A groomer friend of mine recently recounted the story of a client who feeds her dog a limited, four-ingredient fresh food diet due to food intolerances. While limited-ingredient diets are common for dogs with food sensitivities, the client was not adding any supplementation for fear of causing the dog a reaction. I was floored, because no four foods can provide all of the dog nutrition a pup needs to live a long, healthy life. Without supplements to fill in the nutritional gaps, this well-intentioned dog guardian is unwittingly causing her canine companion more harm than good.

All living organisms need a wide variety of nutrients — substances from food that provide energy and enable our bodies to function — to survive. There are six major classes of nutrients for dogs and people: water, protein, fat, carbohydrates, vitamins and minerals. Let’s take a closer look at dog nutrition and six essential nutrients your dog needs to eat:

1. Water

• What it is: A tasteless, colorless, odorless chemical made up of two hydrogen molecules and one oxygen molecule — hence the name H2O.
• Why it’s important: Without water, life cannot exist. Water makes up 70 to 80 percent of a mature dog’s lean body mass. Water’s many important functions include: dissolving and transporting nutrients to the cells; helping regulate body temperature; hydrolyzing protein, fat and carbohydrates for digestion; cushioning the organs and nervous system; flushing waste from the body.
• Special considerations: A dog’s water requirements vary based on health, activity level and environmental temperature. Most dogs self-regulate their water intake to meet their needs. Dogs fed high-moisture foods typically drink less than kibble-fed dogs. All dogs should always have access to clean, fresh H2O.
• Get it from: Straight from the tap fitted with a good quality filter.

2. Protein

• What it is: Along with fats and carbohydrates, protein is a macronutrient, meaning that it supplies energy. Protein is made up of amino acids, the building blocks of life.
• Why it’s important: Protein supplies essential and non-essential amino acids that are critical to life. Proteins give the body structure (think strong hair, skin, nails, muscles and bones) and are necessary to make hormones, neurotransmitters, enzymes and antibodies that keep the body functioning optimally. Dogs must receive the essential amino acids from diet, as their bodies cannot produce them at the required levels. Protein can also supply energy in the absence of sufficient carbohydrates and fats. Because the body can’t store protein, it needs a constant dietary supply.
• Special considerations: Growing puppies and pregnant and lactating females require about twice as much protein as an adult dog at maintenance.
• Get it from: Animal sources such as lean-muscle meats, fish and eggs; plant-based sources such as beans and lentils.

3. Fat

• What it is: A macronutrient made up of fatty acids. Dietary fats are either saturated (e.g., butter, cheese meat), polyunsaturated (e.g., fish oil, flaxseed oil, sunflower oil) or monounsaturated (e.g., olive oil).
• Why it’s important: Fat supplies the most concentrated source of energy, with more than twice as many calories as protein and carbohydrates. It also provides essential omega-3 and omega-6 fatty acids; enables absorption of fat-soluble vitamins; protects the internal organs; regulates body temperature; and promotes a healthy nervous system.
• Special considerations: Too much fat can trigger pancreatitis or gastrointestinal issues. Avoid fatty table scraps. Be aware that coconut oil does not supply essential fatty acids.
• Get it from: Low-mercury fish and fish oil; plant-based oils, such as flaxseed and hempseed.

4. Vitamins

• What they are: Vitamins are organic compounds (meaning that they contain carbon) that are required in small quantities for proper metabolic function. Vitamins can be soluble in fat (A, D, E and K) or in water (B and C). Fat-soluble vitamins are stored in fatty tissues and the liver; water-soluble vitamins are not stored. Because the body can’t synthesize vitamins in sufficient quantities, they must come from the diet.
• Why they’re important: Vitamins play a variety of critical roles, including: regulating calcium and phosphorus levels (D); boosting the immune system (A); serving as antioxidants (C and E); enabling the blood to clot (K); and maintaining nervous system function (B12).
• Special considerations: All home-prepared diets require vitamin supplementation. If you feed a commercial “complete and balanced” food, do not add additional fat-soluble vitamins, as toxicity can occur. Toxicity of water-soluble vitamins is unlikely, as excess is excreted in the urine.
• Get THEM from: A varied diet containing organ and muscle meats and dog-friendly plant-based foods.

