark to me, and not on the “side” that supports feeding a whole lot of veggies all the time, either, although to be fair, I like to see them used intelligently. For those who follow my blog, you’ll already know why – I don’t see nutrition as that simplistic, and I always evaluate pros and cons, with an eye to what best serves the individual.
With that in mind, let’s look at areas I think are worthy of exploration.
1) bioavailability of nutrients
2) concerns about “anti-nutrients”
3) health benefits of phytochemicals
4) potential effect on stool
5) potential contamination with pesticides etc.
6) concerns about feeding anything containing carbohydrate
All of these are important considerations, and after we’ve looked into them a bit more, you will see why I don’t take a single point of view here, but evaluate each case as I see them. In a client case, I develop recipes initially with usually only a starchy vegetable such as sweet potato, and once the goals of the consultation are met, and the dog is on a balanced diet that agrees with him, then I have people experiment with and add rotated greens, and other vegetables and fruit. I don’t rely on them for a significant portion of energy, or nutrient for that matter – although they do provide some, but I do want to have dogs eating a sensible amount of veggies specifically for the phytochemicals. More on those in a second entry.
Let’s look at these issues a little more indepth.
1) Bioavailability of nutrients from plants.
Despite what you may have heard, dogs can indeed digest and utilize nutrient from plants.
It’s as simple as that.
Anyone who says they cannot, is misguided.
The reality here is that dogs are not actually obligate carnivores like cats; they can convert nutrients to some extent, such as beta-carotene from carrots, into a bioavailable form. They can indeed digest cooked carbohydrates.
Fiber is another issue – fiber is really an umbrella term that applies to those parts of plants that are not digested (not by them, not by us either). There are different types of fiber and we know, study after study shows, the value of fiber in the diet (again, canine and human). I wrote a fair bit about this here: http://www.thepossiblecanine.com/carbs-part-two
But because fiber is not digested, but fermented in the colon, in no way means that all other types of carb is “undigestible”. Furthermore, the fermentation process provides food for the “good” microorganisms we want to see proliferating away in there. So we can safely say that the indigestibilty of fiber is no reason to avoid the many health benefits of fruits and vegetables.
Now to be clear, I personally feel that carbs should not be relied on for more than 25-30% of the total energy intake(calories) unless indicated by the individual, and often much less, many of my client’s dogs are on 10-15%, which is really very little. . and for that portion of the diet I much prefer cooked starchy vegetables, a little bit of well prepared legume, and nutritious seeds such as buckwheat and quinoa. Rice is not high on my list, mostly due to the arsenic issue – but again, in some cases we need to use rice (and again, the source and preparation are key).
And also to be clear – I do not rely on fruits and vegetables as major means to providing energy. A cup of broccoli has 40 calories, give or take, so if I need 500 calories of carb in a given recipe, to achieve that 25% – you can see how much broccoli we need! whereas sweet potato gives us a whopping 200 – 240 calories. So I can use much less.
But don’t be fooled by sites that claim dogs cannot derive any nutrients from plants. They certainly are not as efficient at it as we are, or the herbivores – but they’re MORE efficient than a cat species.
Sidenote: I admit I find it a little strange to hear people oppose veggies in the diet using the”unnecessary”, at the same time that they give turmeric and coconut oil and whatever else is currently trending! Thinking like a nutritionist here – dogs don’t actually “need” ANY specific foods, they require vitamins and minerals, fats and fatty acids, – in other words, nutrients. Some foods are better sources. And not all dogs, I repeat! are the same. 🙂
I am adding here that it is very important to either lightly cook or grind up veggies, when feeding them to dogs – doing so will liberate nutrients that may pass through undigested if simply fed raw. If your dog likes a raw carrot to chew on, great! But to optimize beta-carotene, or any other nutrient/phytochemical you want to emphasize – steam them before feeding.
2) Concerns about “anti-nutrients”
This is a point that carries some validity, but again, once we identify what these anti nutrients actually are, which foods they are found in, how to prepare foods to minimize content and how much to feed, we can see that there really isn’t a case for withholding veggies unless a specific medical condition indicate that we do. I will be fairly brief here – the top problems are as follows:
-Solanine from plants in the Solanaceae family, eg nightshades. This includes tomatoes, eggplant, peppers and white potato. While there is disagreement amongst researchers as to just how much of a problem this is, I simply don’t use these foods. I suffer from Solanine sensitivity myself, with joint pain and GI upset after I eat potatoes, so I am fairly sure it’s a real concern. In addition, I don’t see any real call to use these foods if there is risk of exacerbating a problem. My approach is – don’t feed nightshades to any dog with arthritis, with a history of GI distress or food intolerance, at all. Feed them judiciously to others. If you have a sensitive dog and you use white potato, watch stool. And don’t overdo it. This, from where I sit, is just common sense.
– Glucosinolates from Brassica family vegetables .Restriction, in my view, really only applies to dogs with thyroid disease, whom I feel should not have veggies from this family on any regular basis. If your dog has had a proper thyroid evaluation and is fine, I encourage you to add brassicas in moderation to his or her diet. Use broccoli, cauliflower, – always cooked gently, and no more than 3 times a week. yes, these veggies offer protection from cancer. So do many other foods and herbs. Use wisely.
