By Elizabeth Wasserman

Thousands of years ago, when dogs were first domesticated, our ancestors fed them table scraps. In other words, they gave them people food, such as bits of meats, vegetables and fruits, which were left over from their own meals.

Fast-forward to the present, and you may have noticed a return to the basics in the ingredients of certain dog foods, especially if you’re the type of person who pores over pet food labels in grocery store aisles. Some of the ingredients showing up in dog foods may surprise you. They sound more like something you'd serve your family for dinner: not only chicken and eggs but also carrots, spinach, apples and more.

"While dogs are predominantly carnivores -- meat eaters -- they're historically scavengers and thrive on eating fresh fruits and vegetables," says Lisa Peterson, communications director for the American Kennel Club. "Adding fresh ingredients to dog food may enhance health, and it may make the food taste good, too."

Dog Food Requirements
All commercially prepared dog food is supposed to adhere to government standards for canine nutritional needs. When you shop, it's important to look for a seal from the Association of American Feed Control Officers (AAFCO), which develops guidelines for the manufacture, labeling and sale of animal foods in the U.S., advises Bonnie Beaver, DVM, past president of the American Veterinary Medicine Association and a veterinary professor at Texas A&M University. "The foods that have the AAFCO seal give you a reasonable assurance that it's appropriate for a healthy dog," Dr. Beaver says.

Under the AAFCO guidelines, healthy adult dog foods are required to have a minimum of 18 percent protein, 5 percent fat and an assortment of required vitamins and minerals. For puppies or expectant mother dogs, the minimum requirement is higher for protein (22 percent) and fat (8 percent).

In the past, some pet food manufacturers met these nutritional requirements by including such ingredients as meat by-products (organs, blood, bone, etc.), fish meal (ground tissue of whole fish or fish cuttings) and corn gluten (by-product of production of corn starch or syrup). However, amid growing interest among Americans in feeding their families and pets more "natural" foods, some dog food manufacturers are now using more natural -- and recognizable -- ingredients in foods they sell.

These ingredients may include:

• Chicken and Egg High-quality protein in these food items helps build and maintain strong muscles.

• Carrots These are high in beta-carotene that can be converted to vitamin A, which helps in vision. AAFCO requirements call for a minimum of 5,000 IU/kg in the canine diet.

• Tomatoes These are rich in beta-carotene and vitamin C, which are antioxidants that can limit damage to cells and promote a strong immune system.

• Peas These have antioxidants, including Vitamin E, which promote a strong immune system and limit damage to cells. AAFCO requirements call for a minimum of 50 IU/kg in a healthy dog's diet.

• Spinach This leafy green vegetable has many of the essential vitamins and minerals -- including vitamin A, manganese, riboflavin, calcium and iron -- that the AAFCO says a dog needs. Spinach is linked to a healthy heart, among other positive benefits.

• Apples and Beets Fruits and vegetables contain natural fiber that helps promote a healthy digestive system in canines.

• Fish Oil and Flaxseed Fish oil and flaxseed, both rich in omega-3 fatty acids, contribute to skin health and coat shine.

• Grains Wholesome whole grains such as rice, sorghum and barley provide a natural source of energy and vitality to dogs.

• Calcium Natural calcium promotes strong teeth and bones, not only in humans but in canines, too.

Ingredients to Avoid
Your definition of "natural" foods for your family probably doesn't include artificial colors, artificial flavors and preservatives. Those may also be ingredients you want to avoid feeding your dog. Artificial colors can often be detected by a reference to a color with a number after it, such as Blue 2, Red 40 and Yellow 5. When it comes to flavoring, it's a good idea to look for a natural flavoring, such as natural chicken flavoring, instead of an animal digest, which is a cooked-down broth of unspecified animal parts. Some of the new natural foods promote the fact that they don't use preservatives. Common preservatives used in dog foods include Ethoxyquin, BHA or BHT.

In addition to bettering the health of your dog, going natural with the foods you feed your pooch may give you more peace of mind. "As the human-animal bond has grown, marketing has lent itself towards what's appealing to the person," says Rebecca Rose, CVT, of Red Valley Rose Consulting, in Gunnison, Colo. "The balanced diet for the animal is the important part. As long as the animal is getting what it needs and maintaining its weight and coat, it’s fine."

Our feeding of dogs is one of the reasons that they became domesticated in the first place. "That's one of the reasons dogs selected humans to bond with -- it was easier for them to please us and get food in return than it was to go out and hunt for it on their own," Peterson says.

And one axiom has remained true throughout the generations: "People," Peterson says, "love to share food with their dogs."