5. Minerals

• What they are: Minerals are inorganic compounds that the body needs to maintain proper metabolic functions. The body cannot manufacture minerals and so must get them from food. There are two classes of minerals: macrominerals (calcium, magnesium, phosphorus, sodium, potassium, chloride) and microminerals (iron, copper, zinc, manganese, selenium, iodine). Macrominerals are required by the body in higher levels than microminerals, but both types are equally important.
• Why they’re important: Like vitamins, minerals perform a variety of functions in the body that are essential for supporting life, including: constituting a major part of bones (calcium, phosphorus); carrying oxygen throughout the body (iron); assisting in wound healing (zinc); providing antioxidant support (selenium); aiding in nerve transmission (sodium, potassium, calcium, magnesium); and regulating fluid balance (sodium, chloride, potassium).
• Special considerations: Growing puppies require more than double the calcium of adult dogs at maintenance. Calcium and phosphorus levels and ratios must be monitored closely in large-breed puppies to avoid risk of developmental orthopedic disease. Read more about what nutrients to feed puppies right here >>
• Get THEM from: Different foods are rich in different minerals. Meat is high in phosphorus, while bone is high in calcium. Organ meats provide copper and iron, while shellfish is rich in zinc.

6. Carbohydrates

• What they are: A macronutrient made up of units of sugars, starches or indigestible fiber. Since dogs can synthesize glucose from sufficient dietary protein and fat, carbohydrates are the only nutrient class that is not essential for dogs. Why they’re important: Carbohydrates are the main source of glucose, the “fuel” the body runs on. Although carbohydrates are not an essential nutrient for dogs, healthy carbohydrates supply important vitamins, minerals, antioxidants and plant-based nutrients that help promote optimum health.
• Special considerations: Consuming a portion of energy from healthy carbohydrates spares protein for other important functions. Steer clear of high-glycemic “junk” carbohydrates that provide little to no nutrition and rapidly raise blood sugar levels.
• Get THEM from: Dog-friendly vegetables, fruits, legumes and gluten-free grains.

The importance of each nutrient class could — and does — take up entire books, so I’ve only skimmed the surface. The bottom line in dog nutrition is that all dogs need an ample supply of nutrients to survive and thrive. The fewer of these nutrients that come from food, the more supplementation is needed to fill the gaps.

Power Sources for Dog Nutrition

Not sure which foods hold the most nutrient “bang for their buck”? Check out this list to get you started:

1. Water • Filtered tap water: Clean; pure; cost-efficient; readily available
2. Protein • Whole egg: Considered the most bioavailable source of protein (1 large egg provides about 6 grams of protein)
3. Fat • Sardines: Low mercury; nutrient-rich; high in the essential omega-3 acids EPA and DHA
4. Carbohydrates • Butternut squash: High in vitamins A and C; loaded with antioxidant-rich carotenes; excellent source of many vitamins and minerals, such as vitamins E and B6, magnesium, manganese and potassium.
5. Vitamins • Dark leafy greens: Rich in vitamins A, C, E, K and folate; also high in carotenoids and many minerals; shown to
   protect against cancer
6. Minerals • Oysters: Excellent source of copper, iron, magnesium, manganese, phosphorus, selenium, zinc; also rich in vitamin D and omega-3 fatty acids

Tell us: Did you know these facts about dog nutrition? What do you feed your dog?

This piece was originally published in 2017.

Thumbnail: Photography ©damedeeso | Thinkstock. 

Diana Laverdure-Dunetz, M.S., is a canine nutritionist and co-author, with M. Jean Dodds, D.V.M., of two books including Canine Nutrigenomics: The New Science of Feeding Your Dog for Optimum Health. Their online course, Complete Canine Nutrition can be found at myhealthydog.dog.

Editor’s note: This article appeared in Dogster magazine. Have you seen the new Dogster print magazine in stores? Or in the waiting room of your vet’s office? Subscribe now to get Dogster magazine delivered straight to you! 

Read more about dog food and treats on Dogster.com:

• What to Do in a Pet Food Recall
• 6 Tips to Slow Down a Dog Who Eats Too Fast
• What Are the Signs of a Truly Hungry Dog?