Human Vitamins for Dogs: Why It’s Not Safe to Share


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Written by: Guest | Best Company Editorial Team

Last Updated: February 24th, 2020

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Guest Post by Krystn Janisse

Do you take a multivitamin every day to stay healthy, or maybe a B vitamin complex to care for your hair and nails. It stands to reason that your dog would also benefit from these supplements, right? What’s the harm in giving human vitamins to your dog?

Maybe more harm than you think!

When fed a complete and balanced diet, most dogs do not need a vitamin supplement. On the other hand, dogs suffering from illness, poor digestion, or those fed an incomplete diet could benefit from a few extra vitamins. 

That being said, are your vitamins the same as theirs? Let’s take a look at the vitamins that dogs need and see if they are the same as the ones that you need.

What vitamins do dogs need?

Before we get into the difference between our vitamins and those made for our pets, let’s talk about which vitamins you might consider and why. 

Your dog can make many of their own vitamins by breaking down and combining other nutrients, but some need to be included in their diet. These are called essential vitamins. 

Here is a quick reference chart of your dog’s essential vitamins and their main functions:



Food Source

Vitamin A (Retinol)

Eye health

Fish, eggs, liver

Vitamin B1 (Thiamine)

Nerve function

Cereal grains, yeast

Vitamin B2 (Riboflavin)

Skin and coat health

Liver, eggs, yeast

Vitamin B3 (Niacin)

Skin and coat health

Fish, cereal grains, fish

Vitamin B5 (Pantothenic Acid)

Energy for cells

Meat, tripe, eggs

Vitamin B6 (Pyridoxine)

Energy for cells

Yeast, meat

Vitamin B9 (Folic Acid)

Synthesize red blood cells

Leafy greens, liver

Vitamin B12 (Cobalamin)

Protein synthesis

Meat, organ meat

Vitamin D (Cholecalciferol)

Bone growth

Fish, fish oils

Vitamin E (Alpha Tocopherol)


Plant oils, cereal grains, 

Vitamin K (Menaquinone -7)

Blood clotting

Spinach, liver, most meat


Fat synthesis, liver function

Liver, heart, eggs, soy


You recognize most of these vitamins, right? That’s because they are the same vitamins we take, but that doesn’t mean that we can share. 

We know that the vitamins that our dogs need and the vitamins that we need are one and the same, but there is a fundamental difference between how we use supplements and how our pets do.

Here are four important reasons to avoid sharing your multivitamins with your pooch:

1. Dosage

If you look at most human vitamin supplements, you may notice that the dosages are much higher than what you’ll see in a formula made for pets. The most significant reason for this difference is our size. 

You might be anywhere from 2-200 times the size of your dog. That weight difference means that your vitamins are not dosed correctly for their weight.  

Our size difference isn’t the only reason that human vitamins could be too much for your dog. Our supplements typically supply a full daily intake of that nutrient, while your dog’s vitamins may contain as little as 15-20% of their daily vitamin needs

Giving your dog your vitamins means that you could be over supplementing your pet by more than 10 times their daily needs. Yikes!

2. Toxicity

There are two types of vitamins. They can either be water-soluble or fat-soluble. 

A water-soluble vitamin will be excreted through their urine when there is more than their bodies need. Over supplementing water-soluble vitamins is an easy way to make very expensive pee.

Fat-soluble vitamins, on the other hand, get stored in the liver and other fatty tissues. This can be dangerous. Over time, this build-up becomes toxic, damaging organs, interfering with digestion, and affecting their bone health. 

dog sitting head tilted

Be careful when supplementing Vitamin A, D, and K, which are all fat-soluble.

3. Formula

We are a little spoiled when it comes to supplements. We want them to be tasty, or at least easy to swallow. This means that extra ingredients must be added to accommodate our preferences. 

Chewable supplements are sure to be loaded with sugar, or worse xylitol, an artificial sweetener that is very toxic to dogs and cats. Another concern in human supplements is the addition of artificial colours and titanium dioxide used to make our vitamins look tastier, like candy. Both are potentially linked to digestive issues, immune function disorders, and even cancer.  

4. Natural vs. man-made 

Some synthetic vitamins work well for both us and our pets, while others have shown to be ineffective. Vitamins in their natural form are paired with enzymes, bioflavonoids, and other vitamins that make them recognizable to your dog’s body. 

Synthetic vitamin supplements are isolated from these organic compounds and may not be as easily digested. Some can even be toxic. Vitamin K’s synthetic form is called Vitamin K3. This isolate could lead to toxicity in the liver, kidney, lungs, and other tissues. 

dog with plant in mouth

Opt for natural

If you give your pet vitamin supplements, avoid offering vitamins designed for humans without consulting your vet first.

If you decide that your pet would benefit from additional vitamins, start by offering vitamin-rich foods instead of supplements. Nutrients from food are difficult to over-supplement, making them safer for your pet

Krystn is a passionate animal enthusiast with over a decade of experience in the pet industry. She loves to share both work and personal experience in hopes of enriching the lives of humans and animals. She is currently the content writer for

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