Vitamins and minerals play a fundamental role in the diet of companion animals.

Your dog or cat can quickly develop nutritional deficiencies that impede normal functioning if he isn't regularly consuming the right vitamins for his species in the right amounts.

According to, a few of the many jobs vitamins do in your pet's body include:

  • Aiding in the release of energy from other nutrients
  • Acting as free radical scavengers
  • Serving as co-enzymes or enzyme precursors in various metabolic processes
  • Helping to preserve cell membrane integrity
  • Aiding in blood clotting
  • Aiding in the transmission of nerve impulses

What Dr Becker has to say

It’s probably no surprise to you that vitamins and minerals, the ‘micronutrients’ in food, are as important in your pet’s diet as they are in yours. Your pet’s body won’t function very well for very long in a nutrient-deficient state.

The best way to consume all the vitamins required for good health is through food. Again, this is true for both you and your dog or cat.

Vitamin and mineral supplements can be useful on a case-by-case basis, and there are situations in which they offer the only option. But bear in mind it’s not just what your pet eats that’s important, but how efficiently her body uses food to nourish itself.

How Well is Your Pet Using the Nutrition You Provide?

Bioavailability is the measure of how efficiently food nutrients are absorbed and used by the body -- in this case the furry, four-legged one running around your home.

The amount of a nutrient your dog’s or cat’s body can actually put to good use is dependent on a number of variables, one of the most important of which is the source of the nutrient.

The nutrients in real food are vastly different from the biologically inert (lifeless) ingredients in multivitamins.

When a nutrient or vitamin is isolated out of its natural environment – food -- it becomes a chemical isolate. The vitamins in whole food bind with other factors also in the food like enzymes and amino acids to act synergistically to provide nutrition to your pet’s body. A chemical isolate does not have the same capacity.

Your pet’s body wasn’t really designed to use chemically derived vitamins, so it can be especially challenging to predict or determine how effectively a supplement is doing its job.

Another point to keep in mind: the difference between the natural and manufactured versions of a nutrient can sometimes quite literally be the difference between life and death.

Non-food based nutrients can cause serious disease in high doses. The same nutrient found naturally in food or in some cases a chelated version of it, can prevent or combat disease. A chelated nutrient is one that is attached to another organic component, usually an amino acid, in order to improve the body’s ability to use it efficiently.

So again, bioavailability refers to the quantity of a nutrient your pet’s body can draw on to help perform specific physiological functions.

Besides the source of the nutrient (either from nature or man-made), there are several other factors that influence bioavailability, including:

  • The health of your pet’s GI tract, which determines the efficiency of digestion and absorption of the food she eats.
  • How well nutrients are distributed in the blood circulating throughout her body.
  • The assimilation of nutrients into the tissues and fluids of her body where they can be physiologically effective.

Vitamins 101

There are two types of vitamins -- fat soluble and water soluble.

Fat-soluble vitamins (A, D, E and K) are absorbed in your pet’s body similar to the way dietary fats are absorbed, and excess amounts are stored in the liver. Because they can be stored, deficiencies in fat-soluble vitamins tend to develop slowly. However, too high amounts of these vitamins can cause toxicity.

Water-soluble vitamins (the B’s and vitamin C) are absorbed in the small intestine. Excess is excreted in urine, so other than vitamin B12, no water-soluble vitamins are on reserve in your pet’s body. Your dog or cat must get these nutrients through his diet every day.

Vitamin Food Sources
Fat-soluble vitamins
Vitamin A Carrots, egg yolks, fish liver oil, leafy greens, liver, yellow fruits
Vitamin D Halibut and cod liver oil, fish, cheese, yogurt, eggs
Vitamin E Asparagus, spinach and other leafy green veggies, corn, nuts, seeds, vegetable oils, wheat germ
Vitamin K Cabbage, cauliflower, leafy greens and other vegetables
Water-soluble vitamins
Vitamin B1 - thiamine Lean meat, liver, fish, wheat germ, whole grains
Vitamin B2 – riboflavin Cheese, eggs, fish, liver, lean meat, nuts, legumes, leafy greens,
Vitamin B3 – niacin Asparagus, leafy green veggies, seeds, nuts, poultry, fish, liver, lean meat
Vitamin B5 – pantothenic acid Eggs, fish, lean beef, legumes, broccoli and other vegetables in the cabbage family, sweet potatoes
Vitamin B6 - pyridoxine Bananas, eggs, fish, meat, whole grains
Vitamin B8 - biotin Bananas, cauliflower, egg yolks, legumes, mushrooms, nuts, sardines, Swiss chard
Vitamin B9 – folic acid Apricots, beans, carrots, egg yolks, leafy greens, liver, melon, pumpkin
Vitamin B12 - cobalamin Cheese, eggs, fish, liver, meat
Vitamin C Berries, citrus fruits, tomatoes, cauliflower, green pepper, green leafy vegetables

Vitamin Deficiency is Uncommon in Today’s Companion Animals – or is It?

The presumption is the majority of commercial pet foods on the market today deliver the right amounts of all the essential nutrients your pet needs for good health.

However, a number of nutrition-related diseases have become prevalent in dogs and cats in recent years.

Seizure disorders in pets are on the rise, and research indicates vitamin and mineral deficiencies could be among the causes. Nutrients found in short supply in pets suffering from epilepsy are vitamins A, B6 and D, calcium, folic acid, magnesium, taurine and zinc.

