Which human food is safe for cats?

Many cats like to scrounge food from their humans at mealtimes. But even as our willpower dissolves under those soulful stares, we are often uncertain.

Which food is safe to pass under the table to the cat, and how much of that food might be harmful? And don't think that your cat will instinctively know what's good for her. In fact, the stronger the bond between cat and human, the more likely the cat is too trustingly accept something that is bad for her.

Many foods which we humans eat are perfectly safe for cats, at least in small amounts, but there are some human foods that cats definitely should avoid. These are: alcoholic and caffeinated drinks, sugary treats, onions, garlic, grapes and raisins. And particularly chocolate, or to be precise, cocoa.

This contains a compound called theobromine. A cat’s body does not have the enzymes to metabolize theobromine, so once it has got into a cat’s system, the theobromine remains in the bloodstream for a long time. Since it doesn’t leave the cat, theobromine accumulates, reaching toxic levels very quickly. For more information about the toxic effects of chocolate see our earlier article: Cats and chocolates - why these two don't mix.

Many humans consider garlic as a wonder herb that helps to lower cholesterol and blood pressure, prevent heart disease and even certain types of cancer. True maybe for humans, but not for all species.

Garlic is bad for vampires - and cats. Garlic, like onions, chives and leeks, is part of the Allium family. As with theobromine in chocolate, cats can’t digest plants from the Allium family. Eating these plants destroys the cat’s red blood cells and causes a condition called hemolytic anemia.

Another side effect experienced by cats which eat Allium plants is gastroenteritis (inflammation of the stomach and intestines causing stomach pain). Grapes and raisins can cause acute kidney failure. The exact compound which causes the illness is not known but the first signs occur within 24 hours of digestion and include lethargy, vomiting and diarrhea. The other symptoms which follow are signs that the kidneys are shutting down (see Kidney failure in Cats).

So chocolate, garlic and grapes are the most dangerous foods. Most others are relatively safe, at least in small amounts. Probably the safest human food for our feline friends is meat. Cats are what is known as 'compulsory carnivores'.

Their bodies do not produce a substance called taurine, so the taurine found in meat from other animals is essential to their diet. Poultry is probably the best choice, but other meats are safe as well. (Just be sure the meat contains no bones or lumps of gristle your cat might choke on.)

Another concern is with raw meat. Make sure such meat is very fresh and from a trusted supplier, because bacteria such as E-coli and Salmonella (which thorough cooking destroys) are common pathogens in raw meat. Liver is very good, and cats will often prefer this to muscle meat.

But don’t overdo the liver because it is rich in vitamin A, and too much of that can cause the development of painful bone deformities. Likewise, muscle tissue is low in calcium, so with a pure meat diet the cat may need a calcium supplement to keep her bones strong.

Calcium can be obtained elsewhere - for example eggshell powder (from fine-ground eggshells) is an excellent source of calcium. Before you decide to boost calcium levels with a saucer of milk, check whether your cat is lactose-intolerant. (See below)Most cats love fish, and fish is an excellent source of proteins and other nutrients, but again don't give too much of a good thing.

The high levels of polyunsaturated fatty acids in a heavy tuna diet will deplete a cat's supply of vitamin E. Inadequate vitamin E leads to 'Brown Bowel Syndrome' - the main symptoms of which are ulceration, hemorrhage and degeneration of the bowels. Also, because Vitamin E is involved in the metabolism of fats, an acute deficiency of Vitamin E may cause 'Yellow Fat Disease'; inflamed fatty tissue caused because the cat’s body can’t process fat adequately.

This disease is only really a concern with cats which are on an exclusive fish diet. But also remember that other kinds of fish (e.g. trout) are very low in fats and lack essential nutrients. Mix and match, and remember animal fat and liver are good sources of Vitamin E.

Although a lot of nutrients are lost through cooking, cooked fish is safer. Raw fish contains an enzyme called thiaminase which destroys thiamin (Vitamin B1) . Vitamin B1 converts glucose to energy and therefore is important for muscle and nerve cell function. Also remember that large carnivorous fish such as swordfish, shark and some types of tuna can absorb a lot of mercury, thanks to human pollution of their habitat.

Mercury is not just bad for cats, but every living species. Note that smaller species of fish such as trout, cod or halibut have negligible amounts of mercury. And again - always watch out for bones!

Eggs are great for cats. They are rich in proteins and many books which promote 'natural' cat diets recommend them. In nature, cats will from time to time raid the nests of birds and eat raw eggs. In the home however, raw chicken eggs always carry the risk of salmonella, so hard-boiled or scrambled eggs are the safer snack. Not every cat likes egg, but if yours does, this is generally a healthy choice.

Many cats love dairy products such as cheese, cream or butter, and if your cat tolerates dairy products well, there is no harm of giving her some as a snack.But keep in mind that many mature cats are lactose intolerant (see: Milk and cats - lactose intolerance).

If you are not sure how well your cat will react to dairy food, start with small amounts and check for any signs of stomach upset, cramps or diarrhea. Also don’t let diary consumption interfere with the cat's 'regular' diet.

Although vegetables are not harmful, cats get most of their energy from proteins rather than carbohydrates. So vegetables mostly provide bulk rather than being nutritionally indispensable. But some vegetables such as steamed asparagus or broccoli, green beans and chopped greens can be a good source of fiber. So, unless it is in the 'no-no' category listed above, sharing the odd mouthful of your food with your cat should not be a problem - nutritionally at least

But remember that cat-food manufacturers take care to add all the necessary nutrients in the right quantities. If you are going to feed your cat a 'home-cooked' diet of human food, it's up to you to do the same.

The information supplied here is intended as a guideline only.