I’m frequently asked by clients and readers if they should add a multi-vitamin product to their dog’s diet, since many “experts” push their use, often because they are selling one product or another themselves.

Here’s a look at claims often made about “complete” and/or “balanced” multi supplements:

1. A supplement needs to be “balanced”

This statement doesn’t make sense because the goal of supplementation is to provide nutrients that are in short supply in the regular diet – which can vary quite a bit from one food product to another, depending on ingredients. In other words, we want to improve upon what’s already provided in the food by adding nutrients that are lacking or in short supply, resulting in a better overall balance. A supplement that is “balanced” in itself may add more of what’s already plentiful in the diet but still not help achieve sufficient levels of something else.

An example: the minerals copper, iron, and zinc interact with each other and ideally should be present in the diet not only in sufficient amounts, but also in the proper ratio. Let’s say we add a supplement which in itself provides a correct ratio of these 3 minerals to a diet that already contains an adequate amount of copper, much more iron than the dog actually needs on a daily basis, but not enough zinc.

That supposedly “balanced” supplement does nothing to fix the issue, as it adds a little bit more copper to what’s already sufficient, adds even more iron, and doesn’t help with addressing the zinc deficiency.

2. Pets need a complete multivitamin/mineral supplement in addition to commercial food

From the discussion above, you can already guess that this claim is incorrect. After investigating many commercial foods and comparing their nutrient content to the nutritional guidelines and recommendations of the National Research Council, I have found that most minerals are supplied in overabundance, many times more than the average dog needs on a daily basis. A few tend to come up short, but these are generally required in tiny amounts, so that not much needs to be added on a weekly basis.

The fat soluble vitamins A and D are generally present in sufficient to high amounts, and adding more is not necessarily a good idea. The content of the water soluble vitamins of the B complex varies greatly from product to product and manufacturer to manufacturer.

3. Pets eating processed foods need lots of antioxidants

I agree that antioxidants are important, but please realize that when supplied in concentrated dosages and too great of an abundance, nutrients with anti-oxidant properties actually start to act as pro-oxidants. My recommendation is to not go overboard, too much of too many “good things” isn’t necessarily in your dog’s best interest, especially if certain health issues are present.

Choose to supplement fresh, unprocessed foods rather than yet another thing from a bottle or jar.

4. Nutrient X and nutrient Y work together, so they are both supplied in this product

This claim brings us back to the discussion under 1. and 2. – you already understand that ultimately the balance in the final diet, composed of food items and supplements is important, not just what the supplement adds. Sometimes it’s wiser to just add one of the two, or more of one and less of another, to get a good balance.

Example: an oil blend supplement claims that it is “balanced in omega 3, 6 and 9 fatty acids”. Most commercial foods, and also many homemade diets, already contain enough (or even excessive levels) of omega 6 fatty acids and no shortage of omega 9 fatty acids, so adding more of these is (a) unnecessary and (b) won’t help to create a better overall balance.

Once again, save money and only add what’s really needed.

5. If adding this supplement doesn’t help, at least it won’t harm, so it’s ok to use

I wish I could say this is true, but it’s not. Even something as innocuous as vitamin C can cause serious problems under certain circumstances.

Sometimes products even contain not only poor quality ingredients best avoided, but outright suspect substances, like the synthetic version of vitamin K, menadione.

As a rule, do not buy any supplements for which you can not obtain a detailed analysis of nutrients and an ingredient list. If a manufacturer is not willing to inform you just how much of a particular nutrient (e.g. iodine) your dog will be ingesting per recommended daily serving of the product – using the excuse that this is “proprietary information” or some such nonsense – you are better off looking for a more trustworthy business.