Research, and common sense, suggests that single vitamins and nutrients extracted from a food may not be as effective for promoting good health as the complete whole food itself. Isolated nutrients don't seem to provide the same benefits. Whole foods and the combinations of whole foods eaten over the course of a day, week and month likely have synergistic effects of which we are not aware. But it's not easy to eat a rainbow of fresh foods and an assortment of lean protein, healthy fats, and whole grain carbohydrates every day for myself, not to mention my dogs!
So what's the next best thing for you and your canine companion? I will let your nutritionist or other healthcare professional make recommendations for you, but as for your dog I recommend using vitamins and nutritional supplements made from a variety of whole foods, combined to maintain synergistic effects, and cooked at low temperatures to preserve nutrients. Organ tissues, whole plants with phytonutrients, in essence a varied diet rich in complex nutrients - in the form of a supplement. Whole foods to support the whole body of your pet!