Dogs evolved to eat leftovers

The science says they evolved to share our food.

For two big, grown-up dogs, Rufus and Louie are particularly good at the puppy dog eyes, particularly around our respective dinner tables. Having food-dropping toddlers doesn’t help but is it a good idea to feed dogs leftovers from your meals? For years, conventional wisdom has advised against feeding dogs table scraps, warning of potential health risks. However, recent research suggests that certain leftovers may actually support your dog’s gut health and even help them live longer. So, what’s the truth? Let’s take a closer look at the pros, cons and best practices for feeding your dog leftovers.

The evolution of dogs' diets

Dogs have been living alongside humans for thousands of years, and during this time, they’ve adapted to eat some of the same foods as us. As humans moved from hunting and gathering to farming, dogs gained access to human food scraps and agricultural waste. Over time, their digestive systems adapted to handle a broader range of foods than their wild ancestors, like wolves. This co-evolution may explain why some human foods can be beneficial to dogs today.

Interestingly, researchers believe that this history of scavenging and sharing food with humans has influenced not only dogs’ diets but also their digestive systems and microbiomes. The idea that dogs “evolved to eat our leftovers” is now backed by scientific evidence.

The benefits of feeding leftovers

Feeding certain types of leftovers to your dog may not be as risky as once thought. Recent research highlights some surprising benefits, particularly for your dog’s gut health and overall well-being.

Gut health and microbiome support: Studies have found that feeding dogs fresh, unprocessed human food – like meat scraps, raw bones, cartilage and certain fruits – can have a positive impact on their gut health. A study published in Scientific Reports revealed that puppies and adolescent dogs who consumed non-processed, human-like diets had a lower risk of developing chronic gastrointestinal conditions in adulthood.

These types of foods help diversify the gut microbiome, which plays a vital role in digestion, immune function, and overall health. Unlike highly processed commercial dog foods, fresh whole foods are rich in natural prebiotics, fibre and live bacteria that support gut balance.

Longer lifespan: There’s also evidence that feeding dogs certain human foods could contribute to a longer, healthier life. Since gut health is closely linked to immune function, reducing the risk of gastrointestinal diseases may extend a dog’s lifespan. A balanced microbiome promotes better digestion, more efficient nutrient absorption, and protection against harmful bacteria and pathogens. It's too early to say that sharing leftovers will make your dog live longer but the evidence linking diet to health and longevity in both humans and dogs is strong.

The risks of feeding leftovers

Of course, not all human food is safe for dogs. Feeding your dog the wrong types of leftovers could lead to digestive issues, nutritional imbalances or serious health problems. Here are some key risks to watch out for:

Toxic foods: Certain human foods are toxic to dogs and should never be included in their diet. These include: 

• • Onions, garlic, and chives – Can cause damage to red blood cells, leading to anaemia.Chocolate – Contains theobromine, which is poisonous to dogs and can cause heart problems or seizures.
  • Grapes and raisins – Can cause kidney failure, even in small amounts.
  • Avocado – Contains persin, which can be toxic to some animals, although dogs are less susceptible than other pets.
  • Xylitol (often found in peanut butter) – Can cause a dangerous drop in blood sugar, leading to seizures, liver failure, or even death.

Digestive upset: Even if the food isn’t toxic, feeding dogs fatty, greasy, or highly seasoned leftovers can lead to upset stomachs or diarrhoea. Foods with high-fat content, such as bacon or fried foods (their favourites in other words), can increase the risk of pancreatitis, a painful inflammation of the pancreas that often requires veterinary treatment.

Bone hazards: Cooked bones can splinter, causing internal injuries or blockages in the digestive tract. It’s best to avoid giving dogs cooked bones, although raw bones, under certain conditions, may be beneficial as part of a balanced diet.

Risk of obesity: Leftovers may contain excess calories, which can contribute to weight gain if not properly managed. Even small treats add up, so it’s important to be mindful of portion sizes and overall caloric intake. Treats and table scraps should make up no more than 10% of your dog’s daily calories.

What leftovers are good for dogs?

Not all human foods are off-limits. In fact, some of the healthiest leftovers for humans are also beneficial for dogs. 

• Lean cooked meats (chicken, turkey, beef, lamb – without seasoning, sauces, or bones)
• Cooked or raw vegetables (like carrots, green beans, and peas – but avoid onions and garlic)
• Fruits (like blueberries, apples, bananas, and strawberries – avoid grapes and raisins)
• Whole grains (like brown rice, quinoa, and plain oatmeal)
• Unseasoned fish (like salmon or sardines – great for omega-3 fatty acids)
• Eggs 

If you want to introduce new foods to your dog, do so gradually to see how they respond. Every dog is different, and some may have food sensitivities or allergies.

How to feed leftovers safely

If you want to feed your dog leftovers, here are some tips to avoid health risks:

• Check for toxic ingredients – Avoid foods with onions, garlic, xylitol, and other known toxins.
• Keep portions small – Leftovers should make up no more than 10% of your dog’s daily diet.
• Avoid highly processed foods – Foods with added sugar, salt, and preservatives offer no benefit and could harm your dog. They aren’t great for us either!
• Stick to fresh, whole foods – Lean meats, vegetables, fruits and grains are the best options.
• Don’t overdo it – Feeding leftovers too often can create bad habits (like the puppy dog eyes we mentioned) and lead to weight gain.

So, should you feed your dog leftovers?

The answer is yes but sensibly. Leftovers can be a healthy, enriching addition to your dog’s diet if you follow a few simple rules. Foods like lean meats, vegetables, fruits and whole grains can support gut health and diversify your dog’s microbiome. Research suggests that a healthier microbiome could reduce the risk of chronic disease, improve digestion, and even contribute to a longer life.

On the flip side, feeding your dog the wrong kinds of leftovers, such as onions, chocolate, or greasy foods, can pose serious health risks. If you’re unsure, it’s always best to check with a veterinarian before making major changes to your dog’s diet.

Feeding your dog fresh, human-grade food doesn’t have to mean sharing everything from your plate. By being selective and offering only dog-safe foods, you can support their health and well-being without sacrificing your dinner.