Watch Out For These 6 Nutrients in Cat Food

PetMD Editorial
Updated: October 16, 2020
Published: December 23, 2014
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Sometimes, Good Ingredients Can Be Harmful Too

“All animals need water, energy — from protein, fat, or carbohydrates — essential fatty acids, vitamins, and minerals,” says Tony Buffington, DVM, PhD, and Professor of Veterinary Clinical Sciences at The Ohio State University Veterinary Medical Center. These dietary nutrients provide our pets the nourishment essential for their growth and wellbeing. There are, however, some essential nutrients that can actually do more harm than good for dogs if fed in excess amounts. Pay extra attention to these nutrients in your cat's food.

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1. Protein

Being carnivores, cats require a higher level of protein than dogs, especially when it comes to animal-based protein. However, cats with renal disease benefit from a diet that contains an easily digestible protein source rather than one that contains excess levels of poor quality protein. Poor quality protein not only causes issues formetabolism and digestibility, it can lead to weight loss, nausea, vomiting, and diarrhea.

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2. Magnesium

Magnesium, though a necessary nutrient, is certainly a nutrient that can cause illness, sometimes severe and life-threatening. When fed in excess amounts, magnesium can have a negative impact on both the nervous system and heart, causing symptoms such as weakness, paralysis, cardiac arrest, respiratory depression, coma, and even death. Magnesium can also contribute to formation of bladder stones. While the problem is more commonly seen in dogs, both dogs and cats can suffer these effects.

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3. Sodium

Sodium is crucial for cats in a numbers of ways — it helps regulate blood pressure, aids in the transmission of nerve impulses, and is partially responsible for maintaining the balance between acids and bases in the body. Despite this, excessive sodium found in a cat's diet can negatively impact the heart, kidneys, and nervous system. In fact, cats with heart and kidney disease should have their sodium intake strictly monitored, as excess levels can cause progression of these diseases.

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4. Vitamin D

Feeding abnormally high levels of vitamin D can result in increased calcium levels, causing a number of adverse symptoms in cats involving the kidneys, gastrointestinaltract, nervous system, and cardiovascular system.

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5 & 6. Calcium and Phosphorus

Calcium and phosphorus are other nutrients that can have a deleterious effect if fed in excess to cats. Of particular importance is the ratio of calcium to phosphorus in the cat food. An abnormally high level of either nutrient may alter the proper ratio and have a negative effect on bones.


Additionally, calcium and phosphorus intake is an important consideration for cats with illnesses like kidney disease. Cats with such illnesses will have different requirements depending on the stage of disease and the individual animal. An excess of either calcium or phosphorus can lead to a progression of kidney disease as well as contribute to the formation of bladder stones.

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