“Glucosinolates are water-soluble compounds that may be leached into cooking water. Boiling cruciferous vegetables from 9-15 minutes resulted in 18-59% decreases in the total glucosinolate content of cruciferous vegetables.”
much more info here: http://lpi.oregonstate.edu/infocenter/phytochemicals/isothio/
-Oxalate – here we have a problem only if the high oxalate foods are used all the time, or if the core diet is low in calcium, or lastly, if the dog has suffered from calcium-oxalate stones in past. In this last case I recommend restricting the higher oxalate foods altogether. Many fruits and veggies that have a lot of oxalate also offer phenomenal health benefits – so do use them, but again, in moderation. Here is a listig of oxalate content in foods, so if your dog has a predisposition toward stones, or if you are homefeeding and concernend about losing calcium – you can choose from low or moderate sources. http://www.ohf.org/docs/OxalateContent092003.pdf
-Phytate – another constituent of plant foods that can have a negative impact on nutrient absorption is phytate. When I was starting out in canine nutrition, people were all up in arms about phytate, as it does hold some potential to bind to some minerals and affect absorption. These days, we know a fair bit more,and phytate – a potent antioxidant – can be reduced in plant foods via pre-soaking and careful preparation. Given that only aout 25% of a canine diet is going to consist of plants, ideally, I think this is one worry we can relax about. Here’s Dr. Andrew Weil on the matter, a nice succinct read: http://www.drweil.com/drw/u/QAA400758/Are-Phytates-Bad-or-Good.html
Note: “You also should be aware that phytates themselves have some health benefits, including anti-inflammatory effects. In laboratory research, phytates have helped normalize cell growth and stopped the proliferation of cancer cells. “
Again – the pros outweigh the cons, significantly so.
3) Health benefits of phytochemicals
There is really no question about the power of all kinds of phytochemicals in plants, to offset the development of illness, reduce inflammation, support health. It is for these compounds, more than anything, that I personally emphasize the use of vegetables and fruit in the canine diet. To keep this entry from becoming overlong, and because beneficial phytochemicals deserve a whole entry of their own, let me offer a link from the American Cancer Society, with regard to a (very general)overview of the benefits of fruits and vegetables.
4) Potential effect on stool – This is another concern that needs to be addressed individually. Just like humans, dogs digestive systems do vary! In my work with literally thousands of cases, I see dogs who can tolerate extraordinary amounts of both soluble and insoluble fiber, and dogs who are incredibly sensitive to small amounts, and everything in between. The volume of vegetables added, the type of fiber, and the context of the total diet all play a role in whether an individual dog develops diarrhea from added vegetables and fruits. So again my advice is simple; start with one vegetable at a time, cook it lightly, and feed a small amount to your dog, increasing a little over a few days. For a small dog you might think about as little as a tsp or two a day, working to 1/4 cup; for a medium dog, start with 1/8 of a cup and work up to 1/4 or 1/2 (daily) and you can go much higher with the big guys, but again, methodically, please! Working with the idea that both the amount of a vegetable and the type can influence response, you will soon find out what your dog’s unique system reacts best to.
5) Potential contamination with pesticides: This is a VERY real concern, and one I believe is not looked at closely enough, especially with the serious rise in canine cancer over the past decade. Organic produce is entirely the way to go, if you can – or at the least, rinse anything you buy extremely well. If possible, grow your own – but be aware that many soils are now contaminated too, sad to say. http://nypost.com/2014/03/16/lead-found-in-community-gardens-soil-may-affect-produce/
My own sense of this issue is this; if you evaluate all our food supply, you will be confronted with a n alarming array of contamination – from pcbs and flame retardant in fish, to antibiotics in factory farmed cows and chickens, to the myriad issues with imported foods and of course, arsenic in rice. It is completely impossible to avoid contaminants, but with vegetables and fruits, organically grown or just very thoroughly washed – we can minimize intake of the nasty stuff while ensuring our dogs get all the health benefits plant foods can offer. So be aware of where your produce comes from, and be careful. That said, don’t let this concern prevent you from adding some vegetables, the cost/benefit analysis comes out on the side of the plants here. One idea might be, to buy organic when using the “Dirty DOzen” pictured below, and use the others carefully, washing well and trying to find local sources as much as you can.
Concerns about carbohydrates: This is such a touchy subject and so hotly debated, I don’t think for one moment that I can change anyone’s mind who is convinced that carbohydrates are all dangerous and should not be fed to dogs in any way shape or form, ever. The best science we have refutes that idea, and my own clinical experience shows otherwise, with dogs whose health issues (or the preference of the vet) mandated I use diets very high in carbohyrates, and living well past life expectancy. It is purely ridiculous to claim that dogs cannot digest carbs (see above) or that the intelligent use of them is a negative practise. So I will discount this idea, if you are reading this blog you likely already understand that carbs can be, like any food group, overfed and deleterious to health or used wisely and health-supportive. Let’s not belabour this point.
In conclusion; I hope the takeaway message here is that vegetables and fruits offer great health benefits, with a few potential drawbacks that can be avoided or minimized, and in general are excellent and important foods to add to your dog’s diet. Whether you raw feed, or prepare a cooked recipe, or feed a commercial diet, think about using a wide variety of veggies in moderate amounts. Spend some time reading more deeply in the science we have with regard to antioxidants, phenolic compounds, carotenoids and more. you can think of whole fresh veggies as THE best supplement you can add – if you are adding lots of lifeless items in little plastic jars – because they’re trendy – do revisit nature’s pharmacy. And be sure to save a little for yourself, too.