Phytonutrients (the pigments that give fresh foods their vibrant hues of red, green, purple, yellow and orange) do more than just make a pretty meal. They contain powerful antioxidant properties that can have a profound effect on total health.
While it’s true that some produce enjoyed by humans isn’t necessarily biologically appropriate (or even safe, in some cases) for canines, many fruits and vegetables are suitable for dogs to eat, and contain compounds that can help to provide protection against many of the ailments and diseases to which domestic dogs are prone. It’s fair to say that as research continues, more and more health benefits are likely to be uncovered and the list of species shown to benefit from them will increase too.
Benefits of Phytonutrients
Phytonutrients, also known as phytochemicals, have been shown to aid in protecting plants from environmental challenges and form part of a plant’s ‘immune system’. They help to protect plants from disease, insects, drought, excessive heat, ultraviolet rays, and poisons or pollutants in the air and soil.
Despite the fact that most phytonutrients are officially considered ‘non-essential nutrients,’ and their consumption isn’t essential for survival (most of them certainly aren’t included in the AAFCO nutrient profiles or other references that many vets and pet owners are familiar with), phytonutrients do seem to be essential for deep-seated good health, wellbeing, immunity - and probably, longevity. Some of the health benefits of consuming the phytonutrients contained in colorful foods, include enhancing immune system activity, protecting against cancer, supporting eye and heart health, improving communication between cells and repairing DNA damage. Antioxidants also help to slow down the signs of aging by cleaning up the by-products of oxidation which takes place within the body’s cells.
The study of phytonutrients is one of the most exciting areas of nutritional research being undertaken today, and is extending our knowledge of the health benefits of food, far beyond the macronutrients (protein, fat, carbohydrates and fiber) and micronutrients (vitamins and minerals) that we’ve studied historically. Some of the best-known phytonutrients are carotenoids (such as beta-carotene, lutein, lycopene and Zeaxanthin) and flavonoids (such as isoflavones, anthocyanins and flavones).
Researchers have identified hundreds of different individual phytonutrients, and it’s estimated that one day we may know about as many as forty-thousand. The powerful health properties of colorful pigments are thought to play an especially important role in cancer prevention. While the majority of the research on phytonutrients is being done on humans, it’s likely that most of the benefits being demonstrated apply to numerous animal species including domesticated pets, as well. Read on, for a snap-shot of the different pigments found in various color-groups of foods.
Phytonutrients in FoodsRed foods such as tomatoes, pink grapefruit, watermelon and papaya are rich in the antioxidant Lycopene (a carotenoid). In addition to its antioxidant activity, lycopene has been shown to suppress the growth of tumors in both laboratory and animal experiments. Researchers believe that poor communication between cells is one of the causes of the abnormal growth of cells, which may ultimately lead to the development of different kinds of cancer. One of the ways that lycopene may limit tumor growth is by stimulating communication between cells. Most of lycopene’s health benefits are related directly to its antioxidant properties. Lycopene is especially effective at quenching the free radicals that can damage cell membranes.
Purple & reddish fruits and vegetables such as blueberries, cranberries, blackberries, eggplant and plums, contain compounds called Anthocyanins, a class of flavonoids, which have been found to help reduce risk of cancer, stroke and heart disease. Some studies have shown that the consumption of blueberries is linked with improved memory function and healthy aging. More than 300 structurally distinct anthocyanins have been identified in nature. Some anthocyanins have anti-inflammatory properties, and some studies are looking at their role in the inhibition of tumor development as well as in diabetes and ulcer treatment. It’s also thought that anthocyanins possess possible anti-viral and anti-microbial properties.
Dark green foods such as spinach, kale, bok choi and cabbage contain lutein, another free-radical-quenching carotenoid antioxidant, that’s especially important for skin and eye health. Lutein is also present in the yolks of eggs. Dark green foods also tend to be a good source of the B-vitamin folate, which gets its name from the Latin word folium, for leaf. Folate helps produce and maintain new cells. Folate is essential for the formation of DNA and RNA, the building blocks of cells. It also helps to prevent the types of DNA changes within cells that may lead to cancer.
Orange, yellow and green foods like sweet potatoes, carrots, mangoes, spinach and pumpkin (a superfood, and one of the richest-known sources of carotenoids) contain beta carotene, which can be converted by the body into retinol, a bioavailable source of vitamin A. This potent antioxidant is beneficial for eye health, immune system function and a healthy heart. Zeaxanthin, which is also found in yellow and green foods like spinach, collard greens as well as egg yolk, is beneficial for the eyes and immune system. Many beta-carotene rich foods such as oranges, papayas, bell peppers & kiwis also contain vitamin C, which helps to protect cells from free radical damage as well as promoting skin and immune system health.
White fruits and vegetables such as bananas, parsnips, potatoes and garlic take their ‘color’ from pigments called anthoxanthins. These contain health-promoting chemicals such as allicin, which may help lower cholesterol and blood pressure and their role in helping to reduce the risk of stomach cancer and heart disease in humans is under study. Some white foods like potatoes and bananas are also good sources of potassium, needed for nerve and muscle function as well as blood pressure – which in turn is associated with diabetes, kidney failure and Cushings disease.
Isoflavones, which are found in flax, rye and red clover, have been researched extensively for their ability to protect against hormone-dependent cancers, such as breast cancer.
Phytonutrients for Dogs
How colorful a food is, is a key factor in identifying its nutritional integrity, and also provides clues about the level of processing it has undergone. Refined and processed food that has turned brown from extreme heat or high pressure (such as kibble), is missing the colorful, magical phytonutrients that natural whole food ingredients possess – and which a body needs in order to stay truly healthy. In many minimally processed types of dog food like dehydrated or freeze dried, you can still see the pigments and colors of the ingredients and know that the phytonutrients are still intact.
Just because our dogs have been domesticated and live with us in houses, doesn’t mean they’ve somehow lost their innate, physiological need for a varied colorful, healthy whole diet just like their wild counterparts. A simple hike in the back-country will reveal the red and purple-stained scat of coyotes who’ve supplemented their mostly-meat diets with some of the colorful pigmented wild berries that nature provides. Even though meat should make up the majority of a canine’s diet, the value and health benefits of the pigments present in fresh or gently prepared colorful produce, probably shouldn’t be overlooked.
Lucy Postins is founder and Chief Integrity Officer at The Honest Kitchen. She is a companion animal nutritionist who started The Honest Kitchen in her kitchen in 2002. She is passionate about advanced nutrition and holistic health including complementary modalities such as herbalism and homeopathy. Considered an expert in her field, Lucy frequently writes articles for local and national media, conducts radio interviews and educational spots, and occasionally holds educational seminars for pet owners on the importance of good nutrition. She also recently authored Dog Obsessed, a guide to a happier, healthier life for the pup you love.