The number of autoimmune disorders in dogs and cats is exploding, and balanced, species-appropriate nutrition is the foundation for a strong immune system. Nutrients that play an important role in immune function include vitamins B6 and E, linoleic acid, zinc and selenium.

Selenium is a trace mineral that when obtained from whole food or in chelated form is a disease fighter, but in manufactured form – specifically the sodium selenite found in some multivitamins – can cause cancer in high doses.

But the Pet Food I Buy Says ‘Complete and Balanced’ Right on the Label

The truth is there’s not a lot of solid science behind the Association of American Feed Control Officials (AAFCO) certification of pet foods as ‘complete and balanced.’ AAFCO’s Nutrient Profiles are all we’ve got, and we are thankful we have some guidelines – but they have significant limitations pet owners need to recognize.

The problem is obvious. Inexpensive pet foods containing very low percentages of rendered meat by-products and very high percentages of grains are certified ‘complete and balanced’ right along with premium formulas made from human-grade ingredients and biologically appropriate ratios of high quality protein, fat and moisture. And all have synthetic vitamins and minerals added.

Based on just this one example, it’s clear that while the AAFCO Nutrient Profiles for dogs and cats have helped to develop some minimum standards for pet food production, they don’t address the quality of ingredients, or the digestibility, palatability or bioavailability of nutrients.

To demonstrate, Dr. Jean Hofve, a holistic veterinarian and renowned expert on pet nutrition, in an article written for The Whole Dog Journal and republished here gave this example:

“One critic of this method of feed formulation designed a "food" that met all the AAFCO nutrient profile requirements – even though the food was primarily formulated from old shoe leather, sawdust and motor oil with a multi-vitamin-mineral supplement.

Obviously, there would be no guarantee that any animal would eat such a food, or could digest it, even though it contained all the vitamins, minerals, protein, fat, etc. that the nutrient profiles required.”

In an effort to compensate for the limitations of the nutrient profiles, AAFCO included a ‘safety factor,’ which involved exceeding the minimum amount of nutrients necessary to meet ‘complete and balanced’ requirements.

So although AAFCO sets a minimum level of vitamins and minerals required to sustain life, they haven’t set a maximum amount. Many pet owners assume their pet’s dry food is probably deficient and add additional vitamins and minerals on a daily basis, dramatically increasing the risk for hypervitaminosis and toxicosis.

Dr. Hofve continues:

"In the case of minimum requirements without a corresponding maximum, some foods contain significant nutrient excesses that may actually be dangerous in the long run.

The Kentucky feed control officials analyzed test data from all pet foods tested during 1994 and 1995, and found that certain nutrients, such as magnesium, iron, and manganese, were present in most dry dog and puppy foods at 200-400 percent or more of their AAFCO Nutrient Profile values.

Their conclusion: the AAFCO profile for certain nutrients is not a reasonable indicator of the actual level present in many products. An excess of many minerals, including copper, magnesium, iodine, and iron, may produce signs of toxicity over time. Excess iodine, for instance, is thought to be one factor contributing to the explosion of hyperthyroidism among older cats."

AAFCO also uses feeding tests to standardize pet food formulas.

The protocol for these tests is a six-month feeding trial involving as few as eight test subjects, and the goal is only to determine whether a formula can sustain life in test participants. Only six of the eight animals need to finish the trial, and if weight and certain blood tests are normal, the food is deemed ‘complete and balanced.’

Needless to say, six pets still alive at the end of six months is hardly a ringing endorsement for a ‘complete and balanced’ pet food formula.

These trials are simply not a good measure of a food’s ability to cause nutritional deficiencies or overdoses over a longer period, nor can they demonstrate the food’s impact on longevity, reproduction or multi-generational health.

If You’re Concerned About the Nutritional Status of Your Dog or Cat ...

There are many ways you can take action to improve the quality of nutrients you feed your pet.

My first recommendation is to locate a holistic veterinarian who is willing to partner with you to achieve your goal of better nutrition for your dog or cat.

A holistic vet will not only help you sort through options for feeding your pet, but can also recommend specific supplements based on your dog’s or cat’s breed, size, weight, age, health status and other factors.

Keep in mind you want to nourish your pet primarily through balanced, species-appropriate real food rather than depending on dietary supplements. And when it comes to supplements, it’s never a good idea to try to guess what your pet’s body requires over and above what she’s getting through the meals you feed her. Making sure you are following a balanced recipe is important, as nutrient deficiencies can be just as harmful as excessive supplementation over time.

Your holistic vet is in a position to advise you on supplementation, when needed -- especially if you’re just starting out on your journey -- and will also be able to answer your questions about the quality of various supplements, whole vs. synthetic vitamins for example.

If you’re curious about how to feed your pet homemade food, I’ve co-authored a book on the subject called Real Food for Healthy Dogs and Cats. This book is written with all pet owners in mind, including:

  • Those who are thinking about switching from store bought pet food to homemade.
  • Those who cook homemade pet meals and are considering moving to raw.
  • Pet parents who feed raw and are looking for recipe suggestions or shopping and storage tips.

There are also many articles and videos right here at on the subject of pet nutrition, as it is my firm belief good nutrition is the foundation for good health. Clicking the related article links below is a great place to begin your exploration.

You can also visit The DogSmith Website, here you will find links and information to a holistic dog and cat food, a full array of vitamins and minerals and other premium pet products.

Dr. Becker is the resident proactive and integrative wellness veterinarian of You can learn holistic ways of preventing illness in your pets by subscribing to, an online resource for animal lovers. For more pet care tips, subscribe for FREE to Mercola Healthy Pet Newsletter.